Acoustic startle and fear-potentiated startle in alcohol-preferring (P) and -nonpreferring (NP) lines of rats

The objective of the present study was to determine whether alcohol-preferr ing P and -nonpreferring NP rats differ in their acoustic startle response and in fear-potentiated startle. In Experiment 1, male P and NP rats were t ested on the startle response to acoustic stimuli ranging from 90-115 dB. E xperiments 2 and 3 examined fear-potentiated startle and extinction of the response. In Experiment 2, rats received two light foot shock training sess ions separated by 3-4 h. Testing consisted of ten acoustic startle (115 dB) and fear-potentiated startle (light preceding the acoustic startle) presen tations administered every 24 h for 9 consecutive days. To test potentiated startle learning under reduced training conditions, a single training sess ion was administered in Experiment 3, and a single within-session extinctio n test of 50 startle and 50 potentiated startle trials occurred the followi ng day. Results of Experiment 1 indicated that P and NP rats did not differ in startle at any of the acoustic intensities tested. Following fear-poten tiated startle conditioning in Experiment 2? however, both acoustic startle and potentiated startle responding were consistently greater in P than NP rats over most of the first 6 test days with P rats having approximately a 100% greater acoustic startle and 50-100% greater potentiated startle respo nse. Moreover, following a single training session in Experiment 3, only P rats showed significant fear-conditioned startle. Additionally, P rats exhi bited a 50-100% elevated acoustic startle response over that observed in NP rats. Taken together, the data indicate that, although experimentally naiv e male P and NP rats show similar acoustic startle responses, P rats become more responsive to both startle-alone and potentiated startle stimuli foll owing fear conditioning. The change in general startle reactivity of the P rat following aversive conditioning, along with facilitated light foot shoc k learning, suggests that stress exposure may be an important variable in e xamining associations between anxiety and alcohol drinking behavior. (C) 20 00 Elsevier Science Inc.