Animal models as tools to study the pathophysiology of depression

The microbiota-gut-brain axis in gastrointestinal disorders: stressed bugs, stressed brain or both?

The gut-brain axis is the bidirectional communication between the gut and the brain, which occurs through multiple pathways that include hormonal, neural and immune mediators. The signals along this axis can originate in the gut, the brain or both, with the objective of maintaining normal gut function and appropriate behaviour. In recent years, the study of gut microbiota has become one of the most important areas in biomedical research. Attention has focused on the role of gut microbiota in determining normal gut physiology and immunity and, more recently, on its role as modulator of host behaviour ('microbiota-gut-brain axis'). We therefore review the literature on the role of gut microbiota in gut homeostasis and link it with mechanisms that could influence behaviour. We discuss the association of dysbiosis with disease, with particular focus on functional bowel disorders and their relationship to psychological stress. This is of particular interest because exposure to stressors has long been known to increase susceptibility to and severity of gastrointestinal diseases.

Pycnogenol ameliorates depression-like behavior in repeated corticosterone-induced depression mice model

Oxidative stress is considered to be a mechanism of major depression. Pycnogenol (PYC) is a natural plant extract from the bark of Pinus pinaster Aiton and has potent antioxidant activities. We studied the ameliorative effect of PYC on depression-like behavior in chronic corticosterone- (CORT-) treated mice for 20 days. After the end of the CORT treatment period, PYC (0.2 mg/mL) was orally administered in normal drinking water. Depression-like behavior was investigated by the forced swimming test. Immobility time was significantly longer by CORT exposure. When the CORT-treated mice were supplemented with PYC, immobility time was significantly shortened. Our results indicate that orally administered PYC may serve to reduce CORT-induced stress by radical scavenging activity.

Levomilnacipran

Objective: To provide a clinical overview of the antidepressant levomilnacipran. Data Sources: Articles were identified by searching the MEDLINE, PubMed, Cochrane Library, and Clinicaltrials.gov databases through March 2014 using the keyword levomilnacipran. The manufacturer provided additional information from unpublished phase II and phase III trials. Study Selection and Data Extraction: Any clinical trial conducted for at least 3 weeks and published in the English language was selected for review. Additional documentation, including the product dossier, package insert, pharmacokinetic studies, and poster presentations supplied by the manufacturer, was also evaluated. Data Synthesis: Levomilnacipran is the more potent enantiomer of milnacipran. It is a selective serotonin and norepinephrine reuptake inhibitor (SNRI), dosed from 20 to 120 mg daily for the treatment of major depressive disorder (MDD). Efficacy and tolerability were established during 3 phase III randomized, double-blind placebo-controlled trials finding levomilnacipran to be significantly more efficacious than placebo in reduction of Montgomery-Åsberg Depression Rating Scale scores. It is not known whether this agent is more efficacious than other antidepressants because direct comparison studies have not been conducted as of the time of this review. Conclusions: Levomilnacipran demonstrates efficacy and tolerability for short-term treatment of MDD in adults. Available evidence does not strongly indicate that there is a specific subpopulation of patients who would benefit from levomilnacipran over currently available SNRIs. Full characterization of the agent’s place in therapy alongside multiple other agents with similar mechanisms and efficacy requires trials with longer duration and active comparators.