Alterations in hypothalamic serotonergic-catecholaminergic relationships in aging C57BL/6J female mice

Abstract The effects of aging and estradiol on the three major hypothalamic monoaminergic systems were measured in female C57BL/6J mice. Both aging and estradiol treatment induced small (10–15%) changes in the levels and ratios of the monoamines and their catabolites. In addition, the levels of 5-hydroxyindoleacetic acid, the major serotonergic catabolite, were strongly correlated with the levels of the two major dopaminergic catabolites, 3,4-dihydrophenylacetic acid and homovanillic acid. Aging affected the relattionship between 5-hydroxyindoleacetic acid and the dopaminergic catabolites such that the slope of the regression lines of 5-hydroxyindoleacetic acid on the dopaminergic compounds was increased in order mice. The age-related alteration in the correlations between the serotonergic and dopaminergic compounds may be due to an effect of aging on the acid export system.