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The participation of silent mating type information regulation 2 homolog 1 (SIRT1) in amyotrophic lateral sclerosis (ALS) has been reported in many studies. However, the role of the expression and function of SIRT1 in the hypothalamus in ALS remains unknown. In the current study, we performed western blot, co-immunoprecipitation and immunofluorescence analyses to determine the expression and in-depth mechanism of SIRT1 in the hypothalamus in SOD1G93A transgenic mice. We found that SIRT1 was overexpressed in the hypothalamus after motor symptom onset. In addition, SIRT1 interacted with prepro-orexin, a molecule involved in energy balance and the sleep/wake cycle, in both preclinical and clinical ALS regardless of whether SIRT1 levels were elevated. These findings indicate that SIRT1 might participate in sleep and metabolic changes in ALS, suggesting that SIRT1 is a new target for ALS treatment. [ABSTRACT FROM AUTHOR]

To know the processes involved in feeding, the dysregulation of hypothalamic neuropeptides promoting anorexigenic/orexigenic mechanisms must be investigated. Many neuropeptides are involved in this behavior and in overweight/obesity. Current pharmacological strategies for the treatment of obesity are unfortunately not very effective and, hence, new therapeutic strategies must be investigated and developed. Due to the crucial role played by orexins in feeding behavior, the aim of this review is to update the involvement of the orexinergic system in this behavior. The studies performed in experimental animal models and humans and the relationships between the orexinergic system and other substances are mentioned and discussed. Promising research lines on the orexinergic system are highlighted (signaling pathways, heterogeneity of the hypothalamic orexinergic neurons, receptor-receptor interaction, and sex differences). Each of the orexin 1 and 2 receptors plays a unique role in energy metabolism, exerting a differential function in obesity. Additional preclinical/clinical studies must be carried out to demonstrate the beneficial effects mediated by orexin receptor antagonists. Because therapies applied are in general ineffective when they are directed against a single target, the best option for successful anti-obesity treatments is the development of combination therapies as well as the development of new and more specific orexin receptor antagonists. [ABSTRACT FROM AUTHOR]

The neuropeptide orexin/hypocretin is implicated in sleep and arousal, energy expenditure, reward, affective state and cognition. Our previous work using diurnal Nile grass rats (Arvicanthis niloticus) found that orexin mediates the effects of environmental light, particularly daytime light intensity, on affective and cognitive behaviours. The present study further investigated how daytime light intensity affects the central orexin system in male and female grass rats. Subjects were housed for 4 weeks in 12:12 hr dim light:dark (50 lux, dimLD) or in 12:12 hr bright light:dark cycle (1000 lux, brightLD). Day/night fluctuations in some orexin measures were also assessed. Despite similar hypothalamic prepro‐orexin mRNA expression across all conditions, there were significantly more orexin‐immunoreactive neurons, larger somata, greater optical density or higher orexin A content at night (ZT14) than during the day (ZT2), and/or in animals housed in brightLD compared to dimLD. Grass rats in brightLD also had higher cisternal CSF levels of orexin A. Furthermore, orexin receptor OX1R and OX2R proteins in the medial prefrontal cortex were higher in brightLD than dimLD males, but lower in brightLD than dimLD females. In the CA1 and dorsal raphe nucleus, females had higher OX1R than males without any significant effects of light condition, and OX2R levels were unaffected by sex or light. These results reveal that daytime light intensity alters the central orexin system of both male and female diurnal grass rats, sometimes sex‐specifically, and provides insight into the mechanisms underlying how daytime light intensity impacts orexin‐regulated functions. [ABSTRACT FROM AUTHOR]

The participation of silent mating type information regulation 2 homolog 1 (SIRT1) in amyotrophic lateral sclerosis (ALS) has been reported in many studies. However, the role of the expression and function of SIRT1 in the hypothalamus in ALS remains unknown. In the current study, we performed western blot, co-immunoprecipitation and immunofluorescence analyses to determine the expression and in-depth mechanism of SIRT1 in the hypothalamus in SOD1G93A transgenic mice. We found that SIRT1 was overexpressed in the hypothalamus after motor symptom onset. In addition, SIRT1 interacted with prepro-orexin, a molecule involved in energy balance and the sleep/wake cycle, in both preclinical and clinical ALS regardless of whether SIRT1 levels were elevated. These findings indicate that SIRT1 might participate in sleep and metabolic changes in ALS, suggesting that SIRT1 is a new target for ALS treatment.

Hypothalamic peptides orexin A (OXA) and orexin B (OXB) are derived from the proteolytic cleavage of a common precursor molecule, prepro-orexin (PPO). They act via two orexin receptors (OX1R and OX2R), which belong to the G-protein coupled receptor superfamily. Orexins are implicated in the regulation of arousal states, energy homeostasis and reproductive neuroendocrine function. The objective of this study was to investigate the presence and changes in orexin expression in the porcine pituitary during the estrous cycle. Adenohypophysis (AP) and neurohypophysis (NP) tissue samples were harvested on days 2 to 3, 10 to 12, 14 to 16, and 17 to 19 of the estrous cycle. The expression of the PPO gene increased in AP and NP during the estrous cycle. The highest PPO protein concentrations in AP were reported on days 2 to 3 (P

The Eurasian beaver (Castor fiber L.) is the largest free-living rodent in Eurasia. Beavers show seasonal patterns of reproduction (long-day breeders), stress reactions, and feeding behavior. These phenomena are associated with the function of hormonal regulatory axes: the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG). In mammals, the above processes are also controlled by orexins (OXA and OXB), neuropeptides derived from the same precursor--prepro-orexin (PPO). We hypothesized that in beavers PPO gene expression in tissues creating the HPA-HPG axes and plasma orexin concentrations differ between seasons and sexes. PPO transcript and PPO and orexin proteins were noted in the mediobasal hypothalamus (MBH), pituitary, adrenals, and gonads in April ("breeding, pregnancy"), July ("post-breeding"), and November ("prebreeding"). In the MBH, seasonal, but not sex-dependent variations were observed in PPO gene expression; however, the transcript content increased in females in July. An interaction between season and sex was noted in the pituitary: PPO gene expression decreased in males in April. The PPO mRNA concentration in adrenals varied between seasons and sexes. Additionally, an interaction between these factors occurred and the highest PPO gene expression was noted in females in April. In the gonads, PPO mRNA levels changed dependent on season, and an interaction between season and sex was found. The PPO transcript increased in November in the testes. Seasonal variations and an interaction between season and sex were observed in plasma OXA. The highest concentration of OXA was noted in July (males) and in November (females). In beavers, PPO gene expression and plasma OXA concentration varied depending on season and these changes were modified by sex. Our results imply that orexin peptides are involved in the regulation of circannual changes of reproductive activity in beavers and seem to be associated with seasonal fluctuations in glucocorticoid secretion and stress reactions. [ABSTRACT FROM AUTHOR]

Orexins, also known as hypocretins, play a regulatory role in the sleep-wake cycle by activating orexin receptors. Previous animal studies have shown that sleep deprivation can elevate orexinergic peptide levels. However, the relationship between insomnia disorder and orexin-A levels in humans has not been explored. In the current study, we examined plasma orexin-A levels in patients with insomnia disorder and in normal sleepers. We also studied the possible mechanisms underlying changes in orexin-A levels between the study groups; this included investigations of prepro-orexin and orexin receptor gene polymorphisms as well as exploration of other variables. We measured plasma orexin-A levels in 228 patients with insomnia disorder and 282 normal sleepers. The results indicated that the patients with insomnia disorder had significantly higher orexin-A levels than normal sleepers (63.42 ± 37.56 vs. 54.84 ± 23.95 pg/ml). A positive relationship was detected between orexin-A level and age in patients with insomnia disorder. Orexin-A levels were elevated in relation to course of insomnia, as well as in relation to increased Insomnia Severity Index score. None of the evaluated prepro-orexin gene single nucleotide polymorphisms were informative between the two study populations. After sequencing all orexin receptor exons, one variation (rs2271933) in the OX1R gene and one variation (rs2653349) in the OX2R gene were found. However, no significant differences were found in either genotypic or allelic frequency distributions between the two study groups. It is suggested that the increased plasma orexin-A levels in patients with insomnia disorder are associated with the course and severity of insomnia, but not with prepro-orexin and orexin receptor gene polymorphisms. [ABSTRACT FROM AUTHOR]

Orexin A and B are hypothalamic peptides with a wide variety of effects such as anti-inflammation and neuroprotection. Impaired function of orexin system has been reported in some neurodegenerative diseases like Parkinson, Huntington and Alzheimer. In this study, the mRNA expression levels of some hypothalamic peptides were investigated in C57BL/6 female mice with experimental autoimmune encephalomyelitis (EAE). Animals were randomly divided into two control and EAE groups. EAE was induced by administration of myelin oligodendrocyte glycoprotein (MOG) with complete Ferund’s adjuvant and pertussis toxin. Twenty-first days following immunization, mice were decapitated to remove the brains. Then, the expression profiles of prepro-orexin, orexin 1 receptors (OX1R) and orexin 2 receptors (OX2R) in hypothalamic region were assessed using real-time PCR method. In this study, we found a considerable increase in the mRNA expression of OX1R and OX2R following EAE induction in C57BL/6 mice. Elevation levels of OX1R and OX2R following EAE induction suggest that alteration in orexinergic system may involve in pathogenesis of multiple sclerosis.

Orexin A and B are hypothalamic peptides with a wide variety of effects such as anti-inflammation and neuroprotection. Impaired function of orexin system has been reported in some neurodegenerative diseases like Parkinson, Huntington and Alzheimer. In this study, the mRNA expression levels of some hypothalamic peptides were investigated in C57BL/6 female mice with experimental autoimmune encephalomyelitis (EAE). Animals were randomly divided into two control and EAE groups. EAE was induced by administration of myelin oligodendrocyte glycoprotein (MOG) with complete Ferund's adjuvant and pertussis toxin. Twenty-first days following immunization, mice were decapitated to remove the brains. Then, the expression profiles of prepro-orexin, orexin 1 receptors (OX1R) and orexin 2 receptors (OX2R) in hypothalamic region were assessed using real-time PCR method. In this study, we found a considerable increase in the mRNA expression of OX1R and OX2R following EAE induction in C57BL/6 mice. Elevation levels of OX1R and OX2R following EAE induction suggest that alteration in orexinergic system may involve in pathogenesis of multiple sclerosis. [ABSTRACT FROM AUTHOR]

Orexin/hypocretin peptide mutations are rare in humans. Even though human narcolepsy is associated with orexin deficiency, this is only extremely rarely due to mutations in the gene coding prepro-orexin, the precursor for both orexin peptides. In contrast, coding and non-coding variants of the OX1 and OX2 orexin receptors have been identified in many human populations; sometimes, these have been associated with disease phenotype, although most confer a relatively low risk. In most cases, these studies have been based on a candidate gene hypothesis that predicts involvement of orexins in the relevant pathophysiological processes. In the current review, the known human OX1/HCRTR1 and OX2/HCRTR2 genetic variants/polymorphisms as well as studies concerning their involvement in disorders such as narcolepsy, excessive daytime sleepiness, cluster headache, polydipsia-hyponatremia in schizophrenia, and affective disorders are presented. In most cases, the functional cellular or pharmacological correlates of orexin variants have not been investigated  with the exception of the possible impact of an amino acid 10 Pro/Ser variant of OX2 on orexin potency  leaving conclusions on the nature of the receptor variant effects speculative. Nevertheless, we present perspectives that could shape the basis for further studies. The pharmacology and other properties of the orexin receptor variants are discussed in the context of GPCR signaling. Since orexinergic therapeutics are emerging, the impact of receptor variants on the affinity or potency of ligands deserves consideration. This perspective (pharmacogenetics) is also discussed in the review.

Objective: To investigate the central and peripheral effects of endogenous Orexin-A(OXA) on gastric motility in rats.Methods: Selecting adult Wistar rats for the study, the synthesis of endogenous OXA was induced by fasting. Plasma OXA concentration was measured by radioimmunoassay. Rats were pretreated with OXA receptor antagonist SB-334867 prior to measurement to observe the effect of OXA.Vagotomy was used to observe vagus nerve-mediated effects. Gastric emptying was measured by spectrophotometric methods. One strain gauge transducers were attached on the antrum to record interdigestive gastric motility. Preproorexin(PPO)expression in stomach and hypothalamus were tested by Western blot. Results: After fasting 18 h, the level of plasma OXA and PPO protein expression were significantly increased(P<0.05). The highest level of plasma OXA and PPO protein expression appeared in 36 h fasting groups(P<0.01). Endogenous OXA promoted gastric emptying(P<0.05), inhibited gastric interdigestive motility(P<0.05). As these effects were abolished with injection of SB-334867, but no effect on PPO expression. Vagotomy surgery did not block endogenous OXA-mediated effects(P>0.05). Conclusion: Fasting can induce the synthesis of endogenous OXA. Endogenous OXA can accelerate gastric emptying, but it suppressed interdigestive gastric motility. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, we report the distribution of orexin A (OXA), orexin B (OXB), and orexin receptor (OX2R) immunoreactive (ir) cells in the hypothalamus and gastrointestinal tract of Oncorhynchus mykiss fed diets with different dietary fatty acid compositions. Trout were fed five iso-energetic experimental diets containing fish oil, or one of four different vegetable oils (olive, sunflower, linseed, and palm oils) as the added dietary lipid source for 12 weeks. OXA, OXB, and OX2R immunoreactive neurons and nervous fibers were identified in the lateral and ventro-medial hypothalamus. OXA, OXB, and OX2R ir cells were found in the mucosa and glands of the stomach and in the mucosa of both the pyloric cecae and intestine. OX2R ir cells were localized in the mucosa layer of both the pyloric cecae and intestine. These immunohistochemical (IHC) results were confirmed via Western blotting. Antibodies against preproorexin (PPO) crossreacted with a band of ∼16 kDa in the hypothalamus, stomach, pyloric cecae, and intestine. Antibodies against OX2R crossreacted with a band of ∼38 kDa in the hypothalamus, pyloric cecae, and intestine. The presence and distribution of OXA, OXB, and OX2R ir cells in the hypothalamus and gastrointestinal tract did not appear to be affected by dietary oils. The presence of orexin system immunoreactive cells in the stomach, pyloric cecae, and intestine of rainbow trout, but not in the enteric nervous system, could suggest a possible role of these peptides as signaling of gastric emptying or endocrine modulation, implying a main local action played by orexins. Microsc. Res. Tech. 78:707-714, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Hypothalamic peptides orexin A (OXA) and orexin B (OXB) are derived from the proteolytic cleavage of a common precursor molecule, prepro-orexin (PPO). They act via two orexin receptors (OX1R and OX2R), which belong to the G-protein coupled receptor superfamily. Orexins are implicated in the regulation of arousal states, energy homeostasis and reproductive neuroendocrine function. The objective of this study was to investigate the presence and changes in orexin expression in the porcine pituitary during the estrous cycle. Adenohypophysis (AP) and neurohypophysis (NP) tissue samples were harvested on days 2 to 3, 10 to 12, 14 to 16, and 17 to 19 of the estrous cycle. The expression of the PPO gene increased in AP and NP during the estrous cycle. The highest PPO protein concentrations in AP were reported on days 2 to 3 (P<0.05), and in NP – on days 10 to 12 and 17 to 19 (P<0.05). The expression of PPO mRNA was lower in AP than in NP, but PPO protein levels were higher in AP. In AP, OXA immunoreactivity was higher (P<0.05) on days 10 to 12 and 14 to 16. In NP, the highest (P<0.05) content of the analyzed protein was observed on days 10 to 12 and the lowest (P<0.05) – on days 14 to 16 and 17 to 19. OXB immunoreactivity in AP reached the highest level (P<0.05) on days 2 to 3, and the lowest level (P<0.05) was determined on days 10 to 12 and 17 to 19. OXB protein concentrations in NP peaked (P<0.05) on days 10 to 12 of the cycle. Our study was the first experiment to demonstrate the expression of the orexin gene and orexin proteins in the porcine pituitary and the correlations between expression levels and the phase of the estrous cycle. [ABSTRACT FROM PUBLISHER]

Appropriate nutritional and vigilance states are needed for reproduction. In previous works, we described the influence of the hormonal milieu of proestrus on the orexinergic system and we found that orexin receptor 1 expression in the hypothalamus, but not other neural areas, and the adenohypophysis was under the influence of oestradiol and the time of the day. Information from the sexual hormonal milieu of proestrous afternoon impacts on various components of the orexinergic system and alertness on this particular night of proestrus would be of importance for successful reproduction. In this review, we summarize the available experimental data supporting the participation of orexins in the hypothalamic-pituitary-ovarian relationships. All together, these results suggest a role of the orexinergic system as an integrative link among vital functions such as reproduction, food intake, alertness and the inner biological clock. [ABSTRACT FROM AUTHOR]

Orexin A (OXA) and orexin B were originally isolated as hypothalamic peptides regulating sleep, wakefulness and feeding. However, growing evidence suggests that orexins have major functions also in the peripheral tissues. Central orexigenic pathways originating from medulla activate the hypothalamus–pituitary axis and can influence the sympathetic tone. Orexins and their receptors are widely dispersed throughout the intestine, where orexin receptors are regulated by the nutritional status, affect insulin secretion and intestinal motility. Although the primary source of the peptide has not been elucidated, OXA is detected in plasma and its level varies in response to the metabolic state. In this review, we focus on the current knowledge on peripheral functions of orexins and discuss possible endocrine, paracrine and neurocrine roles. [ABSTRACT FROM AUTHOR]

Various high-fat diets are obesogenic but not to the same extent. The aim of the present study was to investigate the effects of saturated fat n-6 and n-3 polyunsaturated fatty acids (PUFAs) on the central neuropeptidergic system in adult rats. Using reverse transcriptase-polymerase chain reaction and in situ hybridisation, we evaluated the net effect of feeding in these fats, comparing the effects of a high- to low-fat diet, and the diversity of the effects of these fats in the same amount within the diet. We also determined plasma lipids, glucose, insulin and leptin concentrations. Six-week feeding with high-saturated fat evoked hyperpahagia and the largest weight gain compared to both high-PUFA diets. Rats fed high-saturated fat were found to have decreased neuropeptide Y (NPY) mRNA expression in the arcuate nucleus (ARC) and the compact zone of the dorsomedial nucleus (DMHc), unchanged pro-opiomelanocortin (POMC), galanin-like peptide (GALP) mRNA expression in the ARC, as well as melanin-concentrating hormone (MCH) and prepro-orexin (preORX) mRNA expression in the lateral hypothalamus, compared to low-saturated fed rats. By contrast, feeding with both high-PUFA diets increased POMC and GALP mRNA expression in the ARC compared to the corresponding low-fat diet and the high-saturated fat diet. Furthermore, feeding with both low-PUFA diets reduced NPY mRNA expression compared to the low-saturated fat diet exclusively in the DMHc. Uniquely, the high n-3 PUFA feeding halved MCH and preORX mRNA expression in the lateral hypothalamus compared to the other high-fat and low n-3 PUFA diets. In rats fed three high-fat diets, plasma insulin and leptin concentrations were significantly increased and the type of fat had no effect on these hormone levels. Rats fed high-saturated fat had both hyperglycaemia and hypertriacylglycerolemia and rats fed high n-3 PUFA only had hyperglycaemia. The present study demonstrates that various forms of dietary fat differentially change the expression of neuropeptide genes involved in energy homeostasis. [ABSTRACT FROM AUTHOR]

Abstract: Orexin-A (OX-A) and -B (OX-B) peptides present in the hippocampus are considered to be exclusively contained in fibers arising from hypothalamus neurons, which were established as the only source of orexins (OXs). Because OX-A is known to exert excitatory actions in the hippocampus, we hypothesized that the level of OXs targeted toward the hippocampus may be increased following status-epilepticus (SE)-induced epileptogenesis in the rat pilocarpine model of temporal lobe epilepsy. We found that tissue concentration of prepro-OX mRNA, which encodes for both peptides, rapidly decreased in the hypothalamus of rats having experienced pilocarpine-induced SE (Pilo-SE) followed by a reduced density of OX-A and OX-B immunopositive fibers arising from these neurons. By contrast, it was unexpected to detect within the hippocampus the presence of prepro-OX mRNA in basal conditions and to evidence its up-regulation during the 1- to 3-day period following Pilo-SE. The number of prepro-OX mRNA copies determined by real-time RT-PCR was ∼50-fold lower in the hippocampus than that in the hypothalamus, precluding the use of in situ hybridization to localize the cells which synthesize the transcript within the hippocampus. The increase in prepro-OX mRNA level within the hippocampus was accompanied by the detection of OX-B-like immunoreactivity 2–3 days post-SE, not only in pyramidal neurons, granule cells and cell bodies resembling interneurons, but also in some astrocytes scattered throughout the hippocampus. The present data suggest that the gene encoding OXs can be activated in the hippocampus, which may play a role in the pathogenesis of epilepsy. [Copyright &y& Elsevier]

Abstract: A CNS component of glucose counterregulatory collapse is supported by evidence for nonuniform genomic responsiveness of neurons in characterized central autonomic loci during recurring insulin-induced hypoglycemia (IIH). We have reported that exacerbated hypoglycemia and attenuated patterns of glucagon and epinephrine secretion in rats treated by daily sc injection of the intermediate-acting insulin formulation, Humulin NPH (NPH), are correlated with diminished immunodemonstrability of the AP-1 transcription factor, Fos, in several components of the central metabolic regulatory circuitry, including the lateral hypothalamic area (LHA). Neurons that synthesize the potent orexigenic peptide neurotransmitter, orexin-A, are restricted to the LHA and adjacent hypothalamic loci, and project throughout the central neuroaxis to structures that govern autonomic and behavioral motor output. Dual-label immunocytochemical and real-time RT-PCR techniques were utilized here to evaluate the functional status of this LHA phenotype during a single versus repetitive exposure to prolonged IIH. Tissue sections were collected at predetermined rostrocaudal levels of the LHA after acute or repeated NPH administration, and processed for nuclear Fos- and cytoplasmic orexin-A-immunoreactivity (-ir). Mean numbers of orexin-A-ir neurons were not different between treatment groups. Colabeling of these cells for Fos was increased relative to controls following a single injection of insulin, but numbers of Fos-ir-positive orexin-A neurons were significantly reduced after treatment with four versus one dose of insulin. Prepro-orexin mRNA levels in microdissected LHA tissue were upregulated during acute hypoglycemia, but were returned to control levels by repeated IIH. These data corroborate previous evidence that IIH is an activational stimulus for orexin-A-synthesizing neurons in the LHA, and further demonstrate that induction of cfos and prepro-orexin gene expression by acute hypoglycemia is attenuated by precedent exposure to hypoglycemia. The current results thus provide unique evidence for neurotransmitter-specific habituation of LHA neuronal sensitivity to IIH. [Copyright &y& Elsevier]

The purpose of this study was to investigate whether orexin expression in the rat brain was changed during pregnancy. Brain samples were obtained from 5 nonpregnant rats and 10 pregnant rats (5; day 10 of gestation, and 5; day 20 of gestation). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was performed to investigate the expression of prepro-orexin mRNA and the housekeeping gene in the rat brain. The signals were quantified by the densitometric analysis. The distribution and expression of orexin-A and orexin-B were determined using immunohistochemistry. The ratio of the prepro-orexin mRNA expressions to the housekeeping gene expression in pregnant rat brain were significantly higher than that in nonpregnant control. There was no significant difference between prepro-orexin mRNA levels of day 10 and day 20 of gestation. Immunohistochemical staining for orexin-A and orexin-B was present in neurons within and around the lateral and posterior hypothalamic areas in both nonpregnant and pregnant rats. These results suggest that increased prepro-orexin mRNA levels at early gestational age in the maternal rat has a role on energy metabolism during pregnancy. [Copyright &y& Elsevier]

The neuropeptides orexin A and B are expressed in the lateral hypothalamic area and are involved in the regulation of energy homeostasis and arousal. Recent results showed gender differences in the expression of orexin receptor subtypes in rats. In the present study, we analyzed the mRNA expression of prepro-orexin (PPO) in the hypothalamus of male and female rats using quantitative real-time PCR. We found significantly higher levels of PPO mRNA in the hypothalamus of female rats compared to male rats. Our study indicates a sex-dependent regulation of hypothalamic PPO expression and suggests gender-specific functions of orexins. [Copyright &y& Elsevier]

In teleosts, starvation induces an increase in appetite-related gene expression and peptide secretion in the hypothalamus. This reduces autonomic nervous activity and promotes food intake and body weight gain. We have previously demonstrated that single nucleotide polymorphisms (SNPs) in the 5′ flanking region of ghrelin affect gene regulation and are associated with superior growth traits in Nile tilapia (Oreochromis niloticus). Recent findings have also suggested that Ghrelin, Neuropeptide Y (NPY), and Prepro-orexin combine in the hypothalamus to regulate appetite in organisms, thus we hypothesized that SNPs in NPY and prepro-orexin may also indirectly regulate the growth of Nile tilapia. Accordingly, we examined the effects of SNPs in NPY and prepro-orexin in two populations of Nile tilapia—the GIFT (GF) and Egyptian (EG) populations—by cloning the 5′ flanking and coding regions of each gene and screening the SNPs in these regions to identify associations with superior growth traits. After preliminary screening and secondary prediction of function, 6 SNP loci (1 from NPY and 5 from prepro-orexin) were identified in the GF population, from which 9 diplotypes were constructed. Of these, four loci from prepro-orexin (g. −1108C > G, g. −1107C > G, g. −1063C > T, and g. −883C > T) and one diplotype were associated with superior growth traits. In the EG population, 4 SNP loci (1 from NPY and 3 from prepro-orexin) were identified and 6 diplotypes were constructed; however, none of these were associated with superior growth traits. Considering these findings, we discuss the necessity for functional prediction of SNP loci, and consider the differential conservativeness of the 5′ flanking and coding regions of appetite-related genes. • Functional secondary identification of SNPs in tilapia for molecular marker development. • NPY and prepro-orexin plays an important role in regulating the food intake. • SNP locus were first genotyped in the NPY and prepro-orexin of Nile Tilapia (Oreochromis niloticus). • Correlations of each genotype and its constituent diplotypes of the SNPs loci with growth traits was discovered. [ABSTRACT FROM AUTHOR]

Abstract We determined the orexin concentration in cerebrospinal fluid (CSF-OX) in two patients with subacute sclerosing panencephalitis who underwent intracerebroventricular (ICV) α-interferon (IFN-α) therapy. In these patients, CSF-OX were in the normal range before ICV administration of IFN-α, and it decreased to undetectable levels after the initiation of IFN-α therapy. It was reported that the production of prepro-OX, which is a precursor of OX, was prevented when IFN-α was given to the gene promoter region of prepro-OX. These results suggest that the production of OX may be suppressed by inhibition of promotor activity when IFN-α is given to the cerebral ventricle in humans. [ABSTRACT FROM AUTHOR]

Objective: Gastric cancer (GC) has been become the second leading cause for cancer-associated death. This study aimed to investigate Orexin A levels and associated receptors in tumor tissues of GC patients., Patients and Methods: Forty-six consecutive gastric cancer patients (GC, n=46) and 13 chronic atrophic gastritis patients (CAG, n=13) were recruited. Meanwhile, 18 health individuals visiting Medical Examination Department were involved as control (N group, n=18). ELISA was used to examine Orexin A concentration. Immunohistochemistry assay was used to examine OX1R and OX2R. HE staining was applied to evaluate inflammation. qRT-PCR was employed to detect OX1R, OX2R, prepro-Orexin mRNAs. Serum Helicobacter pylori (H. pylori) infection was measured., Results: Orexin A expression in GC patients was significantly up-regulated compared to N group and CAG group (p<0.05). Orexin A expression was increased in CAG group compared to N group (p<0.05). Gastric cancer tissues exhibited significantly obvious inflammation compared to N group and CAG group (p<0.05). OX1R and OX2R expressions were significantly down-regulated in GC group compared to N group and CAG group (p<0.05). OX1R and OX2R were lower significantly in GC group compared to CAG group (p<0.05). Prepro-Orexin was significantly depleted in tumor tissues of GC group compared to N group and CAG group (p<0.05). Orexin A expression was un-associated with gender, age and differential grades (p>0.05). CAG and GC patients demonstrated higher H. pylori infection rates., Conclusion: Orexin A was associated with inflammation by interacting with OX1R/OX2R receptor and activating prepro-Orexin in tumor tissues of gastric cancer patients., (Copyright © 2019. Publicado por Elsevier España, S.L.U.)

In this study, we report the distribution of orexin A (OXA), orexin B (OXB), and orexin receptor (OX2R) immunoreactive (ir) cells in the hypothalamus and gastrointestinal tract of Oncorhynchus mykiss fed diets with different dietary fatty acid compositions. Trout were fed five iso-energetic experimental diets containing fish oil, or one of four different vegetable oils (olive, sunflower, linseed, and palm oils) as the added dietary lipid source for 12 weeks. OXA, OXB, and OX2R immunoreactive neurons and nervous fibers were identified in the lateral and ventro-medial hypothalamus. OXA, OXB, and OX2R ir cells were found in the mucosa and glands of the stomach and in the mucosa of both the pyloric cecae and intestine. OX2R ir cells were localized in the mucosa layer of both the pyloric cecae and intestine. These immunohistochemical (IHC) results were confirmed via Western blotting. Antibodies against preproorexin (PPO) crossreacted with a band of ∼16 kDa in the hypothalamus, stomach, pyloric cecae, and intestine. Antibodies against OX2R crossreacted with a band of ∼38 kDa in the hypothalamus, pyloric cecae, and intestine. The presence and distribution of OXA, OXB, and OX2R ir cells in the hypothalamus and gastrointestinal tract did not appear to be affected by dietary oils. The presence of orexin system immunoreactive cells in the stomach, pyloric cecae, and intestine of rainbow trout, but not in the enteric nervous system, could suggest a possible role of these peptides as signaling of gastric emptying or endocrine modulation, implying a main local action played by orexins., (© 2015 Wiley Periodicals, Inc.)

This review summarizes data regarding the brain expression of the orexin (hypocretin) system including: prepro-orexin (PPO), orexin A (OxA), orexin B (OxB) and the two orexin receptors 1 and 2 (OxR1, OxR2). Clinical data is limited to OxA and OxB in cerebral spinal fluid and serum/plasma, thus necessitating the development of animal models to undertake mechanistic studies. We focus on changes in animal models that were either exposed to a regime of altered sleep, metabolic energy homeostasis, exposed to drugs and noxious insults. Many more expressional studies are available for PPO, OxA and OxB levels, compared to studies of the receptors. Interestingly, the direction and pattern of change for PPO, OxA and OxB is inconsistent amongst studies, whereas for the receptors, there tends to be increased expression for both OxR1 and OxR2 after alterations in energy homeostasis, and an increased expression after noxious insults or exposure to some drugs. The clinical implications of these results from animal models are discussed in light of the findings from human studies, and future research directions are suggested to fill knowledge gaps with regard to the orexin system, particularly during early brain development., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The hypothalamus plays a central role in the integrated control of feeding. Thus, leptin has been shown to inhibit food intake apparently by inhibition of hypothalamic NPY. It has been proposed that the recently discovered orexigenic peptides named orexins could play a role analogous to that of NPY in the control of feeding. To test this hypothesis we determined the relative levels of hypothalamic prepro-orexin mRNA expression 2 h after a single dose (1 mg/kg, ip) of recombinant murine leptin in 48 h fasted mice by semiquantitative RT-PCR. We found an unexpected increase (34%; p < 0.04) of prepro-orexin mRNA which indicates that the neuronal pathways controlling feeding behaviour are more complex than initially thought and that the short-term regulation of neurotransmitters which control food intake may be different than medium- or long-term.