NICOTINE ADMINISTRATION IMPAIRS SENSORY GATING IN LONG-EVANS RATS

In rats, effects of nicotine administration on sensory gating as index ed by prepulse inhibition (PPI)of the acoustic startle reflex (ASR) ar e unclear. We have found that nicotine administration enhances ASR and PPI in Sprague-Dawley rats, but other investigators, using Long-Evans rats, have reported no effects or enhancement of PPI only. Numerous m ethodological differences exist among studies in addition to subject s train, however, making it unclear whether inconsistent behavioral resp onses are the result of different experimental procedures or indicate a true strain difference. To investigate the role of strain in nicotin e's effects on ASR and PPI, 192 male and female Long-Evans rats were a dministered 12 mg/kg/day nicotine via osmotic minipump for 14 days usi ng identical methodologies employed in studies with Sprague-Dawley sub jects. Effects of grouped vs. individual housing on these responses al so were examined. Nicotine administration impaired ASR and PPI in Long -Evans subjects. These effects occurred in female rats regardless of h ousing condition, and interacted with housing in male rats. Results in dicate that sex and housing are important variables in nicotine's effe cts. Results suggest that subject strain may be an important variable in nicotine's effects on sensory gating, and that responses of Sprague -Dawley vs. Long-Evans rats may represent a true strain difference. (C ) 1998 Elsevier Science Inc.