Competitive behavior: intact male rats but not hyperdefensive males with medial hypothalamic lesions share water with females.
Male hooded rats with medial hypothalamic lesions or sham lesions were given tests of defensiveness toward an experimenter. The 8 lesioned males with the highest defensiveness scores and 7 sham-lesioned males were each placed in a double cage with a single intact female. For each pair of rats, food was continuously present but water was available for only 1 hr/day through a single water spout. Beginning on the fifth day of water deprivation, each pair of animals was given a 4-min water competition test on 3 consecutive days. Competition for water was created by placing a plastic ring over the hole in the cage where the water spout entered the cage. The ring restricted access to the spout to a single animal and was put in place 5 min before water was given. One hr following the competition test, each pair of animals was given access to a single unencumbered spout for a 1-hr period. Rats with medial hypothalamic lesions drank significantly more and initiated more aggression than their female cagemates during the 4-min competition tests. Sham-lesioned rats neither drank significantly more nor were more aggressive than their female cagemates. These results are consistent with previous observations indicating that the aggressiveness of rats with medial hypothalamic lesions can be elicited by a competition situation.
Psychology Department, University of British Columbia, Vancouver, Canada.
D J
DJ
Albert
E M
EM
Dyson
M L
ML
Walsh
D000374:Aggression / Q000502:physiology; D000818:Animals; D003163:Competitive Behavior / Q000502:physiology*; D004327:Drinking Behavior / Q000502:physiology; D005260:Female; D007033:Hypothalamus, Middle / Q000502:physiology*; D008297:Male; D051381:Rats; D012726:Sexual Behavior, Animal / Q000502:physiology