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.

• Klíčová slova
• AM251, Haloperidol, Kynurenine Pathway, Novel object recognition test, Peripubertal treatment, Schizophrenia,
• MeSH
• antipsychotika farmakologie   MeSH
• haloperidol farmakologie   MeSH
• kognitivní dysfunkce metabolismus   farmakoterapie   MeSH
• krysa rodu Rattus MeSH
• kyselina kynurenová * metabolismus   MeSH
• methylazoxymethanolacetát * analogy a deriváty   MeSH
• modely nemocí na zvířatech MeSH
• piperidiny farmakologie   MeSH
• potkani Sprague-Dawley * MeSH
• prefrontální mozková kůra * metabolismus   účinky léků   MeSH
• pyrazoly farmakologie   MeSH
• receptor kanabinoidní CB1 metabolismus   MeSH
• schizofrenie * metabolismus   farmakoterapie   MeSH
• těhotenství MeSH
• zpožděný efekt prenatální expozice * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• AM 251 MeSH Prohlížeč
• antipsychotika MeSH
• haloperidol MeSH
• kyselina kynurenová * MeSH
• methylazoxymethanolacetát * MeSH
• piperidiny MeSH
• pyrazoly MeSH
• receptor kanabinoidní CB1 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.

• Klíčová slova
• dopamine D2/D3 receptors, methylazoxymethanol acetate, psychopathology, Δ9-tetrahydrocannabinol,
• MeSH
• dopamin metabolismus   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• prefrontální mozková kůra účinky léků   metabolismus   MeSH
• receptory dopaminu D3 metabolismus   MeSH
• schizofrenie * chemicky indukované   MeSH
• těhotenství MeSH
• tetrahydrokanabinol * toxicita   MeSH
• zpožděný efekt prenatální expozice * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dopamin MeSH
• receptory dopaminu D3 MeSH
• tetrahydrokanabinol * 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.

• Klíčová slova
• 2-arachidonoylglycerol (2-AG), AM251, MAM model, cannabinoid CB1 receptor, endocannabinoid system, schizophrenia,
• MeSH
• krysa rodu Rattus MeSH
• methylazoxymethanolacetát * MeSH
• modely nemocí na zvířatech MeSH
• potkani Sprague-Dawley MeSH
• receptor kanabinoidní CB1 MeSH
• schizofrenie * chemicky indukované   farmakoterapie   genetika   MeSH
• těhotenství MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• methylazoxymethanolacetát * MeSH
• receptor kanabinoidní CB1 MeSH