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.
- 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
Hypofunctioning of NMDA receptors, and the resulting shift in the balance between excitation and inhibition, is considered a key process in the pathophysiology of schizophrenia. One important manifestation of this phenomenon is changes in neural oscillations, those above 30 Hz (i.e., gamma-band oscillations), in particular. Although both preclinical and clinical studies observed increased gamma activity following acute administration of NMDA receptor antagonists, the relevance of this phenomenon has been recently questioned given the reduced gamma oscillations typically observed during sensory and cognitive tasks in schizophrenia. However, there is emerging, yet contradictory, evidence for increased spontaneous gamma-band activity (i.e., at rest or under baseline conditions). Here, we use the sub-chronic phencyclidine (PCP) rat model for schizophrenia, which has been argued to model the pathophysiology of schizophrenia more closely than acute NMDA antagonism, to investigate gamma oscillations (30-100 Hz) in the medial prefrontal cortex of anesthetized animals. While baseline gamma oscillations were not affected, oscillations induced by train stimulation of the posterior dorsal CA1 (pdCA1) field of the hippocampus were enhanced in PCP-treated animals (5 mg/kg, twice daily for 7 days, followed by a 7-day washout period). This effect was reversed by pharmacological enhancement of endocannabinoid levels via systemic administration of URB597 (0.3 mg/kg), an inhibitor of the catabolic enzyme of the endocannabinoid anandamide. Intriguingly, the pharmacological blockade of CB1 receptors by AM251 unmasked a reduced gamma oscillatory activity in PCP-treated animals. The findings are consistent with the observed effects of URB597 and AM251 on behavioral deficits reminiscent of the symptoms of schizophrenia and further validate the potential for cannabinoid-based drugs as a treatment for schizophrenia.
- MeSH
- Amidohydrolases * antagonists & inhibitors metabolism MeSH
- Excitatory Amino Acid Antagonists pharmacology administration & dosage MeSH
- Benzamides * pharmacology MeSH
- Endocannabinoids metabolism MeSH
- Phencyclidine * pharmacology MeSH
- Gamma Rhythm physiology drug effects MeSH
- Carbamates * pharmacology MeSH
- Rats MeSH
- Arachidonic Acids metabolism pharmacology MeSH
- Disease Models, Animal MeSH
- Piperidines * pharmacology MeSH
- Polyunsaturated Alkamides metabolism pharmacology MeSH
- Rats, Sprague-Dawley MeSH
- Prefrontal Cortex drug effects metabolism physiopathology MeSH
- Pyrazoles pharmacology MeSH
- Schizophrenia * physiopathology metabolism drug therapy MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- 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.
- 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
In agreement with the neurodevelopmental hypothesis of schizophrenia, prenatal exposure of rats to the antimitotic agent methylazoxymethanol acetate (MAM) at gestational day 17 produced long-lasting behavioral alterations such as social withdrawal and cognitive impairment in the social interaction test and in the novel object recognition test, respectively. At the molecular level, an increased cannabinoid receptor type-1 (CB1) mRNA and protein expression, which might be due to reduction in DNA methylation at the gene promoter in the prefrontal cortex (PFC), coincided with deficits in the social interaction test and in the novel object recognition test in MAM rats. Both the schizophrenia-like phenotype and altered transcriptional regulation of CB1 receptors were reversed by peripubertal treatment (from PND 19 to PND 39) with the non-psychotropic phytocannabinoid cannabidiol (30 mg/kg/day), or, in part, by treatment with the cannabinoid CB1 receptor antagonist/inverse agonist AM251 (0.5 mg/kg/day), but not with haloperidol (0.6 mg/kg/day). These results suggest that early treatment with cannabidiol may prevent both the appearance of schizophrenia-like deficits as well as CB1 alterations in the PFC at adulthood, supporting that peripubertal cannabidiol treatment might be protective against MAM insult.
- MeSH
- Endocannabinoids metabolism MeSH
- Ethanolamines metabolism MeSH
- Glycerides metabolism MeSH
- Hippocampus metabolism MeSH
- Interpersonal Relations MeSH
- Cannabidiol pharmacology MeSH
- Rats MeSH
- Arachidonic Acids metabolism MeSH
- Oleic Acids metabolism MeSH
- Palmitic Acids metabolism MeSH
- RNA, Messenger metabolism MeSH
- Methylazoxymethanol Acetate pharmacology MeSH
- Disease Models, Animal MeSH
- Piperidines pharmacology MeSH
- Motor Activity drug effects MeSH
- Polyunsaturated Alkamides metabolism MeSH
- Prefrontal Cortex metabolism MeSH
- Puberty MeSH
- Pyrazoles pharmacology MeSH
- Receptor, Cannabinoid, CB1 metabolism MeSH
- Recognition, Psychology drug effects MeSH
- Schizophrenia chemically induced drug therapy metabolism MeSH
- Pregnancy MeSH
- Prenatal Exposure Delayed Effects drug therapy metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Pregnancy MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The CB1 cannabinoid receptors have been found in the rodent suprachiasmatic nucleus, and their activation suppresses the light-induced phase shift in locomotor rhythmicity of mice and hamsters. Here, we show that the CB1 receptor agonist CP55940 significantly attenuates the light-induced phase delay in rats as well. Furthermore, it blocks the light induction of c-Fos and light-induced downregulation of pERK1/2 in the SCN, and the CB1 antagonist AM251 prevents the photic induction of pERK1/2 and reduces pGSK3β after photic stimulation. Our data suggest that the modulation of the cannabinoid receptor activity may affect the photic entrainment via the setting of the SCN sensitivity to light.
- MeSH
- Cannabinoid Receptor Agonists pharmacology MeSH
- Cannabinoid Receptor Antagonists pharmacology MeSH
- Cyclohexanols pharmacology MeSH
- Suprachiasmatic Nucleus drug effects physiology radiation effects MeSH
- Piperidines pharmacology MeSH
- Motor Activity drug effects radiation effects MeSH
- Rats, Wistar MeSH
- Pyrazoles pharmacology MeSH
- Light MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't 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.
- 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
The aim of this study was to investigate changes in the activity of individual mitochondrial respiratory chain complexes (I, II/III, IV) and citrate synthase induced by pharmacologically different cannabinoids. In vitro effects of selected cannabinoids on mitochondrial enzymes were measured in crude mitochondrial fraction isolated from pig brain. Both cannabinoid receptor agonists, Δ(9)-tetrahydrocannabinol, anandamide, and R-(+)-WIN55,212-2, and antagonist/inverse agonists of cannabinoid receptors, AM251, and cannabidiol were examined in pig brain mitochondria. Different effects of these cannabinoids on mitochondrial respiratory chain complexes and citrate synthase were found. Citrate synthase activity was decreased only by Δ(9)-tetrahydrocannabinol and AM251. Significant increase in the complex I activity was induced by anandamide. At micromolar concentration, all the tested cannabinoids inhibited the activity of electron transport chain complexes II/III and IV. Stimulatory effect of anandamide on activity of complex I may participate on distinct physiological effects of endocannabinoids compared to phytocannabinoids or synthetic cannabinoids. Common inhibitory effect of cannabinoids on activity of complex II/III and IV confirmed a non-receptor-mediated mechanism of cannabinoid action on individual components of system of oxidative phosphorylation.
- MeSH
- Cannabinoid Receptor Antagonists pharmacology MeSH
- Citrate (si)-Synthase metabolism MeSH
- Cannabinoids pharmacology MeSH
- Mitochondria drug effects metabolism MeSH
- Brain drug effects metabolism MeSH
- Swine MeSH
- Electron Transport Complex I metabolism MeSH
- Electron Transport Complex II metabolism MeSH
- Electron Transport Complex III metabolism MeSH
- Electron Transport Complex IV metabolism MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Cannabinoids exert various biological effects that are either receptor-mediated or independent of receptor signaling. Mitochondrial effects of cannabinoids were interpreted either as non-receptor-mediated alteration of mitochondrial membranes, or as indirect consequences of activation of plasma membrane type 1 cannabinoid receptors (CB1). Recently, CB1 receptors were confirmed to be localized to the membranes of neuronal mitochondria, where their activation directly regulates respiration and energy production. Here, we performed in-depth analysis of cannabinoid-induced changes of mitochondrial respiration using both an antagonist/inverse agonist of CB1 receptors, AM251 and the cannabinoid receptor agonists, Δ(9)-tetrahydrocannabinol (THC), cannabidiol, anandamide, and WIN 55,212-2. Relationships were determined between cannabinoid concentration and respiratory rate driven by substrates of complex I, II or IV in pig brain mitochondria. Either full or partial inhibition of respiratory rate was found for the tested drugs, with an IC50 in the micromolar range, which verified the significant role of non-receptor-mediated mechanism in inhibiting mitochondrial respiration. Effect of stepwise application of THC and AM251 evidenced protective role of AM251 and corroborated the participation of CB1 receptor activation in the inhibition of mitochondrial respiration. We proposed a model, which includes both receptor- and non-receptor-mediated mechanisms of cannabinoid action on mitochondrial respiration. This model explains both the inhibitory effect of cannabinoids and the protective effect of the CB1 receptor inverse agonist.
- MeSH
- Cannabinoid Receptor Agonists pharmacology MeSH
- Benzoxazines pharmacology MeSH
- Cell Respiration drug effects MeSH
- Endocannabinoids pharmacology MeSH
- Energy Metabolism drug effects MeSH
- Drug Inverse Agonism MeSH
- Cannabidiol pharmacology MeSH
- Cannabinoids pharmacology MeSH
- Arachidonic Acids pharmacology MeSH
- Mitochondria drug effects metabolism MeSH
- Morpholines pharmacology MeSH
- Brain drug effects metabolism MeSH
- Naphthalenes pharmacology MeSH
- Piperidines pharmacology MeSH
- Polyunsaturated Alkamides pharmacology MeSH
- Swine MeSH
- Pyrazoles pharmacology MeSH
- Receptor, Cannabinoid, CB1 drug effects metabolism MeSH
- Signal Transduction drug effects MeSH
- Dronabinol pharmacology MeSH
- Dose-Response Relationship, Drug MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
