Environmental influence on somatostatin levels and gene expression in the rat brain.

In the present study we have quantified preprosomatostatin-mRNA and somatostatin levels in rat brain following environmental stimulation. Animals were housed for 30 days in an enriched or impoverished environment prior to analysis. After 30 days of housing half of the rats from each environment were behaviourally tested for 3 days. Housing in enriched environment improved performance in a spatial learning situation. The open-field behaviour of these animals was characterized by initially higher rearing scores and a more rapid habituation to novel environment as measured by spontaneous locomotor activity. We found significantly elevated somatostatin levels in the cortex following enriched environment, compared with impoverished environment. Exposure to behavioural testing of impoverished animals led to increased cortical somatostatin levels. Hypothalamic somatostatin levels increased significantly after housing in enriched environment, while the testing procedure had no influence. Our data shows that the somatostatin system in the rat brain was activated in association with cognitive changes, that were induced by housing in an enriched environment.