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-preferring 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 tested on the startle response to acoustic stimuli ranging from 90-115 dB. Experiments 2 and 3 examined fear-potentiated startle and extinction of the response. In Experiment 2, rats received two light foot shock training sessions separated by 3-4 h. Testing consisted of ten acoustic startle (115 dB) and fear-potentiated startle (light preceding the acoustic startle) presentations administered every 24 h for 9 consecutive days. To test potentiated startle learning under reduced training conditions, a single training session was administered in Experiment 3, and a single within-session extinction test of 50 startle and 50 potentiated startle trials occurred the following 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-potentiated 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 response. Moreover, following a single training session in Experiment 3, only P rats showed significant fear-conditioned startle. Additionally, P rats exhibited a 50-100% elevated acoustic startle response over that observed in NP rats. Taken together, the data indicate that, although experimentally naive male P and NP rats show similar acoustic startle responses, P rats become more responsive to both startle-alone and potentiated startle stimuli following fear conditioning. The change in general startle reactivity of the P rat following aversive conditioning, along with facilitated light foot shock learning, suggests that stress exposure may be an important variable in examining associations between anxiety and alcohol drinking behavior.
Mckinzie
D L
DL
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine and VA Medical Ctr, Indianopolis, IN 46202-4887, USA.
Sajdyk
T J
TJ
Mcbride
W J
WJ
Murphy
J M
JM
Lumeng
L
L
Li
T K
TK
Shekhar
A
A
D000161:Acoustic Stimulation; D000428:Alcohol Drinking / Q000235:genetics* / Q000523:psychology*; D000818:Animals; D005108:Extinction, Psychological / Q000187:drug effects; D005239:Fear / Q000523:psychology*; D008297:Male; D051381:Rats; D013216:Reflex, Startle / Q000235:genetics* / Q000502:physiology