Effects of ethanol and naltrexone on aggressive display in the Siamese fighting fish, Betta splendens
Alcohol, 2 (5):
637--640 (September 1985)Abstract
Studied the effects of ethanol (0, 0.25, 0.50, and 0.75 g%) and naltrexone (NTX 0 and 5 mg/l), on the aggressive display of 80 Siamese fighting fish. Ss responses to a mirror were used as an index of aggressive display. Findings of previous studies suggest that NTX produces an opiate receptor blockade, providing a test of the hypothesis that ethanol effects on aggression are mediated by the opioid system. Ss were randomly assigned to 1 of 8 groups in a 4 x 2 factorial design with ethanol and NTX as the main factors. Results show that the 0.75 g% dose of ethanol reliably suppressed aggressive display as measured by number of gill show responses, but lower doses had no effect or tended to increase aggressive display. At the same time, all doses of ethanol increased arousal in Ss as measured by airgulping. NTX alone did not have effects on aggression or arousal and did not interact with ethanol on either measure. Thus the results did not support the ethanol-opioid common-link hypothesis.