Larval feeding status regulates the transcript levels of genes encoding PTTH and allatoregulatory peptides in silkworm Bombyx mori

In Bombyx mori, two dorsolateral neurosecretory cells (NSCs) in each of the two brain lobes have been identified as prothoracicotropic hormone (PTTH) producing cells. This neuropeptide in insects stimulates the prothoracic gland for the synthesis and release of ecdysone, responsible for the molting events. Allatotropin (AT) and allatostatin (AST) are allatoregulatory neuropeptides that regulate juvenile hormone biosynthesis. Here, by using RT-qPCR, we showed that in B. mori, nutritional stress modulates the mRNA expression of AT and AST-C (allatostain type C) in the central nervous system consisting of the brain lobes and all the associated ganglia. Using whole-mount in situ hybridization, we showed that the feeding status of Bombyx larvae also influences the expression of PTTH in the NSCs of the brain. Food deprivation significantly decreased the mRNA expression levels of PTTH in larvae at active or terminal growth period. Further, we showed that insulin modulates the expression level of PTTH. However, its action was dependent on the feeding status of the larvae. At feeding, the insulin decreased the PTTH expression level, while at food deprivation, the insulin increased the PTTH expression level. The data thus indicates that larval feeding status plays an important role in altering the mRNA expression levels of allatoregulatory peptide genes and PTTH.

Biocidal efficacy of tutin and its influence on immune cells and expression of growth-blocking and neuroglian peptides in Mythimna separata (Lepidoptera: Noctuidae)

Mythimna separata Walker (Lepidoptera: Noctuidae) is one of the major pests that can cause severe damage to grain crops. The development of low-toxicity and high-performance botanical insecticides is becoming the focus of new pesticide research to control M. separata. Tutin, a sesquiterpene lactone compound obtained from Coriaria sinica Maxim, a native Chinese poisonous plant, has antifeedant, absorption, and stomach poisoning against a variety of pests. To understand the toxic effect of tutin on M. separata larvae, we set out to determine their antifeedant, mortality, paralysis, weight change, and to examine the spreading of M. separata hemocytes under different concentrations of tutin treatment. Tissue distribution of the immune-associated gene growth-blocking peptide (GBP) and neuroglian peptide (Nrg) was detected by reverse transcription polymerase chain reaction (PCR). Furthermore, real-time quantitative PCR was carried out to determine the expression profiles of GBP and Nrg after different concentrations of tutin stimulation. Our results revealed that tutin exhibited significant antifeedant and insecticidal activities, paralysis, weight loss to M. separata. Besides, tutin significantly influenced on the morphology of hemocytes and enhanced the expression of GBP and Nrg in M. separata.

The endocannabinoid system is affected by a high-fat-diet in rainbow trout

The endocannabinoid system (ECs) is a well known contributor to the hedonic regulation of food intake (FI) in mammals whereas in fish, the knowledge regarding hedonic mechanisms that control FI is limited. Previous studies reported the involvement of ECs in FI regulation in fish since anandamide (AEA) treatment induced enhanced FI and changes of mRNA abundance of appetite-related neuropeptides through cannabinoid receptor 1 (cnr1). However, no previous studies in fish evaluated the impact of palatable food like high-fat diets (HFD) on mechanisms involved in hedonic regulation of FI including the possible involvement of ECs. Therefore, we aimed to evaluate the effect of feeding a HFD on the response of ECs in rainbow trout (Oncorhynchus mykiss). First, we demonstrated a higher intake over 4 days of HFD compared with a control diet (CD). Then, we evaluated the postprandial response (1, 3 and 6 h) of components of the ECs in plasma, hypothalamus, and telencephalon after feeding fish with CD and HFD. The results obtained indicate that the increased FI of HFD occurred along with increased levels of 2-arachidonoylglycerol (2-AG) and AEA in plasma and in brain areas like hypothalamus and telencephalon putatively involved in hedonic regulation of FI in fish. Decreased mRNA abundance of EC receptors like cnr1, gpr55 and trpv1 suggest a feed-back counter-regulatory mechanism in response to the increased levels of EC. Furthermore, the results also suggest that neural activity players associated to FI regulation in mammals as cFOS, γ-Amino butyric acid (GABA) and brain derived neurotrophic factor (BDNF)/neurotrophic receptor tyrosine kinase (NTRK) systems could be involved in the hedonic eating response to a palatable diet in fish.

Pleiotropic effects of proopiomelanocortin and VGF nerve growth factor inducible neuropeptides for the long-term regulation of energy balance

Seasonal rhythms in energy balance are well documented across temperate and equatorial zones animals. The long-term regulated changes in seasonal physiology consists of a rheostatic system that is essential to successful time annual cycles in reproduction, hibernation, torpor, and migration. Most animals use the annual change in photoperiod as a reliable and robust environmental cue to entrain endogenous (i.e. circannual) rhythms. Research over the past few decades has predominantly examined the role of first order neuroendocrine peptides for the rheostatic changes in energy balance. These anorexigenic and orexigenic neuropeptides in the arcuate nucleus include neuropeptide y (Npy), agouti-related peptide (Agrp), cocaine and amphetamine related transcript (Cart) and pro-opiomelanocortin (Pomc). Recent studies also indicate that VGF nerve growth factor inducible (Vgf) in the arcuate nucleus is involved in the seasonal regulation of energy balance. In situ hybridization, qPCR and RNA-sequencing studies have identified that Pomc expression across fish, avian and mammalian species, is a neuroendocrine marker that reflects seasonal energetic states. Here we highlight that long-term changes in arcuate Pomc and Vgf expression is conserved across species and may provide rheostatic regulation of seasonal energy balance.

Modulatory effects of neuropeptides on pentylenetetrazol-induced epileptic seizures and neuroinflammation in rats

OBJECTIVE

We aimed to explore the effects of neuropeptides ghrelin, obestatin, and vasoactive intestinal peptide (VIP) on seizures and plasma concentrations of neuroinflammation biomarkers including calcitonin gene-related peptide (CGRP), substance-P (SP), and interleukin-1 beta (IL-1β) in pentylenetetrazol-induced seizures in rats.

METHODS

Ghrelin (80 µg/kg), obestatin (1 µg/kg), VIP (25 ng/kg) or saline were administered to rats intraperitoneally 30 min before pentylenetetrazole (PTZ, 50 mg/kg) injections. Stages of epileptic seizures were evaluated by Racine's scale, and plasma CGRP, SP, and IL-1β concentrations were measured using ELISA.

RESULTS

Both obestatin and VIP shortened onset-time of generalized tonic-clonic seizure, respectively, moreover VIP also shortened the onset-time of first myoclonic-jerk induced by PTZ. While PTZ increased plasma CGRP, SP and IL-1β concentrations, ghrelin reduced the increases evoked by PTZ. While VIP further increased PTZ-evoked CGRP levels, it diminished IL-1β concentrations. However, obestatin did not change CGRP, SP, and IL-1β concentrations.

CONCLUSION

Our results suggest that ghrelin acts as an anticonvulsant, obestatin acts as a proconvulsant, and VIP has dual action on epilepsy. Receptors of those neuropeptides may be promising targets for epilepsy treatment.

Sex Differences in Steroid Receptor Coexpression and Circadian-Timed Activation of Kisspeptin and RFRP-3 Neurons May Contribute to the Sexually Dimorphic Basis of the LH Surge

In rodents, the ovulation-inducing luteinizing hormone (LH) surge is sexually dimorphic, occurring only in females, but the reasons for this sex difference are unclear. Two neuropeptides, kisspeptin and RFamide-related peptide 3 (RFRP-3), are hypothesized to regulate the gonadotropin-releasing hormone (GnRH)/LH surge. In females, both of these systems show circadian changes coincident with the LH surge, but whether males show similar temporal changes under comparable hormonal conditions is unknown. Here, we evaluated circadian time (CT)-dependent changes in gene expression and neuronal activation of Kiss1 and Rfrp neurons of female and male mice given identical LH surge-inducing estrogen regimens. As expected, females, but not males, displayed a late afternoon LH surge and GnRH neuronal activation. Kiss1 expression in the anteroventral periventricular nucleus (AVPV) was temporally increased in females in the late afternoon, whereas males demonstrated no temporal changes in AVPV Kiss1 expression. Likewise, neuronal activation of AVPV Kiss1 neurons was dramatically elevated in the late afternoon in females but was low at all circadian times in males. Estrogen receptor α levels in AVPV Kiss1 neurons were sexually dimorphic, being higher in females than males. AVPV progesterone receptor levels were also higher in females than males. Hypothalamic Rfrp messenger RNA levels showed no CT-dependent changes in either sex. However, Rfrp neuronal activation was temporally diminished in the afternoon/evening in females but not males. Collectively, the identified sex differences in absolute and CT-dependent AVPV Kiss1 levels, AVPV sex steroid receptor levels, and circadian-timed changes in neuronal activation of both Kiss1 and Rfrp neurons suggest that multiple sexually dimorphic processes in the brain may underlie proper LH surge generation.

Role of Hypothalamic VGF in Energy Balance and Metabolic Adaption to Environmental Enrichment in Mice

Environmental enrichment (EE), a housing condition providing complex physical, social, and cognitive stimulation, leads to improved metabolic health and resistance to diet-induced obesity and cancer. One underlying mechanism is the activation of the hypothalamic-sympathoneural-adipocyte axis with hypothalamic brain-derived neurotrophic factor (BDNF) as the key mediator. VGF, a peptide precursor particularly abundant in the hypothalamus, was up-regulated by EE. Overexpressing BDNF or acute injection of BDNF protein to the hypothalamus up-regulated VGF, whereas suppressing BDNF signaling down-regulated VGF expression. Moreover, hypothalamic VGF expression was regulated by leptin, melanocortin receptor agonist, and food deprivation mostly paralleled to BDNF expression. Recombinant adeno-associated virus-mediated gene transfer of Cre recombinase to floxed VGF mice specifically decreased VGF expression in the hypothalamus. In contrast to the lean and hypermetabolic phenotype of homozygous germline VGF knockout mice, specific knockdown of hypothalamic VGF in male adult mice led to increased adiposity, decreased core body temperature, reduced energy expenditure, and impaired glucose tolerance, as well as disturbance of molecular features of brown and white adipose tissues without effects on food intake. However, VGF knockdown failed to block the EE-induced BDNF up-regulation or decrease of adiposity indicating a minor role of VGF in the hypothalamic-sympathoneural-adipocyte axis. Taken together, our results suggest hypothalamic VGF responds to environmental demands and plays an important role in energy balance and glycemic control likely acting in the melanocortin pathway downstream of BDNF.

[Effects of polygala on the neurogenesis of manganese poisoned mice]

OBJECTIVE

To investigate the effects of polygala on leaning and memory and the expression of Microtubule associated protein on manganese poisoned mice.

METHODS

60 female Kunming mice were randomly and equally divided into 5 group. They are normal control group (CG), manganese poisoned group (MG), manganese poisoned with polygala high dose group (MHG), manganese poisoned with polygala middle dose group (MMG), manganese poisoned with polygala low dose group (MLG). The model of manganese poisoned mice was prepared of the way of intraperitoneal injection of manganese chloride (MnCl2 15 mg/kg), the spatial learning and memory ability was tested by Morris water maze, the Doublecortin (DCX) was tested by the way of immunofluorescent staining in the SVZ and SGZ.

RESULT

In the navigation test, compared with MG, the escape latency of MHG, MMG and MLG were significantly decreased (P < 0.05), in space exploration experiments, MHG, MMG, MLG compared with MG, the number increased significantly across platforms (P < 0.05). compared with MG, the DCX expression of MHG, MMG and MLG were significantly increased (P < 0.05).

CONCLUTION

The leaning and memory ability of manganese poisoned mice can be improved by the polygala, and the mechanism may be related to promote the expression of DCX and neurogenesis in the brain.

The advancement of the onset of vaginal opening in female rats subjected to chronic testosterone treatment occurs independently of hypothalamic Kiss1 and RFRP expression

OBJECTIVE

The neonatal and/or prepubertal androgen milieu affects sexual maturation. In rodents, neonatal chronic testosterone treatment, which is used as a model of polycystic ovary syndrome (PCOS), results in the onset of vaginal opening occurring earlier in the pubertal period.

DESIGN

In the present study, the changes in hypothalamic Kiss1 (a gonadotropin-releasing hormone (GnRH)-stimulating factor) and RF-amide related peptide (RFRP; a GnRH inhibitory factor) mRNA expression induced by testosterone treatment were examined in order to clarify whether these factors are involved in the testosterone-induced acceleration of sexual maturation.

RESULTS

The onset of vaginal opening occurred earlier and uterine weight was increased in female rats subjected to chronic (from postnatal day 23 to day 31) testosterone treatment. Contrary to our expectations, the rats' hypothalamic Kiss1 and Kiss1 receptor mRNA levels were not changed, and their serum luteinizing hormone (LH) levels were decreased. Although hypothalamic RFRP mRNA expression was decreased in the testosterone-treated rats, this change was not reflected in their serum LH levels.

CONCLUSIONS

These results indicate that the advancement of sexual maturation observed in chronic testosterone-treated rats might be caused by a peripheral, rather than a central, mechanism.

The central amygdala and alcohol: role of γ-aminobutyric acid, glutamate, and neuropeptides

Alcohol dependence is a chronically relapsing disorder characterized by compulsive drug seeking and drug taking, loss of control in limiting intake, and the emergence of a withdrawal syndrome in the absence of the drug. Accumulating evidence suggests an important role for synaptic transmission in the central amygdala (CeA) in mediating alcohol-related behaviors and neuroadaptative mechanisms associated with alcohol dependence. Acute alcohol facilitates γ-aminobutyric acid-ergic (GABAergic) transmission in CeA via both pre- and postsynaptic mechanisms, and chronic alcohol increases baseline GABAergic transmission. Acute alcohol inhibits glutamatergic transmission via effects at N-methyl-d-aspartate (NMDA) and AMPA receptors in CeA, whereas chronic alcohol up-regulates N-methyl-d-aspartate receptor (NMDAR)-mediated transmission. Pro- (e.g., corticotropin-releasing factor [CRF]) and anti-stress (e.g., NPY, nociceptin) neuropeptides affect alcohol- and anxiety-related behaviors, and also alter the alcohol-induced effects on CeA neurotransmission. Alcohol dependence produces plasticity in these neuropeptide systems, reflecting a recruitment of those systems during the transition to alcohol dependence.

Neuropeptides and enzymes are targets for the action of endocrine disrupting chemicals in the vertebrate brain

Endocrine-disrupting chemicals (EDC) are molecules that interfere with endocrine signaling pathways and produce adverse consequences on animal and human physiology, such as infertility or behavioral alterations. Some EDC act through binding to androgen or/and estrogen receptors primarily operating through a genomic mechanism regulating gene expression. This mechanism of action may induce profound developmental adverse effects, and the major targets of the EDC action are the gene products, i.e., mRNAs inducing the synthesis of various peptidic molecules, which include neuropeptides and enzymes related to neurotransmitters syntheses. Available immunohistochemical data on some of the systems that are affected by EDC in lower and higher vertebrates are detailed in this review.

[Molecular and physiological characterization of the pyrokinin insect neuropeptide family]

Peptides from the pyrokinin (PK) family are a large, structurally and functionally diverse group of the insect neuropeptides produced by neurosecretory cells of the insect nervous system. This family contains short and long peptides which share C-terminal -FXPRLa amino acid sequence. Pyrokinins regulate the visceral muscle contractions, pheromone biosynthesis, pupariation and diapause duration in insects. They are encoded by two genes PBAN and capa, which are mainly expressed in the suboesophageal ganglion. Peptides are then transported to the retrocerebral complex and released into haemolymph. Recent studies are focused on application of pyrokinins as biopesticides in the regulation of insect pests growth and development.

Central nervous system delivery of the antipsychotic olanzapine induces hepatic insulin resistance

OBJECTIVE

Olanzapine (OLZ) is an atypical antipsychotic whose clinical efficacy is hampered by side effects including weight gain and diabetes. Recent evidence shows that OLZ alters insulin sensitivity independent of changes in body weight and composition. The present study addresses whether OLZ-induced insulin resistance is driven by its central actions.

RESEARCH DESIGN AND METHODS

Sprague-Dawley rats received an intravenous (OLZ-IV group) or intracerebroventricular (OLZ-ICV group) infusion of OLZ or vehicle. Glucose kinetics were assessed before (basal period) and during euglycemic-hyperinsulinemic clamp studies.

RESULTS

OLZ-IV caused a transient increase in glycemia and a higher rate of glucose appearance (R(a)) in the basal period. During the hyperinsulinemic clamp, the glucose infusion rate (GIR) required to maintain euglycemia and the rate of glucose utilization (R(d)) were decreased in OLZ-IV, whereas endogenous glucose production (EGP) rate was increased compared with vehicle-IV. Consistent with an elevation in EGP, the OLZ-IV group had higher hepatic mRNA levels for the enzymes glucose-6-phosphatase and phosphoenolpyruvate carboxykinase. Phosphorylation of hypothalamic AMP-activated protein kinase (AMPK) was increased in OLZ-IV rats compared with controls. Similarly, an intracerebroventricular infusion of OLZ resulted in a transient increase in glycemia as well as a higher R(a) in the basal period. During the hyperinsulinemic period, OLZ-ICV caused a decreased GIR, an increased EGP, but no change in R(d). Furthermore, OLZ-ICV rats had increased hepatic gluconeogenic enzymes and elevated hypothalamic neuropeptide-Y and agouti-related protein mRNA levels.

CONCLUSIONS

Acute central nervous system exposure to OLZ induces hypothalamic AMPK and hepatic insulin resistance, pointing to a hypothalamic site of action for the metabolic dysregulation of atypical antipsychotics.

Risperidone alters food intake, core body temperature, and locomotor activity in mice

Risperidone induces significant weight gain in female mice; however, the underlying mechanisms related to this effect are unknown. We investigated the effects of risperidone on locomotor activity, core body temperature, and uncoupling protein (UCP) and hypothalamic orexin mRNA expression. Female C57BL/6J mice were acclimated to individual housing and randomly assigned to either risperidone (4 mg/kg BW day) or placebo (PLA). Activity and body temperature were measured over 48-hour periods twice a week for 3 weeks. Food intake and body weights were measured weekly. UCP1 (BAT), UCP3 (gastrocnemius), and orexin (hypothalamus) mRNA expressions were measured using RT-PCR. Risperidone-treated mice consumed more food (p=0.050) and gained more weight (p=0.0001) than PLA-treated mice after 3 weeks. During the initial 2 days of treatment, there was an acute effect of treatment on activity (p=0.046), but not body temperature (p=0.290). During 3 weeks of treatment, average core body temperatures were higher in risperidone-treated mice compared to controls during the light phase (p=0.0001), and tended to be higher during the dark phase (p=0.057). Risperidone-treated mice exhibited lower activity levels than controls during the dark phase (p=0.006); there were no differences in activity during the light phase (p=0.47). UCP1 (p<0.01) and UCP3 (p<0.05) mRNA expressions were greater in risperidone-treated mice compared to controls, whereas, orexin mRNA expression was lower in risperidone-treated mice (p<0.01). These results suggest that risperidone-induced weight gain in mice is a consequence of increased energy intake and reduced activity, while the elevation in body temperature may be a result of thermogenic effect of food intake and elevated UCP1, UCP3, and a reduced hypothalamic orexin expression.

[Domino principle--monoamines in bottom-view]

One of the first neurobiological theories of major depression was the monoamine deficiency hypothesis. The classic monoamine theory of depression suggested that a deficit in monoamine neurotransmitters in the synaptic cleft was the main and primary cause of depression. Recent and newer versions and modifications of the primary classic theory also mainly included this postulate, while other theories of depression preferred departing from the monoamine-based model altogether. Unfortunately, the clear neurobiology of major depression remains an elusive issue, despite intense research. It is clearly held that most, if not all, antidepressant pharmacotherapies treatments produce their therapeutic antidepressant effects, at least in part, by modulating monoamine systems (noradrenergic, serotonergic, and dopaminergic) by a selective or a multi-acting way; however, much less is known about the neurobiological pathology of these monoamine systems in depression. Much of the past 10-15 years of research in the biology of mood disorders has led to considerable evidence in depression implicating multiple system pathology, including abnormalities of monoamine as well as other neurotransmitter systems. These approaches and findings have led researchers to propose broader theories regarding the neurobiology of depression, just like a spreading disorder of specific neuronal networks in the brain. A model for the pathophysiology of depression ill be discussed in the next pages, after describing the main components of depression pathogenesis. Suggestion is that the primary defect emerges in the cross-regulation and vulnerability of special monoaminergic and non-monoaminergic neural networks, which leads to a decrease in the tonic release of neurotransmitters in their projection areas, altering postsynaptic sensitivity, and following, overexaggerated responses to acute increases in the presynaptic firing rate and transmitter release. It is proposed that the primary defect should be involved, in the noradrenergic innervation spreading from the locus coeruleus (LC). Dysregulation of the LC projection activities may lead in turn to malfunction of serotonergic and dopaminergic neurotransmission. Failure of the LC function could explain the basic impairments in the processing of novel information, intensive processing of irrational beliefs, and anxiety. Consecutive deficits in the serotonergic neurotransmission may contribute to the mood changes and reduction in the mesotelencephalic dopaminergic activity to loss of motivation, and anhedonia. Malfunction and dysregulation of CRF and other neuropeptides such as neuropeptide Y, galanin and substance P may reinforce the LC dysfunction and thus further weaken the adaptive ability to stressful stimuli. The new SNRI antidepressants seem to be more superior and effective in the treatment of major depression and in the prophylaxis of recurrent depressive episodes because of their coexistent noradrenergic activity.

Drug resistance and neurotransmitter receptors of nematodes: recent studies on the mode of action of levamisole

Here we review recent studies on the mode of action of the cholinergic anthelmintics (levamisole, pyrantel etc.). We also include material from studies on the free living nematode Caenorhabditis elegans. The initial notion that these drugs act on a single receptor population, while attractive, has proven to be an oversimplification. In both free living and parasitic nematodes there are multiple types of nicotinic acetylcholine receptor (nAChR) on the somatic musculature. Each type has different (sometimes subtly so) pharmacological properties. The implications of these findings are: (1) combinations of anthelmintic that preferentially activate a broad range of nAChR types would be predicted to be more effective; (2) in resistant isolates of parasite where a subtype has been lost, other cholinergic anthelmintics may remain effective. Not only are there multiple types of nAChR, but relatively recent research has shown these receptors can be modulated; it is possible to increase the response of a parasite to a fixed concentration of drug by altering the receptor properties (e.g. phosphorylation state). These findings offer a potential means of increasing efficacy of existing compounds as an alternative to the costly and time consuming development of new anthelmintic agents.

Inter-phyla studies on neuropeptides: the potential for broad-spectrum anthelmintic and/or endectocide discovery

Flatworm, nematode and arthropod parasites have proven their ability to develop resistance to currently available chemotherapeutics. The heavy reliance on chemotherapy and the ability of target species to develop resistance has prompted the search for novel drug targets. In view of its importance to parasite/pest survival, the neuromusculature of parasitic helminths and pest arthropod species remains an attractive target for the discovery of novel endectocide targets. Exploitation of the neuropeptidergic system in helminths and arthropods has been hampered by a limited understanding of the functional roles of individual peptides and the structure of endogenous targets, such as receptors. Basic research into these systems has the potential to facilitate target characterization and its offshoots (screen development and drug identification). Of particular interest to parasitologists is the fact that selected neuropeptide families are common to metazoan pest species (nematodes, platyhelminths and arthropods) and fulfil specific roles in the modulation of muscle function in each of the three phyla. This article reviews the inter-phyla activity of two peptide families, the FMRFamide-like peptides and allatostatins, on motor function in helminths and arthropods and discusses the potential of neuropeptide signalling as a target system that could uncover novel endectocidal agents.

Linkage and association studies in African- and Caucasian-American populations demonstrate that SHC3 is a novel susceptibility locus for nicotine dependence

Our previous linkage study demonstrated that the 9q22-q23 chromosome region showed a 'suggestive' linkage to nicotine dependence (ND) in the Framingham Heart Study population. In this study, we provide further evidence for the linkage of this region to ND in an independent sample. Within this region, the gene encoding Src homology 2 domain-containing transforming protein C3 (SHC3) represents a plausible candidate for association with ND, assessed by smoking quantity (SQ), the Heaviness of Smoking Index (HSI) and the Fagerström Test for ND (FTND). We utilized 11 single-nucleotide polymorphisms within SHC3 to examine the association with ND in 602 nuclear families of either African-American (AA) or European-American (EA) origin. Individual SNP-based analysis indicated three SNPs for AAs and one for EAs were significantly associated with at least one ND measure. Haplotype analysis revealed that the haplotypes A-C-T-A-T-A of rs12519-rs3750399-rs4877042-rs2297313-rs1547696-rs1331188, with a frequency of 27.8 and 17.6%, and C-T-A-G-T of rs3750399-rs4877042-rs2297313-rs3818668-rs1547696, at a frequency of 44.7 and 30.6% in the AA and Combined samples, respectively, were significantly inversely associated with the ND measures. In the EA sample, another haplotype with a frequency of 10.6%, A-G-T-G of rs1331188-rs1556384-rs4534195-rs1411836, showed a significant inverse association with ND measures. These associations remained significant after Bonferroni correction. We further demonstrated the SHC3 contributed 40.1-59.2% (depending on the ND measures) of the linkage signals detected on chromosome 9. As further support, we found that nicotine administered through infusion increased the Shc3 mRNA level by 60% in the rat striatum, and decreased it by 22% in the nucleus accumbens (NA). At the protein level, Shc3 was decreased by 38.0% in the NA and showed no change in the striatum. Together, these findings strongly implicate SHC3 in the etiology of ND, which represents an important biological candidate for further investigation.

Voltage-gated Na+channels in neuropathic pain

Neuropathic pain occurs as a result of some form of injury to the nervous system. Although the basis of the disease remains to be fully elucidated, numerous studies have suggested a major role for ion channels in the pathogenesis of neuropathic pain. As Na+ channels play a fundamental role in not only the generation but also in the conduction of an action potential, they have received considerable attention in the aetiology of pain sensation and have become important pharmacological targets. In this review, the authors discuss the importance of specific Na+ channel isoforms in the pathophysiology of neuropathic pain and the present use of Na+ channel antagonists in the treatment of neuropathic pain.

Topical pimecrolimus and tacrolimus transiently induce neuropeptide release and mast cell degranulation in murine skin

BACKGROUND

The topical calcineurin inhibitors pimecrolimus and tacrolimus have been demonstrated to be an effective new anti-inflammatory therapy. The only clinically relevant side-effect reported is transient application site burning and stinging itch at the beginning of topical therapy.

OBJECTIVES

In order to understand the underlying mechanism of this effect, we examined whether or not the compounds are able to stimulate neuropeptide release in normal murine skin as well as in a mouse model of experimentally induced irritant contact dermatitis.

METHODS

Balb/c mice were treated with 1% pimecrolimus cream or 0.1% tacrolimus ointment. Untreated and corresponding vehicle-treated mice served as controls. Skin specimens were investigated by light, immunofluorescence and electron microscopy as well as enzyme-linked immunosorbent assay and polymerase chain reaction.

RESULTS

Topical application of pimecrolimus and tacrolimus was followed by an initial release of substance P and calcitonin gene-related peptide from primary afferent nerve fibres in murine skin during the early inflammatory response. The release of the neuropeptides and their binding to mast cells (MCs) led to MC degranulation. Mediators of MCs such as histamine and tryptase may induce pruritus and burning by binding to the corresponding receptors (histamine receptor 1, proteinase-activated receptor 2) on sensory nerve fibres, which explains the initial side-effects during therapy with calcineurin inhibitors.

CONCLUSIONS

It may be speculated that calcineurin inhibitors directly stimulate intracellular signalling pathways or bind to ion channels such as transient receptor potential vanilloid 1 or receptors involved in nociception.

Pharmacological dissection and distribution of NaN/Nav1.9, T-type Ca2+ currents, and mechanically activated cation currents in different populations of DRG neurons

Low voltage–activated (LVA) T-type Ca²⁺ (I_CaT) and NaN/Nav1.9 currents regulate DRG neurons by setting the threshold for the action potential. Although alterations in these channels have been implicated in a variety of pathological pain states, their roles in processing sensory information remain poorly understood. Here, we carried out a detailed characterization of LVA currents in DRG neurons by using a method for better separation of NaN/Nav1.9 and I_CaT currents. NaN/Nav1.9 was inhibited by inorganic I_Ca blockers as follows (IC₅₀, μM): La³⁺ (46) > Cd²⁺ (233) > Ni²⁺ (892) and by mibefradil, a non-dihydropyridine I_CaT antagonist. Amiloride, however, a preferential Cav3.2 channel blocker, had no effects on NaN/Nav1.9 current. Using these discriminative tools, we showed that NaN/Nav1.9, Cav3.2, and amiloride- and Ni²⁺-resistant I_CaT (AR-I_CaT) contribute differentially to LVA currents in distinct sensory cell populations. NaN/Nav1.9 carried LVA currents into type-I (CI) and type-II (CII) small nociceptors and medium-Aδ–like nociceptive cells but not in low-threshold mechanoreceptors, including putative Down-hair (D-hair) and Aα/β cells. Cav3.2 predominated in CII-nociceptors and in putative D-hair cells. AR-I_CaT was restricted to CII-nociceptors, putative D-hair cells, and Aα/β-like cells. These cell types distinguished by their current-signature displayed different types of mechanosensitive channels. CI- and CII-nociceptors displayed amiloride-sensitive high-threshold mechanical currents with slow or no adaptation, respectively. Putative D-hair and Aα/β-like cells had low-threshold mechanical currents, which were distinguished by their adapting kinetics and sensitivity to amiloride. Thus, subspecialized DRG cells express specific combinations of LVA and mechanosensitive channels, which are likely to play a key role in shaping responses of DRG neurons transmitting different sensory modalities.

Inhibitory effect of somatostatin on inflammation and nociception

The present review focuses on promising new opportunities for anti-inflammatory and analgesic therapy. The theoretical background is an original observation based on our own experimental results. These data demonstrate that somatostatin is released from capsaicin-sensitive, peptidergic sensory nerve endings in response to noxious heat and chemical stimuli such as vanilloids, protons or lipoxygenase products. It reaches distant parts of the body via the circulation and exerts systemic anti-inflammatory and analgesic effects. Somatostatin binds to G-protein-coupled membrane receptors (sst(1)-sst(5)) and diminishes neurogenic inflammation by prejunctional action on sensory-efferent nerve terminals, as well as by postjunctional mechanisms on target cells. It decreases the release of pro-inflammatory neuropeptides from sensory nerve endings and also acts on receptors of vascular endothelial, inflammatory and immune cells. Analgesic effect is mediated by an inhibitory action on peripheral terminals of nociceptive neurons, since circulating somatostatin cannot exert central action. Somatostatin itself is not suitable for drug development because of its broad spectrum and short elimination half life, stable, receptor-selective agonists have been synthesized and investigated. The present overview is aimed at summarizing the physiological importance of somatostatin and sst receptors, pharmacological significance of synthetic agonists and their potential in the development of novel anti-inflammatory and analgesic drugs. These compounds might provide novel perspectives in the pharmacotherapy of acute and chronic painful inflammatory diseases, as well as neuropathic conditions.

Plectin-controlled keratin cytoarchitecture affects MAP kinases involved in cellular stress response and migration

Plectin is a major intermediate filament (IF)-based cytolinker protein that stabilizes cells and tissues mechanically, regulates actin filament dynamics, and serves as a scaffolding platform for signaling molecules. In this study, we show that plectin deficiency is a cause of aberrant keratin cytoskeleton organization caused by a lack of orthogonal IF cross-linking. Keratin networks in plectin-deficient cells were more susceptible to osmotic shock-induced retraction from peripheral areas, and their okadaic acid-induced disruption (paralleled by stress-activated MAP kinase p38 activation) proceeded faster. Basal activities of the MAP kinase Erk1/2 and of the membrane-associated upstream protein kinases c-Src and PKCdelta were significantly elevated, and increased migration rates, as assessed by in vitro wound-closure assays and time-lapse microscopy, were observed. Forced expression of RACK1, which is the plectin-binding receptor protein for activated PKCdelta, in wild-type keratinocytes elevated their migration potential close to that of plectin-null cells. These data establish a link between cytolinker-controlled cytoarchitecture/scaffolding functions of keratin IFs and specific MAP kinase cascades mediating distinct cellular responses.

The Prototoxin lynx1 Acts on Nicotinic Acetylcholine Receptors to Balance Neuronal Activity and Survival In Vivo

Nicotinic acetylcholine receptors (nAChRs) affect a wide array of biological processes, including learning and memory, attention, and addiction. lynx1, the founding member of a family of mammalian prototoxins, modulates nAChR function in vitro by altering agonist sensitivity and desensitization kinetics. Here we demonstrate, through the generation of lynx1 null mutant mice, that lynx1 modulates nAChR signaling in vivo. Its loss decreases the EC(50) for nicotine by approximately 10-fold, decreases receptor desensitization, elevates intracellular calcium levels in response to nicotine, and enhances synaptic efficacy. lynx1 null mutant mice exhibit enhanced performance in specific tests of learning and memory. Consistent with reports that mutations resulting in hyperactivation of nAChRs can lead to neurodegeneration, aging lynx1 null mutant mice exhibit a vacuolating degeneration that is exacerbated by nicotine and ameliorated by null mutations in nAChRs. We conclude that lynx1 functions as an allosteric modulator of nAChR function in vivo, balancing neuronal activity and survival in the CNS.

Purification of a novel aminopeptidase from the pollen of Parietaria judaica that alters epithelial integrity and degrades neuropeptides

BACKGROUND

Parietaria judaica pollen is a common cause of pollinosis in the Mediterranean area.

OBJECTIVE

This study sought to purify and characterize the peptidase responsible for the majority of proteolytic activity present in the pollen extract of P judaica, and to investigate its contribution to the allergic response.

METHODS

A serial of chromatographic steps was applied to isolate the peptidase from P judaica's pollen, and its biochemical properties were determined. Bioactive peptides present in the airways were incubated with the peptidase, and their degradation was visualized by direct protein sequencing. In addition, we measured the cellular detachment, by methylene blue binding assay, of an airway-derived epithelial cell line (A549) in the presence of the peptidase, and visualized, by Western blot, the degradation of proteins from intercellular junctions.

RESULTS

We purified a 98-kDa peptidase from the pollen of P judaica that was classified as an aminopeptidase on the basis of its biochemical properties and internal amino acid sequence. The aminopeptidase was able to degrade bioactive peptides. Moreover, the aminopeptidase caused cellular detachment of A549 cell line and degradation of occludin and E-cadherin.

CONCLUSION

Our results suggest that the P judaica aminopeptidase can alter the integrity of the epithelium barrier by degrading occludin as well as E-cadherin. In addition, P judaica aminopeptidase can degrade bioactive peptides, which can exacerbate the overall bronchoconstrictive effect detected in asthmatic lungs.

CLINICAL IMPLICATIONS

The novel aminopeptidase described here could constitute a relevant therapeutic target in the treatment of allergic disorders induced by the pollen of P judaica.

Hypocretin-1 dose-dependently modulates maternal behaviour in mice

Increases in neuronal activity of hypocretin (HCRT), a peptide involved in arousal, and in HCRT-1 receptor mRNA expression have recently been identified in association with lactation. HCRT is released within brain regions regulating maternal behaviour and it is possible that increased HCRT neurotransmission during lactation supports maternal care. The present study examined for the first time the behavioural effects of HCRT on lactating mice. At intermediate doses, intracerebroventricular (i.c.v.) injections of HCRT-1 (0.06 and 0.1 microg) elevated levels of licking and grooming of pups (but not self-grooming) and number of nursing bouts without affecting other behaviours. At the highest dose, HCRT-1 (0.3 microg, i.c.v) delayed latency to nurse, decreased nursing, increased time off nest, and decreased maternal aggression. Intraperitoneal injections of the HCRT-1 receptor antagonist, SB-334867, exhibited a general trend towards increasing time spent low-arched back nursing (P = 0.053) and decreasing licking and grooming of pups while high-arched back nursing (P = 0.052). This suggests that the endogenous release of HCRT, working independently or dependently with other neuromodulators, may be necessary for full maternal behaviour expression. Possible sites of HCRT action in enhancing and impairing maternal care were identified via examinations of c-Fos immunoreactivity in association with i.c.v. HCRT injections. Together, these finding support the idea of HCRT modulating maternal behaviour, with intermediate levels (0.06 and 0.1 microg) supporting (even augmenting) some behaviours, but with levels that are too high (0.3 microg HCRT, i.c.v.), maternal behaviour and aggression are suppressed.

Dissecting the role of sodium currents in visceral sensory neurons in a model of chronic hyperexcitability using Nav1.8 and Nav1.9 null mice

Tetrodotoxin-resistant (TTX-R) sodium currents have been proposed to underlie sensory neuronal hyperexcitability in acute inflammatory models, but their role in chronic models is unknown. Since no pharmacological tools to separate TTX-R currents are available, this study employs Na(v)1.8 and Na(v)1.9 null mice to evaluate these currents roles in a chronic hyperexcitability model after the resolution of an inflammatory insult. Transient jejunitis was induced by infection with Nippostrongylus brasiliensis (Nb) in Na(v)1.9 and Na(v)1.8 null, wild-type and naïve mice. Retrogradely labelled dorsal root ganglia (DRG) neurons were harvested on day 20-24 post-infection for patch clamp recording. Rheobase and action potential (AP) parameters were recorded as measures of excitability, and Na(v)1.9 and Na(v)1.8 currents were recorded. DRG neuronal excitability was significantly increased in post-infected mice compared to sham animals, despite the absence of ongoing inflammation (sham = 1.9 +/- 0.3, infected = 3.6 +/- 0.7 APs at 2x rheobase, P = 0.02). Hyperexcitability was associated with a significantly increased amplitude of TTX-R currents. Hyperexcitability was maintained in Na(v)1.9(-/-) mice, but hyperexcitability was absent and APs were blunted in Na(v)1.8(-/-) mice. This study identifies a critical role for Na(v)1.8 in chronic post-infectious visceral hyperexcitability, with no contribution from Na(v)1.9. Nb infection-induced hyperexcitability is not observed in Na(v)1.8(-/-) mice, but is still present in Na(v)1.9(-/-) mice. It is not clear whether hyperexcitability is due to a change in the function of Na(v)1.8 channels or a change in the number of Na(v)1.8 channels.

Chronic cocaine exposure impairs progenitor proliferation but spares survival and maturation of neural precursors in adult rat dentate gyrus

Recent observations indicate that drugs of abuse, including alcohol and opiates, impair adult neurogenesis in the hippocampus. We have studied in rats the impact of cocaine treatment (20 mg/kg, daily, i.p.) on cell proliferation, survival and maturation following short-term (8-day) and long-term (24-day) exposure. Using 5'-bromo-2-deoxyuridine (BrdU) and Ki-67 as mitotic markers at the end of the drug treatments, we found that both short- and long-term cocaine exposures significantly reduced cell proliferation in the dentate gyrus (DG) of the hippocampus. By labelling mitotic cells with BrdU pulses before or during the early stages of the drug treatment, we determined that long-term cocaine exposure did not affect the survival of newly generated cells. In register with this finding, cocaine chronic exposure did not increase the number of apoptotic cells labelled by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling). Using doublecortin (DCX) immunocytochemistry and electron microscopy, we next examined the effects of cocaine exposure on the maturation of the neural precursors and on synaptic output to CA3. DCX immunocytochemistry showed that immature hippocampal cells of rats exposed to cocaine displayed normal arborization patterns and similar degrees of colocalization with BrdU at two different developmental stages. Moreover, cocaine did not produce significant morphological alterations of the mossy fibre projection system to stratum lucidum in the CA3 area of the hippocampus. The results presented demonstrate that chronic cocaine exposure impairs proliferation dynamics in the DG without significantly altering either the survival and growth of immature cells or the structural features of terminal projections to CA3.

Molecular mechanisms contributing to dendritic spine alterations in the prefrontal cortex of subjects with schizophrenia

Postmortem studies have revealed reduced densities of dendritic spines in the dorsal lateral prefrontal cortex (DLPFC) of subjects with schizophrenia. However, the molecular mechanisms that might contribute to these alterations are unknown. Recent studies of the intracellular signals that regulate spine dynamics have identified members of the RhoGTPase family (e.g., Cdc42, Rac1, RhoA) as critical regulators of spine structure. In addition, Duo and drebrin are spine-specific proteins that are critical for spine maintenance and spine formation, respectively. In order to determine whether the mRNA expression levels of Cdc42, Rac1, RhoA, Duo or drebrin are altered in schizophrenia, tissue sections containing DLPFC area 9 from 15 matched pairs of subjects with schizophrenia and control subjects were processed for in situ hybridization. Expression levels of these mRNAs were also correlated with DLPFC spine density in a subset of the same subjects. In order to assess the potential influence of antipsychotic medications on the expression of these mRNAs, similar studies were conducted in monkeys chronically exposed to haloperidol or olanzapine. The expression of each of these mRNAs was lower in the gray matter of the subjects with schizophrenia compared to the control subjects, although only the reductions in Cdc42 and Duo remained significant after corrections for multiple comparisons. In addition, spine density was strongly correlated with the expression levels of both Duo (r=0.73, P=0.007) and Cdc42 (r=0.71, P=0.009) mRNAs. In contrast, the expression levels of Cdc42 and Duo mRNAs were not altered in monkeys chronically exposed to antipsychotic medications. In conclusion, reduced expression of Cdc42 and Duo mRNAs may represent molecular mechanisms that contribute to the decreased density of dendritic spines in the DLPFC of subjects with schizophrenia.

Sugar and alcohol molecules provide a therapeutic strategy for the serpinopathies that cause dementia and cirrhosis

Mutations in neuroserpin and alpha1-antitrypsin cause these proteins to form ordered polymers that are retained within the endoplasmic reticulum of neurones and hepatocytes, respectively. The resulting inclusions underlie the dementia familial encephalopathy with neuroserpin inclusion bodies (FENIB) and Z alpha1-antitrypsin-associated cirrhosis. Polymers form by a sequential linkage between the reactive centre loop of one molecule and beta-sheet A of another, and strategies that block polymer formation are likely to be successful in treating the associated disease. We show here that glycerol, the sugar alcohol erythritol, the disaccharide trehalose and its breakdown product glucose reduce the rate of polymerization of wild-type neuroserpin and the Ser49Pro mutant that causes dementia. They also attenuate the polymerization of the Z variant of alpha1-antitrypsin. The effect on polymerization was apparent even when these agents had been removed from the buffer. None of these agents had any detectable effect on the structure or inhibitory activity of neuroserpin or alpha1-antitrypsin. These data demonstrate that sugar and alcohol molecules can reduce the polymerization of serpin mutants that cause disease, possibly by binding to and stabilizing beta-sheet A.

Lack of interaction between orexinergic and α2-adrenergic neuronal systems in rat cerebrocortical slices

Orexinergic and norepinephrinergic alpha2-adrenoceptor expressing neurons contribute to the regulation of the sleep-wakefulness cycle. In the present study, we have examined a possible interaction between orexinergic and alpha2-adrenergic systems in orexin-A (100 nM)- and K+ (25 mM)-evoked norepinephrine release from slices of rat cerebrocortex. In this tissue norepinephrinergic neurons are predominantly innervated via the locus coeruleus. Clonidine concentration-dependently inhibited K+-evoked norepinephrine release with pIC50 (Imax) of 6.44+/-0.38 (48.8+/-6.9%). A selective orexin-1 receptor antagonist, SB-334867 was ineffective. SB-334867 concentration-dependently inhibited orexin A-evoked norepinephrine release with pIC50 (Imax) of 6.05+/-0.14 (86.4+/-5.4%); clonidine (alpha2-agonist) was ineffective. In contrast, yohimbine reversed the inhibitory effects of clonidine (1 microM) on K+-evoked norepinephrine release with pIC50 (Imax) of 6.50+/-0.34 (77.6+/-10.9%); orexin A was ineffective. The present data suggest a lack of interaction between orexinergic and alpha2-adrenergic neurons in rat cerebral cortex.

Contactin regulates the current density and axonal expression of tetrodotoxin-resistant but not tetrodotoxin-sensitive sodium channels in DRG neurons

Contactin, a glycosyl-phosphatidylinositol (GPI)-anchored predominantly neuronal cell surface glycoprotein, associates with sodium channels Nav1.2, Nav1.3 and Nav1.9, and enhances the density of these channels on the plasma membrane in mammalian expression systems. However, a detailed functional analysis of these interactions and of untested putative interactions with other sodium channel isoforms in mammalian neuronal cells has not been carried out. We examined the expression and function of sodium channels in small-diameter dorsal root ganglion (DRG) neurons from contactin-deficient (CNTN-/-) mice, compared to CNTN+/+ litter mates. Nav1.9 is preferentially expressed in isolectin B4 (IB4)-positive neurons and thus we used this marker to subdivide small-diameter DRG neurons. Using whole-cell patch-clamp recording, we observed a greater than two-fold reduction of tetrodotoxin-resistant (TTX-R) Nav1.8 and Nav1.9 current densities in IB4+ DRG neurons cultured from CNTN-/- vs. CNTN+/+ mice. Current densities for TTX-sensitive (TTX-S) sodium channels were unaffected. Contactin's effect was selective for IB4+ neurons as current densities for both TTX-R and TTX-S channels were not significantly different in IB4- DRG neurons from the two genotypes. Consistent with these results, we have demonstrated a reduction in Nav1.8 and Nav1.9 immunostaining on peripherin-positive unmyelinated axons in sciatic nerves from CNTN-/- mice but detected no changes in the expression for the two major TTX-S channels Nav1.6 and Nav1.7. These data provide evidence of a role for contactin in selectively regulating the cell surface expression and current densities of TTX-R but not TTX-S Na+ channel isoforms in nociceptive DRG neurons; this regulation could modulate the membrane properties and excitability of these neurons.

Dopaminergic regulation of orexin neurons

Orexin/hypocretin neurons in the lateral hypothalamus and adjacent perifornical area (LH/PFA) innervate midbrain dopamine (DA) neurons that project to corticolimbic sites and subserve psychostimulant-induced locomotor activity. However, it is not known whether dopamine neurons in turn regulate the activity of orexin cells. We examined the ability of dopamine agonists to activate orexin neurons in the rat, as reflected by induction of Fos. The mixed dopamine agonist apomorphine increased Fos expression in orexin cells, with a greater effect on orexin neurons located medial to the fornix. Both the selective D1-like agonist, A-77636, and the D2-like agonist, quinpirole, also induced Fos in orexin cells, suggesting that stimulation of either receptor subtype is sufficient to activate orexin neurons. Consistent with this finding, combined SCH 23390 (D1 antagonist)-haloperidol (D2 antagonist) pretreatment blocked apomorphine-induced activation of medial as well as lateral orexin neurons; in contrast, pretreatment with either the D1-like or D2-like antagonists alone did not attenuate apomorphine-induced activation of medial orexin cells. In situ hybridization histochemistry revealed that LH/PFA cells rarely express mRNAs encoding dopamine receptors, suggesting that orexin cells are transsynaptically activated by apomorphine. We therefore lesioned the nucleus accumbens, a site known to regulate orexin cells, but this treatment did not alter apomorphine-elicited activation of medial or lateral orexin neurons. Interestingly, apomorphine failed to activate orexin cells in isoflurane-anaesthetized animals. These data suggest that apomorphine-induced arousal but not accumbens-mediated hyperactivity is required for dopamine to transsynaptically activate orexin neurons.

Mode of leptin action in chicken hypothalamus

While there have been many studies in various species examining the mode of central leptin action on food intake, there is however a paucity of data in birds. We have, therefore, addressed this issue in broiler chickens because this strain was selected for high growth rate, hence high food intake. Continuous infusion of recombinant chicken leptin (8 microg/kg/h) during 6 h at a constant rate of 3 ml/h resulted in a significant reduction (49-57%) of food intake in 3-week-old broiler chickens (P < 0.05). The effect of leptin within the central nervous system (CNS) was mediated via selective hypothalamic neuropeptides. Leptin significantly decreased the expression of its receptor (Ob-R), neuropeptide Y (NPY), orexin (ORX), and orexin receptor (ORXR) (P < 0.05), but not that of agouti-related protein (AgRP) (anabolic/orexigenic effectors) in chicken hypothalamus. However, the catabolic/anorexigenic neuropeptides namely proopiomelanocortin (POMC) and corticotropin-releasing hormone (CRH) mRNA levels remained unchanged after leptin treatment. Despite the absence of leptin effect on AgRP (the antagonist of melanocortin receptor MCR) and POMC (the precursor of alpha-melanocyte stimulating hormone which is a potent agonist for MCR), leptin significantly decreased the expression of MCR-4/5 gene in chicken hypothalamus (P < 0.05) suggesting that leptin acts directly (as ligand) or indirectly (via other ligands) on MCRs to regulate food intake in birds. Additionally, leptin down-regulated the expression of fatty acid synthase (FAS) gene in chicken hypothalamus, indicating an additional pathway of leptin action on food intake such as described for FAS inhibitors. These findings provide new insight into the mechanism of leptin control of food intake in chickens.

Resveratrol inhibits Na+ currents in rat dorsal root ganglion neurons

Resveratrol, a phytoalexin found in grapevines, exerts neuroprotective, cancer chemopreventive, antiinflammatory and cardioprotective activities. Studies have also shown that resveratrol exhibits analgesic effects. Cyclooxygenase inhibition and K+ channel opening have been suggested as underlying mechanisms for the resveratrol-induced analgesia. Here, we investigated the effects of resveratrol on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na+ currents in rat dorsal root ganglion (DRG) neurons. Resveratrol suppressed both Na+ currents evoked at 0 mV from -80 mV. TTX-S Na+ current (K(d), 72 microM) was more susceptible to resveratrol than TTX-R Na+ current (K(d), 211 microM). Although the activation voltage of TTX-S Na+ current was shifted in the depolarizing direction by resveratrol, that of TTX-R Na+ current was not. Resveratrol caused a hyperpolarizing shift of the steady-state inactivation voltage and slowed the recovery from inactivation of both Na+ currents. However, no frequency-dependent inhibition of resveratrol on either type of Na+ current was observed. The suppression and the unfavorable effects on the kinetics of Na+ currents in terms of the excitability of DRG neurons may make a great contribution to the analgesia by resveratrol.

Pharmacological modulation of circadian rhythms: a new drug target in psychotherapeutics

Daily variation in an organism's physiology and behaviour is regulated by the synchrony that is achieved between the internal timing mechanisms - the circadian rhythms of the biological clock - and the prevailing environmental cues. Proper synchrony constitutes an adaptive response; improper or lost synchrony may well yield maladaptation and, in the case of humans, a psychiatric disorder. On a basic level, the circadian system is comprised of three parts: a central oscillator, its various neuronal inputs and its outputs. For all three of these parts, the dissemination of new information is moving at an unprecedented pace, and the number of molecular targets for the opportunistic pharmacologist is growing in step. Monoamines, neuropeptides, kinases - sorting through all these, much less developing one into a drug discovery programme, may be the biggest challenge. However, the potential benefits in targeting a basic flaw in a fundamental biological system may be enormous.

PGE2 increases the tetrodotoxin-resistant Nav1.9 sodium current in mouse DRG neurons via G-proteins

Inflammation caused by tissue damage results in pain, reflecting an increase in excitability of the primary afferent neurons innervating the area. There is some evidence to suggest that altered function of voltage-gated sodium channels is responsible for the hyperexcitability produced by inflammatory agents, possibly acting through G-proteins, but the role of different channel subtypes has not been fully explored. The tetrodotoxin-resistant (TTX-R) sodium channel Na(v)1.9 is expressed selectively in C- and A-fibre nociceptive-type units and is upregulated by G-protein activation. In this study, we examined the effects of the inflammatory agent prostaglandin-E(2) (PGE(2)) on Na(v)1.9 current in both Na(v)1.8-null and wild-type (WT) mice and explored the role of specific G-proteins in modulation. PGE(2) caused a twofold increase in Na(v)1.9 current (p<0.05) in both systems. Steady-state activation was shifted in a hyperpolarizing direction by 6-8 mV and availability of channels by 12 mV. No differences in the activation and inactivation kinetics could be detected. The increase in current was blocked by pertussis toxin (PTX) but not cholera toxin (CTX), showing involvement of G(i/o) but not G(s) subunits. Our data indicate that Na(v)1.9 current can be increased during inflammation via a G-protein dependent mechanism and suggest that this could contribute to the regulation of electrogenesis in dorsal root ganglia (DRG) neurons.

Neuropeptide signalling: a repository of targets for novel endectocides?

The only available parasiticides with a spectrum of action that includes a broad range of helminth and arthropod parasites are the macrocyclic lactones. Designated endectocides, these drugs have action against both endoparasitic nematodes and ectoparasitic arthropods. Unfortunately, the discovery of such drugs is exceedingly rare and there is no evidence that novel endectocidal agents will be identified and developed in the short to medium term. However, the discovery of neuropeptides with motor-modulatory activities in both arthropods and helminths, coupled with recent progress in the characterization of invertebrate neuropeptide receptors, has the potential to propel neuropeptide signalling to the forefront of efforts to develop a novel endectocide.

Plasticity of the different neuropeptide-containing nerve fibres in the tongue of the diabetic rat

Common oral complications of diabetes mellitus are xerostomia, impairment of taste, atrophic lesions of the tongue, leukoplakia, lichen oris planus, and tumours, which might be the consequence of chronic inflammation and changes in innervation. In this work, we examined the density of different neuropeptide-containing nerve fibres immunohisto- and immunocytochemically in the root of the control and diabetic rat's tongue. Quantitative analysis showed that the number of immunoreactive (IR) nerve fibres was decreased after 1 week of the streptozotocin treatment, which was prevented by immediate insulin treatment. However, after 4 weeks duration of diabetes, the number of all investigated IR nerve fibres increased significantly (p<0.05), which was further enhanced by the delayed insulin treatment. The numbers of substance P (SP) and vasoactive intestinal polypeptide IR perikarya were also increased by insulin treatment. The electron-microscopic investigations showed that some of the nerve terminals from diabetic animals were found in degeneration. After 4 weeks duration of diabetes, the number of inflammatory cells as well as the mast cell/nerve fibre contacts was also increased. The immunocells also showed IR for SP and neuropeptide Y in the diabetic rats. The insulin treatment decreased both the number and the immunoreactivity of these cells. The increased synthesis and/or regeneration of neuropeptide-containing nerves might indicate the plasticity of nerve fibres in diabetes mellitus, which might happen as a consequence of the changes in the level of neurotrophic factors released by increased number of inflammatory cells or as an effect of insulin.

Effects of neuropeptides B and W on the secretion and growth of rat adrenocortical cells

Neuropeptide-B (NPB) and neuropeptide-W (NPW) are recently discovered endogenous ligands of the GPR7- and GPR8-receptors (R), which in humans are expressed in the hypothalamus and probably involved in the regulation of energy homeostasis and neuroendocrine axes. GPR8-Rs are absent in rodents, where the GPR8-like-R has been described. Reverse transcription-polymerase chain reaction detected the expression of NPB, NPW, GPR7-R and GPR8-like-R mRNAs in rat adrenocortical cells (both freshly-dispersed and 4-day-cultured cells). NPB did not acutely (60-min exposure) alter basal aldosterone secretion from freshly dispersed zona glomerulosa cells, while NPW raised it. Both NPB and NPW enhanced ACTH-stimulated aldosterone secretion and did not affect either basal or ACTH-stimulated corticosterone production by dispersed zona fasciculata/reticularis (ZF/R) cells. The prolonged (4-day) exposure to NPW, but not NPB, raised corticosterone secretion from cultured ZF/R cells, and both neuropeptides increased the proliferation rate of cultured cells. Taken together, our findings indicate that NPB and NPW affect rat adrenocortical function, so they may be included in that large family of peptides involved in the autocrine-paracrine stimulation of secretion and growth of adrenal cortex.

Effect of memantine on the levels of glial cells, neuropeptides, and peptide-degrading enzymes in rat brain regions of ibotenic acid-treated alzheimer's disease model

It has been implicated that glia activation plays a critical role in the progression of Alzheimer's disease (AD). However, the precise mechanism of glia activation is not clearly understood yet. In our present studies, we confirmed our previous results where change the levels of neuropeptides and peptidases in ibotenic acid (IBO) infusion into the rat nucleus basalis magnocellularis, an animal model of AD. Furthermore, we extended our study to investigate a possible protection effect of co-administration on the changes of neuropeptides, and neuronal and glial cells in IBO-infused rat brain by memantine treatment. The levels of substance P and somatostatin were decreased in the striatum and frontal cortex 1 week after IBO infusion, and recovered to the control level by memantine treatment, indicating the involvement of neuropeptides in AD pathology. Furthermore, the immunohistochemical and enzymatic studies of GFAP and CD 11b, and peptidylarginine deiminase, markers of glia, in the striatum and frontal cortex showed the increase in IBO-treated rat brain as compared with controls, while co-administration of memantine and IBO no increase of astrocytes and microglia activation was observed. The present biochemical and immunohistochemical results suggest that glia activation might play an important role to the pathology of AD, and correlate with the changes of neuropeptide levels in AD brain that is recovered by memantine treatment.

Gating and modulation of presumptive NaV1.9 channels in enteric and spinal sensory neurons

The NaV1.9 subunit is expressed in nociceptive dorsal root ganglion (DRG) neurons and sensory myenteric neurons in which it generates 'persistent' tetrodotoxin-resistant (TTX-R) Na+ currents of yet unknown physiological functions. Here, we have analyzed these currents in details by combining single-channel and whole-cell recordings from cultured rat DRG and myenteric neurons. Comparison of single-channel with whole-cell data indicates that recording using internal CsCl best reflects the basic electrical features of NaV1.9 currents. Inclusion of fluoride in the pipette solution caused a negative shift in the activation and inactivation gates of NaV1.9 but not NaV1.8. Fluoride acts by promoting entry of NaV1.9 channels into a preopen closed state, which causes a strong bias towards opening and enhances the ability of sensory neurons to sustain spiking. Thus, the modulation of the resting-closed states of NaV1.9 channels strongly influences nociceptor excitability and may provide a mechanism by which inflammatory mediators alter pain threshold.

Inhibition of Activator Protein 1 by Barbiturates Is Mediated by Differential Effects on Mitogen-Activated Protein Kinases and the Small G Proteins Ras and Rac-1

Barbiturates are known to suppress protective immunity, and their therapeutic use is associated with nosocomial infections. Although barbiturates inhibit T cell proliferation, differentiation, and cytokine synthesis, only thiobarbiturates markedly reduce the activation of immune regulatory transcription factors such as nuclear factor-kappaB and nuclear factor of activated T cells. In this study, we investigated barbiturate-mediated effects on the regulation of the transcription factor activator protein 1 (AP-1) in primary T lymphocytes. We show that both thiobarbiturates and their oxy-analogs inhibit AP-1-dependent gene expression and AP-1 complex formation at clinically relevant doses. Furthermore, mitogen-activated protein (MAP) kinase activity, which transcriptionally and posttranslationally regulates AP-1 complex formation, is suppressed by most barbiturates. CD3/CD28- or phorbol 12-myristate 13-acetate (PMA)/ionomycin-induced p38 and extracellular signal-regulated kinase 1/2 phosphorylation or c-jun NH2-terminal kinase (JNK) 1/2 kinase activity was significantly diminished by pentobarbital, thiamylal, secobarbital, or methohexital treatment. These barbiturates also inhibited the initiators of the MAP kinase cascade, the small G proteins ras and rac-1, and prevented binding to their partners raf-1 and PAK, respectively. Thiopental, unlike the other barbiturates, only reduced ras and JNK activity upon direct CD3/CD28 receptor engagement. Contrarily, upon PMA/ionomycin stimulation, thiopental blocked AP-1-dependent gene expression independently of the small G protein ras and MAP kinases, thus suggesting an additional, unknown mechanism of AP-1 regulation. In conclusion, our results contribute to the explanation of a clinically manifested immune suppression in barbiturate-treated patients and support the idea of a MAP kinase-independent regulation of AP-1 by PKC and calcium in human T cells.

The Proinflammatory Cytokines Tumor Necrosis Factor-α and Interleukin-1 Stimulate Neuropeptide Gene Transcription and Secretion in Adrenochromaffin Cells via Activation of Extracellularly Regulated Kinase 1/2 and p38 Protein Kinases, and Activator Protein-1 Transcription Factors

Immune-autonomic interactions are known to occur at the level of the adrenal medulla, and to be important in immune and stress responses, but the molecular signaling pathways through which cytokines actually affect adrenal chromaffin cell function are unknown. Here, we studied the effects of the proinflammatory cytokines, TNF-alpha and IL-1, on gene transcription and secretion of bioactive neuropeptides, in primary bovine adrenochromaffin cells. TNF-alpha and IL-1 induced a time- and dose-dependent increase in galanin, vasoactive intestinal polypeptide, and secretogranin II mRNA levels. The two cytokines also stimulated the basal as well as depolarization-provoked release of enkephalin and secretoneurin from chromaffin cells. Stimulatory effects of TNF-alpha on neuropeptide gene expression and release appeared to be mediated through the type 2 TNF-alpha receptor, and required activation of ERK 1/2 and p38, but not Janus kinase, MAPKs. In addition, TNF-alpha increased the binding activity of activator protein-1 (AP-1) and stimulated transcription of a reporter gene containing AP-1-responsive elements in chromaffin cells. The AP-1-responsive reporter gene could also be activated through the ERK pathway. These results suggest that neuropeptide biosynthesis in chromaffin cells is regulated by TNF-alpha via an ERK-dependent activation of AP-1-responsive gene elements. Either locally produced or systemic cytokines might regulate biosynthesis and release of neuropeptides in chromaffin cells, integrating the adrenal medulla in the physiological response to inflammation. This study describes, for the first time, a signal transduction pathway activated by TNF-alpha in a major class of neuroendocrine cells that, unlike TNF-alpha signaling in lymphoid cells, employs ERK and p38 rather than Janus kinase and p38 to transmit gene-regulatory signals to the cell nucleus.

In vivo activation of invariant Vα14 natural killer T?cells byα-galactosylceramide sequentially induces Fas-dependent and -independent cytotoxicity

The present study was designed to clarify the cytotoxic capacities of invariant V alpha 14 natural killer T (iNKT) cells activated in vivo. We found that as early as 2 h after a single injection of alpha-galactosylceramide (alpha-GalCer), sorted iNKT splenocytes from treated mice kill Fas-transfected target cells. The implication of the Fas pathway in this lysis was strengthened by both the blockage of cytotoxicity in the presence of anti-Fas ligand (FasL) monoclonal antibody (mAb) and the up-regulation of FasL expression on iNKT cells. Sorted NK cells did not participate in the lytic activity at this time point. Yet, they became cytotoxic later on, 24 h post-treatment, when target cell lysis was mainly independent of the Fas pathway. This type of cell killing was predominant at this later time point, even though iNKT cells conserved a slight Fas-dependent cytotoxicity. NK cells failed to acquire the ability to kill target cells when IFN-gamma production in alpha-GalCer-injected mice was blocked by anti-IFN-gamma mAb, underscoring the major role of this cytokine. In conclusion, our findings provide the first direct evidence that iNKT cells can exert Fas-dependent cytotoxicity very shortly after in vivo alpha-GalCer activation and later, through IFN-gamma secretion, enable NK cells to kill target cells in a Fas-independent pathway.

Intralaminar thalamic nuclei lesions: widespread impact on dopamine denervation-mediated cellular defects in the rat basal ganglia

Intralaminar thalamic nuclei represent a major site of non-dopaminergic degeneration in Parkinson disease, but the impact of this degeneration on the pathophysiological functioning of basal ganglia remains unknown. To address this issue, we compared the effects of 6-hydroxydopamine-induced lesions of nigral dopamine neurons alone or combined with ibotenate-induced lesions of intralaminar thalamic neurons on markers of neuronal metabolic activity in the rat basal ganglia using in situ hybridization histochemistry. Thalamic lesions prevented most of the dopamine denervation-induced changes (i.e. the increases in mRNA levels of enkephalin and GAD67 in the striatum, of GAD67 in the globus pallidus and entopeduncular nucleus, and of cytochrome oxidase subunit-I in the subthalamic nucleus), but did not affect the downregulation of striatal substance P and upregulation of GAD67 in the substantia nigra pars reticulata. We also provide immunohistochemical evidence that thalamic lesions markedly decreased striatal expression of the vesicular glutamate transporter vGluT2, confirming the association of this transporter with the thalamic projections to the basal ganglia. Altogether, these data reveal a major antagonistic influence of thalamic and dopaminergic afferents onto the basal ganglia and suggest that degeneration of thalamic neurons in Parkinson disease may represent an important factor counteracting expression of the defects associated with the dopamine denervation.

Structural Determinants Required for the Bioactivities of Prokineticins and Identification of Prokineticin Receptor Antagonists

Prokineticins are cysteine-rich secreted proteins that regulate diverse biological processes, including gastrointestinal motility, angiogenesis, and circadian rhythms. Two closely related G protein-coupled receptors that mediate signal transduction of prokineticins have recently been cloned. The structural elements required for prokineticins' bioactivities are still unknown. We show here that both the N-terminal hexapeptide (AVITGA) and C-terminal cysteine-rich domains are critical for the bioactivities of prokineticins. Substitutions, deletions, and insertions to the conserved N-terminal hexapeptides result in the loss of agonist activity. Mutant prokineticins with the substitution of the first N-terminal alanine with methionine or the addition of a methionine to the N terminus inhibit the activation of prokineticin receptors and thus are considered as antagonists of prokineticin receptors. We have further shown that mutations in selected cysteine residues in the C-terminal domain result in prokineticins without biological activity. The essential role of C-terminal domain is reinforced by two observations: that peptides without the carboxyl domain and proteins with the N-terminal hexapeptide fused to the carboxyl domains of colipase or dickkopf are devoid of biological activity. We demonstrate that limited structural changes of C-terminal cysteine-rich regions of prokineticins are tolerable because chimeric prokineticins with swapped cysteine-rich domains between prokineticin 1 and prokineticin 2, as well as a splice variant of prokineticin 2 that contains extra 21 residue insertion in its C-terminal domain, are biologically active.

Effects of lipopolysaccharide treatment on feeding of goldfish: role of appetite-regulating peptides

The gram-negative bacteria-derived endotoxin lipopolysaccharide (LPS) is known to play an important role in immune and neurological manifestations during bacterial infections. In mammals, peripheral or brain administration of LPS induces anorexia and is thought to exert its effects through activation of pro-inflammatory cytokines. In this study, we investigated the effects of peripheral (intraperitoneal, IP) and central (intracerebroventricular, ICV) injections of LPS on food intake of goldfish. Fish treated IP with 10, 25, 50, 100 or 250 ng/g LPS or ICV with 1, 10 and 100 ng/g LPS showed a significant dose-dependent decrease in food intake, compared to the saline-treated fish. We also examined the brain mRNA expression of several hypothalamic appetite-related neuropeptides in response to the administration of LPS. IP injections of LPS (100 ng/g) induced a decrease in NPY expression and an increase in CCK, CRF and CART expression. These results indicate that LPS is a potent anorexigenic factor in goldfish and that this endotoxin induces a reduction in appetite, at least in part, by influencing gene expression of appetite-related neuropeptides.

Induction of neuropeptide gene expression and blockade of retrograde transport in facial motor neurons following local peripheral nerve inflammation in severe combined immunodeficiency and BALB/C mice

Peripheral nerve inflammation is a common clinical problem that accompanies nerve injury and several diseases including Guillain-Barre syndrome and acute and chronic inflammatory demyelinating polyneuropathy. To determine if neuropeptides are induced in motor neurons after inflammation and to study the mechanisms involved, a nerve cuff soaked in complete Freund's adjuvant (CFA) was applied locally to the facial nerve of Balb/C mice. This procedure resulted in an influx of lymphocytes and macrophages to the affected area and a blockade of retrograde axonal transport distal, but not proximal, to the site of application. The same treatment resulted in a strong ipsilateral induction of pituitary adenylyl cyclase activating peptide (PACAP) gene expression in motor neurons in the facial motor nucleus. Because the changes could have occurred due to the loss of target-derived factors or to the production of new factors by immune cells, we studied the effect of the inflammatory stimulus on PACAP mRNA in mice with severe combined immunodeficiency (SCID). As expected, SCID mice showed a severely reduced influx of T-lymphocytes but not macrophages to the peripheral nerve. Moreover, although retrograde transport distal to the inflammation site was blocked similarly in control and SCID mice, the number of motor neurons expressing PACAP mRNA after CFA application was significantly reduced in SCID mice. The data indicate that the induction of PACAP mRNA during nerve inflammation requires the involvement of lymphocytes. However, because the induction of PACAP gene expression was only partially blocked in SCID mice, macrophages, loss of target-derived factors, or other mechanisms may also contribute to the upregulation of PACAP gene expression in motor neurons after nerve inflammation.

Laminin-induced aggregation of the inwardly rectifying potassium channel, Kir4.1, and the water-permeable channel, AQP4, via a dystroglycan-containing complex in astrocytes

Dystroglycan (DG) is part of a multiprotein complex that links the extracellular matrix to the actin cytoskeleton of muscle fibers and that is involved in aggregating acetylcholine receptors at the neuromuscular junction. This complex is also expressed in regions of the central nervous system where it is localized to both neuronal and glial cells. DG and the inwardly rectifying potassium channels, Kir4.1, are concentrated at the interface of astroglia and small blood vessels. These channels are involved in siphoning potassium released into the extracellular space after neuronal excitation. This raises the possibility that DG may be involved in targeting Kir4.1 channels to specific domains of astroglia. To address this question, we used mixed hippocampal cultures to investigate the distribution of DG, syntrophin, dystrobrevin, and Kir4.1 channels, as well as aquaporin-permeable water channels, AQP4. These proteins exhibit a similar distribution pattern and form aggregates in astrocytes cultured on laminin. Both DG and syntrophin colocalize with Kir4.1 channel aggregates in astrocytes. Similarly, DG colocalizes with AQP4 channel aggregates. Quantitative studies show a significant increase of Kir4.1 and AQP4 channel aggregates in astrocytes cultured in the presence of laminin when compared with those in the absence of laminin. These findings show that laminin has a role in Kir4.1 and AQP4 channel aggregation and suggest that this may be mediated via a dystroglycan-containing complex. This study reveals a novel functional role for DG in brain including K+ buffering and water homeostasis.