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Although well-studied in the context of neurodegenerative disease, a clear biological function for the synuclein proteins remains elusive. Emerging data indicate a role for synucleins in monoamine neurotransmitter homeostasis. A key regulatory component of monoamine neurotransmission is re-uptake of neurotransmitter by the dopamine transporter, norepinephrine transporter, and serotonin transporter, which are common drug targets in the treatment of depression and other mood disorders. Through interactions with these transporters, the neuronal cytoskeleton, and pre-synaptic scaffolding proteins, α-synuclein, β-synuclein, and γ-synuclein modulate trafficking, expression and function of monoamine transporters at the cell surface, thus playing a central role in regulating monoamine re-uptake., (Copyright © 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)

Central and peripheral neurons as well as neuroendocrine cells express a variety of neurotransmitters/modulators that play critical roles in regulation of physiological systems. The synthesis of several neurotransmitters/modulators is regulated by O(2)-requiring rate-limiting enzymes. Consequently, hypoxia resulting from perturbations in O(2) homeostasis can affect neuronal functions by altering neurotransmitter synthesis. Two broad categories of hypoxia are frequently encountered: continuous hypoxia (CH) and intermittent hypoxia (IH). CH is often seen during high altitude sojourns, whereas IH is experienced in sleep-disordered breathing with recurrent apneas (i.e., brief, repetitive cessations of breathing). This article presents what is currently known on the effects of both forms of hypoxia on neurotransmitter levels and neurotransmitter synthesizing enzymes in the central and peripheral nervous systems.

Mitochondrial function is of particular importance in brain because of its high demand for energy (ATP) and efficient removal of reactive oxygen species (ROS). We developed rat mitochondrion-neuron focused microarray (rMNChip) and integrated bioinformatics tools for rapid identification of differential pathways in brain tissues. rMNChip contains 1,500 genes involved in mitochondrial functions, stress response, circadian rhythms and signal transduction. The bioinformatics tool includes an algorithm for computing of differentially expressed genes, and a database for straightforward and intuitive interpretation for microarray results. Our application of these tools to RNA samples derived from rat frontal cortex (FC), hippocampus (HC) and hypothalamus (HT) led to the identification of differentially-expressed signal-transduction-bioenergenesis and neurotransmitter-synthesis pathways with a dominant number of genes (FC/HC = 55/6; FC/HT = 55/4) having significantly (p<0.05, FDR<10.70%) higher (≥1.25 fold) RNA levels in the frontal cortex than the others, strongly suggesting active generation of ATP and neurotransmitters and efficient removal of ROS. Thus, these tools for rapid and efficient identification of differential pathways in brain regions will greatly facilitate our systems-biological study and understanding of molecular mechanisms underlying complex and multifactorial neurodegenerative diseases.

Drosophila, the fruit fly, is a common model organism in biology; however, quantifying neurotransmitters in Drosophila is challenging because of the small size of the central nervous system (CNS). Here, we develop neurotransmitter quantification by capillary electrophoresis with fast-scan cyclic voltammetry (CE-FSCV) detection, which allows peak identification by both migration time and the cyclic voltammogram, in contrast to traditional amperometric detection which provides no chemical identification. Tissue content of biogenic amine neurotransmitters was determined in a single CNS dissected from a Drosophila larva. Low detection limits, 1 nM for dopamine and serotonin, 2.5 nM for tyramine, and 4 nM for octopamine, were achieved using field-amplified sample stacking by diluting the homogenized tissue with percholoric acid and acetonitrile. Two different strains of wild-type flies, Oregon R and Canton S, have similar dopamine and serotonin levels but different octopamine content. When flies are fed NSD-1015, which inhibits dopamine decarboxylase (Ddc) a synthesis enzyme in the dopamine and serotonin pathways, dopamine significantly decreases by 52%. A genetically altered driver line, Ddc-GAL4, had lower serotonin and dopamine content as did w(118) flies. When the Ddc-GAL4 line was used to produce flies overexpressing the serotonin synthesis enzyme tryptophan hydroxylase (Ddc-GAL4;UAS-Trh), the serotonin tissue content was greater than for Ddc-GAL4 but not significantly different than the wild-type. These results show that CE-FSCV is useful for monitoring the impact of genetic and pharmacological manipulations on the content of multiple neurotransmitters in a CNS from a Drosophila larva.

Progesterone plays a key role in ovarian cycle-related synaptic plasticity and neuronal excitability. Progesterone receptors (PRs), which mediate the cellular actions of progesterone, are expressed in the hippocampus and other limbic regions, but their functional significance remains unknown. Here, we report a novel role of PRs as crucial mediators in the development of epileptogenesis, which is the process whereby a normal brain becomes progressively epileptic because of precipitating factors. The PR knock-out (PR(-/-)) mouse, which lacks both the PR-A and PR-B isoforms, exhibited an increased resistance to epileptogenesis in the hippocampus and amygdala kindling models. Lack of PRs markedly impaired the persistence of seizure expression at 4 weeks after kindling development. We further show that selective inhibition of PRs in the brain by antisense oligos or pharmacological blockade of PRs by RU-486 [11β-[p-(dimethylamino)phenyl]-17β-hydroxy-17-(1-propynyl)estra-4,9-dien-3-one] resulted in a significant decrease in epileptogenesis in wild-type (PR(+/+)) mice. The delayed epileptogenesis in PR knock-out mice was not substantially affected by inhibition of neurosteroid synthesis. Mice lacking PRs show supersensitivity to the antiseizure responses of progesterone. Collectively, these results suggest that PRs in the hippocampus are linked to signaling pathways that control susceptibility to epileptogenesis and possibly persistence of an epileptic-like state. The PR pathway may represent a unique target for preventing or retarding epileptogenesis in females.

Glutamate is the principal excitatory neurotransmitter in the brain, and its excessive release plays a key role in neuronal death associated with a wide range of neural disorders. Real-time monitoring of extracellular glutamate levels would be very helpful in understanding the excitotoxic process of neurotransmitters on brain injury. Toward the detection of L: -glutamate, we describe in this chapter the preparation of carbon nanotube (CNT) network probes with immobilized L: -glutamate oxidase (GLOD) by using a non-covalent functionalized method. Such GOLD-CNT network probes are evaluated with real-time electronic responses corresponding to standard glutamate solutions in vitro and a 11-vessel occlusion (11 VO) rat model in vivo. The ultrahigh sensitivity, selectivity, and fast response time of GLOD-CNT network probes are greatly promising for the real-time electronic detection of extracellular glutamate levels in brain.

In this review, we focused on the intersection between steroid metabolomics, obstetrics and steroid neurophysiology to give a comprehensive insight into the role of sex hormones and neuroactive steroids (NAS) in the mechanism controlling pregnancy sustaining. The data in the literature including our studies show that there is a complex mechanism providing synthesis of either pregnancy sustaining or parturition provoking steroids. This mechanism includes the boosting placental synthesis of CRH with approaching parturition inducing the excessive synthesis of 3beta-hydroxy-5-ene steroid sulfates serving primarily as precursors for placental synthesis of progestogens, estrogens and NAS. The distribution and changing activities of placental oxidoreductases are responsible for the activation or inactivation of the aforementioned steroids, which is compartment-specific (maternal and fetal compartments) and dependent on gestational age, with a tendency to shift the production from the pregnancy-sustaining steroids to the parturition provoking ones with an increasing gestational age. The fetal and maternal livers catabolize part of the bioactive steroids and also convert some precursors to bioactive steroids. Besides the progesterone, a variety of its 5alpha/beta-reduced metabolites may significantly influence the maintenance of human pregnancy, provide protection against excitotoxicity following acute hypoxic stress, and might also affect the pain perception in mother and fetus.

The serotonin 5-HT(2C) receptor (5-HT(2C)R) is localized to the limbic-corticostriatal circuit, which plays an integral role in mediating attention, motivation, cognition, and reward processes. The 5-HT(2C)R is linked to modulation of mesoaccumbens dopamine neurotransmission via an activation of γ-aminobutyric acid (GABA) neurons in the ventral tegmental area (VTA). However, we recently demonstrated the expression of the 5-HT(2C)R within dopamine VTA neurons suggesting the possibility of a direct influence of the 5-HT(2C)R upon mesoaccumbens dopamine output. Here, we employed double-label fluorescence immunochemistry with the synthetic enzymes for dopamine (tyrosine hydroxylase; TH) and GABA (glutamic acid decarboxylase isoform 67; GAD-67) and retrograde tract tracing with FluoroGold (FG) to uncover whether dopamine and GABA VTA neurons that possess 5-HT(2C)R innervate the nucleus accumbens (NAc). The highest numbers of FG-labeled cells were detected in the middle versus rostral and caudal levels of the VTA, and included a subset of TH- and GAD-67 immunoreactive cells, of which >50% also contained 5-HT(2C)R immunoreactivity. Thus, we demonstrate for the first time that the 5-HT(2C)R colocalizes in DA and GABA VTA neurons which project to the NAc, describe in detail the distribution of NAc-projecting GABA VTA neurons, and identify the colocalization of TH and GAD-67 in the same NAc-projecting VTA neurons. These data suggest that the 5-HT(2C)R may exert direct influence upon both dopamine and GABA VTA output to the NAc. Further, the indication that a proportion of NAc-projecting VTA neurons synthesize and potentially release both dopamine and GABA adds intriguing complexity to the framework of the VTA and its postulated neuroanatomical roles.

Inhibition of phosphodiesterase 10A (PDE10A) promotes cyclic nucleotide signaling, increases striatal activation, and decreases behavioral activity. Enhanced cyclic nucleotide signaling is a well established route to producing changes in gene expression. We hypothesized that chronic suppression of PDE10A activity would have significant effects on gene expression in the striatum. A comparison of the expression profile of PDE10A knockout (KO) mice and wild-type mice after chronic PDE10A inhibition revealed altered expression of 19 overlapping genes with few significant changes outside the striatum or after administration of a PDE10A inhibitor to KO animals. Chronic inhibition of PDE10A produced up-regulation of mRNAs encoding genes that included prodynorphin, synaptotagmin10, phosphodiesterase 1C, glutamate decarboxylase 1, and diacylglycerol O-acyltransferase and a down-regulation of mRNAs encoding choline acetyltransferase and Kv1.6, suggesting long-term suppression of the PDE10A enzyme is consistent with altered striatal excitability and potential utility as a antipsychotic therapy. In addition, up-regulation of mRNAs encoding histone 3 (H3) and down-regulation of histone deacetylase 4, follistatin, and claspin mRNAs suggests activation of molecular cascades capable of neuroprotection. We used lentiviral delivery of cAMP response element (CRE)-luciferase reporter constructs into the striatum and live animal imaging of 2-{4-[-pyridin-4-yl-1-(2,2,2-trifluoro-ethyl)-1H-pyrazol-3-yl]-phenoxymethyl}-quinoline succinic acid (TP-10)-induced luciferase activity to further demonstrate PDE10 inhibition results in CRE-mediated transcription. Consistent with potential neuroprotective cascades, we also demonstrate phosphorylation of mitogen- and stress-activated kinase 1 and H3 in vivo after TP-10 treatment. The observed changes in signaling and gene expression are predicted to provide neuroprotective effects in models of Huntington's disease.

Benzodiazepines (BDZs) enhance GABA(A) receptor inhibition by direct actions on central BDZ receptors (CBRs). Although some BDZs also bind mitochondrial receptors [translocator protein (18 kDa) (TSPO)] and promote the synthesis of GABA-enhancing neurosteroids, the role of neurosteroids in the clinical effects of BDZs is unknown. In rat hippocampal slices, we compared midazolam, an anesthetic BDZ, with clonazepam, an anticonvulsant/anxiolytic BDZ that activates CBRs selectively. Midazolam, but not clonazepam, increased neurosteroid levels in CA1 pyramidal neurons without changing TSPO immunostaining. Midazolam, but not clonazepam, also augmented a form of spike inhibition after stimulation adjacent to the pyramidal cell layer and inhibited induction of long-term potentiation. These effects were prevented by finasteride, an inhibitor of neurosteroid synthesis, or 17PA [17-phenyl-(3α,5α)-androst-16-en-3-ol], a blocker of neurosteroid effects on GABA(A) receptors. Moreover, the synaptic effects were mimicked by a combination of clonazepam with FGIN (2-[2-(4-fluorophenyl)-1H-indol-3-yl]-N,N-dihexylacetamide), a selective TSPO agonist, or a combination of clonazepam with exogenous allopregnanolone. Consistent with these in vitro results, finasteride abolished the effects of midazolam on contextual fear learning when administrated 1 d before midazolam injection. Thus, dual activation of CBRs and TSPO appears to result in unique actions of clinically important BDZs. Furthermore, endogenous neurosteroids are shown to be important regulators of pyramidal neuron function and synaptic plasticity.

This review discusses the role of beta-alanine as a neurotransmitter. Beta-alanine is structurally intermediate between alpha-amino acid (glycine, glutamate) and gamma-amino acid (GABA) neurotransmitters. In general, beta-alanine satisfies a number of the prerequisite classical criteria for being a neurotransmitter: beta-alanine occurs naturally in the CNS, is released by electrical stimulation through a Ca(2+) dependent process, has binding sites, and inhibits neuronal excitability. beta-Alanine has 5 recognized receptor sites: glycine co-agonist site on the NMDA complex (strychnine-insensitive); glycine receptor site (strychnine sensitive); GABA-A receptor; GABA-C receptor; and blockade of GAT protein-mediated glial GABA uptake. Although beta-alanine binding has been identified throughout the hippocampus, limbic structures, and neocortex, unique beta-alaninergic neurons with no GABAergic properties remain unidentified, and it is impossible to discriminate between beta-alaninergic and GABAergic properties in the CNS. Nevertheless, a variety of data suggest that beta-alanine should be considered as a small molecule neurotransmitter and should join the ranks of the other amino acid neurotransmitters. These realizations open the door for a more comprehensive evaluation of beta-alanine's neurochemistry and for its exploitation as a platform for drug design., ((c) 2010 Elsevier Ltd. All rights reserved.)

Acute ethanol administration increases potent GABAergic neuroactive steroids, specifically (3α,5α)-3-hydroxypregnan-20-one (3α,5α-THP) and (3α,5α)-3,21-dihydroxypregnan-20-one. In addition, neuroactive steroids contribute to ethanol actions. Chronic ethanol exposure results in tolerance to many effects of ethanol, including ethanol-induced increases in neuroactive steroid levels. To determine the mechanisms of tolerance to ethanol-induced increases in neuroactive steroids, we investigated critical signaling molecules that are required for acute ethanol effects. Male Sprague-Dawley rats were administered ethanol via liquid diet for 2 weeks and steroid levels, adrenocorticotrophic hormone (ACTH) and adrenal steroidogenic acute regulatory (StAR) protein expression were measured. Chronic ethanol exposure elicits tolerance to ethanol-induced elevation of serum ACTH and the steroids pregnenolone and progesterone. Surprisingly, chronic ethanol exposure does not result in tolerance to ethanol-induced increases in adrenal StAR protein. However, ethanol-induced StAR phosphorylation is decreased when compared to acute ethanol administration. A separate group of rats exposed to chronic ethanol diet were subsequently challenged with ethanol (2 g/kg) and exhibited a blunted elevation of serum ACTH and progesterone as well as cerebral cortical and hippocampal 3α,5α-THP. Administration of ACTH with the ethanol challenge restored the elevation of serum ACTH and progesterone as well as cerebral cortical 3α,5α-THP levels to those observed in ethanol-naïve rats. Thus, chronic ethanol exposure disrupts ACTH release, which results in tolerance to ethanol-induced increases in neuroactive steroid levels. Loss of the ethanol-induced increases in neuroactive steroids may contribute to behavioral tolerance to ethanol and influence the progression towards alcoholism., (© 2010 The Authors. Journal Compilation © 2010 International Society for Neurochemistry.)

Dorsal root ganglia (DRG) which contain glial cells and somas of primary sensory neurons are pivotal for neural transmission between the peripheral and central nervous systems. It is well established that neuropeptides such as substance P and calcitonin gene-related peptide located in DRG neurons control sensory and pain mechanisms. However, contrary to the brain and spinal cord which are extensively investigated, DRG received little attention. Therefore, the current knowledge on DRG may be far to represent their complete neurochemical potential. For instance, until 1997, nothing was known on DRG neurosteroidogenic ability but recently, several investigations have shown that DRG contain various key enzymes synthesizing neuroactive neurosteroids. To provide new advances into DRG neurochemistry, we reviewed and highlighted herein basic and functional evidence showing that neurosteroids are produced in DRG through a neuron-glia crosstalk mechanism. Indeed, key enzymes producing neurosteroids including pregnenolone, progesterone, dihydroprogesterone and estradiol are differentially expressed in DRG cell types. Cytochrome P450side-chain-cleavage is located in DRG neurons and satellite glial cells, 3beta-hydroxysteroid dehydrogenase is expressed in Schwann cells and neurons, 5alpha-reductase is localized in satellite glial and Schwann cells (not in neurons) while aromatase is present in neurons but not in glia. Recent studies also revealed that DRG neurosteroidogenesis is a physiologically relevant process selectively regulated under pathological conditions. Acting through paracrine and autocrine mechanisms, endogenous neurosteroids modulate DRG sensory functions and protect DRG neurons against death. The paper suggests that DRG neurosteroidogenic components may be targeted for the development of therapies against peripheral nerve injury-induced afferent noxious stimulations., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Acetyl-L-carnitine (ALCAR) is an endogenous metabolic intermediate that facilitates the influx and efflux of acetyl groups across the mitochondrial inner membrane. Exogenously administered ALCAR has been used as a nutritional supplement and also as an experimental drug with reported neuroprotective properties and effects on brain metabolism. The aim of this study was to determine oxidative metabolism of ALCAR in the immature rat forebrain. Metabolism was studied in 21-22 day-old rat brain at 15, 60 and 120 min after an intraperitoneal injection of [2-(13)C]acetyl-L-carnitine. The amount, pattern, and fractional enrichment of (13)C-labeled metabolites were determined by ex vivo(13)C-NMR spectroscopy. Metabolism of the acetyl moiety from [2-(13)C]ALCAR via the tricarboxylic acid cycle led to incorporation of label into the C4, C3 and C2 positions of glutamate (GLU), glutamine (GLN) and GABA. Labeling patterns indicated that [2-(13)C]ALCAR was metabolized by both neurons and glia; however, the percent enrichment was higher in GLN and GABA than in GLU, demonstrating high metabolism in astrocytes and GABAergic neurons. Incorporation of label into the C3 position of alanine, both C3 and C2 positions of lactate, and the C1 and C5 positions of glutamate and glutamine demonstrated that [2-(13)C]ALCAR was actively metabolized via the pyruvate recycling pathway. The enrichment of metabolites with (13)C from metabolism of ALCAR was highest in alanine C3 (11%) and lactate C3 (10%), with considerable enrichment in GABA C4 (8%), GLN C3 (approximately 4%) and GLN C5 (5%). Overall, our (13)C-NMR studies reveal that the acetyl moiety of ALCAR is metabolized for energy in both astrocytes and neurons and the label incorporated into the neurotransmitters glutamate and GABA. Cycling ratios showed prolonged cycling of carbon from the acetyl moiety of ALCAR in the tricarboxylic acid cycle. Labeling of compounds formed from metabolism of [2-(13)C]ALCAR via the pyruvate recycling pathway was higher than values reported for other precursors and may reflect high activity of this pathway in the developing brain. This is, to our knowledge, the first study to determine the extent and pathways of ALCAR metabolism for energy and neurotransmitter biosynthesis in the brain.

Relaxation of gastrointestinal smooth muscle caused by release of non-adrenergic non-cholinergic (NANC) transmitters from enteric nerves occurs in several physiologic digestive reflexes. Likely candidate NANC inhibitory agents include nitric oxide (NO), adenosine triphosphate (ATP), vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP), carbon monoxide (CO), protease-activated receptors (PARs), hydrogen sulfide (H2S), neurotensin (NT) and beta-nicotinamide adenine dinucleotide (beta-NAD). Multiple NANC transmitters work in concert, are pharmacologically coupled and are closely coordinated. Individual contribution varies regionally in the gastrointestinal tract and between species. NANC inhibition of gastrointestinal smooth muscle involves several intracellular mechanisms, including increase of cyclic guanosine monophosphate (cGMP), increase of cyclic adenosine monophosphate (cAMP) and hyperpolarization of the cell membrane via direct or indirect activation of potassium ion (K+) channels.

Gene transfer has been used to examine the role of putative neurotransmitters in the nucleus tractus solitarii (NTS). Most such studies used adenovirus vector-mediated gene transfer although adenovirus vector transfects both neuronal and non-neuronal cells. Successful transfection in the NTS has also been reported with lentivirus as the vector. Feline immunodeficiency virus (FIV), a lentivirus, may preferentially transfect neurons and could be a powerful tool to delineate physiological effects produced by altered synthesis of transmitters in neurons. However, it has not been studied in NTS. Therefore, we sought to determine whether FIV transfects rat NTS cells and to define the type of cell transfected. We found that injection of FIV encoding LacZ gene (FIVLacZ) into the NTS led to transfection of numerous NTS cells. Injection of FIVLacZ did not alter immunoreactivity (IR) for neuronal nitric oxide synthase, which we have shown resides in NTS neurons. A majority (91.7 +/- 3.9%) of transfected cells contained IR for neuronal nuclear antigen, a neuronal marker; 2.1 +/- 3.8% of transfected cells contained IR for glial fibrillary acidic protein, a glial marker. No transfected neurons or fibers were observed in the nodose ganglion, which sends afferents to the NTS. We conclude that FIV almost exclusively transfects neurons in the rat NTS from which it is not retrogradely transported. The cell-type specificity of FIV in the NTS may provide a molecular method to study local physiological functions mediated by potential neurotransmitters in the NTS.

Agriculture surplus were used as substrates to synthesize gamma-aminobutyric acid (GABA) by Lactobacillus plantarum DSM19463 for the manufacture of a functional beverage or as a novel application for dermatological purposes. Dilution of the grape must to 1 or 4% (w/v) of total carbohydrates favored higher cell yield and synthesis of GABA with respect to whey milk. Optimal conditions for synthesizing GABA in grape must were: initial pH 6.0, initial cell density of Log 7.0 cfu/mL, and addition of 18.4 mM L-glutamate. L. plantarum DSM19463 synthesized 4.83 mM of GABA during fermentation at 30 degrees C for 72 h. The fermented grape must also contain various levels of niacin, free minerals, and polyphenols, and Log 10.0 cfu/g of viable cells of L. plantarum DSM19463. Freeze dried preparation of grape must was applied to the SkinEthic(R) Reconstructed Human Epidermis or multi-layer human skin model (FT-skin tissue). The effect on transcriptional regulation of human beta-defensin-2 (HBD-2), hyaluronan synthase (HAS1), filaggrin (FGR), and involucrin genes was assayed through RT-PCR. Compared to GABA used as pure chemical compound, the up-regulation HBD-2 was similar while the effect on the expression of HAS1 and FGR genes was higher.

The forebrain circuits involved in singing and audition (the 'song system') in songbirds exhibit a remarkable capacity to synthesize and respond to steroid hormones. This review considers how local brain steroid production impacts the development, sexual differentiation, and activity of song system circuitry. The songbird forebrain contains all of the enzymes necessary for the de novo synthesis of steroids - including neuroestrogens - from cholesterol. Steroid production enzymes are found in neuronal cell bodies, but they are also expressed in pre-synaptic terminals in the song system, indicating a novel mode of brain steroid delivery to local circuits. The song system expresses nuclear hormone receptors, consistent with local action of brain-derived steroids. Local steroid production also occurs in brain regions that do not express nuclear hormone receptors, suggesting a non-classical mode of action. Recent evidence indicates that local steroid levels can change rapidly within the forebrain, in a manner similar to traditional neuromodulators. Lastly, we consider growing evidence for modulatory interactions between brain-derived steroids and neurotransmitter/neuropeptide networks within the song system. Songbirds have therefore emerged as a rich and powerful model system to explore the neural and neurochemical regulation of social behavior., (Copyright 2009 Elsevier B.V. All rights reserved.)

We examined the distribution patterns and axonal pathways of cholinergic, GABAergic, and dopaminergic neurons in the central nervous system of Ciona intestinalis larvae, based on the expression patterns of two reporter genes (GFP and LacZ) driven by the promoters of several neuron-specific genes (vesicular acetylcholine transporter, glutamic acid decarboxylase, tyrosine 3-hydroxylase and dopa decarboxylase). Putative cholinergic and GABAergic cells were found in the sensory vesicle (SV) and visceral ganglion (VG), while putative dopaminergic cells were found only in the SV. The axons of almost all putative cholinergic and GABAergic cells in the SV extend posteriorly towards the VG and seem to connect with motor neurons. Some cells extend axons to the proximal region of the tail beyond the trunk-tail boundary. As this tail region contains several neurons, these cells may modulate larval behavior through the latter neurons. We also found that some putative cholinergic and GABAergic cells in the dorsal VG form a complex and extend axons anteriorly to the SV, posteriorly to the tail, and possibly ventrally to some motor neurons. Finally, we observed that one pair of the anterior most putative cholinergic cells in the ventral VG extends axons contralaterally to the right and left caudal axon tracts. We discuss the similarity of these cells to the Mauthner cells in vertebrates.

Although alterations in the functions of neurotransmitter systems have been implicated in the pathology of Alzheimer's disease (AD), the mechanisms that give rise to these alterations are not well understood. The amount of p25, an aberrant cleavage product of p35 that activates cyclin-dependent kinase 5 (Cdk5), is elevated in AD brains. The role of Cdk5 in neurotransmitter release has been well established. In this study, we examined whether p25 was linked to altered neurotransmitter release in AD. Transient or stable expression of p25 significantly increased basal secretion of human growth hormone (hGH) or neurotransmitter in PC12 cells. Expression of a p25 phosphorylation-deficient mutant, T138A, inhibited basal hGH secretion relative to the p25 wild type, suggesting the involvement of Thr138 phosphorylation in secretion. The expression and activity of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), a key protease in the generation of beta-amyloid, are increased in AD brains. Our previous studies indicated that overexpression of BACE1 enhanced basal secretion of hGH in PC12 cells. Transient coexpression of p25 and BACE1 further stimulated spontaneous basal secretion. These results indicate a novel role for p25 in the secretory pathway and suggest that elevated levels of p25 and BACE1 in AD brains may contribute to altered neurotransmitter pathology of AD through enhancing spontaneous basal secretion.

This chapter provides an overview of neurosteroids, especially their impact on the brain, sex differences and their therapeutic potentials. Neurosteroids are synthesized within the brain and rapidly modulate neuronal excitability. They are classified as pregnane neurosteroids, such as allopregnanolone and allotetrahydrodeoxycorticosterone, androstane neurosteroids, such as androstanediol and etiocholanolone, and sulfated neurosteroids such as pregnenolone sulfate. Neurosteroids such as allopregnanolone are positive allosteric modulators of GABA-A receptors with powerful anti-seizure activity in diverse animal models. Neurosteroids increase both synaptic and tonic inhibition. They are endogenous regulators of seizure susceptibility, anxiety, and stress. Sulfated neurosteroids such as pregnenolone sulfate, which are negative GABA-A receptor modulators, are memory-enhancing agents. Sex differences in susceptibility to brain disorders could be due to neurosteroids and sexual dimorphism in specific structures of the human brain. Synthetic neurosteroids that exhibit better bioavailability and efficacy and drugs that enhance neurosteroid synthesis have therapeutic potential in anxiety, epilepsy, and other brain disorders. Clinical trials with the synthetic neurosteroid analog ganaxolone in the treatment of epilepsy have been encouraging. Neurosteroidogenic agents that lack benzodiazepine-like side effects show promise in the treatment of anxiety and depression., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Hormones are trophic factors that integrate central and peripheral nervous system functions, and can influence social, cognitive, emotional and physical (SCEP) processes. Greater understanding of behavioral and neurobiological underpinnings of mental, cognitive, and/or physical changes with maturation is becoming increasingly important as the world's population ages. There are individual differences in how people age, but the factors that influence these differences are not well understood. Social supports are one factor that may influence the trajectory of age-related processes. The loss of close relationships, especially among older persons, is one of the greatest risk factors for mental and physical decline. Progesterone, secreted by the ovaries, or produced de novo in the brain, is readily converted centrally to 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), and can influence SCEP, through rapid, non-classical steroid-mediated actions. Our hypothesis is that 3alpha,5alpha-THP is a key trophic factor in SCEP and development. Our research has demonstrated that 3alpha,5alpha-THP facilitates social and sexual behavior of rodents, which evokes further increases in 3alpha,5alpha-THP in midbrain and hippocampus, brain areas involved in SCEP. The role of 3alpha,5alpha-THP to influence social and/or sexual experience, and thereby SCEP, is discussed in this review. Further understanding of these neurobiological and/or behavioral factors may lead to findings that ultimately can promote health and prevent disease.

This review summarizes the current understanding of neurotransmitter phenotype specification of postganglionic sympathetic neurons, focusing, in particular, on the cellular processes of induction versus trans-differentiation. The emerging evidence is discussed that the noradrenergic and cholinergic neurotransmitter phenotypes are co-induced during early development and that the mature phenotypes develop by positive and negative selection of cellular properties in initially bimodal neurons, depending on extracellular signals during migration and after target contact.

The neurosteroid allopregnanolone (AP) is a GABAergic agonist that suppresses central nervous system (CNS) activity in the adult brain, and by reducing excitotoxicity is considered to be neuroprotective. A role for neurosteroids in the developing brain, particularly in late gestation, is still debated. The aim of this study was to investigate effects on proliferation and cell death in the brain of late gestation fetal sheep after inhibition of AP synthesis using finasteride, a 5alpha-reductase type 2 (5alpha-R2) inhibitor. Catheters were implanted in fetal sheep at approximately 125 days of gestation. At 3-4 days postsurgery, fetuses received infusions of either finasteride (20 mg/kg/h; n=5), the AP analogue alfaxalone (5 mg/kg/h; n=5), or finasteride and alfaxalone together (n=5). Brains were obtained at 24 h after infusion to determine cell death (apoptotic or necrotic) and cell proliferation in the hippocampus and cerebellum, areas known to be susceptible to excitotoxic damage. Finasteride treatment significantly increased apoptosis (activated caspase-3 expression) in hippocampal CA3 and CA1, and cerebellar molecular and granular layers, an effect abolished by co-infusion of alfaxalone and finasteride. Double-label immunohistochemistry showed that both neurons and astrocytes were caspase-3 positive. Finasteride treatment also increased the number of dead (pyknotic) cells in the hippocampus and cerebellum (Purkinje cells), but not when finasteride+alfaxalone was infused. Cell proliferation (Ki-67-immunoreactivity) increased after finasteride treatment; double-labeling showed the majority of Ki-67-positive cells were astrocytes. Thus, steroids such as AP appear to influence the constitutive rate of apoptosis and proliferation in the hippocampus and cerebellum of the fetal brain, and suggest an important role for neurosteroids in the development of the brain.

Growth dynamics of the synthesis of monoamine neuromediators serotonin, norepinephrine, and dopamine in Escherichia coli K-12 was investigated for the first time using high performance liquid chromatography with electrodetection. Maximum (micromolar) concentrations of these compounds were detected in E. coli cells during the early growth phases; their intracellular content decreases after the transition to late growth phases. E. coli biomass contains the substances DOPA and 5-hydroxytryptamine that serve in animal cells as neuromediator precursors and the products of their oxidative deamination. Presumably, the biosynthesis and degradation of monoamine neuromediators in bacterial cells involves enzyme systems analogous to those typical of animals. The culture fluid of E. coli contains micromolar concentrations of DOPA and nanomolar of serotonin, dopamine, and norepinephrine during the late growth phase. These concentrations are sufficient for animal/human receptors to bind them. This article deals with the potential biotechnological applications of the data obtained.

Concepts of brain-steroid signaling have traditionally placed emphasis on the gonads and adrenals as the source of steroids, the strict dichotomy of early developmental ("organizational") and mature ("activational") effects, and a relatively slow mechanism of signaling through intranuclear receptors. Continuing research shows that these concepts are not inaccurate, but they are certainly incomplete. In this review, we focus on the song control circuit of songbird species to demonstrate how each of these concepts is limited. We discuss the solid evidence for steroid synthesis within the brain ("neurosteroidogenesis"), the role of neurosteroids in organizational events that occur both early in development and later in life, and how neurosteroids can act in acute and non-traditional ways. The songbird model therefore illustrates how neurosteroids can dramatically increase the diversity of steroid-sensitive brain functions in a behaviorally-relevant system. We hope this inspires further research and thought into neurosteroid signaling in songbirds and other animals.

Brain sex steroids are derived from both peripheral (primarily gonadal) and local (neurosteroids) sources and are crucial for neurogenesis, neural differentiation and neural function. The mechanism(s) regulating the production of neurosteroids is not understood. To determine whether hypothalamic-pituitary-gonadal axis components previously detected in the extra-hypothalamic brain comprise a feedback loop to regulate neuro-sex steroid (NSS) production, we assessed dynamic changes in expression patterns of steroidogenic acute regulatory (StAR) protein, a key regulator of steroidogenesis, and key hypothalamic-pituitary-gonadal endocrine receptors, by modulating peripheral sex hormone levels in female mice. Ovariectomy (OVX; high serum gonadotropins, low serum sex steroids) had a differential effect on StAR protein levels in the extrahypothalamic brain; increasing the 30- and 32-kDa variants but decreasing the 37-kDa variant and is indicative of cholesterol transport into mitochondria for steroidogenesis. Treatment of OVX animals with E(2), P(4), or E(2) + P(4) for 3 days, which decreases OVX-induced increases in GnRH/gonadotropin production, reversed this pattern. Suppression of gonadotropin levels in OVX mice using the GnRH agonist leuprolide acetate inhibited the processing of the 37-kDa StAR protein into the 30-kDa StAR protein, confirming that the differential processing of brain StAR protein is regulated by gonadotropins. OVX dramatically suppressed extra-hypothalamic brain gonadotropin-releasing hormone 1 receptor expression, and was further suppressed in E(2)- or P(4)-treated OVX mice. Together, these data indicate the existence of endocrine and autocrine/paracrine feedback loops that regulate NSS synthesis. Further delineation of these feedback loops that regulate NSS production will aid in developing therapies to maintain brain sex steroid levels and cognition.

Traumatic brain injury (TBI) results in a cerebral metabolic crisis that contributes to poor neurologic outcome. The aim of this study was to characterize changes in oxidative glucose metabolism in early periods after injury in the brains of immature animals. At 5 h after controlled cortical impact TBI or sham surgery to the left cortex, 21-22 day old rats were injected intraperitoneally with [1,6-13C]glucose and brains removed 15, 30 and 60 min later and studied by ex vivo 13C-NMR spectroscopy. Oxidative metabolism, determined by incorporation of 13C into glutamate, glutamine and GABA over 15-60 min, was significantly delayed in both hemispheres of brain from TBI rats. The most striking delay was in labeling of the C4 position of glutamate from neuronal metabolism of glucose in the injured, ipsilateral hemisphere which peaked at 60 min, compared with the contralateral and sham-operated brains, where metabolism peaked at 30 and 15 min, respectively. Our findings indicate that (i) neuronal-specific oxidative metabolism of glucose at 5-6 h after TBI is delayed in both injured and contralateral sides compared with sham brain; (ii) labeling from metabolism of glucose via the pyruvate carboxylase pathway in astrocytes was also initially delayed in both sides of TBI brain compared with sham brain; (iii) despite this delayed incorporation, at 6 h after TBI, both sides of the brain showed apparent increased neuronal and glial metabolism, reflecting accumulation of labeled metabolites, suggesting impaired malate aspartate shuttle activity. The presence of delayed metabolism, followed by accumulation of labeled compounds is evidence of severe alterations in homeostasis that could impair mitochondrial metabolism in both ipsilateral and contralateral sides of brain after TBI. However, ongoing oxidative metabolism in mitochondria in injured brain suggests that there is a window of opportunity for therapeutic intervention up to at least 6 h after injury.

Focal ischemia leads to functional deafferentation of regions connected to the ischemic area via fiber tracts. Using i.v. administration of 13C-labeled glucose and acetate combined with ex vivo 13C MR spectroscopy and HPLC of brain extracts we identify the effect of middle cerebral artery occlusion (MCAO) on neurotransmitter synthesis and turnover, and on neuro-astrocytic interactions in the non-ischemic cerebellum and in contralesional lateral caudoputamen plus lower parietal cortex (LPC), and upper frontoparietal cortex (UFPCx) in the rat after 30, 60, 120 and 240 min of ischemia. In all regions, there was a significant persisting loss of glutamate, and in LCP and UFPCx also of glutamine, but only in LCP was GABA reduced at all times. Metabolism and blood flow were uncoupled in all regions. In cerebellum, glucose metabolism as well as utilization of intermediates derived from astrocytic tricarboxylic acid cycle activity were significantly decreased at all times in both glutamatergic and GABAergic neurons. In LCP and UFPCx, there were normal or increased enrichment in glutamate and GABA from glucose. Glutamate derived from astrocytic acetate metabolism was increased, but GABA synthesis from acetate was initially impaired. The results showed that both the type of afferent connection, i.e., glutamatergic and/or GABAergic, and local cytoarchitecture, determined the effect MCAO had on metabolic activity in the non-ischemic regions. In conclusion, it was primarily excitatory input into non-ischemic regions that was affected by MCAO, perhaps enabling resetting of the excitatory/inhibitory balance, aiding reshaping of the receptive fields and thus facilitating recovery.

The brains of animals show chemical, anatomical, and functional differences, such as dopamine production and structure of sleep, between Amniota and older groups. In addition, play behavior, capacity to acquire taste aversion, sensory pleasure in decision making, and expression of emotional tachycardia and fever started also to be displayed by Amniota, suggesting that the brain may have began to work differently in early Amniota than in Lissamphibia and earlier vertebrates. Thus we propose that emotion, and more broadly speaking consciousness, emerged in the evolutionary line among the early Amniota. We also propose that consciousness is characterized by a common mental pathway that uses pleasure, or its counterpart displeasure, as a means to optimize behavior.

Purpose: Cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc) catalyzes the initial step in the biosynthesis of neurosteroids within the brain. We sought to determine which cells express P450cc and whether neurosteroids play a role in the regulation of epileptogenesis following pilocarpine-induced status epilepticus (SE)., Methods: Rats experienced uninterrupted SE or SE terminated with diazepam at 60, 120, and 180 min. P450scc induction in CA3 hippocampus was determined by double immunolabeling with P450scc antiserum and monoclonal antibodies against GFAP (astrocytes), RIP (oligodendrocytes), or heme oxygenase-1 (microglia)., Results: SE was associated with P450scc induction in many astrocytes and a small number of microglia and oligodendrocytes in the hippocampal CA3 strata radiatum and lacunosum-moleculare. The extent of P450scc induction increased with increasing SE duration. Paradoxically, increased P450scc induction in rats experiencing SE for 180 min or more was associated with the delayed onset of spontaneous recurrent seizures. Treatment with the 5 alpha-reductase inhibitor finasteride (100 mg/kg/day for 25 days), which inhibits the synthesis of gamma-aminobutyric acid (GABA)(A) receptor modulating neurosteroids such as allopregnanolone, was associated with a significant reduction in time to the onset of spontaneous seizures in rats exposed to 180-min but not 90-min SE., Discussion: P450scc is induced by SE in a diverse population of hippocampal glia. Induction of P450scc is associated with the delayed onset of spontaneous seizures. Conversely, inhibition of neurosteroid synthesis accelerated the onset of spontaneous seizures, but only in animals exhibiting significant increases in P450scc. These findings suggest that induction of neurosteroid synthesis in reactive glial cells is associated with delayed onset of spontaneously recurrent seizures.

The aim of this work was evaluation of expression of ghrelin and GHS-R1a receptor in somatotrops and in neuronal cells of brain tissue in the process of human fetal ontogenesis. Relations were also looked for between GHRH and SS in the pituitary and in the CNS neurones of the studied fetuses. The study was based on 8 pituitaries and 8 brains from fetuses in different periods of intrauterine life. The immunocytochemical technique was used. The presence of ghrelin, GHS-R was shown in the glandular part of the pituitary and CNS during the whole period of intrauterine life. Neurohormones in the stalk of the pituitary were found in fetuses from the 32nd week of pregnancy whereas in the CNS neurones these hormones could be detected throughout the whole period of intrauterine life. The results obtained suggest that stimulation of GH secretion by ghrelin is independent of the feedback concentration and these two hormones act like signals of metabolic balance. GH release by ghrelin in fetal life is independent of somatostatin. The hypothalamic-pituitary axis which regulates pulsatile GH release from the pituitary matures functionally in the third trimester of pregnancy independent of the previous anatomical differentiation.

Inborn errors of metabolism (IEMs) may present in adolescence or adulthood with various movement disorders including parkinsonism, dystonia, chorea, tics or myoclonus. Main diseases causing movement disorders are metal-storage diseases, neurotransmitter synthesis defects, energy metabolism disorders and lysosomal storage diseases. IEMs should not be missed as many are treatable. Here we briefly review IEMs causing movement disorders in adolescence and adults and propose a simple diagnostic approach to guide metabolic investigations based on the clinical course of symptoms, the type of abnormal movements, and brain MRI abnormalities.

The neuronal ceroidlipofuscinoses (NCL) are a group of neurodegenerative disorders and are the most common lysosomal storage diseases of infancy and childhood. Juvenile NCL is caused by CLN3 mutation, producing retinal degeneration, uncontrollable seizures, cognitive and motor decline, and early death before the age of 30 years. To study the pathogenetic mechanisms of the disease, Cln3 knock-in mice (Cln3(Deltaex7/8)) have been generated, which reproduce the 1.02-kb deletion in the CLN3 gene observed in more than 85% of juvenile NCL patients. To characterize the impact of the common Cln3 mutation on development of autofluorescent storage material, gliosis, glucose metabolism, oxidative stress, and transmitter receptors during postnatal brain maturation, brain tissue of Cln3(Deltaex7/8) mice at the ages of 3, 4, 5, 6, 9, and 19 months was subjected to immunocytochemistry to label gliotic markers and nitric oxide synthases; photometric assays to assess enzyme activities of glycolysis and antioxidative defense systems; and level of reactive nitrogen species as well as quantitative receptor autoradiography to detect select cholinergic, glutamatergic, and GABAergic receptor subtypes. The developmental increase in cerebral cortical autofluorescent lipofuscin-like deposition is accompanied by a significant astro- and microgliosis, increased activities of lactate dehydrogenase and phosphofructokinase, decreased level of glutathione peroxidase, enhanced amount of reactive nitrogen species, and lowered binding levels of N-methyl-D-aspartate- and M1-muscarinic acetylcholine receptors in select brain regions but hardly in GABA(A) receptor sites compared with wild-type mice. Detailed elucidation of the sequence of pathological events during postnatal development highlights new potential strategies for symptomatic treatment of the disease., ((c) 2008 Wiley-Liss, Inc.)

Hypocretins (orexins) are wake-promoting neuropeptides produced by hypothalamic neurons. These hypocretin-producing cells are lost in people with narcolepsy, possibly due to an autoimmune attack. Prior studies described hypocretin neurons in the enteric nervous system, and these cells could be an additional target of an autoimmune process. We sought to determine whether enteric hypocretin neurons are lost in narcoleptic subjects. Even though we tried several methods (including whole mounts, sectioned tissue, pre-treatment of mice with colchicine, and the use of various primary antisera), we could not identify hypocretin-producing cells in enteric nervous tissue collected from mice or normal human subjects. These results raise doubts about whether enteric neurons produce hypocretin.

The combination of pulse-chase experiments with high-performance liquid chromatography and continuous flow scintillation detection was used successfully to determine the effects of chronic diabetes on neurosteroid production in the adult rat spinal cord. The long-term diabetes was induced by treatment of adult rats with streptozotocin. In the first part, the review provides an extensive description of the HPLC combined with continuous flow scintillation detection method, its advantages and appropriateness for the question investigated. Afterwards, the paper shows that progesterone formation is up-regulated in the spinal cord of diabetic rats while the biosynthesis of tetrahydroprogesterone decreased. The down-regulation of tetrahydroprogesterone appeared as a mechanism facilitating progesterone accumulation in the spinal cord of streptozotocin-treated rats. Progesterone is well known to be a potent neuroprotective steroid. Enhancement of its biosynthesis may be an endogenous mechanism triggered by neural cells in the spinal tissue to cope with degenerative effects provoked by chronic diabetes. Since steroid metabolism in the spinal cord is pivotal for the modulation of several neurobiological processes including sensorimotor activities, the data analyzed herein may constitute useful information for the development of efficient strategies against deleterious effects of diabetes on the nervous system.

Steroid hormones play a key role in the pathophysiology of several brain disorders. Testosterone modulates neuronal excitability, but the underlying mechanisms are obscure. There is emerging evidence that testosterone-derived "androgenic neurosteroids", 3alpha-androstanediol and 17beta-estradiol, mediate the testosterone effects on neural excitability and seizure susceptibility. Testosterone undergoes metabolism to neurosteroids via two distinct pathways. Aromatization of the A-ring converts testosterone into 17beta-estradiol. Reduction of testosterone by 5alpha-reductase generates 5alpha-dihydrotestosterone, which is then converted to 3alpha-androstanediol, a powerful GABA(A) receptor-modulating neurosteroid with anticonvulsant properties. Although the 3alpha-androstanediol is an emerging neurosteroid in the brain, there is no specific and sensitive assay for determination of 3alpha-androstanediol in biological samples. This article describes the development and validation of mass spectrometric assay of 3alpha-androstanediol, and the molecular mechanisms underlying the testosterone modulation of seizure susceptibility. A liquid chromatography-tandem mass spectrometry assay to measure 3alpha-androstanediol is validated with excellent linearity, specificity, sensitivity, and reproducibility. Testosterone modulation of seizure susceptibility is demonstrated to occur through its conversion to neurosteroids with "anticonvulsant" and "proconvulsant" actions and hence the net effect of testosterone on neural excitability and seizure activity depends on the levels of distinct testosterone metabolites. The proconvulsant effect of testosterone is associated with increases in plasma 17beta-estradiol concentrations. The 5alpha-reduced metabolites of testosterone, 5alpha-dihydrotestosterone and 3alpha-androstanediol, had powerful anticonvulsant activity. Overall, the testosterone-derived neurosteroids 3alpha-androstanediol and 17beta-estradiol could contribute to the net cellular actions of testosterone in the brain. Because 3alpha-androstanediol is a potent positive allosteric modulator of GABA(A) receptors, it could serve as an endogenous neuromodulator of neuronal excitability in men. The 3alpha-androstanediol assay is an important tool in this area because of the growing interest in the potential to use adjuvant aromatase inhibitor therapy to improve treatment of epilepsy.

Delirium, or acute brain dysfunction, is a life-threatening global disturbance in cognitive functioning that frequently manifests in critically ill patients. This review examines the current status of knowledge regarding the pathophysiology of delirium in the ICU, in particular, evaluating the role of iatrogenic factors such as sedatives and analgesic administration in brain dysfunction. This hypothesis is considered along with several other plausible mechanisms of ICU delirium, including sepsis, postoperative cognitive dysfunction, and changes in biomarkers and neurotransmitters. The review concludes by highlighting potential future directions in molecular genetics for the elucidation of delirium and its long-term consequences.

Peptide neurotransmitters and peptide hormones, collectively known as neuropeptides, are required for cell-cell communication in neurotransmission and for regulation of endocrine functions. Neuropeptides are synthesized from protein precursors (termed proneuropeptides or prohormones) that require proteolytic processing primarily within secretory vesicles that store and secrete the mature neuropeptides to control target cellular and organ systems. This review describes interdisciplinary strategies that have elucidated two primary protease pathways for prohormone processing consisting of the cysteine protease pathway mediated by secretory vesicle cathepsin L and the well-known subtilisin-like proprotein convertase pathway that together support neuropeptide biosynthesis. Importantly, this review discusses important areas of current and future biomedical neuropeptide research with respect to biological regulation, inhibitors, structural features of proneuropeptide and protease interactions, and peptidomics combined with proteomics for systems biological approaches. Future studies that gain in-depth understanding of protease mechanisms for generating active neuropeptides will be instrumental for translational research to develop pharmacological strategies for regulation of neuropeptide functions. Pharmacological applications for neuropeptide research may provide valuable therapeutics in health and disease.

Hydrogen sulfide (H2S), which is well known traditionally as a toxic gas, has been proven to be produced endogenously by 3 enzymes in mammalian tissues and plays important roles in physiological and pathophysiological conditions. In the central nervous system, H2S functions as not only a neuromodulator, but also a neuroprotectant against oxidative stress. In the cardiovascular system, H2S relaxes vascular smooth muscles by the activation of KATP channels and inhibits smooth muscle cell proliferation via the mitogen-activated protein kinase signaling pathway. These effects are important for maintaining blood pressure and preventing vessel structural remodeling, and identifies H2S as an important factor in the development of some vascular diseases, such as hypertension. H2S also shows cardioprotective effects in ischemic myocardium and septic and endotoxin shock. Recent studies have demonstrated a new mechanism to explain the motor effect of H2S on the rat detrusor muscle, which is through the activation of the capsaicin-sensitive primary neuron. This review focuses on the recent research achievements on H2S and discloses the great potential of H2S as the third gaseous transmitter in cardiac protection.

Intracerebral haemorrhage (ICH) is a devastating form of stroke that accounts for roughly 10% of all strokes and the effects on those that survive are often debilitating. To date, no suitable therapy exists. Recent work has examined alterations in gene and protein expression after ICH. The focus of this review is to outline the current knowledge of changes in genetic and protein expression after ICH and how those changes may affect the course of brain injury. Both animal and human data are reviewed.

Mesenchymal stem cells (MSCs) are mesoderm-derived cells, primarily resident in adult bone marrow (BM). MSCs exhibit lineage differentiation to generate cells such as BM stroma, fat, and cartilage. Recent studies have reported the transdifferentiation of MSCs to cells of ectodermal and endodermal origin. Previously, we have reported transdifferentiation of human (h) MSCs into neuronal cells using retinoic acid (RA) as a differentiating agent. This study presents a more efficient induction method and rigorously characterizes the development using molecular, cellular, and functional approaches. A cocktail of induction agents containing basic fibroblast growth factor (bFGF) and RA generated cells that expressed glial and neuronal progenitor markers (GFAP) at day 2 post-induction. By day 12, 90% of hMSCs differentiated into cells that expressed markers consistent for neurons, including transcription factors linked to the development of differentiated neurons. Furthermore, cell proliferation studies and western blots for cell cycle-specific proteins demonstrated day-12 induced cells to be post-mitotic cells with no evidence of cell death. The cells exhibited spontaneous post-synaptic currents and were capable of neurotransmitter synthesis, packaging, and release. Together, the improved induction protocol, combined with an interdisciplinary approach to verify that hMSCs can differentiate into neuronal cells, provides a step toward translational application with models of regenerative medicine.

Proteins of the interleukin-1 (IL-1) system include the secreted agonist IL-1beta, and the receptor antagonist IL-1ra, both competing for binding to the IL-1 receptor (IL-1R). IL-1beta and IL-1ra are highly inducible under different forms of stress, such as excitatory neurotransmitter excess occurring during seizures, in infection and inflammation, and during neurotrauma. In each of these conditions induction of IL-1beta precedes that of IL-1ra, resulting in up to 10-20-fold elevation of IL-1beta concentrations. Consequently, IL-1beta induces the elevation of other proinflammatory molecules, including IL-6, IL-1R1, COX2, and iNOS, as well as of IL-1ra. Elevation of IL-1ra is of key importance for quenching the inflammatory response at the IL-1R1 as part of an autoregulatory loop. In seizures, IL-1ra is a strong anticonvulsant and in IL-1beta-dependent fever, a powerful antipyretic. In traumatic brain injury (TBI), the ability of patients to mount an IL-1ra response, as measured in the CSF, strongly correlated with the neurological outcome. Selective induction or pharmacological application of IL-1ra may be sparing neurons in seizures and neurotrauma.

Theanine (r-glutamylethylamide) is one of the major amino acid components in green tea. Recent studies suggest that theanine affects neurotransmission, especially inhibitory neurotransmission. In this study, we investigated whether theanine affects brain development in infant rats, because inhibitory neurotransmission is required for mature brain function. Mother rats were fed theanine ad libitum after confinement. The body weight gain rate of infants was not different from control infants. We detected theanine in the infant serum and measured neurotransmitter concentration and nerve growth factor (NGF) mRNA level in the infant rat brain. Some neurotransmitters, including dopamine, serotonin, glycine and GABA concentration, increased in the infant brain and NGF mRNA level increased in the cerebral cortex and hippocampus. However, these differences were lost by the end of nerve maturity. These results suggest that theanine enhanced synthesis of nerve growth factor and neurotransmitters during a nerve maturing period and promoted central nerve system maturation (CNS). Thus, theanine accelerated maturation. In conclusion, theanine may assist in healthy brain function development.

Ubiquitination regulates the degradation, membrane trafficking, and transcription of proteins. At mammalian synapses, the ubiquitin-proteasome system (UPS) influences synaptic transmission and plasticity. Nicotine also has the ability to affect synaptic function via mechanisms that remain partially unknown. We found that nicotine, at concentrations achieved by smokers, reduced proteasomal activity, produced accumulation of ubiquitinated synaptic proteins, and increased total protein levels. In particular, a 24 h exposure to nicotine decreased proteasome-dependent degradation of the alpha7 nicotinic acetylcholine receptor (nAChR) subunit, as indicated by the accumulation of ubiquitinated alpha7. The same nicotine treatment increased the levels of the AMPA glutamate receptor subunit GluR1, the NMDA receptor subunit NR2A, the metabotropic receptor mGluR1alpha, the plasticity factor Homer-1A, and the scaffolding postsynaptic density protein PSD-95, whereas the levels of another scaffolding protein, Shank, were reduced. These changes were associated with an inhibition of proteasomal chymotrypsin-like activity by nicotine. The nAChR antagonist mecamylamine was only partially able to block the effects of nicotine on the UPS, indicating that nAChR activation does not completely explain nicotine-induced inhibition of proteasomal catalytic activity. A competition binding assay suggested a direct interaction between nicotine and the 20S proteasome. These results suggest that the UPS might participate in nicotine-dependent synaptic plasticity.

Changes in the response to release of a single synaptic vesicle have generally been attributed to postsynaptic modification of receptor sensitivity, but considerable evidence now demonstrates that alterations in vesicle filling also contribute to changes in quantal size. Receptors are not saturated at many synapses, and changes in the amount of transmitter per vesicle contribute to the physiological regulation of release. On the other hand, the presynaptic factors that determine quantal size remain poorly understood. Aside from regulation of the fusion pore, these mechanisms fall into two general categories: those that affect the accumulation of transmitter inside a vesicle and those that affect vesicle size. This review will summarize current understanding of the neurotransmitter cycle and indicate basic, unanswered questions about the presynaptic regulation of quantal size.

Initially, the idea that neurotransmitters could serve as immunomodulators emerged with the discovery that their release and diffusion from nervous tissue could lead to signaling through lymphocyte cell-surface receptors and the modulation of immune function. It is now evident that neurotransmitters can also be released from leukocytes and act as autocrine or paracrine modulators. Here, we review the data indicating that leukocytes synthesize and release 'neurotransmitters' and we also discuss the diverse effects that these compounds exert in a variety of immune cells. The role of neurotransmitters in immune-related diseases is also reviewed succinctly. Current and future developments in understanding the cross-talk between the immune and nervous systems will probably identify new avenues for treating immune-mediated diseases using agonists or antagonists of neurotransmitter receptors.

Brain glutamate/glutamine cycling is incomplete without return of ammonia to glial cells. Previous studies suggest that alanine is an important carrier for ammonia transfer. In this study, we investigated alanine transport and metabolism in Guinea pig brain cortical tissue slices and prisms, in primary cultures of neurons and astrocytes, and in synaptosomes. Alanine uptake into astrocytes was largely mediated by system L isoform LAT2, whereas alanine uptake into neurons was mediated by Na(+)-dependent transporters with properties similar to system B(0) isoform B(0)AT2. To investigate the role of alanine transport in metabolism, its uptake was inhibited in cortical tissue slices under depolarizing conditions using the system L transport inhibitors 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid and cycloleucine (1-aminocyclopentanecarboxylic acid; cLeu). The results indicated that alanine cycling occurs subsequent to glutamate/glutamine cycling and that a significant proportion of cycling occurs via amino acid transport system L. Our results show that system L isoform LAT2 is critical for alanine uptake into astrocytes. However, alanine does not provide any significant carbon for energy or neurotransmitter metabolism under the conditions studied.