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

ROSSETTI M.F; MORENO PIOVANO GS; DUDIUK C; VARAYOUD J; MUÑOZ- DE-TORO M; LUQUE E.H; RAMOS J.G

Huerta Grande, Córdoba, Argentina

Congreso; XXV Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias (SAN) y XII Taller Argentino de Neurociencias (TAN); 2010

It has been shown that estrogens influence neurobiological functions associated with the hippocampus being estrogen receptor alpha and beta main mediators. In  addition,  some  studies  described  the  beneficial  effects  of  the  exposure  to enriched environments on neuronal plasticity, including structural modifications and cognitive functions. In the present study, we examined the effects of living in a long term continuous enriched environment on the expression of ER alpha in  the  female  mouse  hippocampus.  Enrichment  consisted  of  social  interaction (10  mouse  in  the  large  cage  vs  2  or  3  in  the  standard  cage),  stimulation  of exploratory  behavior  with  objects  such  as  toys  and  a  set  of  tunnels,  and physical activity. A group of female mice was exposed to an enriched sensory environment (n = 20), while another group was kept in a standard environment (n = 22). The animals were kept under the experimental conditions from 2 to 11 months of age. By microsurgery complete hippocampus were extracted, which were   individually   processed.   The   expression   of   ER   alpha   mRNA   and transcriptional activity of promoter A, C and F were evaluated by real time RT-PCR.  Continuously  enriched  mice  showed  a  significant  decrease  in  the expression  of  ER  alpha  mRNA  when  compared  with  controls  (p  0.05) on the relative activity of each  of  the  ER  alpha  gene  promoters.  These  results  show  that  a  long  term continuous enriched environment produced a down-regulation of the expression of ER alpha in the hippocampus of female mice. This down-regulation would not be mediated by a differential usage of the promoters studied.