Heart rate and motor-activating effects of orally self-administered ethanol in alcohol-preferring (P) rats.
BACKGROUND
Autonomic and behavioral arousals often accompany reinforcement. Additionally, contextual cues associated with alcohol consumption elicit increases in heart rate in alcoholics. This study examined changes in heart rate (HR) and motor activity before and during limited-access to ethanol, saccharin, or water in adult male alcohol-preferring (P) rats.


METHODS
Adult male P rats were implanted with radiotelemetric transmitters to measure HR and motor activity. The experiment involved placing the animals in a test chamber for a 90-min pretest period, with water available. Thereafter, the animals were given a 90-min test session with access to one of three test solutions: water, 0.0125% saccharin, or 15% (v/v) ethanol (EtOH). After a week of habituation (water served as the test solution for all three groups), the animals were given their respective test solution for 3 weeks.


RESULTS
Analyses of HR revealed that the saccharin and EtOH groups had significantly higher HR than the water group during the pretest period of the third test week. Both the saccharin and EtOH groups had significantly higher HR than the water group during the test period of all three test weeks. Analyses of motor activity revealed that the EtOH group displayed higher motor activity than the water and saccharin groups during the pretest period of the third test week.


CONCLUSIONS
The data indicate that oral self-administration of EtOH enhances behavioral and autonomic activation, compared with saccharin or water, in adult male P rats and support previous observations that changes in HR can be used as an index of reinforcement. Additionally, it seems that the behavioral and autonomic activation elicited by EtOH self-administration can be conditioned to the environment in which EtOH was self-administered. These findings parallel reports on cued reactivity (behavioral and autonomic activation) in alcoholics exposed to alcohol-associated stimuli.
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, 791 Union Drive, Indianapolis, IN 46202-4887, USA. ribell@iupui.edu
Richard L
RL
Bell
Zachary A
ZA
Rodd-Henricks
Amy A
AA
Webster
Lawrence
L
Lumeng
Ting-Kai
TK
Li
William J
WJ
McBride
James M
JM
Murphy
D000284:Administration, Oral; D000428:Alcohol Drinking / Q000235:genetics*; D000818:Animals; D000431:Ethanol / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects* / Q000235:genetics; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000235:genetics; D051381:Rats; D012439:Saccharin / Q000494:pharmacology; D012646:Self Administration / Q000379:methods
D000431:Ethanol; D012439:Saccharin