Noradrenaline, dopamine, serotonin: Different effects of psychological stress on brain biogenic amines in mice and rats

The effect of restraint stress on central neurotransmission was evaluated i n mice and rats. Noradrenaline (NA), dopamine (DA) and serotonin (5-MT) lev els and their primary metabolites were measured in discrete brain regions f ollowing exposure to stress. Mice and rats demonstrated a similar response to stress in some brain regions. Both species responded to stress with lowe r NA and 5-HT in the locus coeruleus compared to nonstressed controls. Dopa minergic activity, assessed by DA turnover, was elevated in the hypothalamu s. While DA turnover was suppressed in the amygdala, 5-HT turnover was simi larly elevated in both species. In most cases, however, there were differen ces in biogenic neurotransmission between mice and rats in response to stre ss. In particular, NA levels were suppressed by stress in the dorsal cortex of mice, but in the rats NA levels were decreased in I:he hypothalamus. Wh ile stress produced lower DA levels in the hypothalamus, DA levels demonstr ated a marked increase in the amygdala of mice. Stress was also associated with a decrease in DA levels in the rat striatum and with an increase of DA turnover in the locus coeruleus of mice. On the other hand, 5-HT was suppr essed in the mouse striatum and in the rat hypothalamus and amygdala, while 5-HT turnover was markedly decreased in the hippocampus and dorsal cortex of rats alone. In conclusion, the changes in thf: central neurotransmission which are evoked by stress appear to be species-specific in most cases, a fact which may trigger discrete alterations in homeostatic mechanisms. (C) 2000 Academic Press.