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Cannabis abuse in adolescence is associated with increased risk of psychotic disorders. Δ-9-tetrahydrocannabinol (THC) is the primary psychoactive component of cannabis. Disrupted-In-Schizophrenia-1 (DISC1) protein is a driver for major mental illness by influencing neurodevelopmental processes. Here, utilizing a unique mouse model based on host (DISC1) X environment (THC administration) interaction, we aimed at studying the pathobiological basis through which THC exposure elicits psychiatric manifestations. Wild-Type and dominant-negative-DISC1 (DN-DISC1) mice were injected with THC (10 mg/kg) or vehicle for 10 days during mid-adolescence-equivalent period. Behavioral tests were conducted to assess exploratory activity (open field test, light-dark box test) and cognitive function (novel object recognition test). Electrophysiological effect of THC was evaluated using acute hippocampal slices, and hippocampal cannabinoid receptor type 1 and brain-derived neurotrophic factor (BDNF) protein levels were measured. Our results indicate that THC exposure elicits deficits in exploratory activity and recognition memory, together with reduced short-term synaptic facilitation and loss of BDNF surge in the hippocampus of DN-DISC mice, but not in wild-type mice. Over-expression of BDNF in the hippocampus of THC-treated DN-DISC1 mice prevented the impairment in recognition memory. The results of this study imply that induction of BDNF following adolescence THC exposure may serve as a homeostatic response geared to maintain proper cognitive function against exogenous insult. The BDNF surge in response to THC is perturbed in the presence of mutant DISC1, suggesting DISC1 may be a useful probe to identify biological cascades involved in the neurochemical, electrophysiological, and behavioral effects of cannabis related psychiatric manifestations.
Molecular Psychiatry , (25 April 2017) | doi:10.1038/mp.2017.87
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Depression is a common mental disorder affecting around 350 million people worldwide. Although selective serotonin reuptake inhibitors (SSRIs) are the most widely used antidepressants, a significant proportion of depressed patients do not achieve remission with SSRIs. In this study, we show that a serotonin type 3 receptor (5HT3R) agonist induces antidepressant effects as well as hippocampal neurogenesis independent of fluoxetine (a commonly used SSRI). Notably, our histological analysis reveals that 5HT3R and insulin-like growth factor 1 (IGF1) are expressed in the same neurons in the subgranular zone of the hippocampal dentate gyrus. Furthermore, our in vivo microdialysis analysis shows that 5HT3R regulates hippocampal extracellular IGF1 levels, and we also show that 5HT3R-dependent hippocampal neurogenesis is mediated by increased IGF1 levels. Altogether, our findings suggest a novel 5HT3R–IGF1 mechanism that is distinct from fluoxetine-induced responses and that provides a new therapeutic target for depression, especially bringing significant benefits for SSRI-resistant depressed patients.
Antipsychotics in Adults With Schizophrenia: Comparative Effectiveness of First-Generation Versus Second-Generation Medications: A Systematic Review and Meta-analysis.
Hartling L, Abou-Setta AM, Dursun S, Mousavi SS, Pasichnyk D, Newton AS.
Debate continues about the comparative benefits and harms of first-generation antipsychotics (FGAs) and second-generation antipsychotics (SGAs) in treating schizophrenia.
To compare the effects of FGAs with those of SGAs in the treatment of adults aged 18 to 64 years with schizophrenia and related psychosis on illness symptoms, diabetes mellitus, mortality, tardive dyskinesia, and a major metabolic syndrome.
English-language studies from 10 electronic databases to March 2012, reference lists of relevant articles, and gray literature.
Randomized trials for efficacy and cohort studies at least 2 years in duration for adverse events.
Two independent reviewers extracted data from 114 studies involving 22 comparisons and graded the strength of evidence for primary outcomes as insufficient, low, moderate, or high using the Grading of Recommendations Assessment, Development and Evaluation approach.
Few differences of clinical importance were found for core illness symptoms; lack of precision in effect estimates precluded firm conclusions for many comparisons. Moderate-strength evidence showed a clinically important benefit of haloperidol over olanzapine for improving positive symptoms, but the benefit was scale-dependent: It was seen when the Scale for the Assessment of Positive Symptoms was used but not when the Positive and Negative Syndrome Scale (PANSS) was used. Moderate-strength evidence showed a clinically important benefit of olanzapine over haloperidol in improving negative symptoms when the PANSS and the Scale for the Assessment of Negative Symptoms were used. Low-strength evidence showed no difference in mortality for chlorpromazine verus clozapine or haloperidol versus aripiprazole, increased incidence of the metabolic syndrome for olanzapine versus haloperidol (risk differences, 2% and 22%), and higher incidence of tardive dyskinesia for chlorpromazine versus clozapine (risk differences, 5% and 9%). Evidence was insufficient to draw conclusions for diabetes mellitus.
All studies had high or unclear risk of bias. Length of study follow-up was often too brief to adequately measure adverse events. Medication comparisons, dosage, and outcome measurement were heterogenous for head-to-head comparisons. Selective patient populations limit generalizability.