Pharmacology, biochemistry, and behavior
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Pharmacol. Biochem. Behav. · Jan 1986
Effects of preshock experience on enhancement of rat brain noradrenaline turnover induced by psychological stress.
The present study examined alterations of brain noradrenaline (NA) turnover as a function of preshock and psychological stress treatments, by measuring contents of NA metabolite, 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), in discrete brain regions of male Wistar rats. Psychological stress induced by exposing to the sight, sound and odor of other rats being shocked produced higher levels of MHPG-SO4 in the hypothalamus, amygdala and locus coeruleus (LC) region, as well as higher levels of plasma corticosterone. ⋯ These results suggest that: a purely psychological stressor caused acutely enhanced NA turnover in specific brain regions; regional NA activity appeared to be reinstated simply by reexposure to the environment previously associated with shock; preshock experience further intensified the enhancement of amygdaloid NA turnover evoked by psychological stress. An additional experiment, studying the aftereffects of preshock experience, clearly showed that these findings result from sensitization or conditioning to the environment previously paired with shock, and not merely from the aftereffects of the shock per se.