Chronic escitalopram treatment attenuated the accelerated rapid eye movement sleep transitions after selective rapid eye movement sleep deprivation: a model-based analysis using Markov chains

BackgroundShortened rapid eye movement (REM) sleep latency and increased REM sleep amount are presumed biological markers of depression. These sleep alterations are also observable in several animal models of depression as well as during the rebound sleep after selective REM sleep deprivation (RD). Furthermore, REM sleep fragmentation is typically associated with stress procedures and anxiety. The selective serotonin reuptake inhibitor (SSRI) antidepressants reduce REM sleep time and increase REM latency after acute dosing in normal condition and even during REM rebound following RD. However, their therapeutic outcome evolves only after weeks of treatment, and the effects of chronic treatment in REM-deprived animals have not been studied yet.ResultsChronic escitalopram- (10 mg/kg/day, osmotic minipump for 24 days) or vehicle-treated rats were subjected to a 3-day-long RD on day 21 using the flower pot procedure or kept in home cage. On day 24, fronto-parietal electroencephalogram, electromyogram and motility were recorded in the first 2 h of the passive phase. The observed sleep patterns were characterized applying standard sleep metrics, by modelling the transitions between sleep phases using Markov chains and by spectral analysis.Based on Markov chain analysis, chronic escitalopram treatment attenuated the REM sleep fragmentation [accelerated transition rates between REM and non-REM (NREM) stages, decreased REM sleep residence time between two transitions] during the rebound sleep. Additionally, the antidepressant avoided the frequent awakenings during the first 30 min of recovery period. The spectral analysis showed that the SSRI prevented the RD-caused elevation in theta (5 inverted question mark9 Hz) power during slow-wave sleep. Conversely, based on the aggregate sleep metrics, escitalopram had only moderate effects and it did not significantly attenuate the REM rebound after RD.ConclusionIn conclusion, chronic SSRI treatment is capable of reducing several effects on sleep which might be the consequence of the sub-chronic stress caused by the flower pot method. These data might support the antidepressant activity of SSRIs, and may allude that investigating the rebound period following the flower pot protocol could be useful to detect antidepressant drug response. Markov analysis is a suitable method to study the sleep pattern

Modulation of central endocannabinoid system results in gastric mucosal protection in the rat.

Previous findings showed that inhibitors of fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), degrading enzymes of anandamide (2-AEA) and 2-arachidonoylglycerol (2-AG), reduced the nonsteroidal anti-inflammatory drug-induced gastric lesions. The present study aimed to investigate: i./whether central or peripheral mechanism play a major role in the gastroprotective effect of inhibitors of FAAH, MAGL and AEA uptake, ii./which peripheral mechanism(s) may play a role in mucosal protective effect of FAAH, MAGL and uptake inhibitors. METHODS: Gastric mucosal damage was induced by acidified ethanol. Gastric motility was measured in anesthetized rats. Catalepsy and the body temperature were also evaluated. Mucosal calcitonin gene-related peptide (CGRP), somatostatin concentrations and superoxide dismutase (SOD) activity were measured. The compounds were injected intraperitoneally (i.p.) or intracerebroventricularly (i.c.v.). RESULTS: 1. URB 597, JZL184 (inhibitors of FAAH and MAGL) and AM 404 (inhibitor of AEA uptake) decreased the mucosal lesions significantly given either i.c.v. or i.p. 2. URB 937, the peripherally restricted FAAH inhibitor failed to exert significant action injected i.p. 3. Ethanol-induced decreased levels of mucosal CGRP and somatostatin were reversed by URB 597, JZL 184 and AM 404, the decreased SOD activity was elevated significantly by URB 597 and JZL 184. 4. Neither compounds given i.c.v. influenced gastric motility, elicited catalepsy, or hypothermia. CONCLUSION: Elevation of central endocannabinoid levels by blocking their degradation or uptake via stimulation of mucosal defensive mechanisms resulted in gastroprotective action against ethanol-induced mucosal injury. These findings might suggest that central endocannabinoid system may play a role in gastric mucosal defense and maintenance of mucosal integrity

Effects of cariprazine, a novel antipsychotic, on cognitive deficit and negative symptoms in a rodent model of schizophrenia symptomatology

AbstractNegative symptoms and cognitive impairment associated with schizophrenia are strongly associated with poor functional outcome and reduced quality of life and remain an unmet clinical need. Cariprazine is a dopamine D3/D2 receptor partial agonist with preferential binding to D3 receptors, recently approved by the FDA for the treatment of schizophrenia and manic or mixed episodes associated with bipolar I disorder. The aim of this study is to evaluate effects of cariprazine in an animal model of cognitive deficit and negative symptoms of schizophrenia. Following sub-chronic PCP administration (2mg/kg, IP for 7 days followed by 7 days drug-free), female Lister Hooded rats were administered cariprazine (0.05, 0.1, or 0.25mg/kg, PO) or risperidone (0.16 or 0.1mg/kg, IP) before testing in novel object recognition (NOR), reversal learning (RL), and social interaction (SI) paradigms. As we have consistently demonstrated, sub-chronic PCP significantly impaired behavior in these tests. Deficits were significantly improved by cariprazine, in a dose dependent manner in the operant RL test with efficacy at lower doses in the NOR and SI tests. Locomotor activity was reduced at the highest doses of 0.1mg/kg and 0.25mg/kg in NOR and SI. Risperidone also reversed the PCP-induced deficit in all tests. In conclusion, cariprazine was effective to overcome PCP-induced deficits in cognition and social behavior in a thoroughly validated rat model in tests representing specific symptom domains in schizophrenia patients. These findings support very recent results showing efficacy of cariprazine in the treatment of negative symptoms in schizophrenia patients