BACKGROUND: Elevated brain levels of kynurenic acid (KYNA), a metabolite in the kynurenine pathway, are associated with cognitive dysfunctions, which are nowadays often considered as fundamental characteristics of several psychopathologies; however, the role of KYNA in mental illnesses, such as schizophrenia, is not fully elucidated. This study aimed to assess KYNA levels in the prefrontal cortex (PFC) of rats prenatally treated with methylazoxymethanol (MAM) acetate, i.e., a well-validated neurodevelopmental animal model of schizophrenia. The effects of an early pharmacological modulation of the endogenous cannabinoid system were also evaluated. METHODS: Pregnant Sprague-Dawley rats were treated with MAM (22 mg/kg, ip) or its vehicle at gestational day 17. Male offspring were treated with the cannabinoid CB1 receptor antagonist/inverse agonist AM251 (0.5 mg/kg/day, ip) or with the typical antipsychotic haloperidol (0.6 mg/kg/day, ip) from postnatal day (PND) 19 to PND39. The locomotor activity and cognitive performance were assessed in the novel object recognition test and the open field test in adulthood. KYNA levels in the PFC of prenatally MAM-treated rats were also assessed. RESULTS: A significant cognitive impairment was observed in prenatally MAM-treated rats (p < 0.01), which was associated with enhanced PFC KYNA levels (p < 0.05). The peripubertal AM251, but not haloperidol, treatment ameliorated the cognitive deficit (p < 0.05), by normalizing the PFC KYNA content in MAM rats. CONCLUSIONS: The present findings suggest that the cognitive deficit observed in MAM rats may be related to enhanced PFC KYNA levels which could be, in turn, mediated by the activation of cannabinoid CB1 receptor. These results further support the modulation of brain KYNA levels as a potential therapeutic strategy to ameliorate the cognitive dysfunctions in schizophrenia.

• Keywords
• AM251, Haloperidol, Kynurenine Pathway, Novel object recognition test, Peripubertal treatment, Schizophrenia,
• MeSH
• Antipsychotic Agents pharmacology   MeSH
• Haloperidol pharmacology   MeSH
• Cognitive Dysfunction metabolism   drug therapy   MeSH
• Rats MeSH
• Kynurenic Acid * metabolism   MeSH
• Methylazoxymethanol Acetate * analogs & derivatives   MeSH
• Disease Models, Animal MeSH
• Piperidines pharmacology   MeSH
• Rats, Sprague-Dawley * MeSH
• Prefrontal Cortex * metabolism   drug effects   MeSH
• Pyrazoles pharmacology   MeSH
• Receptor, Cannabinoid, CB1 metabolism   MeSH
• Schizophrenia * metabolism   drug therapy   MeSH
• Pregnancy MeSH
• Prenatal Exposure Delayed Effects * metabolism   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• AM 251 MeSH Browser
• Antipsychotic Agents MeSH
• Haloperidol MeSH
• Kynurenic Acid * MeSH
• Methylazoxymethanol Acetate * MeSH
• Piperidines MeSH
• Pyrazoles MeSH
• Receptor, Cannabinoid, CB1 MeSH

AIM: Widely used second-generation antipsychotics are associated with adverse metabolic effects, contributing to increased cardiovascular mortality. To develop strategies to prevent or treat adverse metabolic effects, preclinical models have a clear role in uncovering underlying molecular mechanisms. However, with few exceptions, preclinical studies have been performed in healthy animals, neglecting the contribution of dysmetabolic features inherent to psychotic disorders. METHODS: In this study, methylazoxymethanol acetate (MAM) was prenatally administered to pregnant Sprague-Dawley rats at gestational day 17 to induce a well-validated neurodevelopmental model of schizophrenia mimicking its assumed pathogenesis with persistent phenotype. Against this background, the dysmetabolic effects of acute treatment with olanzapine and haloperidol were examined in female rats. RESULTS: Prenatally MAM-exposed animals exhibited several metabolic features, including lipid disturbances. Half of the MAM rats exposed to olanzapine had pronounced serum lipid profile alteration compared to non-MAM controls, interpreted as a reflection of a delicate MAM-induced metabolic balance disrupted by olanzapine. In accordance with the drugs' clinical metabolic profiles, olanzapine-associated dysmetabolic effects were more pronounced than haloperidol-associated dysmetabolic effects in non-MAM rats and rats exposed to MAM. CONCLUSION: Our results demonstrate metabolic vulnerability in female prenatally MAM-exposed rats, indicating that findings from healthy animals likely provide an underestimated impression of metabolic dysfunction associated with antipsychotics. In the context of metabolic disturbances, neurodevelopmental models possess a relevant background, and the search for adequate animal models should receive more attention within the field of experimental psychopharmacology.

• Keywords
• adipokine, antipsychotic, lipid profile, methylazoxymethanol, schizophrenia,
• MeSH
• Antipsychotic Agents * therapeutic use   MeSH
• Haloperidol * toxicity   MeSH
• Rats MeSH
• Lipids MeSH
• Methylazoxymethanol Acetate toxicity   analogs & derivatives   MeSH
• Disease Models, Animal MeSH
• Olanzapine toxicity   MeSH
• Rats, Sprague-Dawley MeSH
• Pregnancy MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Antipsychotic Agents * MeSH
• Haloperidol * MeSH
• Lipids MeSH
• methylazoxymethanol MeSH Browser
• Methylazoxymethanol Acetate MeSH
• Olanzapine MeSH

Adolescent exposure to cannabinoids as a postnatal environmental insult may increase the risk of psychosis in subjects exposed to perinatal insult, as suggested by the two-hit hypothesis of schizophrenia. Here, we hypothesized that peripubertal Δ9-tetrahydrocannabinol (aTHC) may affect the impact of prenatal methylazoxymethanol acetate (MAM) or perinatal THC (pTHC) exposure in adult rats. We found that MAM and pTHC-exposed rats, when compared to the control group (CNT), were characterized by adult phenotype relevant to schizophrenia, including social withdrawal and cognitive impairment, as revealed by social interaction test and novel object recognition test, respectively. At the molecular level, we observed an increase in cannabinoid CB1 receptor (Cnr1) and/or dopamine D2/D3 receptor (Drd2, Drd3) gene expression in the prefrontal cortex of adult MAM or pTHC-exposed rats, which we attributed to changes in DNA methylation at key regulatory gene regions. Interestingly, aTHC treatment significantly impaired social behavior, but not cognitive performance in CNT groups. In pTHC rats, aTHC did not exacerbate the altered phenotype nor dopaminergic signaling, while it reversed cognitive deficit in MAM rats by modulating Drd2 and Drd3 gene expression. In conclusion, our results suggest that the effects of peripubertal THC exposure may depend on individual differences related to dopaminergic neurotransmission.

• Keywords
• dopamine D2/D3 receptors, methylazoxymethanol acetate, psychopathology, Δ9-tetrahydrocannabinol,
• MeSH
• Dopamine metabolism   MeSH
• Rats MeSH
• Humans MeSH
• Disease Models, Animal MeSH
• Prefrontal Cortex drug effects   metabolism   MeSH
• Receptors, Dopamine D3 metabolism   MeSH
• Schizophrenia * chemically induced   MeSH
• Pregnancy MeSH
• Dronabinol * toxicity   MeSH
• Prenatal Exposure Delayed Effects * metabolism   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Humans MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Dopamine MeSH
• Receptors, Dopamine D3 MeSH
• Dronabinol * MeSH

OBJECTIVE: Addiction is a chronic disease with limited pharmacological options for intervention. Focusing on reducing glutamate levels in the brain seems to be a promising strategy in addiction treatment research. Our research aimed to evaluate the effects of CNQX, an antagonist that targets AMPA and kainate glutamatergic receptors while also exhibiting affinity for the NMDA receptor, especially by modulating its glycine site. We conducted this assessment on the self-administration of nicotine and methamphetamine via intravenous (IV) administration in rats. METHODS: An operant IV self-administration model was used in male Wistar rats. When animals maintained a stable intake of nicotine or methamphetamine, we administered a single injection of CNQX (in the dose of 3 or 6 mg/kg IV) to evaluate its effect on drug intake. Subsequently, the rats were forced to abstain by staying in their home cages for 2 weeks. The period of abstinence was followed by a context-induced relapse-like session before which animals were pretreated with the injection of CNQX (3 or 6 mg/kg IV) to evaluate its effect on drug seeking. RESULTS: CNQX significantly reduced nicotine intake during the maintenance phase, but no effect was revealed on nicotine seeking after forced abstinence. CNQX did not affect methamphetamine taking or seeking. CONCLUSION: The effect of reducing nicotine taking but not seeking could be explained by different involvement of glutamatergic receptors in various stages of nicotine dependence.

• Keywords
• AMPA/kainate receptor, CNQX, methamphetamine, nicotine, relapse, self-administration,
• Publication type
• Journal Article MeSH

In agreement with the neurodevelopmental hypothesis of schizophrenia, prenatal exposure of Sprague-Dawley rats to the antimitotic agent methylazoxymethanol acetate (MAM) at gestational day 17 produces long-lasting behavioral alterations such as social withdrawal and cognitive impairment in adulthood, mimicking a schizophrenia-like phenotype. These abnormalities were preceded at neonatal age both by the delayed appearance of neonatal reflexes, an index of impaired brain maturation, and by higher 2-arachidonoylglycerol (2-AG) brain levels. Schizophrenia-like deficits were reversed by early treatment [from postnatal day (PND) 2 to PND 8] with the CB1 antagonist/inverse agonist AM251 (0.5 mg/kg/day). By contrast, early CB1 blockade affected the behavioral performance of control rats which was paralleled by enhanced 2-AG content in the prefrontal cortex (PFC). These results suggest that prenatal MAM insult leads to premorbid anomalies at neonatal age via altered tone of the endocannabinoid system, which may be considered as an early marker preceding the development of schizophrenia-like alterations in adulthood.

• Keywords
• 2-arachidonoylglycerol (2-AG), AM251, MAM model, cannabinoid CB1 receptor, endocannabinoid system, schizophrenia,
• MeSH
• Rats MeSH
• Methylazoxymethanol Acetate * MeSH
• Disease Models, Animal MeSH
• Rats, Sprague-Dawley MeSH
• Receptor, Cannabinoid, CB1 MeSH
• Schizophrenia * chemically induced   drug therapy   genetics   MeSH
• Pregnancy MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Methylazoxymethanol Acetate * MeSH
• Receptor, Cannabinoid, CB1 MeSH

Clinical studies consistently report structural impairments (i.e.: ventricular enlargement, decreased volume of anterior cingulate cortex or hippocampus) and functional abnormalities including changes in regional cerebral blood flow in individuals suffering from schizophrenia, which can be evaluated by magnetic resonance imaging (MRI) techniques. The aim of this study was to assess cerebral blood perfusion in several schizophrenia-related brain regions using Arterial Spin Labelling MRI (ASL MRI, 9.4 T Bruker BioSpec 94/30USR scanner) in rats. In this study, prenatal exposure to methylazoxymethanol acetate (MAM, 22 mg/kg) at gestational day (GD) 17 and the perinatal treatment with Δ-9-tetrahydrocannabinol (THC, 5 mg/kg) from GD15 to postnatal day 9 elicited behavioral deficits consistent with schizophrenia-like phenotype, which is in agreement with the neurodevelopmental hypothesis of schizophrenia. In MAM exposed rats a significant enlargement of lateral ventricles and perfusion changes (i.e.: increased blood perfusion in the circle of Willis and sensorimotor cortex and decreased perfusion in hippocampus) were detected. On the other hand, the THC perinatally exposed rats did not show differences in the cerebral blood perfusion in any region of interest. These results suggest that although both pre/perinatal insults showed some of the schizophrenia-like deficits, these are not strictly related to distinct hemodynamic features.

• MeSH
• Circle of Willis diagnostic imaging   drug effects   embryology   MeSH
• Hippocampus blood supply   diagnostic imaging   drug effects   embryology   MeSH
• Rats MeSH
• Humans MeSH
• Magnetic Resonance Angiography methods   MeSH
• Methylazoxymethanol Acetate toxicity   MeSH
• Disease Models, Animal MeSH
• Cerebrovascular Circulation drug effects   MeSH
• Neurogenesis drug effects   MeSH
• Schizophrenia chemically induced   diagnosis   MeSH
• Sensorimotor Cortex blood supply   diagnostic imaging   drug effects   embryology   MeSH
• Behavior Observation Techniques MeSH
• Pregnancy MeSH
• Dronabinol toxicity   MeSH
• Prenatal Exposure Delayed Effects chemically induced   diagnostic imaging   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Humans MeSH
• Male MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Methylazoxymethanol Acetate MeSH
• Dronabinol MeSH

The devastating consequences of alcohol-use disorder (AUD) on the individual and the society are well established. Current treatments of AUD encompass various strategies, all of which have only modest effectiveness. Hence, there is a critical need to develop more efficacious therapies. Recently, specific glutamatergic receptors have been identified as potential novel targets for intervention in AUD. Thus, the current study was designed to evaluate the effects of acute administration of sub-anesthetic doses of ketamine, an NMDA receptor antagonist, as well as NBQX, an AMPA/kainate receptor antagonist on alcohol intake and its possible behavioural consequences. Adult male Wistar rats were trained in drinking in dark paradigm (3 weeks), and following stable alcohol intake, ketamine, NBQX as well as their combination were injected prior to a 90 min drinking session. In addition to alcohol intake, sucrose preference (overnight), and locomotor activity and forced swim test (FST) were also evaluated before and following alcohol intake. Both doses of ketamine (5 and 10 mg/kg) and NBQX (5 and 10 mg/kg) significantly attenuated percent alcohol intake. The combination of the higher dose of ketamine and NBQX, however, did not significantly affect percent alcohol intake. Moreover, animals exposed to alcohol showed decreased sucrose intake (reflective of anhedonia), decreased locomotor activity and swimming in the FST (reflective of helplessness), that were not affected by ketamine and/or NBQX. These results suggest that selective antagonism of the NMDA or AMPA/kainate receptors may be of therapeutic potential in AUD.

• Keywords
• AMPA receptor, Alcohol use disorder, Alcoholism, Glutamatergic receptors, Kainate receptor, NMDA receptor,
• MeSH
• Receptors, AMPA antagonists & inhibitors   MeSH
• Quinoxalines pharmacology   MeSH
• Depression drug therapy   MeSH
• Ketamine pharmacology   MeSH
• Kainic Acid pharmacology   MeSH
• Alcohol Drinking adverse effects   MeSH
• Rats, Wistar MeSH
• Receptors, N-Methyl-D-Aspartate antagonists & inhibitors   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• 2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline MeSH Browser
• Receptors, AMPA MeSH
• Quinoxalines MeSH
• Ketamine MeSH
• Kainic Acid MeSH
• Receptors, N-Methyl-D-Aspartate MeSH

Although histone acetylation is one of the most widely studied epigenetic modifications, there is still a lack of information regarding how the acetylome is regulated during brain development and pathophysiological processes. We demonstrate that the embryonic brain (E15) is characterized by an increase in H3K9 acetylation as well as decreases in the levels of HDAC1 and HDAC3. Moreover, experimental induction of H3K9 hyperacetylation led to the overexpression of NCAM in the embryonic cortex and depletion of Sox2 in the subventricular ependyma, which mimicked the differentiation processes. Inducing differentiation in HDAC1-deficient mouse ESCs resulted in early H3K9 deacetylation, Sox2 downregulation, and enhanced astrogliogenesis, whereas neuro-differentiation was almost suppressed. Neuro-differentiation of (wt) ESCs was characterized by H3K9 hyperacetylation that was associated with HDAC1 and HDAC3 depletion. Conversely, the hippocampi of schizophrenia-like animals showed H3K9 deacetylation that was regulated by an increase in both HDAC1 and HDAC3. The hippocampi of schizophrenia-like brains that were treated with the cannabinoid receptor-1 inverse antagonist AM251 expressed H3K9ac at the level observed in normal brains. Together, the results indicate that co-regulation of H3K9ac by HDAC1 and HDAC3 is important to both embryonic brain development and neuro-differentiation as well as the pathophysiology of a schizophrenia-like phenotype.

• Keywords
• H3K9 acetylation, HDACs, acetylome, mouse neurogenesis, schizophrenia,
• MeSH
• Acetylation MeSH
• Cannabinoid Receptor Antagonists pharmacology   MeSH
• Antipsychotic Agents pharmacology   MeSH
• Time Factors MeSH
• Epigenesis, Genetic MeSH
• Gestational Age MeSH
• Histone Deacetylase 1 antagonists & inhibitors   genetics   metabolism   MeSH
• Histone Deacetylases genetics   metabolism   MeSH
• Histones metabolism   MeSH
• Histone Deacetylase Inhibitors pharmacology   MeSH
• Methylazoxymethanol Acetate MeSH
• Disease Models, Animal MeSH
• Neural Cell Adhesion Molecules genetics   metabolism   MeSH
• Brain drug effects   embryology   enzymology   pathology   MeSH
• Mice, Inbred C57BL MeSH
• Neurogenesis * drug effects   MeSH
• Neurons drug effects   enzymology   pathology   MeSH
• Protein Processing, Post-Translational MeSH
• Rats, Sprague-Dawley MeSH
• Receptor, Cannabinoid, CB1 antagonists & inhibitors   metabolism   MeSH
• Schizophrenia chemically induced   drug therapy   enzymology   genetics   MeSH
• Signal Transduction MeSH
• SOXB1 Transcription Factors genetics   metabolism   MeSH
• Gene Expression Regulation, Developmental MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cannabinoid Receptor Antagonists MeSH
• Antipsychotic Agents MeSH
• Cnr1 protein, rat MeSH Browser
• Hdac1 protein, mouse MeSH Browser
• Hdac1 protein, rat MeSH Browser
• Histone Deacetylase 1 MeSH
• Histone Deacetylases MeSH
• histone deacetylase 3 MeSH Browser
• Histones MeSH
• Histone Deacetylase Inhibitors MeSH
• Methylazoxymethanol Acetate MeSH
• Neural Cell Adhesion Molecules MeSH
• Receptor, Cannabinoid, CB1 MeSH
• Sox2 protein, mouse MeSH Browser
• SOXB1 Transcription Factors MeSH

Ketamine may prove to be a potential candidate in treating the widespread drug addiction/substance abuse epidemic among patients with schizophrenia. Clinical studies have shown ketamine to reduce cocaine and heroin cravings. However, the use of ketamine remains controversial as it may exacerbate the symptoms of schizophrenia. Therefore, the aim of this study is to characterize the effects of ketamine on drug addiction in schizophrenia using the methylazoxymethanol (MAM) acetate rat model on operant IV methamphetamine (METH) self-administration. MAM was administered intraperitoneally (22 mg/kg) on gestational day 17. Locomotor activity test and later IV self-administration (IVSA) were then performed in the male offspring followed by a period of forced abstinence and relapse of METH taking. After reaching stable intakes in the relapse phase, ketamine (5 mg/kg) was administered intraperitoneally 30 min prior to the self-administration session. As documented previously, the MAM rats showed a lack of habituation in the locomotor activity test but developed stable maintenance of METH self-administration with no difference in operant behaviour to control animals. Results show that ketamine treatment significantly reduced the METH intake in the control animals but not in MAM animals. Ketamine effect on METH self-administration may be explained by increased glutamatergic signalling in the prefrontal cortex caused by the N-methyl-D-aspartate antagonism and disinhibition of GABA interneurons which was shown to be impaired in the MAM rats. This mechanism may at least partly explain the clinically proven anti-craving potential of ketamine and allow development of more specific anti-craving medications with fewer risks.

• Keywords
• Ketamine, MAM model, Methamphetamine, Self-administration, Sprague-Dawley rats,
• MeSH
• Analysis of Variance MeSH
• Self Administration MeSH
• Ketamine pharmacology   toxicity   MeSH
• Rats MeSH
• Locomotion drug effects   MeSH
• Methamphetamine administration & dosage   MeSH
• Methylazoxymethanol Acetate analogs & derivatives   toxicity   MeSH
• Disease Models, Animal MeSH
• Conditioning, Operant drug effects   MeSH
• Rats, Sprague-Dawley MeSH
• Schizophrenia chemically induced   drug therapy   MeSH
• Central Nervous System Stimulants administration & dosage   MeSH
• Dose-Response Relationship, Drug MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Ketamine MeSH
• Methamphetamine MeSH
• methylazoxymethanol MeSH Browser
• Methylazoxymethanol Acetate MeSH
• Central Nervous System Stimulants MeSH