FEAR-POTENTIATED STARTLE ELEVATES CATECHOLAMINE LEVELS IN THE DORSOMEDIAL HYPOTHALAMUS OF RATS

The norepinephrine (NE), dopamine (DA), and serotonin (5-HT) systems a re thought to be important in the development of anxiety and stress. T he dorsomedial hypothalamus (DMH) of rats has been implicated in the r egulation of physiological and behavioral responses associated with fe ar and anxiety. In order to elucidate the interactions between the mon oamine systems and the DMH, we studied the effects of subjecting rats to the fear-potentiated startle test, a commonly used test of anxiety in rats, on the NE, DA, and 5-HT levels in the DMH. Rats in the potent iated startle test, but not those exposed to just foot shocks or acous tic startle, showed significantly higher levels of NE and DA in the DM H compared to cage controls. In contrast, foot shocks significantly el evated the 5-HT levels in the DMH.