Melatonin rescued methotrexate-induced spatial deficit and hyperhomocysteinemia and increased asymmetric dimethylarginine in plasma and dorsal hippocampus in developing rats.

AIMS: With the improvement of the survival rates in children acute lymphoblastic leukemia (ALL), some children ALL survivors show impaired cognitive function. Methotrexate (MTX), an essential component in ALL treatment, has been reported to be related to neurologic sequelae and to increased oxidative stress through its interactions with enzymes in the folate pathway. Asymmetric dimethylarginine (ADMA) is the main endogenous inhibitor of nitric oxide synthase, and increased ADMA may result from increased oxidants. Melatonin is an antioxidant; however, its role in MTX neuropathy is not well studied. We developed a rat model mimicking child ALL treatment to explore peripheral and central homocysteine and ADMA regulation after MTX and found potential treatment choice. MAIN METHODS: Preweaning male Sprague-Dawley rats were used in this study. Experiment 1 evaluated spatial performance in rats with intrathecal (IT) MTX, intraperitoneal (IP) MTX, or combined IT and IP MTX, protocols mimicking ALL treatment in children. Experiment 2 focused on rats with combined IT and IP MTX, evaluating spatial performance and plasma and dorsal hippocampal homocysteine and ADMA levels, their regulation, and the protective effect of melatonin. KEY FINDINGS: Combined IT and IP MTX treatment caused in spatial deficits in developing rats, and melatonin restored the spatial performance. Alterations in peripheral and central homocysteine and ADMA concentrations and their regulation were found and could be alleviated by melatonin treatment. SIGNIFICANCES: Combined IP and IT MTX treatment caused spatial deficits in developing rats. Melatonin could restore spatial performance through alleviating the effects on the imbalance of oxidative stress.

The kisspeptin derivative kissorphin reduces the acquisition, expression, and reinstatement of ethanol-induced conditioned place preference in rats.

Research has shown that opioids are involved in the rewarding effects of ethanol. Neuropeptide FF (NPFF) has been described as an anti-opioid peptide because, in many cases, it inhibits opioid and ethanol effects in rodents. Kissorphin (KSO) is a new peptide derived from kisspeptin-10 with structural similarities to NPFF. This peptide possesses NPFF-like biological activity in vitro. The aim of the current study was to investigate whether KSO (Tyr-Asn-Trp-Asn-Ser-Phe-NH2) influences the acquisition, expression, and reinstatement of ethanol-induced conditioned place preference (ethanol-CPP) in rats. The ethanol-CPP was established (conditioning for 5 days) by intraperitoneal (i.p.) administration of ethanol (1 g/kg, 20%, w/v) using an unbiased procedure. After that, one group of rats was used in final post-conditioning testing (expression of CPP) and the other group received a priming injection of ethanol after 10 days of extinction (reinstatement of CPP). Our experiments showed that KSO, given intravenously (i.v.) at the doses of 1, 3, and 10 nmol before every ethanol administration, inhibited the acquisition and, given acutely before the post-conditioning test or before the priming dose of ethanol, inhibited the expression and reinstatement of ethanol-CPP, respectively, in a dose-dependent manner. KSO given by itself neither induced place preference nor aversion and did not alter locomotor activity and coordination of rats. These results suggest that KSO can alter rewarding/motivational effects of ethanol. These data suggest this peptide possesses an anti-opioid character.

Inhibition of N-acylethanolamine acid amidase reduces nicotine-induced dopamine activation and reward.

Tobacco smoke is the leading preventable cause of death in the world and treatments aimed to increase success rate in smoking cessation by reducing nicotine dependence are sought. Activation of peroxisome proliferator-activated receptor-alpha (PPARα) by synthetic or endogenous agonists was shown to suppress nicotine-induced activation of mesolimbic dopamine system, one of the major neurobiological substrates of nicotine dependence, and nicotine-seeking behavior in rats and monkeys. An alternative indirect way to activate PPARα is inhibition of N-acylethanolamine acid amidase (NAAA), one of the major hydrolyzing enzyme for its endogenous agonists palmitoylethanolamide (PEA) and oleoylethanolamide (OEA). We synthetized a novel specific brain permeable NAAA inhibitor, AM11095. We administered AM11095 to rats and carried out brain lipid analysis, a functional observational battery (FOB) to assess toxicity, in vivo electrophysiological recording from dopamine cells in the ventral tegmental area, brain microdialysis in the nucleus accumbens shell and behavioral experiments to assess its effect on nicotine -induced conditioned place preference (CPP). AM11095 (5 and 25 mg/kg, i.p.) was devoid of neurotoxic and behavioral effects and did not affect motor behavior and coordination. This NAAA inhibitor (5 mg/kg i.p.) increased OEA and PEA levels in the hippocampus and cortex, prevented nicotine-induced activation of mesolimbic dopamine neurons in the ventral tegmental area, nicotine-induced elevation of dopamine levels in the nucleus accumbens shell and decreased the expression of nicotine CPP. Our results indicate that NAAA inhibitors represent a new class of pharmacological tools to modulate brain PEA/PPARα signalling and show potential in the treatment of nicotine dependence.

5-HIAA induces neprilysin to ameliorate pathophysiology and symptoms in a mouse model for Alzheimer's disease.

Serotoninergic activation which decreases brain Aß peptides is considered beneficial in mouse models for Alzheimer's disease (AD), but the mechanisms involved remain unclear. Because growing evidence suggested that the stimulation of proteases digesting Aß, especially the endopeptidase neprilysin (NEP) may be effective for AD therapy/prevention, we explored the involvement of serotonin precursors and derivatives in NEP regulation. We found that 5-hydroxyindolacetic acid (5-HIAA), the final metabolite of serotonin, considered until now as a dead-end and inactive product of serotonin catabolism, significantly reduces brain Aß in the transgenic APPSWE mouse model for AD-related Aß pathology and in the phosphoramidon-induced cerebral NEP inhibition mouse model. 5-HIAA treatment improves memory performance in APPSWE mice. Furthermore, 5-HIAA and its precursors increase NEP level in vivo and in neuroblastoma cells. Inhibition of ERK 1/2 cascade by 5-HIAA or SCH772984 enhanced NEP levels, suggesting MAP-kinase pathway involvement in 5-HIAA-induced regulation of NEP expression. Our results provide the first demonstration that 5-HIAA is an active serotonin metabolite that increases brain Aß degradation/clearance and improves symptoms in the APPSWE mouse model for AD.

Rapid effects of sex steroids on zebra finch (Taeniopygia guttata) pair maintenance.

Although steroids are widely known to affect behavior through activation of nuclear/cytosolic receptors ("genomic" effects), steroids can also rapidly affect behavior via modulation of signal transduction pathways ("nongenomic," fast actions, or rapid effects). In zebra finches, there is evidence that sex steroids have context-specific effects on pair-maintenance behavior, on both acute and chronic timescales. Here, we quantified the effects of orally administered testosterone and 17ß-estradiol (E2) on pair-maintenance behavior. We show that E2 rapidly affects female, but not male, affiliative behavior profiles during a partner separation and reunion paradigm. More specifically, E2 rapidly (within 5-15 min of administration) increased females' spatial proximity to a partner. This effect was present regardless of breeding condition (water restriction or water ad libitum). Combined, these results contribute to a growing body of evidence implicating sex steroids in the regulation of prosocial behavior. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Thioredoxin-1 downregulation in the nucleus accumbens promotes methamphetamine-primed reinstatement in mice.

Relapse of drug abuse after abstinence is a major challenge to the treatment of addicts. Thioredoxin-1 (Trx-1) is an important regulator of neuroprotection, and inhibits morphine-induced hyperlocomotion, reward and withdrawal signs, as well as blocks methamphetamine (METH)-induced conditioned place preference (CPP). The nucleus accumbens (NAc) is essential for relapse like behavior in reinstatement animal models. In the present study, we aimed to investigate the role of Trx-1 in the NAc in METH-primed reinstatement by using a reinstatement procedure in mice. Adeno-associated virus vectors expressing shRNA-mTrx-1 (AAV-shRNA-mTrx-1) were bilaterally microinjected into the NAc after METH-CPP extinction. The results showed that Trx-1 downregulation in the NAc promoted the reinstatement of METH-CPP. We also examined the expression of N-methyl-D-asparate (NMDA) receptor 2B subunit (GluN2b), the levels of phosphorylated extracellular signal-regulated kinase (p-ERK) and phosphorylated cAMP-response element binding protein (p-CREB) in the NAc by western blot analysis, and found that the GluN2b expression, p-ERK and p-CREB levels were increased in the NAc in response to low-dose METH in AAV-shRNA-mTrx-1 mice, but were not changed in control and AAV-vehicle mice. These data indicate that the increased GluN2b expression, and p-ERK and p-CREB levels in the NAc of AAV-shRNA-mTrx-1 mice may be responsible for the METH-primed reinstatement. Thus, we suggest that downregulation of Trx-1 in the NAc may make mice more sensitive to METH reinstatement.

The effects of lateral line ablation and regeneration in schooling giant danios.

Fish use multiple sensory systems, including vision and their lateral line system, to maintain position and speed within a school. Although previous studies have shown that ablating the lateral line alters schooling behavior, no one has examined how the behavior recovers as the sensory system regenerates. We studied how schooling behavior changes in giant danios, Devario aequipinnatus, when their lateral line system is chemically ablated and after the sensory hair cells regenerate. We found that fish could school normally immediately after chemical ablation, but that they had trouble schooling 1-2 weeks after the chemical treatment, when the hair cells had fully regenerated. We filmed groups of giant danios with two high-speed cameras and reconstructed the three-dimensional positions of each fish within a group. One fish in the school was treated with gentamycin to ablate all hair cells. Both types of neuromasts (canal and superficial) were completely ablated after treatment, but fully regenerated after 1 week. We quantified the structure of the school using nearest neighbor distance, bearing, elevation, and the cross-correlation of velocity between each pair of fish. Treated fish maintained a normal position within the school immediately after the lateral line ablation, but could not school normally 1 or 2 weeks after treatment, even though the neuromasts had fully regenerated. By 4-8 weeks post-treatment, the treated fish could again school normally. These results demonstrate that the behavioral recovery after lateral line ablation is a longer process than the regeneration of the hair cells themselves.

Evaluation of the rewarding properties of nicotine and caffeine by implementation of a five-choice conditioned place preference task in zebrafish.

The rewarding properties of drugs in zebrafish can be studied using the conditioned place preference (CPP) paradigm. Most devices that have been used for CPP consist of two-half tanks with or without a central chamber. Here we evaluated the rewarding effects of nicotine and caffeine using a tank with five arms distributed radially from a central chamber that we have denoted Fish Tank Radial Maze (FTRM). Zebrafish were trained to associate nicotine or caffeine with a coloured arm. In testing sessions to assess CPP induction, between two and five different arms were available to explore. We found that when offering the two arms, one of them associated to the drug mediating conditioning for 14 days, zebrafish showed nicotine-induced CPP but not caffeine-induced CPP. When zebrafish had the option to explore drug-paired arms together with new coloured arms as putative distractors, the nicotine-CPP strength was maintained for at least three days. The presence of novel environments induced caffeine-CPP, which was still positive after three days of testing sessions. Complementary behavioural data supported these findings. Nicotine-CPP was prevented by the histone deacetylase inhibitor phenylbutyrate administered during conditioning; however, there were no effects on caffeine-CPP. The specific acetylation of lysine 9 in histone 3 (H3-K9) was increased in nicotine-conditioned zebrafish brains. This study suggests that novel environmental cues facilitate drug-environment associations, and hence, the use of drugs of abuse.

Mid-gestational sevoflurane exposure inhibits fetal neural stem cell proliferation and impairs postnatal learning and memory function in a dose-dependent manner.

Advancements in fetal intervention procedures have led to increases in the number of pregnant women undergoing general anesthesia during the second trimester-a period characterized by extensive proliferation of fetal neural stem cells (NSCs). However, few studies have investigated the effects of mid-gestational sevoflurane exposure on fetal NSC proliferation or postnatal learning and memory function. In the present study, pregnant rats were randomly assigned to a control group (C group), a low sevoflurane concentration group (2%; L group), a high sevoflurane concentration group (3.5%; H group), a high sevoflurane concentration plus lithium chloride group (H + Li group), and a lithium chloride group (Li group) at gestational day 14. Rats received different concentrations of sevoflurane anesthesia for 2 h. The offspring rats were weaned at 28 days for behavioral testing (i.e., Morris Water Maze [MWM]), and fetal brains or postnatal hippocampal tissues were harvested for immunofluorescence staining, real-time PCR, and Western blotting analyses in order to determine the effect of sevoflurane exposure on NSC proliferation and the Wnt/ß-catenin signaling pathway. Our results indicated that maternal exposure to 3.5% sevoflurane (H group) during the mid-gestational period impaired the performance of offspring rats in the MWM test, reduced NSC proliferation, and increased protein levels of fetal glycogen synthase kinase-3 beta (GSK-3ß). Such treatment also decreased levels of ß-catenin protein, CD44 RNA, and Cyclin D1 RNA relative to those observed in the C group. However, these effects were transiently attenuated by treatment with lithium chloride. Conversely, maternal exposure to 2% sevoflurane (L group) did not influence NSC proliferation or the Wnt signaling pathway. Our results suggest that sevoflurane exposure during the second trimester inhibits fetal NSC proliferation via the Wnt/ß-catenin pathway and impairs postnatal learning and memory function in a dose-dependent manner.

An analysis of the rewarding and aversive associative properties of nicotine in the neonatal quinpirole model: Effects on glial cell line-derived neurotrophic factor (GDNF).

This study analyzed the associative properties of nicotine in a conditioned place preference (CPP) paradigm in adolescent rats neonatally treated with quinpirole (NQ) or saline (NS). NQ produces dopamine D2 receptor supersensitivity that persists throughout the animal's lifetime, and therefore has relevance towards schizophrenia. In two experiments, rats were ip administered quinpirole (1mg/kg) or saline from postnatal day (P)1-21. After an initial preference test at P42-43, animals were conditioned for eight consecutive days with saline or nicotine (0.6mg/kg free base) in Experiment 1 or saline or nicotine (1.8mg/kg free base) in Experiment 2. In addition, there were NQ and NS groups in each experiment given the antipsychotic haloperidol (0.05mg/kg) or clozapine (2.5mg/kg) before nicotine conditioning. A drug free post-conditioning test was administered at P52. At P53, the nucleus accumbens (NAc) was analyzed for glial cell-line derived neurotrophic factor (GDNF). Results revealed that NQ enhanced nicotine CPP, but blunted the aversive properties of nicotine. Haloperidol was more effective than clozapine at blocking nicotine CPP in Experiment 1, but neither antipsychotic affected nicotine conditioned place aversion in Experiment 2. NQ increased accumbal GDNF which was sensitized in NQ rats conditioned to nicotine in Experiment 1, but the aversive dose of nicotine reduced GDNF in NQ animals in Experiment 2. Both antipsychotics in combination with the aversive dose of nicotine decreased accumbal GDNF. In sum, increased D2 receptor sensitivity influenced the associative properties and GDNF response to nicotine which has implications towards pharmacological targets for smoking cessation in schizophrenia.

Lesions within the head direction system reduce retrosplenial c-fos expression but do not impair performance on a radial-arm maze task.

The lateral mammillary nuclei are a central structure within the head direction system yet there is still relatively little known about how these nuclei contribute to spatial performance. In the present study, rats with selective neurotoxic lesions of the lateral mammillary nuclei were tested on a working memory task in a radial-arm maze. This task requires animals to distinguish between eight radially-oriented arms and remember which arms they have entered within a session. Even though it might have been predicted that this task would heavily tax the head direction system, the lesion rats performed equivalently to their surgical controls on this task; no deficit emerged even when the task was made more difficult by rotating the maze mid-way through testing in order to reduce reliance on intramaze cues. Rats were subsequently tested in the dark to increase the use of internally generated direction cues but the lesion rats remained unimpaired. In contrast, the lateral mammillary nuclei lesions were found to decrease retrosplenial c-Fos levels. These results would suggest that the head direction system is not required for the acquisition of the standard radial-arm maze task. It would also suggest that small decreases in retrosplenial c-Fos are not sufficient to produce behavioural impairments.

Retrieval-Induced Upregulation of Tet3 in Pyramidal Neurons of the Dorsal Hippocampus Mediates Cocaine-Associated Memory Reconsolidation.

Background: Memory retrieval refers to reexposure to information previously encoded and stored in the brain. Following retrieval, a once-consolidated memory destabilizes and undergoes reconsolidation, during which gene expression changes to restabilize memory. Investigating epigenetic regulation during reconsolidation could provide insights into normal memory formation and pathological memory associated with psychiatric disorders. Methods: We used cocaine-induced conditioned place preference to assess the cocaine-associated memory of mice and used chemogenetic methods to manipulate the activity of the pyramidal neurons in the dorsal hippocampus. We isolated the ribosome-associated transcripts from the excitatory neurons in the dorsal hippocampus by RiboTag purification to identify the potential epigenetic regulators, and we specifically knocked down gene expression in pyramidal neurons with a Cre-dependent lentivirus. Results: Chemogenetically silencing the activity of the pyramidal neurons in the dorsal hippocampus immediately after memory retrieval markedly impaired memory reconsolidation, and the ribosome-associated mRNA level of the ten-eleven translocation (Tet) family methylcytosine dioxygenase Tet3, but not Tet1 or Tet2, was dramatically upregulated 10 minutes after memory retrieval. The protein level of Tet3 in the dorsal hippocampus but not in the anterior cingulate cortex was dramatically increased 1 hour after memory retrieval. Specifically, knockdown of Tet3 in pyramidal neurons in the dorsal hippocampus decreased the activation of pyramidal neurons and impaired the reconsolidation of cocaine-associated memory. Conclusions: Our findings highlight the new function of the DNA demethylation regulator Tet3 in pyramidal neurons of the dorsal hippocampus in regulating the reconsolidation of cocaine-associated memory.

Facial pain and anxiety-like behavior are reduced by pregabalin in a model of facial carcinoma in rats.

Pain and anxiety are common symptoms in head and neck cancer patients. The anticonvulsant pregabalin has therapeutic indication for the treatment of pain and anxiety, and may represent a useful drug for both conditions. Thus, the aim of this study was to investigate the relationship between pain and anxiety in rats with facial carcinoma, as the influence of pregabalin treatment in both aspects. Facial carcinoma was induced by subcutaneous inoculation of Walker-256 tumor cells in the vibrissa pad of Wistar rats. On day 6 after inoculation spontaneous facial grooming and conditioned place preference were assessed as non-evoked pain measurements and facial mechanical hyperalgesia were assessed 3 and 6 days after tumor cells inoculation. Moreover, anxiety-like behavior was evaluated on the elevated plus maze and light-dark transition tests at the same time points. The effect of pregabalin treatment (30 mg/kg, p.o.) was evaluated in all tests. Our results demonstrated that pregabalin treatment reduced the spontaneous facial grooming and induced conditioned place preference 6 days post tumor inoculation. Tumor-bearing rats developed mechanical hyperalgesia starting 3 days post tumor induction, which was also significant on day 6, but the anxiety-like behavior was detected only in tumor-bearing rats that developed mechanical hyperalgesia and only six days after tumor cells inoculation. Both, the mechanical hyperalgesia and the anxiety-like behavior related to the tumor were significantly reduced by pregabalin treatment on day 6. Pregabalin treatment resulted in antinociceptive and anxiolytic-like effects on facial tumor-bearing rats and may represent a promising therapeutic option for cancer patients.

TRPV1 modulates morphine-induced conditioned place preference via p38 MAPK in the nucleus accumbens.

Emerging evidence suggests that the transient receptor potential vanilloid type 1 channel (TRPV1) is a novel target for the treatment of drug addiction, such as cocaine and morphine. Previously we reported that TRPV1 inhibition reduced morphine reward in the dorsal striatum (DSt) of mice and morphine self-administration through a decrease in accumbal activity in rats. However, the role of TRPV1 on morphine-conditioned reward in addiction-related brain regions, such as the nucleus accumbens (NAc), has not been previously established. Here, we investigated the effects of TRPV1 on morphine conditioned place preference (CPP) and intracellular mechanisms of TRPV1 using Western blot analysis and immunohistochemistry (IHC) in morphine-administered mice. TRPV1 knockout mice did not exhibit morphine reward responses, and both i.p. and intra-NAc injections of SB366791, a selective TRPV1 antagonist, reduced morphine-induced CPP in wild-type mice. Furthermore, i.p. injection of SB203580, a selective p38 MAPK inhibitor, also dampened morphine-induced CPP. To determine the molecular mechanisms of the TRPV1/p38 MAPK pathway in morphine CPP, we investigated the expression of adenylyl cyclase type 1 (AC1) and phospho-p38 mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) in the NAc. Either SB366791 or SB203580 decreased the protein expression levels of phospho-p38 MAPK, phosphor-NF-κB, and AC1 in the NAc of morphine CPP mice. Taken together, our findings suggest that TRPV1 may modulate morphine-induced conditioned reward effects via the p38 MAPK signaling pathway in the NAc. Therefore, blockade of TRPV1 may provide a novel therapeutic approach for the prevention and treatment of opioid addiction.

Neonatal Injury Results in Sex-Dependent Nociceptive Hypersensitivity and Social Behavioral Deficits During Adolescence, Without Altering Morphine Response.

Neonatal injury is associated with persistent changes in sensory function and altered nociceptive thresholds that give rise to aberrant pain sensitivity in later life. Although these changes are well documented in adult rodents, little is known about the consequences of neonatal injury during adolescence. Because adolescence is a critical developmental period during which persistent pain conditions can arise, we examined the effect of neonatal injury on nociception, social behavior, and response to morphine in adolescent Sprague Dawley rats. Male and female rats exposed to plantar incision injury at postnatal day 3 displayed mechanical hypersensitivity that resolved by 24 hours after incision. When these animals reached adolescence (postnatal day 28-40), neonatally-injured male rats showed ipsilaterally restricted mechanical, heat, and cold hypersensitivity, as well as social behavioral deficits. In contrast, these effects were not seen in female rats. Neonatal injury did not alter acute morphine antinociception or the development of analgesic tolerance in either sex. Morphine-induced conditioned place preference, behavioral sensitization, and physical withdrawal were also not affected by neonatal incision. Thus, early-life injury results in sex-dependent pain-related hypersensitivity and social behavior deficits during adolescence, without altering the response to opioids. PERSPECTIVE: Neonatal surgery has greater effects on adolescent male than female rats, resulting in pain-related hypersensitivity and social behavioral deficits. Neonatal surgery does not alter the antinociceptive effects of morphine or abuse liability.

Protective effects of a green tea polyphenol, epigallocatechin-3-gallate, against sevoflurane-induced neuronal apoptosis involve regulation of CREB/BDNF/TrkB and PI3K/Akt/mTOR signalling pathways in neonatal mice.

Epigallocatechin-3-gallate (EGCG), a polyphenol in green tea, is an effective antioxidant and possesses neuroprotective effects. Brain-derived neurotrophic factor (BDNF) and cyclic AMP response element-binding protein (CREB) are crucial for neurogenesis and synaptic plasticity. In this study, we aimed to assess the protective effects of EGCG against sevoflurane-induced neurotoxicity in neonatal mice. Distinct groups of C57BL/6 mice were given EGCG (25, 50, or 75 mg/kg body weight) from postnatal day 3 (P3) to P21 and were subjected to sevoflurane (3%; 6 h) exposure on P7. EGCG significantly inhibited sevoflurane-induced neuroapoptosis as determined by Fluoro-Jade B staining and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL). Increased levels of cleaved caspase-3, downregulated Bad and Bax, and significantly enhanced Bcl-2, Bcl-xL, xIAP, c-IAP-1, and survivin expression were observed. EGCG induced activation of the PI3K/Akt pathway as evidenced by increased Akt, phospho-Akt, GSK-3ß, phospho-GSK-3ß, and mTORc1 levels. Sevoflurane-mediated downregulation of cAMP/CREB and BDNF/TrkB signalling was inhibited by EGCG. Reverse transcription PCR analysis revealed enhanced BDNF and TrkB mRNA levels upon EGCG administration. Improved performance of mice in Morris water maze tests suggested enhanced learning and memory. The study indicates that EGCG was able to effectively inhibit sevoflurane-induced neurodegeneration and improve learning and memory retention of mice via activation of CREB/BDNF/TrkB-PI3K/Akt signalling.

Sensitivity to cocaine in adult mice is due to interplay between genetic makeup, early environment and later experience.

Although early aversive postnatal events are known to increase the risk to develop psychiatric disorders later in life, rarely they determine alone the nature and outcome of the psychopathology, indicating that interaction with genetic factors is crucial for expression of psychopathologies in adulthood. Moreover, it has been suggested that early life experiences could have negative consequences or confer adaptive value in different individuals. Here we suggest that resilience or vulnerability to adult cocaine sensitivity depends on a "triple interaction" between genetic makeup x early environment x later experience. We have recently showed that Repeated Cross Fostering (RCF; RCF pups were fostered by four adoptive mothers from postnatal day 1 to postnatal day 4. Pups were left with the last adoptive mother until weaning) experienced by pups affected the response to a negative experience in adulthood in opposite direction in two genotypes leading DBA2/J, but not C57BL/6J mice, toward an "anhedonia-like" phenotype. Here we investigate whether exposure to a rewarding stimulus, instead of a negative one, in adulthood induces an opposite behavioral outcome. To test this hypothesis, we investigated the long-lasting effects of RCF on cocaine sensitivity in C57 and DBA female mice by evaluating conditioned place preference induced by different cocaine doses and catecholamine prefrontal-accumbal response to cocaine using a "dual probe" in vivo microdialysis procedure. Moreover, cocaine-induced c-Fos activity was assessed in different brain regions involved in processing of rewarding stimuli. Finally, cocaine-induced spine changes were evaluated in the prefrontal-accumbal system. RCF experience strongly affected the behavioral, neurochemical and morphological responses to cocaine in adulthood in opposite direction in the two genotypes increasing and reducing, respectively, the sensitivity to cocaine in C57 and DBA mice.

Methamphetamine induces Shati/Nat8L expression in the mouse nucleus accumbens via CREB- and dopamine D1 receptor-dependent mechanism.

Shati/Nat8L significantly increased in the nucleus accumbens (NAc) of mice after repeated methamphetamine (METH) treatment. We reported that Shati/Nat8L overexpression in mouse NAc attenuated METH-induced hyperlocomotion, locomotor sensitization, and conditioned place preference. We recently found that Shati/Nat8L overexpression in NAc regulates the dopaminergic neuronal system via the activation of group II mGluRs by elevated N-acetylaspartylglutamate following N-acetylaspartate increase due to the overexpression. These findings suggest that Shati/Nat8L suppresses METH-induced responses. However, the mechanism by which METH increases the Shati/Nat8L mRNA expression in NAc is unclear. To investigate the regulatory mechanism of Shati/Nat8L mRNA expression, we performed a mouse Shati/Nat8L luciferase assay using PC12 cells. Next, we investigated the response of METH to Shati/Nat8L expression and CREB activity using mouse brain slices of NAc, METH administration to mice, and western blotting for CREB activity of specific dopamine receptor signals in vivo and ex vivo. We found that METH activates CREB binding to the Shati/Nat8L promoter to induce the Shati/Nat8L mRNA expression. Furthermore, the dopamine D1 receptor antagonist SCH23390, but not the dopamine D2 receptor antagonist sulpiride, inhibited the upregulation of Shati/Nat8L and CREB activities in the mouse NAc slices. Thus, the administration of the dopamine D1 receptor agonist SKF38393 increased the Shati/Nat8L mRNA expression in mouse NAc. These results showed that the Shati/Nat8L mRNA was increased by METH-induced CREB pathway via dopamine D1 receptor signaling in mouse NAc. These findings may contribute to development of a clinical tool for METH addiction.

Combined effect of BCG vaccination and enriched environment promote neurogenesis and spatial cognition via a shift in meningeal macrophage M2 polarization.

BACKGROUND: The spatial learning abilities of developing mice benefit from extrinsic cues, such as an enriched environment, with concomitant enhancement in cognitive functions. Interestingly, such enhancements can be further increased through intrinsic Bacillus Calmette-Guérin (BCG) vaccination. RESULTS: Here, we first report that combined neonatal BCG vaccination and exposure to an enriched environment (Enr) induced combined neurobeneficial effects, including hippocampal long-term potentiation, and increased neurogenesis and spatial learning and memory, in mice exposed to the Enr and vaccinated with BCG relative to those in the Enr that did not receive BCG vaccination. Neonatal BCG vaccination markedly induced anti-inflammatory meningeal macrophage polarization both in regular and Enr breeding mice. The meninges are composed of the pia mater, dura mater, and choroid plexus. Alternatively, this anti-inflammatory activity of the meninges occurred simultaneously with increased expression of the neurotrophic factors BDNF/IGF-1 and the M2 microglial phenotype in the hippocampus. Our results reveal a critical role for BCG vaccination in the regulation of neurogenesis and spatial cognition through meningeal macrophage M2 polarization and neurotrophic factor expression; these effects were completely or partially prevented by minocycline or anti-IL-10 antibody treatment, respectively. CONCLUSIONS: Together, we first claim that immunological factor and environmental factor induce a combined effect on neurogenesis and cognition via a common pathway-meningeal macrophage M2 polarization. We also present a novel functional association between peripheral T lymphocytes and meningeal macrophages after evoking adaptive immune responses in the periphery whereby T lymphocytes are recruited to the meninges in response to systemic IFN-γ signaling. This leads to meningeal macrophage M2 polarization, subsequent to microglial M2 activation and neurotrophic factor expression, and eventually promotes a positive behavior.

Blockade of patch-based µ opioid receptors in the striatum attenuates methamphetamine-induced conditioned place preference and reduces activation of the patch compartment.

The behavioral effects of methamphetamine (METH) are mediated by the striatum, which is divided into the patch compartment, which mediates limbic and reward functions, and the matrix compartment, which mediates sensorimotor tasks. METH treatment results in repetitive behavior that is related to enhanced relative activation of the patch versus the matrix compartment. The patch, but not the matrix compartment contains a high density of µ opioid receptors, and localized blockade of patch-based µ opioid receptors attenuates METH-induced patch-enhanced activity and repetitive behaviors. Numerous studies have examined patch-enhanced activity and the contribution of patch-associated µ opioid receptors to METH-induced repetitive behavior, but it is not known whether patch-enhanced activity occurs during METH-mediated reward, nor is it known if patch-based µ opioid receptors contribute to METH reward. The goals of this study were to determine if blockade of patch-based µ opioid receptors alters METH-induced conditioned place preference (CPP), as well activation of the patch and matrix compartments following METH-mediated CPP. A biased conditioning paradigm was used to assess CPP, and conditioning occurred over an 8-d period. Animals were bilaterally infused in the striatum with the µ-specific antagonist CTAP or vehicle prior to conditioning. Animals were tested for preference 24h after the last day of conditioning, sacrificed and the brains processed for immunohistochemistry. Blockade of patch-based µ opioid receptors reduced METH-induced CPP, and reduced patch-enhanced c-Fos expression in the striatum following METH-mediated CPP. These data indicate that patch-enhanced activity is associated with METH-mediated reward and patch-based µ opioid receptors contribute to this phenomenon.