Search

Background: Increasing age increases the incidence of chronic constipation and fecal impaction. The contribution of the natural aging process to this phenotype is unclear. This study explored the effects of age on key motility patterns in the murine colon and determined the contribution that altered neurokinin 2 (NK2) ‐mediated signaling made to the aging phenotype. Methods: Mucosal reflexes, colonic migrating motor complexes (CMMCs) and colonic motility assays were explored in isolated ex vivo colons from 3, 12–14, 18‐ and 24‐months old mice and the NK2‐mediated response determined. Electrical field stimulation (EFS) or exogenous drug application were used to explore the role of the mucosa in colonic segments. Key Results: Aging reduced the force of contraction of the distal colon mucosal reflex, the frequency and force of contraction of CMMCs and the NK2‐mediated component of both motility patterns. Ondansetron, a 5‐HT3 receptor antagonist, blocked a component of both motility patterns in full thickness but not in mucosa‐free segments of the distal colon. 5, hydroxytryptamine (5‐HT) and EFS‐evoked NK2‐dependent contractions were reduced with increasing age. Smooth muscle sensitivity to 5‐HT or neurokinin A (NKA) was not altered with age. In isolated colon motility assays application of NKA decreased transit time in 24‐months colon and the NK2 antagonist GR159897 increased transit times in both 3‐ and 24‐months old colons. Conclusions and Inferences: Aging impairs key motility patterns in the murine colon. These changes involve a decrease in mucosally‐evoked NK2‐mediated signaling. Targeting NK2‐mediated signaling may provide a novel approach to treating age‐related motility disorders in the lower bowel. [ABSTRACT FROM AUTHOR]

Background. Basal cell carcinoma is the most widespread malignant skin neoplasm. Angiogenesis is critical for the growth and metastasis of malignant tumors. Aims. To study the levels of representation of transcripts in the foci of basal cell skin cancer before and after the therapy of genes for angiogenesis proteins and their receptors: angiopoietin 2 ANGPT2, calcitonin-related polypeptide alpha CALCA, epidermal growth factor receptor EGRF, fibroblast growth factor FGF2, intracellular adhesion molecule ICAM1, vascular endothelial growth factor VEGFA and its type 2 receptor VEGFR2, matrix metalloproteinase MMP9, homologue protein of phosphatase and tensin PTEN, tachykinin receptor TAC1, and tumor necrosis factor protein genes TNF. Methods. The study included 31 patients with histologically confirmed basal cell skin cancer who received treatment at the consultative and diagnostic center of the State Research Center of Dermatovenereology and Cosmetology of Russian Ministry of Health, Moscow in the period from 2020 to 2021, using a pulsed dye laser (wavelength — 585 nm) and long-pulsed neodymium laser (wavelength — 1064 nm). The patients provided skin punch biopsies from BCC lesions and after therapy from the same localization. The gene expression was analyzed with real-time reverse transcription PCR using endogeneous control, and the gene expression ration changes during the therapy were calculated according to Livak’s double delta formulae. Results. An increased expression of the matrix metalloproteinase MMP9 and the tachykinin precursor TAC1 genes were revealed in skin biopsy samples of the superficial form of basal cell skin cancer during laser pulsed therapy. The expression of tumor necrosis factor TNF, epidermal growth factor receptor EGFR, fibroblast growth factor FGF2 genes increases to a lesser extent. The increasing expression of MMP9 and TAC1 genes also established in skin biopsy samples of the nodular form of basal cell skin cancer. It was shown that the expression of the calcitonin-related polypeptide alpha CALCA gene in the skin of patients is at basal level, which makes it possible to exclude the influence of the neuropeptide on the basal cell skin cancer pathogenesis. Despite the bidirectional changes in expression due to individuality of patients, the average values allow to conclude the expression of all the studied genes is increased after pulse laser destruction therapy. This means neoangiogenesis is continued at the skin even after the destruction of basal cell skin cancer lesions. This could be due to the presence of the basal cell carcinoma microenvironment, likely mast cells, at the affected skin area. Conclusions. Among the factors of neoangiogenesis potentially influencing the development of basal cell skin cancer, the leading role of expression of the MMP9 matrix metalloproteinase and TAC1 precursor protein of tachykinin has been shown. Simultaneous changes in the level of these proteins may be due to neuroimmune interactions in the epidermis, which is probably realized by mast cells as the microenvironment of the basal cell carcinoma. In the process of laser destruction, there is also a slightly pronounced increased expression of additional factors of neoangiogenesis.

Social enrichment or social isolation affects a range of innate behaviors, such as sex, aggression, and sleep, but whether there is a shared mechanism is not clear. Here, we report a neural mechanism underlying social modulation of spontaneous locomotor activity (SoMo-SLA), an internal-driven behavior indicative of internal states. We find that social enrichment specifically reduces spontaneous locomotor activity in male flies. We identify neuropeptides Diuretic hormone 44 (DH44) and Tachykinin (TK) to be up- and down-regulated by social enrichment and necessary for SoMo-SLA. We further demonstrate a sexually dimorphic neural circuit, in which the male-specific P1 neurons encoding internal states form positive feedback with interneurons coexpressing doublesex (dsx) and Tk to promote locomotion, while P1 neurons also form negative feedback with interneurons coexpressing dsx and DH44 to inhibit locomotion. These two opposing neuromodulatory recurrent circuits represent a potentially common mechanism that underlies the social regulation of multiple innate behaviors. [ABSTRACT FROM AUTHOR]

In recent years, numerous approaches have been developed to comprehend the molecular alterations underlying thyroid cancer (TC) oncogenesis and explore novel therapeutic strategies for TC. It is now well established that the neurokinin-1 receptor (NK-1R) is overexpressed in cancer cells and that NK-1R is essential for the viability of cancer cells. The binding of substance P (SP) to NK-1R in neoplastic cells plays a pivotal role in cancer progression by promoting neoplastic cell growth, protecting tumor cells from apoptosis, triggering invasion and metastasis through the enhanced migration of cancer cells, and stimulating endothelial cell proliferation for tumor angiogenesis. Remarkably, all types of human TC (papillary, follicular, medullary, anaplastic), as well as metastatic lesions, exhibit the overexpression of SP and NK-1R compared to the normal thyroid gland. TC cells synthesize and release SP, which exerts its multiple functions through autocrine, paracrine, intracrine, and neuroendocrine processes, including the regulation of tumor burden. Consequently, the secretion of SP from TC results in increased SP levels in plasma, which are significantly higher in TC patients compared to controls. Additionally, NK-1R antagonists have demonstrated a dose-dependent antitumor action. They impair cancer cell proliferation on one side and induce apoptosis of tumor cells on the other side. Furthermore, it has been demonstrated that NK-1R antagonists inhibit neoplastic cell migration, thereby impairing both invasiveness and metastatic abilities, as well as angiogenesis. Given the consistent overexpression of NK-1R in all types of TC, targeting this receptor represents a promising therapeutic approach for TC. Therefore, NK-1R antagonists, such as the drug aprepitant, may represent novel drugs for TC treatment. [ABSTRACT FROM AUTHOR]

Neuropeptides influence animal behaviors through complex molecular and cellular mechanisms, the physiological and behavioral effects of which are difficult to predict solely from synaptic connectivity. Many neuropeptides can activate multiple receptors, whose ligand affinity and downstream signaling cascades are often different from one another. Although we know that the diverse pharmacological characteristics of neuropeptide receptors form the basis of unique neuromodulatory effects on distinct downstream cells, it remains unclear exactly how different receptors shape the downstream activity patterns triggered by a single neuronal neuropeptide source. Here, we uncovered two separate downstream targets that are differentially modulated by tachykinin, an aggression-promoting neuropeptide in Drosophila. Tachykinin from a single male-specific neuronal type recruits two separate downstream groups of neurons. One downstream group, synaptically connected to the tachykinergic neurons, expresses the receptor TkR86C and is necessary for aggression. Here, tachykinin supports cholinergic excitatory synaptic transmission between the tachykinergic and TkR86C downstream neurons. The other downstream group expresses the TkR99D receptor and is recruited primarily when tachykinin is overexpressed in the source neurons. Differential activity patterns in the two groups of downstream neurons correlate with levels of male aggression triggered by the tachykininergic neurons. These findings highlight how the amount of neuropeptide released from a small number of neurons can reshape the activity patterns of multiple downstream neuronal populations. Our results lay the foundation for further investigations into the neurophysiological mechanism by which a neuropeptide controls complex behaviors. [ABSTRACT FROM AUTHOR]

Diabetes is a significant public health issue known as the world's fastest‐growing disease condition. It is characterized by persistent hyperglycemia and subsequent chronic complications leading to organ dysfunction and, ultimately, the failure of target organs. Substance P (SP) is an undecapeptide that belongs to the family of tachykinin (TK) peptides. The SP‐mediated activation of the neurokinin 1 receptor (NK1R) regulates many pathophysiological processes in the body. There is also a relation between the SP/NK1R system and diabetic processes. Importantly, deregulated expression of SP has been reported in diabetes and diabetes‐associated chronic complications. SP can induce both diabetogenic and antidiabetogenic effects and thus affect the pathology of diabetes destructively or protectively. Here, we review the current knowledge of the functional relevance of the SP/NK1R system in diabetes pathogenesis and its exploitation for diabetes therapy. A comprehensive understanding of the role of the SP/NK1R system in diabetes is expected to shed further light on developing new therapeutic possibilities for diabetes and its associated chronic conditions. [ABSTRACT FROM AUTHOR]

Neurokinin B is a tachykinin peptide involved in a diverse range of neuronal functions. It rapidly forms an amyloid, which is considered physiologically important for efficient packing into dense core secretory vesicles within hypothalamic neurons. Disassembly of the amyloid is thought to require the presence of copper ions, which interact with histidine at the third position in the peptide sequence. However, it is unclear how the histidine is involved in the amyloid structure and why copper coordination can trigger disassembly. In this work, we demonstrate that histidine contributes to the amyloid structure via π-stacking interactions with nearby phenylalanine residues. The ability of neurokinin B to form an amyloid is dependent on any aromatic residue at the third position in the sequence; however, only the presence of histidine leads to both amyloid formation and rapid copper-induced disassembly. [ABSTRACT FROM AUTHOR]

Tachykinin (TK) families, including the first neuropeptide substance P, have been intensively explored in bilaterians. Knowledge of signaling of TK receptors (TKRs) has enabled the comprehension of diverse physiological processes. However, TK signaling systems are largely unknown in Lophotrochozoa. This study identified two TK precursors and two TKR isoforms in the Pacific abalone Haliotis discus hannai (Hdh), and characterized Hdh-TK signaling. Hdh-TK peptides harbored protostomian TK-specific FXGXRamide or unique YXGXRamide motifs at the C-termini. A phylogenetic analysis showed that lophotrochozoan TKRs, including Hdh-TKRs, form a monophyletic group distinct from arthropod TKRs and natalisin receptor groups. Although reporter assays demonstrated that all examined Hdh-TK peptides activate intracellular cAMP accumulation and Ca2+ mobilization in Hdh-TKRexpressing mammalian cells, Hdh-TK peptides with N-terminal aromatic residues and C-terminal FXGXRamide motifs were more active than shorter or less aromatic Hdh-TK peptides with a C-terminal YXGXRamide. In addition, we showed that ligand-stimulated Hdh-TKRs mediate ERK1/2 phosphorylation in HEK293 cells and that ERK1/2 phosphorylation is inhibited by PKA and PKC inhibitors. In three-dimensional in silico Hdh-TKR binding modeling, higher docking scores of Hdh-TK peptides were consistent with the lower EC50 values in the reporter assays. The transcripts for Hdh-TK precursors and Hdh- TKR were highly expressed in the neural ganglia, with lower expression levels in peripheral tissues. When abalone were starved for 3 weeks, Hdh-TK1 transcript levels, but not Hdh-TK2, were increased in the cerebral ganglia (CG), intestine, and hepatopancreas, contrasting with the decreased lipid content and transcript levels of sterol regulatory element-binding protein (SREBP). At 24 h post-injection in vivo, the lower dose of Hdh-TK1 mixture increased SREBP transcript levels in the CG and hepatopancreas and accumulative food consumption of abalone. Higher doses of Hdh-TK1 and Hdh-TK2 mixtures decreased the SREBP levels in the CG. When Hdh-TK2-specific siRNA was injected into abalone, intestinal SREBP levels were significantly increased, whereas administration of both Hdh-TK1 and Hdh-TK2 siRNA led to decreased SREBP expression in the CG. Collectively, our results demonstrate the first TK signaling system in gastropod mollusks and suggest a possible role for TK peptides in regulating lipid metabolism in the neural and peripheral tissues of abalone. [ABSTRACT FROM AUTHOR]

Background: Papillary thyroid carcinoma (PTC) is the most prevalent malignancy of the endocrine system. This study was aimed at evaluating the serum substance P (SP) levels, the tissue distribution of Neurokinin-1 receptors (NK1-R), and their possible diagnostic value in PTC. Method: The present case-control study included 31 healthy volunteers and 31 cases (age range: 25-64, 40.26 ±12.77), who were primarily diagnosed with PTC and were candidates for total thyroidectomy. Pre-operative serum level of SP was measured using a commercial ELISA kit. The tissue distribution of NK1-R was assessed immunohistochemically. Results: The serum level of SP in the patient group was higher than the healthy volunteers (P = 0.005). Besides, the expression of NK1-R was higher in tumoral tissues compared with their normal surroundings (P = 0.005). However, we observed no significant correlation between either SP level or NK1-R expression and the disease stage or lymph node involvement. Conclusion: SP level and NK1-R expression were upregulated in PTC patients, showing the involvement of SP/NK1R complex in PTC pathophysiology. Nonetheless, proposing SP/NK1R as a diagnostic factor requires further studies because we found no correlation between SP/NK1R and clinical stage or lymph node involvement.

Simple Summary: Improving the response, quality of life and survival of oncologic patients through the design and application of the most appropriate treatment for each case is a great scientific challenge. Given the role of the axis formed by Substance P (SP) and its preferred receptor neurokinin-1 receptor (NK-1R) in cancer progression and resistance to oncologic treatments, in this review, we evaluate if the repurposing of aprepitant, which is a safe, efficient and marketed NK-1R antagonist, may be of help to overcome resistance to anticancer treatments. Nowadays, the identification of new therapeutic targets that allow for the development of treatments, which as monotherapy, or in combination with other existing treatments can contribute to improve response rates, prognosis and survival of oncologic patients, is a priority to optimize healthcare within sustainable health systems. Recent studies have demonstrated the role of Substance P (SP) and its preferred receptor, Neurokinin 1 Receptor (NK-1R), in human cancer and the potential antitumor activity of NK-1R antagonists as an anticancer treatment. In this review, we outline the relevant studies published to date regarding the SP/NK-1R complex as a key player in human cancer and also evaluate if the repurposing of already marketed NK-1R antagonists may be useful in the development of new treatment strategies to overcome cancer resistance. [ABSTRACT FROM AUTHOR]

Bacterial infections are increasing in recent years and developing with more resistance to antibiotics. There is a need of designing antimicrobial peptides (AMP) against these bacterial pathogens. In this study, we derived an AMP, substance P (SP) named RM12, from tachykinin protein obtained from an earlier developed transcriptome library of a teleost, Channa striatus. This, RM12 which is similar to SP was functional against multidrug resistance bacteria (MDR) or one of the ESKAPE pathogen, Pseudomonas aeruginosa ATCC 25668 which causes nosocomial infections in human beings. The RM12 peptide sequence obtained from tachykinin protein was screened using antimicrobial prediction programs, which showed the possible antimicrobial performance of RM12, thus the peptide was synthesized with 96.83% HPLC purity. The toxicity of RM12 was analyzed using human blood cells and human dermal fibroblast (HDF) cells that showed the safeties of RM12 usage. The antibacterial activities of RM12 including antibiofilm were determined using different assays and exhibited the peptide potent against the MDR or ESKAPE pathogen, P. aeruginosa ATCC 25668. Moreover, the mechanism of action of RM12 against P. aeruginosa ATCC 25668 was determined using field emission scanning electron microscopy and fluorescence assisted cell sorter flow cytometer analysis; both the analysis confirmed bacterial membrane disruption due to RM12. Further, in vitro infectivity assays were performed in HDF cells infected with P. aeruginosa ATCC 25668 that showed the longer duration, as well as the higher concentration of RM12, reduced the bacterial viability. Hence, it can be concluded that RM12 can be used as a potent antimicrobial source against the MDR or ESKAPE pathogen, P. aeruginosa ATCC 25668; however, further clinical trials need to be carried out to find out the possibility of RM12 usage in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Diversity, a hallmark of G protein-coupled receptor (GPCR) signaling, partly stems from alternative splicing of a single gene generating more than one isoform for a receptor. Additionally, receptor responses to ligands can be attenuated by desensitization upon prolonged or repeated ligand exposure. Both phenomena have been demonstrated and exemplified by the deuterostome tachykinin signaling system, although the role of phosphorylation in desensitization remains a subject of debate. Here, we describe the signaling system for tachykinin-related peptides (TKRPs) in a protostome, mollusk Aplysia. We cloned the Aplysia TKRP precursor, which encodes three TKRPs (apTKRP-1, apTKRP-2a, and apTKRP-2b) containing the FXGXR-amide motif. In situ hybridization and immunohistochemistry showed predominant expression of TKRP mRNA and peptide in the cerebral ganglia. TKRPs and their posttranslational modifications were observed in extracts of central nervous system ganglia using mass spectrometry. We identified two Aplysia TKRP receptors (apTKRPRs), named apTKRPR-A and apTKRPR-B. These receptors are two isoforms generated through alternative splicing of the same gene and differ only in their intracellular C termini. Structure-activity relationship analysis of apTKRP-2b revealed that both C-terminal amidation and conserved residues of the ligand are critical for receptor activation. C-terminal truncates and mutants of apTKRPRs suggested that there is a C-terminal phosphorylation-independent desensitization for both receptors. Moreover, apTKRPR-B also exhibits phosphorylation-dependent desensitization through the phosphorylation of C-terminal Ser/Thr residues. This comprehensive characterization of the Aplysia TKRP signaling system underscores the evolutionary conservation of the TKRP and TK signaling systems, while highlighting the intricacies of receptor regulation through alternative splicing and differential desensitization mechanisms., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Papillary thyroid carcinoma (PTC) is the most prevalent malignancy of the endocrine system. This study was aimed at evaluating the serum substance P (SP) levels, the tissue distribution of Neurokinin-1 receptors (NK1-R), and their possible diagnostic value in PTC. Method: The present case-control study included 31 healthy volunteers and 31 cases (age range: 25-64, 40.26 ±12.77), who were primarily diagnosed with PTC and were candidates for total thyroidectomy. Pre-operative serum level of SP was measured using a commercial ELISA kit. The tissue distribution of NK1-R was assessed immunohistochemically. Results: The serum level of SP in the patient group was higher than the healthy volunteers (P = 0.005). Besides, the expression of NK1-R was higher in tumoral tissues compared with their normal surroundings (P = 0.005). However, we observed no significant correlation between either SP level or NK1-R expression and the disease stage or lymph node involvement. Conclusion: SP level and NK1-R expression were upregulated in PTC patients, showing the involvement of SP/NK1R complex in PTC pathophysiology. Nonetheless, proposing SP/NK1R as a diagnostic factor requires further studies because we found no correlation between SP/NK1R and clinical stage or lymph node involvement. [ABSTRACT FROM AUTHOR]

Neurokinin B is a tachykinin peptide involved in a diverse range of neuronal functions. It rapidly forms an amyloid, which is considered physiologically important for efficient packing into dense core secretory vesicles within hypothalamic neurons. Disassembly of the amyloid is thought to require the presence of copper ions, which interact with histidine at the third position in the peptide sequence. However, it is unclear how the histidine is involved in the amyloid structure and why copper coordination can trigger disassembly. In this work, we demonstrate that histidine contributes to the amyloid structure via π-stacking interactions with nearby phenylalanine residues. The ability of neurokinin B to form an amyloid is dependent on any aromatic residue at the third position in the sequence; however, only the presence of histidine leads to both amyloid formation and rapid copper-induced disassembly.

Age‐related behavioral plasticity is a major prerequisite for the ecological success of insect societies. Although ecological aspects of behavioral flexibility have been targeted in many studies, the underlying intrinsic mechanisms controlling the diverse changes in behavior along the individual life history of social insects are not completely understood. Recently, the neuropeptides allatostatin‐A, corazonin, and tachykinin have been associated with the regulation of behavioral transitions in social insects. Here, we investigated changes in brain localization and expression of these neuropeptides following major behavioral transitions in Cataglyphis nodus ants. Our immunohistochemical analyses in the brain revealed that the overall branching pattern of neurons immunoreactive (ir) for the three neuropeptides is largely independent of the behavioral stages. Numerous allatostatin‐A‐ and tachykinin‐ir neurons innervate primary sensory neuropils and high‐order integration centers of the brain. In contrast, the number of corazonergic neurons is restricted to only four neurons per brain hemisphere with cell bodies located in the pars lateralis and axons extending to the medial protocerebrum and the retrocerebral complex. Most interestingly, the cell‐body volumes of these neurons are significantly increased in foragers compared to freshly eclosed ants and interior workers. Quantification of mRNA expression levels revealed a stage‐related change in the expression of allatostatin‐A and corazonin mRNA in the brain. Given the presence of the neuropeptides in major control centers of the brain and the neurohemal organs, these mRNA‐changes strongly suggest an important modulatory role of both neuropeptides in the behavioral maturation of Cataglyphis ants. [ABSTRACT FROM AUTHOR]

In this study, substance P, an antioxidant peptide of tachykinin, was identified using bioinformatics tools from the earlier established muscle transcriptome of a freshwater murrel Channa striatus and the peptide was named RM12. The antioxidant properties of RM12 were screened using various colorimetric assays. The toxicity of RM12 was experimented using fish erythrocytes, and it is observed that the maximum concentration (320 μM) of RM12 was found to have 15 or 20% of hemolytic activity; however, it was not significant with other tested concentrations (10, 20, 40, 80, and 160 μM). Further, the in vivo antioxidant properties of RM12 were experimented on zebrafish embryo, the intracellular ROS level was estimated by 5 mM H2O2 stress in the zebrafish embryo, and inhibition of apoptosis was evaluated. The antioxidant enzymes were extracted from the H2O2-stressed zebrafish embryo, and the intracellular ROS was eliminated due to RM12. Collectively, the experiment showed that the substance P from the freshwater murrel C. striatus possessed potent antioxidant properties; thus, it can further be focused to develop it as antioxidant molecule in aquaculture organisms. [ABSTRACT FROM AUTHOR]

Tachykinin-like peptides, such as substance P, neurokinin A, and neurokinin B, are among the earliest discovered and best-studied neuropeptide families, and research on them has contributed greatly to our understanding of the endocrine control of many physiological processes. However, there are still many orphan tachykinin receptor homologs for which cognate ligands have not yet been identified, especially in small invertebrates, such as the nematode Caenorhabditis elegans (C. elegans). We here show that the C. elegans nlp-58 gene encodes putative ligands for the orphan G protein-coupled receptor (GPCR) TKR-1, which is a worm ortholog of tachykinin receptors. We first determine, through an unbiased biochemical screen, that a peptide derived from the NLP-58 preprotein stimulates TKR-1. Three mature peptides that are predicted to be generated from NLP-58 show potent agonist activity against TKR-1. We designate these peptides as C. elegans tachykinin (CeTK)-1, −2, and −3. The CeTK peptides contain the C-terminal sequence GLR-amide, which is shared by tachykinin-like peptides in other invertebrate species. nlp-58 exhibits a strongly restricted expression pattern in several neurons, implying that CeTKs behave as neuropeptides. The discovery of CeTKs provides important information to aid our understanding of tachykinin-like peptides and their functional interaction with GPCRs. • A biochemical screen for C. elegans tachykinin revealed a peptide derived from nlp-58. • nlp-58 encodes three tachykinin-like peptides, CeTK-1, -2, and -3. • CeTKs act as potent ligands for the orphan tachykinin-like receptor TKR-1. • C-terminal GLR-amide is conserved among CeTKs and other invertebrate tachykinins. • CeTKs are expressed specifically in several neurons, such as nociceptive neurons. [ABSTRACT FROM AUTHOR]

Neurokinin B (NKB) is a tachykinin peptide that has diverse roles in biology, including in human reproductive development. Cellular processing of this peptide is thought to involve formation of a dense core vesicle during transit through the regulated secretory pathway. The ability of NKB to rapidly form an amyloid can contribute to formation of the secretory granule but features that support amyloid formation of NKB are not well understood. NKB contains a diphenylalanine sequence well recognised as an important motif for self-assembly of other peptides including amyloid β. Using mutations of the diphenylalanine motif we show that this motif in NKB is necessary for amyloid formation, and it is the unique combination of aromaticity and hydrophobicity of phenylalanine that is crucial for aggregation. Using disulfide cross-linking we propose that phenylalanine at sequence position 6 is important for stabilising inter-sheet interactions in the NKB amyloid fibril. Although having a highly conserved sequence, the NKB peptide from zebrafish only contains a single phenylalanine and does not fibrillise as extensively as mammalian NKB. Analysis of self-assembly of NKB-like peptides from different species may help in elucidating their biological roles. Taken together, this work shows that mammalian NKB has evolved, within only 10 residues, a sequence optimised for rapid self-assembly, whilst also containing residues for metal-binding, receptor binding and receptor discrimination. [Display omitted] • Mutation of the diphenylalanine motif in neurokinin B disrupts amyloid formation. • Fibrillogenesis needs hydrophobic and π-π interactions at peptide positions 5 and 6. • Intermolecular disulfide crosslinking supports fibril formation. [ABSTRACT FROM AUTHOR]

To meet the high energy demands of brain function, cerebral blood flow (CBF) parallels changes in neuronal activity by a mechanism known as neurovascular coupling (NVC). However, which neurons play a role in mediating NVC is not well understood. Here, we identify in mice and humans a specific population of cortical GABAergic neurons that co-express neuronal nitric oxide synthase and tachykinin receptor 1 (Tacr1). Through whole-tissue clearing, we demonstrate that Tacr1 neurons extend local and long-range projections across functionally connected cortical areas. We show that whisker stimulation elicited Tacr1 neuron activity in the barrel cortex through feedforward excitatory pathways. Additionally, through optogenetic experiments, we demonstrate that Tacr1 neurons are instrumental in mediating CBF through the relaxation of mural cells in a similar fashion to whisker stimulation. Finally, by electron microscopy, we observe that Tacr1 processes contact astrocytic endfeet. These findings suggest that Tacr1 neurons integrate cortical activity to mediate NVC. [Display omitted] • Tacr1 neurons are long-range-projecting somatostatin neurons that co-express Nos1 and NPY • Tacr1 neurons receive input from excitatory neurons and respond to sensory stimulation • Tacr1 neurons are strong regulators of cerebral blood flow • Tacr1 neurons regulate vasodilation via pericyte and vascular smooth muscle relaxation Ruff et al. identify a subpopulation of inhibitory neurons, Tacr1 neurons, that regulate cerebral blood flow. Tacr1 neurons are long-range-projecting neurons that use feedforward excitatory pathways to mediate neurovascular coupling. [ABSTRACT FROM AUTHOR]

The tachykinins, exemplified by substance P, are one of the most intensively studied neuropeptide families. They comprise a series of structurally related peptides that derive from alternate processing of three Tac genes and are expressed throughout the nervous and immune systems. Tachykinins interact with three neurokinin G protein-coupled receptors. The signaling, trafficking, and regulation of neurokinin receptors have also been topics of intense study. Tachykinins participate in important physiological processes in the nervous, immune, gastrointestinal, respiratory, urogenital, and dermal systems, including inflammation, nociception, smooth muscle contractility, epithelial secretion, and proliferation. They contribute to multiple diseases processes, including acute and chronic inflammation and pain, fibrosis, affective and addictive disorders, functional disorders of the intestine and urinary bladder, infection, and cancer. Neurokinin receptor antagonists are selective, potent, and show efficacy in models of disease. In clinical trials there is a singular success: neurokinin 1 receptor antagonists to treat nausea and vomiting. New information about the involvement of tachykinins in infection, fibrosis, and pruritus justifies further trials. A deeper understanding of disease mechanisms is required for the development of more predictive experimental models, and for the design and interpretation of clinical trials. Knowledge of neurokinin receptor structure, and the development of targeting strategies to disrupt disease-relevant subcellular signaling of neurokinin receptors, may refine the next generation of neurokinin receptor antagonists.

The tachykinin hemokinin-1 (HK-1) is involved in immune cell development and inflammation, but little is known about its function in pain. It acts through the NK1 tachykinin receptor, but several effects are mediated by a yet unidentified target. Therefore, we investigated the role and mechanism of action of HK-1 in arthritis models of distinct mechanisms with special emphasis on pain. Arthritis was induced by i.p. K/BxN serum (passive transfer of inflammatory cytokines, autoantibodies), intra-articular mast cell tryptase or Complete Freund’s Adjuvant (CFA, active immunization) in wild type, HK-1- and NK1-deficient mice. Mechanical- and heat hyperalgesia determined by dynamic plantar esthesiometry and increasing temperature hot plate, respectively, swelling measured by plethysmometry or micrometry were significantly reduced in HK-1-deleted, but not NK1-deficient mice in all models. K/BxN serum-induced histopathological changes (day 14) were also decreased, but early myeloperoxidase activity detected by luminescent in vivo imaging increased in HK-1-deleted mice similarly to the CFA model. However, vasodilation and plasma protein extravasation determined by laser Speckle and fluorescent imaging, respectively, were not altered by HK-1 deficiency in any models. HK-1 induced Ca2+-influx in primary sensory neurons, which was also seen in NK1-deficient cells and after pertussis toxin-pretreatment, but not in extracellular Ca2+-free medium. These are the first results showing that HK-1 mediates arthritic pain and cellular, but not vascular inflammatory mechanisms, independently of NK1 activation. HK-1 activates primary sensory neurons presumably via Ca2+ channel-linked receptor. Identifying its target opens new directions to understand joint pain leading to novel therapeutic opportunities.

• Substance P suppressed EPSCs recorded from pyramidal cells via NK1 receptors. • Substance P increased the paired-pulse ratio and failure rate. • Substance P synthesized NO principally in a subset of GABAergic neurons. • Substance P-induced EPSC suppression was blocked by an NOS inhibitor/NO scavenger. • NO synthesized by substance P may reduce release probability of glutamate. Substance P (SP) regulates inhibitory synaptic transmission mediated by GABA A receptors in the cerebral cortex; however, SP-mediated regulation of excitatory synaptic transmission remains poorly understood. We performed whole-cell patch-clamp recordings from pyramidal neurons to examine the effects of SP on excitatory postsynaptic currents (EPSCs) mediated via AMPA receptors in the insular cortex (IC), which is involved in nociceptive information processing. First, EPSCs evoked by minimal electrical stimulation (eEPSCs) including stepwise EPSCs and failure events, were examined. SP dose-dependently suppressed mean eEPSC amplitude, partially due to an increase in the failure rate of eEPSCs. The SP-induced suppression of eEPSCs was accompanied by an increase in the paired-pulse ratio and was inhibited by the preapplication of SR140333, an NK1 receptor antagonist. [Sar9,Met(O 2)11]-substance P, an NK1 receptor-selective agonist, mimicked the effects of SP on eEPSCs and decreased the frequency of miniature EPSCs (mEPSCs) without changing the average mEPSC amplitude. Considering that most NK1 receptors in the cerebral cortex are expressed in nitric oxide synthase (NOS)-positive GABAergic neurons, the SP-induced suppressive effect on EPSCs may be mediated by nitric oxide (NO) in this subtype of GABAergic neurons. NO imaging using the fluorescent probe DAX-J2 Red supports this hypothesis: SP increased the fluorescence intensity of DAX-J2 Red in some GABAergic neurons. Furthermore, both L-NAME, an NOS inhibitor, and PTIO, an NO scavenger, diminished the SP-induced suppression of eEPSCs. These results suggest that the activation of presynaptic NK1 receptors contributes to SP-induced eEPSC suppression by activating the NO synthesis pathway in GABAergic neurons. (246 words) [ABSTRACT FROM AUTHOR]

Post-traumatic stress disorder (PTSD) is characterized by hypervigilance, increased reactivity to unpredictable versus predictable threat signals, deficits in fear extinction, and an inability to discriminate between threat and safety. First-line pharmacotherapies for psychiatric disorders have limited therapeutic efficacy in PTSD. However, recent studies have advanced our understanding of the roles of several limbic neuropeptides in the regulation of defensive behaviors and in the neural processes that are disrupted in PTSD. For example, preclinical studies have shown that blockers of tachykinin pathways, such as the Tac2 pathway, attenuate fear memory consolidation in mice and thus might have unique potential as early post-trauma interventions to prevent PTSD development. Targeting this pathway might also be beneficial in regulating other symptoms of PTSD, including trauma-induced aggressive behavior. In addition, preclinical and clinical studies have shown the important role of angiotensin receptors in fear extinction and the promise of using angiotensin II receptor blockade to reduce PTSD symptom severity. Additional preclinical studies have demonstrated that the oxytocin receptors foster accurate fear discrimination by facilitating fear responses to predictable versus unpredictable threats. Complementary human imaging studies demonstrate unique neural targets of intranasal oxytocin and compare its efficacy with well-established anxiolytic treatments. Finally, promising data from human subjects have demonstrated that a selective vasopressin 1A receptor antagonist reduces anxiety induced by unpredictable threats. This review highlights these novel promising targets for the treatment of unique core elements of PTSD pathophysiology. [ABSTRACT FROM AUTHOR]

Introduction: Irritable bowel syndrome (IBS) has a significant impact on society and quality of life. Current treatments are ineffective, and new investigational drugs are necessary., Areas Covered: Numerous potential therapies are developing, targeting different areas such as cannabinoid signaling, opioid receptors, tachykinin (NK2) receptors, β3-adrenergic receptors, intestinal microbiota, inflammation, and 5HT receptors. Clinical trial evidence has shown that loperamide, eluxadoline, alosetron, ramosetron, bile acid sequestrants, and rifaximin can modulate GI alterations and benefit patients with IBS-D. Among the potential therapies, ibodutant, ibudilast, blautix, BOS-589, solabegron, vibegron, olorinab, ebastine, and ORP-101 have demonstrated possible effects but remain confirmed., Expert Opinion: Individuals with IBS-D require cost-effective treatment options that do not impede their productivity or that of their caregivers. This is necessary for consistent healthcare and improved quality of life. Therefore, we should focus on developing new, efficient, and affordable medications for IBS-D. The government, insurers, and society must recognize this need and collaborate to ensure its fulfillment.

To develop a new therapeutic strategy against thyroid cancer (TC), the expression of both substance P (SP) and neurokinin-1 receptor (NK-1R) must be demonstrated in TC cells. This study aims to examine by immunohistochemistry, the localization of SP and the NK-1R in human TC samples (papillary, follicular, medullary, anaplastic), in metastasis and in healthy thyroid samples. SP and the NK-1R were expressed in all normal and TC samples. In healthy glands, SP was located in follicular cells (nucleus) and colloid and NK-1R in follicular cells (cytoplasm) and stroma. In TC samples, SP was visualized in follicular cells (nucleus and cytoplasm), stroma and colloid and NK-1R in follicular cells (cytoplasm), stroma and colloid. A semiquantitative scoring system (Allred Unit Scoring System) was applied. The expression (Allred total score) of SP and NK-1R was weaker in normal thyroid glands than in TC. In comparison with TC samples, a lower intensity/proportion of SP (nucleus and cytoplasm of follicular cells; stroma) was observed in normal samples. By contrast, in the colloid of TC samples the presence of SP was lower than in normal samples. In comparison with TC samples, the presence of the NK-1R in the cytoplasm of follicular cells and colloid was lower in normal thyroid samples, whereas the expression of this receptor in the stroma was higher. The results reported in this study suggest that the NK-1R could be a new target for the treatment of TC and use of the NK-1R antagonists could serve as a new anti-TC therapeutic strategy.

To further to understand the structure and function of the TAC1 gene, we cloned the full-length cDNAs of the TAC1 genes from goat by rapid amplification of cDNA ends-PCR and the qRT-PCR was used to analyze the TAC1 mRNA expression patterns of goat various tissues. The full-length cDNA of goat TAC1 was 1176 bp, with a 339 bp open reading frame encoding 112 amino acids. The amino acid sequence analysis revealed that goat TAC1 gene encoded a water-drain protein and its relative molecular weight and isoelectric point was 13,012.86 Da and 6.29 respectively. Alignment and phylogenetic analyses revealed that their amino acid sequences were highly similar to those of other vertebrates. TAC1 expression of the goat of the brain, cerebellum, medulla oblongata, heart, liver, spleen, lung, kidney, uterus, ovaries. These results serve as a foundation for further study on the Capra hircus TAC1 gene. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is known as the most common form of malignancies in the world and its occurrence is annually increasing. Due to the relatively high death rates in patients, finding better diagnostic and prognostic factors are required. Substance P (SP) belongs to the tachykinin family that acts as an immunomodulator by binding to the neurokinin-1 receptor (NK1R). The interaction of SP with NK1R might be involved in tumor cell proliferation, angiogenesis, and migration. Hence, this study was aimed to evaluate the serum SP level and tissue distribution of NK1Rs in CRC. Also, we assessed the relationship between tissue distribution of NK1R and some different tumor characteristics, including tumor size, and lymph node status. Recruiting 38 patients primarily diagnosed with CRC, the tissue distribution of NK1R was immunohistochemically evaluated in tumor tissues and their adjacent normal tissue. The serum level of SP was measured using an ELISA method in both cases and healthy control group. The SP value was significantly increased in the serum of patients in comparison with the healthy group (p = 0.001). Tumor tissues expressed a higher number of NK1R than adjacent normal tissues (p = 0.01) considering both the percentage of stained cells and intensity of staining. However, there was not any statistically significant relevance between NK1R distribution and tumor characteristics. The SP/NK1R system is involved in tumorigenesis of CRC, and might be suggested as a potent prognostic or diagnostic factor, or a new target in the treatment of CRC. [ABSTRACT FROM AUTHOR]

Neurokinin B (NKB) is a key neuropeptide in reproductive endocrinology where it contributes to the generation of pulses of gonadotropin-releasing hormone. NKB is a copper-binding peptide; in the absence of metal NKB rapidly adopts an amyloid structure, but copper binding inhibits amyloid formation and generates a structure that can activate the neurokinin 3 receptor. The fate of copper once it binds NKB and activates the neurokinin 3 receptor is not understood, but endocytosis of NKB occurs even when the peptide is coordinated to copper. Using astrocytoma cells that express endogenous neurokinin 3 receptor, this work shows that endocytosis of apo- and copper-bound NKB occurs in concert with the receptor via a trafficking pathway that includes the early endosome. When cells are stimulated with copper-bound NKB the cellular copper concentration does not significantly increase, however when the cells are pre-treated with the recycling inhibitor, brefeldin A, they are capable of accumulating copper. This data shows that copper-bound NKB can activate the neurokinin 3 receptor then endocytosis abstracts metal, peptide and receptor from the cell surface. The cell does not accumulate the copper but instead it enters recycling pathways that ultimately leads to metal release from the cell. The work reveals a novel receptor-mediated copper trafficking pathway that retains metal in membrane bound organelles until it is exported from the cell. Image 1 • The copper-complex of neurokinin B is endocytosed with the neurokinin 3 receptor. • Endocytosis of copper-bound neurokinin B does not lead to cellular copper accumulation. • Lack of accumulation is due to export of metal via recycling pathways. [ABSTRACT FROM AUTHOR]

The P. pinaster species, known as 'Pino nigral or rodeno', is used in the treatment of colds, asthma, flu, and tuberculosis. This study determined the anti-inflammatory, analgesic, and antibacterial activities of the P. pinaster resin, identifying the compounds with higher biological activity. A bio-guided isolation of the compounds of P. pinaster was carried out by selecting the most active extracts with anti-inflammatory and analgesic effects in the HBEC3-KT, MRC-5, and THP-1 cell lines. The antibacterial activity was determined against the S. aureus , S. pneumoniae , K. pneumoniae and P. aeruginosa strains. The following compounds were identified by NMR: dehydroabietic acid (1), (+) - cis -abienol (2), pimaric acid (3), isopimaric acid (4), 7α-hydroxy-dehydroabietic acid (5), 7-oxo-dehydroabietic acid (6), 15-hydroxy-abietic acid (7), 7-oxo-15-hydroxy-dehydroabietic acid (8), 13-oxo-8 (14)-podocarpen-18-oic acid (9), and pinyunin A (10). Regarding their anti-inflammatory activity, all compounds inhibited NF-κB. Compound 9 was the most active (IC 50 = 3.90–12.06 μM). Concerning the analgesic activity, all the compounds inhibited NK-1, yet compound 9 was the most active (IC 50 = 0.28–0.33 μM). Finally, compounds 6 (MIC = 12.80–25.55 μM) and 9 (MIC = 9.80–24.31 μM) were the most promising antibacterial compounds in all strains. This study managed to identify, for the first time, six diterpenes from the resin of P. pinaster , with anti-inflammatory, analgesic, and antibacterial activity. Among the identified compounds, compound 9 was the most active, being considered a promising candidate as an antagonist of the tachykinin NK-1 receptor and as an analgesic agent against inflammation and neuropathic pain. It also had an antibacterial effect against Gram negative bacteria. [Display omitted] • Pinus pinaster resin showed anti-inflammatory, analgesic, and antibacterial activities. • Six diterpenoids were identified for the first time from this plant species. • All compounds showed anti-inflammatory (NF-κB inhibition), analgesic (Tachykinin inhibition), and antibacterial activities. [ABSTRACT FROM AUTHOR]

Response to threatening environmental stimuli requires detection and encoding of important environmental features that dictate threat. Aversive events are highly salient, which promotes associative learning about stimuli that signal this threat. The nucleus accumbens is uniquely positioned to process this salient, aversive information and promote motivated output, through plasticity on the major projection neurons in the brain area. We describe a nucleus accumbens core local circuit whereby excitatory plasticity facilitates learning and recall of discrete aversive cues. We demonstrate that putative nucleus accumbens substance P release and long-term excitatory plasticity on dopamine 2 receptor-expressing projection neurons are required for cue-dependent fear learning. Additionally, we find that fear learning and recall is dependent on distinct projection neuron subtypes. Our work demonstrates a critical role for nucleus accumbens substance P in cue-dependent aversive learning. [Display omitted] • Aversive stimuli activate D1-MSNs and D2-MSNs and promote acetylcholine release • D1-MSN substance P is necessary for cue-dependent aversive learning • Excitatory LTP on D2-MSNs caused by aversive cues requires substance P signaling • D2-MSN activity is necessary for cue-dependent recall of aversive cues Belilos et al. find that nucleus accumbens core substance P through cell-type-selective plasticity is required for cue-dependent aversive learning. These findings implicate substance P signaling in aversive learning and response, which may underlie the development of anxiety and mood disorders. [ABSTRACT FROM AUTHOR]

Social enrichment or social isolation affects a range of innate behaviors, such as sex, aggression, and sleep, but whether there is a shared mechanism is not clear. Here, we report a neural mechanism underlying social modulation of spontaneous locomotor activity (SoMo-SLA), an internal-driven behavior indicative of internal states. We find that social enrichment specifically reduces spontaneous locomotor activity in male flies. We identify neuropeptides Diuretic hormone 44 (DH44) and Tachykinin (TK) to be up- and down-regulated by social enrichment and necessary for SoMo-SLA. We further demonstrate a sexually dimorphic neural circuit, in which the male-specific P1 neurons encoding internal states form positive feedback with interneurons coexpressing doublesex ( dsx ) and Tk to promote locomotion, while P1 neurons also form negative feedback with interneurons coexpressing dsx and DH44 to inhibit locomotion. These two opposing neuromodulatory recurrent circuits represent a potentially common mechanism that underlies the social regulation of multiple innate behaviors., Competing Interests: Competing interests statement:The authors declare no competing interest.

Highlights • We measured the changes of Tacr2 expression in the hypothalamus of CUMS-sensitive rats. • Stress may change the DNA methylation levels of the CpG island in Tacr2 promoter region. • Tacr2 expression of CUMS-sensitive rats may correlated with the DNA methylation of Tacr2 gene.. Abstract Tacr2, the gene encoding the NK2 receptor, belongs to G protein-coupled receptors. Accumulating evidence has indicated that the tachykinin receptors may contribute to the pathophysiology of depression. During the last decade, some studies have shown that Tacr2 activation is involved in the modulation of emotional processes. However, the extent, to which stress impacts Tacr2 expression remains unclear. The molecular mechanisms underlying depression also remain poorly understood. In this study, we subjected adult male Sprague Dawley (SD) rats to chronic unpredictable mild stress (CUMS) to induce a depression-like phenotype. We then measured the body weight and performed the sucrose preference test, forced swimming test (FST) and open field test to detect the effects of stress on anhedonia and activity. Western blotting and real-time PCR were used to study the protein and mRNA expression levels of Tacr2, respectively, in the hypothalamus. To explore DNA methylation of the Tacr2 gene, we used methylated DNA immunoprecipitation sequencing (MeDIP-seq). Additionally, we used the bisulfite sequencing PCR (BSP) to further verify the DNA methylation levels of the Tacr2 receptor gene in rats. We found that the CUMS-sensitive rats exhibited a decrease in body weight and sucrose preference, a decrease in the distance traveled, rearing frequency and velocity in the open field test, and an increase in immobility time in the FST. Compared with the expression in the control rats, Tacr2 protein and mRNA expression in the hypothalamus significantly increased in the CUMS-sensitive rats; however, the DNA methylation levels of the Tacr2 gene were significantly lower than in the control rats. In summary, according to our findings, the stress-induced increase in Tacr2 expression in the hypothalamus correlated with a specific decrease in DNA methylation of the Tacr2 gene. These results may enrich the understanding of the pathological processes of depression and provide insights into therapeutic approaches for its treatment. [ABSTRACT FROM AUTHOR]

Hot flushes remain a debilitating aspect of menopause, disrupting daytime activities and sleep, and may last for years. Estrogen replacement is an effective treatment, but takes time to become maximally effective and is contraindicated in a significant proportion of women, most notably after breast cancer. Effective, non-hormonal therapies are therefore required. Recent years have seen substantial increases in understanding of the role of novel neuropeptides and tachykinins in hypothalamic function, particularly in the regulation of the reproductive axis through control of gonadotropin releasing hormone secretion, but with links to the control of vasomotor function. Neurokinin B, often co-expressed with kisspeptin in hypothalamic neurons, appears to be a key factor in the control of both systems. Several neurokinin B antagonists have been developed; data are emerging as to their effectiveness in the treatment of menopausal hot flushes. While data remain limited, these agents appear to have a remarkably fast onset of action, with the first 1 or 2 days of administration, and with a dramatic effect on both daytime flushes and night sleep disturbance. If safety and long-term function can be confirmed, these novel agents will be an important advance in therapy. [ABSTRACT FROM AUTHOR]

Substance P (SP), a neuropeptide belonging to the tachykinin family, exerts different biological activities mainly through neurokinin-1 receptor (NK1R). The role of SP/NK1R system in tumoral growth and spread is reported in several cancers. We aimed to evaluate the serum SP concentration and NK1R tissue distribution in endometrial cancer, and to study the relationship between these factors with tumor size, lymph node involvement, disease stage and cancer grade. Recruiting 22 patients with endometrial cancer and 21 patients with leiomyoma as the control group, serum SP concentration was measured using an ELISA method, and NK1R tissue distributions were immunohistochemically analyzed. Serum SP concentration in patients was significantly higher than the control group (p-value = 0.005). The expression level of NK1R in tumoral tissue was more than normal tissue (p-value < 0.001). The NK1R expression had a significant relationship with lymph node involvement (p-value = 0.005) and disease stage (p-value = 0.017). The NK1R expression was higher in more advanced and less-differentiated tumors. SP/NK1R system seems to play a role in tumor growth and development in endometrial cancer. As well, the NK1R expression increased in endometrial cancer, and may be considered as a prognostic factor; but further studies are needed in this field. [ABSTRACT FROM AUTHOR]

Leucokinins (LKs) constitute a family of neuropeptides identified in numerous insects and many other invertebrates. LKs act on G-protein-coupled receptors that display only distant relations to other known receptors. In adult Drosophila, 26 neurons/neurosecretory cells of three main types express LK. The four brain interneurons are of two types, and these are implicated in several important functions in the fly’s behavior and physiology, including feeding, sleep–metabolism interactions, state-dependent memory formation, as well as modulation of gustatory sensitivity and nociception. The 22 neurosecretory cells (abdominal LK neurons, ABLKs) of the abdominal neuromeres co-express LK and a diuretic hormone (DH44), and together, these regulate water and ion homeostasis and associated stress as well as food intake. In Drosophila larvae, LK neurons modulate locomotion, escape responses and aspects of ecdysis behavior. A set of lateral neurosecretory cells, ALKs (anterior LK neurons), in the brain express LK in larvae, but inconsistently so in adults. These ALKs co-express three other neuropeptides and regulate water and ion homeostasis, feeding, and drinking, but the specific role of LK is not yet known. This review summarizes Drosophila data on embryonic lineages of LK neurons, functional roles of individual LK neuron types, interactions with other peptidergic systems, and orchestrating functions of LK.

The effect of a neuropeptide, the tachykinin on α-amylase, protease and lipase activities in the midgut of American cockroach, Periplaneta americana (Linnaeus) is evaluated . Immunohistochemical reactivities against tachykinin (tachykinin- ir) were detected in the midgut. Tachykinin-ir cells in three regions (anterior, median and posterior) of the midgut were counted in normally fed, starved for four weeks and refed cockroaches. The number of tachykinin-ir cells decreased during 4 weeks of starvation and increased 3 h after refeeding. The results of the competitive ELISA were consistent with the profile of immunohistochemical reactivity. Incubation of the dissected midgut with tachykinin led to an increase in α-amylase, protease and lipase activities while the buffer remained ineffective. Tachykinin injection into the hemocoel increased α-amylase, protease and lipase activities, but PBS injection showed no sign of effectiveness. The results seggest that nutrients upregulate midgut cells secreting tachykinin causing further activities of digestive enzymes.

Background Canine chronic bronchitis (CCB) results in cough lasting ≥2 months and airway inflammation. Adverse effects include risk of secondary infection associated with lifelong corticosteroid administration and prompt investigation into alternative therapies. Neurogenic pathways mediated by tachykinins that bind neurokinin (NK) 1 receptors may induce cough and airway inflammation. Maropitant, a NK‐1 receptor antagonist, has been advocated for treatment of CCB based on anecdotal improvement, but without scientific evidence. Hypothesis/Objectives Maropitant will blunt clinical signs and airway inflammation associated with CCB. Animals Client‐owned dogs (n = 8) with cough >2 months, thoracic radiographic evidence of airway disease and sterile airway inflammation (>7% non‐degenerate neutrophils, >7% eosinophils or both) on bronchoalveolar lavage (BAL) enrolled. Methods Maropitant (2 mg/kg) administered q48h for 14 days. Study endpoints included client perception of clinical signs (surveys at baseline and 14 days, and visual analogue scale [VAS] at baseline, 7, and 14 days), and BAL % neutrophils and eosinophils (baseline and 14 days). One‐way repeated measures ANOVA (VAS) and Wilcoxon‐signed rank‐sum tests (BAL cells, cough frequency) used with P < .05 considered significant. Results Maropitant significantly decreased cough frequency (P < .001) and VAS scores (P = .005). No differences in BAL % neutrophils or % eosinophils noted with treatment (P = .279 and P = .382, respectively). Conclusions and Clinical Importance Preliminary results suggest that although maropitant may have antitussive properties leading to perceived clinical improvement, its failure to diminish airway inflammation makes it unsuitable for treatment of CCB. Future studies could evaluate maropitant as a cough suppressant for other respiratory disorders in dogs.

To regulate physiological homeostasis and behavior in Bombyx mori, more than 20 peptide hormones in the midgut of larvae are secreted upon detection of food substances at the lumen. Although it is logical to assume that the timings of peptide hormone secretions are regulated, little is known about the mechanisms. In this study, the distributions of enteroendocrine cells (EECs) producing five peptide hormones and EECs expressing gustatory receptors (Grs), as candidate receptors for luminal food substances and nutrients, were examined via immunostaining in B. mori larvae. Three patterns of peptide hormone distribution were observed. Tachykinin (Tk)- and K5-producing EECs were located throughout the midgut; myosuppressin-producing EECs were located in the middle-to-posterior midgut; and allatostatin C- and CCHamide-2-producing EECs were located in the anterior-to-middle midgut. BmGr4 was expressed in some Tk-producing EECs in the anterior midgut, where food and its digestive products arrived 5 min after feeding began. Enzyme-linked immunosorbent assay (ELISA) revealed secretion of Tk starting approximately 5 min after feeding began, suggesting that food sensing by BmGr4 may regulate Tk secretion. BmGr6 was expressed in a few Tk-producing EECs in the middle-to-posterior midgut, although its significance was unclear. BmGr6 was also expressed in many myosuppressin-producing EECs in the middle midgut, where food and its digestive products arrived 60 min after feeding began. ELISA revealed secretion of myosuppressin starting approximately 60 min after feeding began, suggesting that food sensing by BmGr6 may regulate myosuppressin secretion. Finally, BmGr9 was expressed in many BmK5-producing EECs throughout the midgut, suggesting that BmGr9 may function as a sensor for the secretion of BmK5., (© 2023 Wiley Periodicals LLC.)

Abstract: Tachykinins are a family of pronociceptive neuropeptides with a specific role in pain and inflammation. Several mechanisms regulate endogenous tachykinins levels, including the differential expression of protachykinin mRNA and the controlled secretion of tachykinin peptides from neurons. We suspect that proteolysis regulates extracellular neuropeptide K (NPK) and neurokinin A (NKA) concentrations and NPK is a precursor of NKA. Here, we provide evidence that proteolysis controls NPK and NKA levels in the spinal cord, leading to the formation of active C‐terminal peptide fragments. Using high‐resolution mass spectrometry, specific tachykinin fragments were identified and characterized. The metabolic stability in rat spinal cord fractions of NPK and NKA was very short, resulting in half‐lives of 1.9 and 2.2 min respectively. Following the degradation of NPK, several C‐terminal fragments were identified, including NPK1–26, NKA, NKA2–10, NKA3–10, NKA5–10 and NKA6–10, which conserve affinity for the neurokinin 2 receptor but also for the neurokinin 1 receptor. Interestingly, the same fragments were identified following the degradation of NKA. A specific proprotein convertases inhibitor was used and showed a significant reduction in the rate of formation of NKA, providing strong evidence that proprotein convertase is involved in C‐terminal processing of NPK in the spinal cord, leading to the formation of NKA. [ABSTRACT FROM AUTHOR]

The presence of substance P (SP) receptor (Neurokinin-1 receptor, NK1R) in the indusium griseum (IG) and anterior hippocampal continuation (AHC) during postnatal development was studied by immunocytochemistry (ICC). NK1R-immunopositive neurons (NK1R IP-n ) first appeared in both areas on postnatal day (P) 5. From P5 onward, their distribution pattern was adult-like. In sagittal sections NK1R IP-n formed a narrow strip of neurons and dendrites that were located over the corpus callosum (cc); in coronal sections they were found in a roughly triangular area at the base of the cingulate cortex (Cg) on the dorsal surface of the cc. NK1R IP-n were also found in the AHC, which is considered as a subcallosal extension of the IG, located ventral to the genu of the cc. At all ages studied, IG NK1R IP-n sent dendrites to the contralateral IG, the underlying cc, and the Cg. Moreover, NK1R IP-n located in the Cg and the cc sent dendrites to the IG. The present findings are in line with previous ICC studies describing dopaminergic and serotoninergic afferents to the IG. Together these data suggest that, through NK1R, SP could play an important role in regulating the release mechanisms of these afferents and that it could be an important developmental factor. Notably, IG neurons could be activated by cortical and intracallosal afferents. [ABSTRACT FROM AUTHOR]

Gonadotropin releasing hormone (GnRH) triggers secretion of luteinizing hormone and follicle stimulating hormone from gonadotropic cells in the anterior pituitary gland. GnRH is able to bind copper, and both in vitro and in vivo studies have suggested that the copper-GnRH complex is more potent at triggering gonadotropin release than GnRH alone. However, it remains unclear whether copper-GnRH is the active species in vivo . To explore this we have estimated the GnRH-copper affinity and have examined whether GnRH remains copper-bound in the presence of serum albumin and the neuropeptide neurokinin B, both copper-binding proteins that GnRH will encounter in vivo . We show that GnRH has a copper dissociation constant of ∼0.9 × 10 −9  M, however serum albumin and neurokinin B can extract metal from the copper-GnRH complex. It is therefore unlikely that a copper-GnRH complex will survive transit through the pituitary portal circulation and that any effect of copper must occur outside the bloodstream in the absence of neurokinin B. [ABSTRACT FROM AUTHOR]

Invertebrate tachykinin-related peptides (TKRPs) comprise a group of signaling molecules having sequence similarities to mammalian tachykinins. A growing body of evidence has demonstrated the presence of TKRPs in the central nervous system of insects. In this investigation, we used an antiserum against locustatachykinin-II to reveal the distribution pattern of these peptides in the brain of the moth Heliothis virescens. Immunolabeling was found throughout the brain of the heliothine moth. Most of the roughly 500 locustatachykinin-II immunoreactive cell bodies, that is, ca. 400, were located in the protocerebrum, whereas the rest was distributed in the deutocerebrum, tritocerebrum, and the gnathal ganglion. Abundant immunoreactive processes were located in the same regions. Labeled processes in the protocerebrum were especially localized in optic lobe, central body, lateral accessory lobe, superior protocerebrum, and lateral protocerebrum, while those in the deutocerebrum were present exclusively in the antennal lobe. In addition to brain interneurons, four pairs of median neurosecretory cells in the pars intercerebralis with terminal processes in the corpora cardiaca and aorta wall were immunostained. No sexual dimorphism in immunoreactivity was found. Comparing the data obtained here with findings from other insect species reveals considerable differences, suggesting species-specific roles of tachykinin-related peptides in insects. [ABSTRACT FROM AUTHOR]

• Three tachykinin genes (tac1 , tac3 and tac4) and three neurokinin receptors (nk1r , nk2r and nk3r) were identified from Chinese sturgeon. • NK1R preferentially selected asSP, NK2R preferentially selected asNKA, and NK3R preferentially selected asNKB. • Both asSP and asNKB could stimulate luteinizing hormone (LH) release in Chinese sturgeon serum. • Estradiol (E2) could stimulate tac3 mRNA expression in hypothalamus. Tachykinins belong to a large, evolutionarily conserved family of brain/gut peptides that are involved in a variety of physiological functions in mammals, such as reproductive regulation. However, little information was available about tachykinins in ancient fish lineage. In the present study, we firstly identified three tachykinin genes (named tac1 , tac3 and tac4) and three neurokinin receptors (named nk1r , nk2r and nk3r) from Chinese sturgeon brain and pituitary. Sequence analysis showed that tac1 encoded substance P (SP) and neurokinin A (NKA), tac3 encoded neurokinin B (NKB) and NKB-related peptide (NKBRP), and tac4 encoded hemokin 1 (HK-1) and hemokin 2 (HK-2), respectively. The luciferase reporter assay results showed that NK1R preferentially selected asSP, NK2R preferentially selected asNKA, and NK3R preferentially selected asNKB. Tissue expression analysis showed that the three tac genes were highly detected in the telencephalon and hypothalamus, whereas nkr genes were widely expressed in peripheral tissues. Spatio-temporal expression analysis showed that all three tac genes were highly expressed in unknown sex individuals. Intraperitoneal injection experiments showed that both asSP and asNKB could stimulate luteinizing hormone (LH) release in Chinese sturgeon serum. At the transcriptional level, asSP and asNKB could significantly reduce pituitary follicle-stimulating hormone beta (fshβ) mRNA expression, but induce pituitary growth hormone (gh) mRNA expression. In addition, estradiol (E2) could stimulate tac3 mRNA expression in hypothalamus. Taken together, this study provided information on the tachykinin family in Chinese sturgeon and demonstrates that asNKB and asSP could be involved in reproductive and growth regulation in pituitary. [ABSTRACT FROM AUTHOR]