Dihydrotestosterone promotes fighting behavior of female mice

Female mice injected once with dihydrotestosterone (DHT) or testosterone propionate (TP) on the day of birth fought sooner following the commencement of chronic exposure to testosterone in adult life than did animals administered only the oil vehicle at birth. Also, adult nonperinatally androgenized females fought in response to chronic exposure to DHT or TP. It appears that DHT shares with TP the ability both to sensitize the perinatal CNS to testosterone and to activate fighting behavior in the adult.     

Induction of maternal nest building in virgin female mice by the presentation of young

Ovariectomized and intact adult virgin female mice presented with two 1-day-old mouse pups built larger nests and more nests rated “maternal” than did intact animals not proffered young. Virgin females presented with live 1-day olds behind a wire partition in their homecages also constructed larger nests and more nests rated “maternal” as compared to animals presented with freshly killed 1-day olds, 19-day olds, or with no pups behind the partition.     

Individual differences in the maternal behavior of male mice: No evidence for a relationship to circulating testosterone levels

Maternal behavior toward newborn pups and endogenous levels of testosterone (T) in peripheral plasma were measured in individual adult male mice. Separate groups of animals that either retrieved, ignored, or killed pups were found not to differ with respect to plasma T levels, body weights, or relative weights of testes, seminal vesicles, and adrenals. Furthermore, animals do not exhibit changes in T following tactile or nontactile interactions with pups.     

Mice: Pregnancy termination, lactation, and aggression

Hysterectomy on the 14th day of gestation in combination with the immediate and repetitive presentation of 1-day-old foster young produced lactation and fighting behavior toward adult males. The fighting behavior was comparable to that displayed by normally parturient mice. Hysterectomy alone or the presentation of pups alone initiated neither lactation nor fighting. Hysterectomy performed prior to the 12th day of gestation plus the presentation of foster young also did not initiate lactation or fighting. Ovariectomy performed in conjunction with hysterectomy on the 14th day of pregnancy together with the presentation of young produced lactation but not fighting behavior, thus suggesting that fighting and lactation are controlled by somewhat different hormonal mechanisms.     

Maternal nest building by pseudopregnant mice.

Pseudopregnant mice displayed maternal nest-building behaviour. Their nests were smaller but qualitatively identical to those constructed by pregnant animals.