Effect of valproic acid on brain serotonin metabolism in isolated and grouped rats

The effect of the GABA transaminase inhibitor valproic acid (DPA) on serotonin (5HT) metabolism of different brain regions were studied in both grouped and isolated rats. One hour after DPA injection 5HT levels in the amygdala were increased in grouped and isolated rats. In the hypothalamus of grouped rats, changes in 5HT metabolism were also found. The alteration in 5HT metabolism in grouped rats was reversed 150 min after injection of DPA. At this same time, a large and significant increase in 5HT turnover was observed in all brain areas examined in isolated rats. It can be concluded that prolonged isolation induces a differential sensitivity to the effects of DPA leading to differences in 5HT metabolism: the drug effect being more intense in isolated rats.