Maternal behavior in rats and the effects of neonatal progestins given to the pups

Abstract

This paper reports changes in maternal behavior of rats following progestin treatment of the neonates. There have been recent reports that hormonal treatment of pups can alter maternal behavior, particularly licking of pups, and that such effects might have implications for the later development of those pups. Accordingly, the major objective of the experiments described was to test the hypothesis that the effects of neonatal progestins on later behavioral development that we have previously described (Birke & Sadler, 1983; 1984) might in part be mediated by changes in maternal behavior. This was done by investigating the behavior of dams, including pup-directed behavior, following the hormone treatments that we have used previously. In the first experiment, medroxyprogesterone acetate (MPA), given via maternal milk, was found to increase rates of pup licking by dams. In the second experiment, anogenital licking was increased to litters containing pups that had received either MPA or progesterone by direct injection. No significant changes in licking following pup treatment with the antiserum to progesterone were observed, however. The results are discussed in relation to our previous work on progestin effects on later behavior, and in relation to the suggestion that hormonal effects on sexually dimorphic behaviors might, at least partly, be mediated through interactions with the mother during the neonatal period.

Differences in maternal behavior of rats and the sociosexual development of the offspring

“…Yet that too seems unlikely, unless we also suppose that reduced rates of maternal licking could result in elevated plasma androgen levels in the pups. Interestingly, we have demonstrated in previous work that neonatal progestin exposure can both reduce levels of play and can also raise levels of maternal anogenital licking (Birke & Sadler, 1985). The existence of such negative correlations between maternal behavior and later play behavior of the pups could usefully be investigated further.…”

“…Maternal rats also differentiate between pups by sex, directing more anogenital licking toward males than females (Moore & Morelli, 1979;Richmond & Sachs, 1984), a distinction which has been shown to have effects on the later expression of sexual behavior by male offspring (Moore, 1984). Such differentiation appears to be influenced by the hormonal status of the pups, presumably through olfactory changes (Moore, 1981); thus, licking rates can be increased by exposure of the pups to testosterone or dihydrotestosterone (Moore, 1982) or by exposure to progestins (Birke & Sadler, 1985).…”

The parental brain and behavior: A target for endocrine disruption

“…It should be noted that skewed litter composition (male only) in mice also lead to higher licking and grooming behaviors from the mother (Alleva et al, 1989;Musi et al, 1993). More importantly, hormone injections to the newborn, using progestins (Birke & Sadler, 1985) or androgens (Moore, 1982), modify maternal behaviors. These studies suggest that manipulations to the endocrine systems of pups are likely to affect maternal responsiveness and the pup-mother social interaction.…”

Genetic, epigenetic and environmental impact on sex differences in social behavior

“…Furthermore, it has long been established that rat dams spend more time licking their male pups than their female offspring [287, 288]. This effect can be manipulated by treating pups with hormones: females given androgens or estradiol are licked at rates equal to untreated males [289], and administration of progestins increases maternal licking all around [290]. As we have seen above, the amount of licking and grooming a pup receives has a profound influence on its LHPA activity later in life.…”