Enriched environment reverses both the depressive-like behavior and the light neurofilament in the rat hippocampus

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

Canc¨²n, M¨¨xico

Congreso; ISN-SN biennial meeting; 2007

International Society for Neurochemistry/American Society for Neurochemistry

Enriched environment reverses the depressive-like behavior, the decrease in the light neurofilament and synaptic markers in rat hippocampus Sifonios L., Wikinski S. Instituto de Investigaciones Farmacol¨®gicas, ININFA (UBA-CONICET). Buenos Aires, Argentina. lsifonios@ffyb.uba.ar. This work is aimed to investigate the potential effect of the enriched environment (EE) on the behavioral impairment and on the light neurofilament (NFL) decrement observed in rats exposed to an experimental model of depression, the Learned Helplessness (LH). Two possible mechanisms involved in the antidepressant-like effect of EE were studied: the increment in neuronal survival as well as the increment in presynaptic and postsynaptic markers, such as synaptophysin (SYN) and postsynaptic density-95 (PSD-95), respectively. Male rats, in which LH behavior was induced, were kept in the EE, a special cage provided with different devices which were changed twice a week (LHEE). LH animals housed in standard cages were the control group (LH). In parallel, a group of animals not exposed to LH paradigm and allocated in regular cages was employed (C). Twenty-one days later, depressive-like behavior was measured in all experimental groups as the latency to escape from footshocks. LHEE animals showed reversion of the behavioral despair in comparison with the LH group. Quantification of the NFL immunoreactive area was performed in the dentate gyrus (DG) and in the CA3 of the hippocampus. LHEE group exhibited a significant increase in the relative immunoreactive area in comparison with the LH group in DG. Regarding CA3, LHEE displayed no differences either with LH or C group. In a double immunofluorescence (IF) against BrdU, a marker of newborn cells, and ¦Â-Tubulin III, a specific marker for immature and mature neurons, no increment in the neuronal survival was observed in the LHEE. Both SYN and PSD-95 labeling were significantly decreased in LH animals in comparison with C ones. In the LHEE group there was a partial reversion in SYN and a complete reversion in PSD-95 labeling. The EE induces an antidepressant-like effect and exerts a beneficial structural action on NFL, SYN and PSD-95 in animals exposed to an experimental model of depression. These changes seem not to be due to an increment in the neuronal survival.