Mechanisms that mediate antidepressant effect of enriched environment in rats

SIFONIOS L; TRINCHERO MF; REINÉS A; CERESETO M; FERRERO A; WIKINSKI S

Ciudad de Córdoba, Argentina

Congreso; XXXVIII Reunión Anual de la Sociedad Argentina de Farmacología Experimental; 2007

Sociedad Argentina de Farmacología Experimental

The objectives of this work were to investigate the effect of an enriched environment (EE) on the helplessness behavior (LH) and on a parameter that we have found altered in this model of  depression: the decrease in the immunostaining of the light subunit of the intermediate neurofilament (NFL) in the hippocampus. We also tested if EE induces neurogenesis in animals exposed to stressful conditions. Male rats in which LH behavior was induced, were kept for 21days in a special cage with different devices: tunnels, ropes, a running wheel, etc (LH-EE rats). LH animals not kept in the EE (LH) were the control group. Depressive-like behavior (escape latency) was measured in an avoidance task, NFL was evaluated by immunohystochemistry, and the number of neurons that co-expressed BrdU (injected the first three days, 50mg/kg)/ Tuj-1 (an immature and mature neuronal marker) were quantified by doubleimmunofluorescenceand confocal microscopy. LH-EE rats showed a reversion of the depressive-like behavior andan increment in NFL immunostaining. In addition, LH animals showed higher BrdU+ cells than LH-EE but no differences in the percentage of BrdU/Tuj-1+ cells were observed. Therefore, the EE reverses the depressive-like behavior as well as the NFL reduction but neurogenesis seems not to be implicated in these phenomena.