TERRITORIAL AGGRESSION, BODY-WEIGHT, CARBOHYDRATE-METABOLISM AND TESTOSTERONE LEVELS OF WILD RATS MAINTAINED IN LABORATORY COLONIES

Citation
Ab. Lucion et al., TERRITORIAL AGGRESSION, BODY-WEIGHT, CARBOHYDRATE-METABOLISM AND TESTOSTERONE LEVELS OF WILD RATS MAINTAINED IN LABORATORY COLONIES, Brazilian journal of medical and biological research, 29(12), 1996, pp. 1657-1662
Citations number
21
Categorie Soggetti
Medicine, Research & Experimental
ISSN journal
0100879X
Volume
29
Issue
12
Year of publication
1996
Pages
1657 - 1662
Database
ISI
SICI code
0100-879X(1996)29:12<1657:TABCAT>2.0.ZU;2-S
Abstract
Aggressive territorial behavior was studied in 15 colonies of wild rat s (Rattus norvegicus), each consisting of 2 males and 1 female. One of the males attacked an intruder rat more frequently and had a higher d e body weight than the less aggressive one. In another experiment, mal e and female rats were raised in colonies from weaning to adulthood. A nimals were weighed every 7 days until 90 days of age when plasma test osterone was measured in males, and plasma glucose, hepatic and muscle glycogen were measured in both males and females. The heavier (and th us possibly dominant) males in the colonies of 3 males and 1 female al so had a higher body weight than males raised with females, but withou t any male partner. In this long-term social relationship there were n o significant differences in carbohydrate metabolism among the animals . The differential growth rate among males was established around the period of sexual maturity. Moreover, when adult, heavier males had hig her plasma testosterone levels compared to the other members of the co lony and also to males that had no other competitive male partner. Thi s higher androgenic hormone level may be one of the causal factors inv olved in the weight increase of the dominant male in the colony.