Circadian-Dependent Learning and Memory Enhancement in Nociceptin Receptor-Deficient Mice with a Novel KUROBOX Apparatus Using Stress-Free Positive Cue Task

Prothymosin α Plays Role as a Brain Guardian through Ecto-F1 ATPase-P2Y12 Complex and TLR4/MD2

Prothymosin alpha (ProTα) was discovered to be a necrosis inhibitor from the conditioned medium of a primary culture of rat cortical neurons under starved conditions. This protein carries out a neuronal cell-death-mode switch from necrosis to apoptosis, which is, in turn, suppressed by a variety of neurotrophic factors (NTFs). This type of NTF-assisted survival action of ProTα is reproduced in cerebral and retinal ischemia-reperfusion models. Further studies that used a retinal ischemia-reperfusion model revealed that ProTα protects retinal cells via ecto-F₁ ATPase coupled with the G_i-coupled P2Y₁₂ receptor and Toll-like receptor 4 (TLR4)/MD2 coupled with a Toll-IL-1 receptor domain-containing adaptor inducing IFN-β (TRIF). In cerebral ischemia-reperfusion models, ProTα has additional survival mechanisms via an inhibition of matrix metalloproteases in microglia and vascular endothelial cells. Heterozygous or conditional ProTα knockout mice show phenotypes of anxiety, memory learning impairment, and a loss of neurogenesis. There are many reports that ProTα has multiple intracellular functions for cell survival and proliferation through a variety of protein-protein interactions. Overall, it is suggested that ProTα plays a key role as a brain guardian against ischemia stress through a cell-death-mode switch assisted by NTFs and a role of neurogenesis.

Differential Modulation of Ventral Tegmental Area Circuits by the Nociceptin/Orphanin FQ System

The neuropeptide nociceptin/orphanin FQ (N/OFQ) can be released by stressors and is associated with disorders of emotion regulation and reward processing. N/OFQ and its receptor, NOP, are enriched in dopaminergic pathways, and intra-ventricular agonist delivery decreases dopamine levels in the dorsal striatum, nucleus accumbens (NAc), and ventral tegmental area (VTA). We used whole-cell electrophysiology in acute rat midbrain slices to investigate synaptic actions of N/OFQ. N/OFQ was primarily inhibitory, causing outward currents in both immunocytochemically identified dopaminergic (tyrosine hydroxylase positive (TH(+))) and non-dopaminergic (TH(-)) VTA neurons; effect at 1 μm: 20 ± 4 pA. Surprisingly, this effect was mediated by augmentation of postsynaptic GABAAR currents, unlike the substantia nigra pars compacta (SNc), where the N/OFQ-induced outward currents were K+ channel dependent. A smaller population, 17% of all VTA neurons, responded to low concentrations of N/OFQ with inward currents (10 nm: -11 ± 2 pA). Following 100 nm N/OFQ, the response to a second N/OFQ application was markedly diminished in VTA neurons (14 ± 10% of first response) but not in SNc neurons (90 ± 20% of first response). N/OFQ generated outward currents in medial prefrontal cortex (mPFC)-projecting VTA neurons, but inward currents in a subset of posterior anterior cingulate cortex (pACC)-projecting VTA neurons. While N/OFQ inhibited NAc-projecting VTA cell bodies, it had little effect on electrically or optogenetically evoked terminal dopamine release in the NAc measured ex vivo with fast scan cyclic voltammetry (FSCV). These results extend our understanding of the N/OFQ system in brainstem circuits implicated in many neurobehavioral disorders.

Blockade of nociceptin/orphanin FQ signaling facilitates an active copying strategy due to acute and repeated stressful stimuli in mice

The role of stress in the etiology of depression has been largely reported. In this line, exogenous glucocorticoids are employed to mimic the influence of stress on the development of depression. The N/OFQ-NOP receptor system has been implicated in the modulation of stress and emotional behaviors. In fact, the blockade of NOP receptors induces antidepressant effects and increases resilience to acute stress. This study investigated the effects of the NOP receptor blockade on dexamethasone-treated mice exposed to acute and prolonged swimming stress. Swiss and NOP(+/+) and NOP(−/−) mice were treated with dexamethasone, and the protective effects of the NOP antagonist SB-612111 (10 mg/kg, ip) or imipramine (20 mg/kg, ip) were investigated in three swimming sessions. The re-exposure to swim stress increased immobility time in Swiss and NOP(+/+), but not in NOP(−/−) mice. Acute and repeated dexamethasone administration induced a further increase in the immobility time, and facilitated body weight loss in Swiss mice. Single administration of SB-612111, but not imipramine, prevented swimming stress- and dexamethasone-induced increase in the immobility time. Repeated administrations of SB-612111 prevented the deleterious effects of 5 days of dexamethasone treatment. Imipramine also partially prevented the effects of repeated glucocorticoid administration on the immobility time, but did not affect the body weight loss. NOP(−/−) mice were more resistant than NOP(+/+) mice to inescapable swimming stress, but not dexamethasone-induced increase in the immobility time and body weight loss. In conclusion, the blockade of the NOP receptor facilitates an active stress copying response and attenuates body weight loss due to repeated stress.

Modulation of the NOP receptor signaling affects resilience to acute stress

BACKGROUND

The peptide nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) are implicated in the modulation of emotional states. Previous human and rodent findings support NOP antagonists as antidepressants. However, the role played by the N/OFQ-NOP receptor system in resilience to stress is unclear.

AIMS

The present study investigated the effects of activation or blockade of NOP receptor signaling before exposure to acute stress.

METHODS

The behavioral effects of the administration before stress of the NOP agonists Ro 65-6570 (0.01-1 mg/kg) and MCOPPB (0.1-10 mg/kg), and the NOP antagonist SB-612111 (1-10 mg/kg) were assessed in mice exposed to inescapable electric footshock and forced swim as stressors. The behavioral phenotype of mice lacking the NOP receptor (NOP(-/-)) exposed to inescapable electric footshock was also investigated.

RESULTS

The activation of NOP receptor signaling with the agonists increased the percentage of mice developing helpless behavior and facilitated immobile posture. In contrast, the blockade of NOP receptor reduced the acquisition of depressive-like phenotypes, and similar resistance to develop helpless behaviors was observed in NOP(-/-) mice. Under the same stressful conditions, the antidepressant nortriptyline (20 mg/kg) did not change the acquisition of helpless behavior and immobile posture.

CONCLUSIONS

These findings support the view that NOP activation during acute stress facilitates the development of depressive-related behaviors, whereas NOP blockade has a protective outcome. This study showed for first time that NOP antagonists are worthy of investigation as preemptive treatments in patients with severe risk factors for depression.

The Nociceptin/Orphanin FQ System and the Regulation of Memory

Nociceptin/orphanin FQ (N/OFQ) is an endogenous neuropeptide of 17 amino acids, related to opioid peptides but with its own receptor, distinct from conventional opioid receptors, the ORL1 or NOP receptor. The NOP receptor is a G protein-coupled receptor which activates Gi/o proteins and thus induces an inhibition of neuronal activity. The peptide and its receptor are widely expressed in the central nervous system with a high density of receptors in regions involved in learning and memory. This review describes the consequences of the pharmacological manipulation of the N/OFQ system by NOP receptor ligands on learning processes and on the consolidation of various types of long-term memory. We also discuss the role of endogenous N/OFQ release in the modulation of learning and memory. Finally we propose several putative neuronal mechanisms taking place at the level of the hippocampus and amygdala and possibly underlying the behavioral amnestic or promnesic effects of NOP ligands.

Blockade of analgesic effects following systemic administration of N-methyl-kyotorphin, NMYR and arginine in mice deficient of preproenkephalin or proopiomelanocortin gene

Kyotorphin is a unique biologically active neuropeptide (l-tyrosine-l-arginine), which is reported to have opioid-like analgesic actions through a release of Met-enkephalin from the brain slices. N-methyl-l-tyrosine-l-arginine (NMYR), an enzymatically stable mimetic of kyotorphin, successfully caused potent analgesic effects in thermal and mechanical nociception tests in mice when it was given through systemic routes. NMYR analgesia was abolished in μ-opioid receptor-deficient (MOP-KO) mice, and by intracerebroventricular (i.c.v.) injection of naloxone and of N-methyl l-leucine-l-arginine (NMLR), a kyotorphin receptor antagonist. In the Ca²⁺-mobilization assay using CHO cells expressing Gα_qi5 and hMOPr or hDOPr, however, the addition of kyotorphin neither activated MOPr-mechanisms, nor affected the concentration-dependent activation of DAMGO- or Met-Enkephalin-induced MOPr activation, and Met-enkephalin-induced DOPr activation. NMYR-analgesia was significantly attenuated in preproenkephalin (PENK)- or proopioimelanocortin (POMC)-KO mice. The systemic administration of arginine, which is reported to elevate the level of endogenous kyotorphin selectively in midbrain and medulla oblongata, pain-related brain regions, caused significant analgesia, and the analgesia was reversed by i.c.v. injection of NMLR or naloxone. In addition, PENK- and POMC-KO mice also attenuated the arginine-induced analgesia. All these findings suggest that NMYR and arginine activate brain kyotorphin receptor in direct and indirect manner, respectively and both compounds indirectly cause the opioid-like analgesia through the action of endogenous opioid peptides.

A systematic review of the role of the nociceptin receptor system in stress, cognition, and reward: relevance to schizophrenia

Schizophrenia is a debilitating neuropsychiatric illness that is characterized by positive, negative, and cognitive symptoms. Research over the past two decades suggests that the nociceptin receptor system may be involved in domains affected in schizophrenia, based on evidence aligning it with hallmark features of the disorder. First, aberrant glutamatergic and striatal dopaminergic function are associated with psychotic symptoms, and the nociceptin receptor system has been shown to regulate dopamine and glutamate transmission. Second, stress is a critical risk factor for first break and relapse in schizophrenia, and evidence suggests that the nociceptin receptor system is also directly involved in stress modulation. Third, cognitive deficits are prevalent in schizophrenia, and the nociceptin receptor system has significant impact on learning and working memory. Last, reward processing is disrupted in schizophrenia, and nociceptin signaling has been shown to regulate reward cue salience. These findings provide the foundation for the involvement of the nociceptin receptor system in the pathophysiology of schizophrenia and outline the need for future research into this system.

The Nociceptin Receptor (NOP) Agonist AT-312 Blocks Acquisition of Morphine- and Cocaine-Induced Conditioned Place Preference in Mice

Treatment of drug addiction remains an unmet medical need due to the dearth of approved pharmacotherapies. There are no approved treatments for cocaine addiction, whereas the current opioid crisis has revealed the stark reality of the limited options to treat prescription and illicit opioid abuse. Preclinical studies in rodents and nonhuman primates have shown that orphanin FQ/nociceptin (N/OFQ), the endogenous ligand for the nociceptin opioid receptor (NOP) reduces the rewarding effects of several abused substances, including opioids, psychostimulants and alcohol. A few nonpeptide small-molecule NOP agonists have also shown efficacy in attenuating the rewarding effects of various abused drugs. We previously demonstrated that a high affinity small-molecule NOP agonist AT-312 selectively reduced the rewarding effects of ethanol in the conditioned place preference paradigm in mice. In the present study, we examined if AT-312 (3 mg/kg, i.p. or s.c. respectively), would alter the rewarding action of morphine (7.5 mg/kg, s.c.) or cocaine (15 mg/kg, i.p.). The effect of AT-312 on morphine- and cocaine-induced motor stimulation was also assessed on the conditioning days. The role of the NOP receptor in the effects of AT-312 was further confirmed by conducting the place conditioning experiments in NOP knockout mice and compared to their wild-type controls. Our results showed that AT-312 significantly reduced the acquisition of morphine and cocaine CPP in wild-type mice but not in mice lacking NOP receptors. AT-312 also suppressed morphine-induced and completely abolished cocaine-induced motor stimulation in NOP wild-type mice, but not in NOP knockout mice. These results show that small-molecule NOP receptor agonists have promising efficacy for attenuating the rewarding effects of morphine and cocaine, and may have potential as pharmacotherapy for opioid and psychostimulant addiction or for treating polydrug addiction.

Nociceptin and the NOP receptor in aversive learning in mice

The endogenous neuropeptide nociceptin (N/OFQ), which mediates its actions via the nociceptin receptor (NOP), is implicated in multiple behavioural and physiological functions. This study examined the effects of the NOP agonists N/OFQ and the synthetic agonist Ro 64-6198, the antagonists NNN and NalBzoH, as well as deletion of the Pronociceptin gene on emotional memory in mice. The animals were tested in the passive avoidance (PA) task, dependent on hippocampal and amygdala functions. N/OFQ injected intraventricularly (i.c.v.) prior to training produced a biphasic effect on PA retention; facilitation at a low dose and impairment at higher doses. Ro 64-6198 also displayed a biphasic effect with memory facilitation at lower doses and impairment at a high dose. None of the agonists influenced PA training latencies. NNN did not significantly modulate retention in the PA task but antagonized the inhibitory effects of N/OFQ. NalBzoH facilitated memory retention in a dose-dependent manner and blocked the impairing effects of N/OFQ. However, neither NNN nor NalBzoH blocked the memory-impairing effects of Ro 64-6198. Finally, the Pnoc knockout mice exhibited enhanced PA retention latencies compared to the wild type mice. The biphasic effect of the natural ligand and Ro 64-6198 and the failure of the antagonists to block the action of Ro 64-6198 indicate complexity in ligand-receptor interaction. These results indicate that brain nociceptin and its NOP has a subtle role in regulation of mechanisms of relevance for treatment of disorders with processing disturbances of aversive events e.g. Alzheimer's disease, anxiety, depression and PTSD.

Prothymosin alpha-deficiency enhances anxiety-like behaviors and impairs learning/memory functions and neurogenesis

Prothymosin alpha (ProTα) is expressed in various mammalian organs including the neuronal nuclei in the brain, and is involved in multiple functions, such as chromatin remodeling, transcriptional regulation, cell proliferation, and survival. ProTα has beneficial actions against ischemia-induced necrosis and apoptosis in the brain and retina. However, characterizing the physiological roles of endogenous ProTα in the brain without stress remains elusive. Here, we generated ProTα-deficiency mice to explore whether endogenous ProTα is involved in normal brain functions. We successfully generated heterozygous ProTα knockout (ProTα^+/- ) mice, while all homozygous ProTα knockout (ProTα^-/- ) offspring died at early embryonic stage, suggesting that ProTα has crucial roles in embryonic development. In the evaluation of different behavioral tests, ProTα^+/- mice exhibited hypolocomotor activity in the open-field test and enhanced anxiety-like behaviors in the light/dark transition test and the novelty induced hypophagia test. ProTα^+/- mice also showed impaired learning and memory in the step-through passive avoidance test and the KUROBOX test. Depression-like behaviors in ProTα^+/- mice in the forced swim and tail suspension tests were comparable with that of wild-type mice. Furthermore, adult hippocampal neurogenesis was significantly decreased in ProTα^+/- mice. ProTα^+/- mice showed an impaired long-term potentiation induction in the evaluation of electrophysiological recordings from acute hippocampal slices. Microarray analysis revealed that the candidate genes related to anxiety, learning/memory-functions, and neurogenesis were down-regulated in ProTα^+/- mice. Thus, this study suggests that ProTα has crucial physiological roles in the robustness of brain.

Age-dependent effects of esculetin on mood-related behavior and cognition from stressed mice are associated with restoring brain antioxidant status

Dietary antioxidants might exert an important role in the aging process by relieving oxidative damage, a likely cause of age-associated brain dysfunctions. This study aims to investigate the influence of esculetin (6,7-dihydroxycoumarin), a naturally occurring antioxidant in the diet, on mood-related behaviors and cognitive function and its relation with age and brain oxidative damage. Behavioral tests were employed in 11-, 17- and 22-month-old male C57BL/6J mice upon an oral 35day-esculetin treatment (25mg/kg). Activity of antioxidant enzymes, GSH and GSSG levels, GSH/GSSG ratio, and mitochondrial function were analyzed in brain cortex at the end of treatment in order to assess the oxidative status related to mouse behavior. Esculetin treatment attenuated the increased immobility time and enhanced the diminished climbing time in the forced swim task elicited by acute restraint stress (ARS) in the 11- and 17-month-old mice versus their counterpart controls. Furthermore, ARS caused an impairment of contextual memory in the step-through passive avoidance both in mature adult and aged mice which was partially reversed by esculetin only in the 11-month-old mice. Esculetin was effective to prevent the ARS-induced oxidative stress mostly in mature adult mice by restoring antioxidant enzyme activities, augmenting the GSH/GSSG ratio and increasing cytochrome c oxidase (COX) activity in cortex. Modulation of the mood-related behavior and cognitive function upon esculetin treatment in a mouse model of ARS depends on age and is partly due to the enhancement of redox status and levels of COX activity in cortex.

Endogenous nociceptin system involvement in stress responses and anxiety behavior

The mechanisms underpinning stress-related behavior and dysfunctional events leading to the expression of neuropsychiatric disorders remain incompletely understood. Novel candidates involved in the neuromodulation of stress, mediated both peripherally and centrally, provide opportunities for improved understanding of the neurobiological basis of stress disorders and may represent targets for novel therapeutic development. This chapter provides an overview of the mechanisms by which the opioid-related peptide, nociceptin, regulates the neuroendocrine stress response and stress-related behavior. In our research, we have employed nociceptin receptor antagonists to investigate endogenous nociceptin function in tonic control over stress-induced activity of the hypothalamo-pituitary-adrenal axis. Nociceptin demonstrates a wide range of functions, including modulation of psychological and inflammatory stress responses, modulation of neurotransmitter release, immune homeostasis, in addition to anxiety and cognitive behaviors. Greater appreciation of the complexity of limbic-hypothalamic neuronal networks, together with attention toward gender differences and the roles of steroid hormones, provides an opportunity for deeper understanding of the importance of the nociceptin system in the context of the neurobiology of stress and behavior.

Changes in brain tissue and behavior patterns induced by single short-term fasting in mice

In humans, emaciation from long-term dietary deficiencies, such as anorexia, reportedly increases physical activity and brain atrophy. However, the effects of single short-term fasting on brain tissue or behavioral activity patterns remain unclear. To clarify the impact of malnutrition on brain function, we conducted a single short-term fasting study as an anorexia model using male adult mice and determined if changes occurred in migratory behavior as an expression of brain function and in brain tissue structure. Sixteen-week-old C57BL/6J male mice were divided into either the fasted group or the control group. Experiments were conducted in a fixed indoor environment. We examined the effects of fasting on the number of nerve cells, structural changes in the myelin and axon density, and brain atrophy. For behavior observation, the amount of food and water consumed, ingestion time, and the pattern of movement were measured using a time-recording system. The fasted mice showed a significant increase in physical activity and their rhythm of movement was disturbed. Since the brain was in an abnormal state after fasting, mice that were normally active during the night became active regardless of day or night and performed strenuous exercise at a high frequency. The brain weight did not change by a fast, and brain atrophy was not observed. Although no textural change was apparent by fasting, the neuronal neogenesis in the subventricular zone and hippocampus was inhibited, causing disorder of the brain function. A clear association between the suppression of encephalic neuropoiesis and overactivity was not established. However, it is interesting that the results of this study suggest that single short-term fasting has an effect on encephalic neuropoiesis.

Dysfunction of the hypothalamic-pituitary-adrenal axis in STX1A knockout mice

HPC-1/syntaxin1A (STX1A) is considered to regulate exocytosis in neurones and endocrine cells. Previously, we reported that STX1A null mutant (STX1A KO) mice unexpectedly showed normal glutamatergic and GABAergic fast synaptic transmission but exhibited disturbances in monoaminergic transmission, such as serotonin, 5-hydroxytryptamine (5-HT), which may induce attenuation of latent inhibition. These results suggest that STX1A may contribute to dense-core vesicle exocytosis in vivo. Thus, we hypothesised that the lack of STX1A might affect the secretion of several hormones, as also mediated by dense-core vesicles exocytosis. In the present study, we focused on the hypothalamic-pituitary-adrenal (HPA) axis, which is a neuroendocrine system that regulates responses to stress stimuli and is considered to be associated with neuropsychiatric disorders. Specifically, we examined whether the HPA axis is impaired in STX1A KO mice. Interestingly, plasma concentrations of both corticosterone (CORT) and adrenocorticotrophin hormone (ACTH) during the resting condition decreased in STX1A KO mice compared to WT mice. Additionally, elevated plasma CORT, ACTH and corticotrophin-releasing hormone (CRH) which were usually observed after acute restraint stress, were also reduced in STX1A KO mice. We also observed the suppression of 5-HT-induced CRH release in STX1A KO mice in vitro. Furthermore, an in vivo microdialysis study revealed that the elevation of extracellular 5-HT in the hypothalamus, which was induced by the selective serotonin reuptake inhibitor, fluoxetine, was significantly reduced in STX1A KO mice compared to WT mice. 5-HT elevation in the hypothalamus, which was induced by acute restraint stress, was also reduced in STX1A KO mice. Finally, STX1A KO mice showed abnormal behavioural responses after mild restraint stress. These results indicate that the lack of STX1A could induce dysfunction of the HPA axis, and the deficit may result in abnormal behavioural properties, such as unusual responses to stress stimuli.

American ginseng improves neurocognitive function in senescence-accelerated mice: possible role of the upregulated insulin and choline acetyltransferase gene expression

AIM

To investigate the effects of American ginseng on neurocognitive function and glucose regulation in senescence-accelerated mice.

METHODS

Male senescence-resistant inbred strains (SAMR1) and senescence-prone inbred strains (SAMP10) mice were divided into five groups and fed either a control diet or an American ginseng-supplemented diet (1% or 2% g/g) from 6 weeks to 10 months of age. Bodyweight, levels of fasting plasma glucose (FPG) and grading scores were monitored every month and neurocognitive functions were evaluated at 9 months of age with a KUROBOX apparatus using a stress-free positive cue task. Gene expressions of peroxisome proliferator-activated receptor delta (PPAR-δ), insulin, choline acetyltransferase (ChAT) and amyloid precursor protein (APP) in the brain were measured by real-time quantitative reverse transcription polymerase chain reaction assays.

RESULTS

American ginseng decreased FPG in SAMR1 mice, but increased FPG in SAMP10 mice. Correct visit ratios were higher in both SAMR1 and SAMP10 strains consuming an American ginseng-supplemented diet. Gene upregulation of insulin and ChAT in the brain, but not of PPAR-δ or APP, was evident in American ginseng-fed groups.

CONCLUSION

Daily consumption of American ginseng induced an enhancement in neurocognitive function in senescence-accelerated mice, which could be related to the upregulation of insulin and ChAT gene expression in the brain. Geriatr Gerontol Int 2012; 12: 123-130.

The nociceptin system and hippocampal cognition in mice: a pharmacological and genetic analysis

This study examines the effects of NOP agonists nociceptin/orphanin FQ (N/OFQ) and Ro 64-6198, NOP antagonists [Nphe(1)]N/OFQ(1-13)-NH(2) Nphe(1) and naloxone benzoylhydrazone (NalBzoH) on spatial memory in NMRI mice and pronociceptin (proNC) knockout (KO) mice using the water maze task. N/OFQ, administered i.c.v. (1, 5 and 10 nmol/mouse) and into hippocampal CA3 (1 nmol/mouse, bilaterally), impaired acquisition and retention in the maze. Impairments were blocked by pre-treatment with Nphe(1) (10 nmol, i.c.v.). Ro 64-6198 (0.1-0.3-1 mg/kg i.p.) also dose-dependently impaired learning. However, pre-treatment with NalBzoH (1 mg/kg, s.c.) failed to modify the effects of Ro 64-6198. Nphe(1) (10 nmol/mouse i.c.v.) and NalBzoH (1 mg/kg, s.c.) by themselves failed to affect maze performance, despite a tendency for enhanced performance. Prepro N/OFQ knockout (ppN/OFQ -/-) showed evidence of improved learning, evident at retention trials and in reversal training. ppN/OFQ -/- mice were not impaired by N/OFQ (10 nmol i.c.v.) in the task, suggesting that changes in postsynaptic NOP receptors may occur in such KO mice. It is concluded that N/OFQ and NOP receptors have an important role in hippocampus-dependent spatial learning and memory, probably by modulation of glutamatergic functions.

Endogenous opiates and behavior: 2007

This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Effects of nestin-antisense treatment in mice on memory-related performance

Nestin is a neuronal stem cell marker. It has been reported that newly generated adult neurons play a role in murine memory. The purpose of this study was to determine whether nestin itself plays a role in memory function in adult animals. Mice were infused intraventricularly with nestin-selective, morpholino-modified antisense oligodeoxynucleotides for 6 days, after which their ability to perform a new memory-related, food-search task was assessed. Such treatment was found to reduce the training effect on food-search test performance. Immunohistochemical staining revealed that nestin-positive cells within the hippocampal dentate gyrus and subventricular zone were attenuated in these animals. These data support a role for nestin in adult memory and learning.