Post-Ischemic Housing Conditions Influence On Gene Transcription And Translation After Permanent Focal Brain Ischemia In Rats

Enriched environment (EE) housing significantly ameliorates neurological deficits induced by cortical brain ischemia without changing infarction size, suggesting that EE-related functional benefits are associated with neuronal plasticity events in the remaining tissue. Brain-derived neurotrophic factor (BDNF), nerve growth factor-induced gene A (NGFI-A) and corticosteroid receptors (mineralocorticoid receptor, MR; glucocorticoid receptor, GR) have been demonstrated to be involved in brain plasticity. The purpose of this thesis was to determine if post-ischemic housing conditions had a significant effect on transcription and/or translation of BDNF, NGFI-A and corticosteroid receptors. We found that BDNF gene was down regulated in EE-housed rats when compared to the rats housed in standard cages at 2~12 days after cortical brain ischemia in peri-infarct cortex, contralateral cortex and bilateral hippocampus. The protein level of BDNF in the ipsilateral frontal cortex was lower in the EE-housed rats than the standard environment (SE)-housed rats at 12d postischemia. The mRNA expression of NGFI-A showed a similar pattern of BDNF except for an increase at 30 d after induction of brain ischemia in EE-housed rats. Ischemia-induced reduction of GR was prevented in the rats housed in EE condition. There was no difference between EE- and SE-housed animals in MR gene expression. Gene expressions, however, are very complex in housing conditions and postischemia. Whether EE-related gene transcription and/or translation reported in this thesis are linked with EE-induced functional benefits to brain ischemia, further studies need be conducted