DOPAMINE AUTORECEPTORS IN RAT NUCLEUS-ACCUMBENS MODULATE PREPULSE INHIBITION OF ACOUSTIC STARTLE

Dopamine and 3,4-dihydroxy phenylacetic acid (DOPAC) levels in discret e regions and apomorphine- or (-)-sulpiride-induced changes in electri cally evoked dopamine release from nucleus accumbens slices were asses sed after testing prepulse inhibition of acoustic startle (PPI) in rat s. Dopamine and DOPAC levels in the nucleus accumbens, but not in the striatum, correlated well with PPI (r = -0.64 for dopamine, r = -0.48 for DOPAC). Evoked dopamine release from the nucleus accumbens did not differ between the high-PPI (more than 60%) and the low-PPI (less tha n 40%) group. When slices were superfused with 1 mu M apomorphine, the S2/S1 ratio in rats showing high PPI was 0.77 +/- 0.02 (mean +/- SEM, 66% of control), significantly smaller than in the low-PPI group (S2/ S1 ratio = 0.97 +/- 0.O08, 94% of control, p < 0.05). Moreover, (-)-su lpiride-induced increase in evoked dopamine release from the nucleus a ccumbens in the high-PPI group was inclined to be greater than in the low-PPI group. The results suggest that PPI differences between indivi duals may reflect the sensitivity of release-modulating dopamine auto receptors in the nucleus accumbens. (C) 1998 Elsevier Science Inc.