Effects of neurotensin administered into the ventral tegmental area on prepulse inhibition of startle

Prepulse inhibition (PPI) of the acoustic startle reflex is an operational measure of sensorimotor gating. Both locomotor activity and PPI are regulat ed by mesolimbic dopamine activity. Neurotensin is a neuropeptide, which co exists with dopamine in mesolimbic neurons. Neurotensin receptors have been identified in the nucleus accumbens (NAC) and ventral tegmental area (VTA) . Previous studies have shown that neurotensin administered into the NAC di fferentially modulates PPI and locomotor activity. In this study we tested the effects of neurotensin administered into the VTA on PPI and locomotor a ctivity. Consistent with previous studies, intra-VTA administered neurotens in significantly increased spontaneous locomotor activity. However, intra-V TA administered neurotensin did not have any significant effect on PPI. The se results suggest that PPT and locomotor activity may have dissociable mes olimbic substrates and that neurotensin in the VTA does not play an importa nt role in regulating PPI. (C) 1999 Elsevier Science B.V. All rights reserv ed.