DIFFERENCES BETWEEN 3 RAT STRAINS IN SENSITIVITY TO PREPULSE INHIBITION OF AN ACOUSTIC STARTLE RESPONSE - INFLUENCE OF APOMORPHINE AND PHENCYCLIDINE PRETREATMENT

In the present study we have examined the effect of varying three prep ulse parameters (prepulse intensity, prepulse duration, prepulse-pulse interval) on the level of prepulse inhibition (PPI) in Lister hooded, Wistar and Sprague-Dawley rats. The results indicate that each strain showed subtle differences in sensitivity to the prepulse. For instanc e, Sprague-Dawley and Lister hooded rats showed PPI to prepulses oflow er saliency compared to Wistar rats. Optimal prepulse parameters were selected for each strain to examine the effects of apomorphine and phe ncyclidine on PPI. Further inter-strain differences were noted; apomor phine (0.1-1 mg/kg) increased startle amplitude in Lister hooded and S prague-Dawley, but not Wistar rats. PPI was attenuated in each strain by apomorphine pretreatment. In a final series of experiments, phencyc lidine disrupted PPI in each strain, although with greater potency in the Lister hooded rats. A marked behavioural syndrome was seen at phen cyclidine doses that disrupted PPI. It is concluded that rat strain an d prepulse parameters are important variables in studying drug effects on PPI.