Long term continuous environmental enrichment decreases estrogen receptor alpha expression in the female mouse hippocampus

ROSSETTI MF; MORENO PIOVANO G; DUDIUK C; VARAYOUD J; MUÑOZ-DE-TORO M; LUQUE EH; RAMOS JG

Congreso; II Reunión Conjunta de Neurociencias.; 2010

Estrogens are neurotrophic factors that modulate synaptic plasticity and neurogenesis. In the hippocampus these actions are mediated by the estrogen receptor alpha (ERa). Some studies demonstrated that the exposure to enriched environments produces similar effects including hippocampal synapse formation. However the influence of enriched environments on hippocampal estrogen action has not been described. In the present study, we examined the effects of living in a long term continuous enriched environment on the expression of ERa in the female mouse hippocampus. Enrichment consisted of social interaction, stimulation of exploratory behaviour and physical activity. One group of female mice (n=12) was exposed to a continuous enriched environment during 9 months, while controls (n=12) were kept in a standard environment. All animals were sacrificed at the same age (11 months-old). By microsurgery complete hippocampus were extracted and individually processed. The expression of ERa mRNA and the relative transcriptional activity of promoters A, C and F were evaluated by real time RT- PCR. Enriched  mice  showed  a  significant  decrease  in  the expression  of  ERa  mRNA  (p  <0.05). However, there was no significant difference (p> 0.05) on the relative activity of each of the ERa gene promoters. These results show that a long term continuous enriched environment produced a down-regulation of the expression of ERa in the hippocampus of female mice, that was not mediated by a differential promoter usage.