The Timing of Mating by Postpartum Estrous Rats

Abstract

and Summary In Norway rats (Rattus norvegicus) postpartum copulation began later, and was more rapid than mating during a cycling estrus. Faster postpartum mating was a result of shorter intervals between intromissions, rather than fewer intromissions. In addition, postpartum pairs showed a trend towards fewer ejaculatory series. Postpartum female sexual initiation and her attractiveness to the male produced rapid postpartum mating. Preliminary evidence indicates that pups' presence does not determine faster postpartum mating, yet postpartum females did exhibit time‐sharing relationships between their mating and maternal demands. We hypothesize that the rapid pace of postpartum mating is produced by intrinsic neuroendocrine changes characteristic of postpartum estrus and possibly by sexual experience.

Adolescence and Postpartum: Two Life Periods to Deepen Our Understanding of the Complexity of Female Rat Sexual Behavior

“…When tested in a sexual arena with a male, females that give birth early in the light phase begin to display lordosis responses approximately 6 h after parturition and exhibit the highest sexual receptivity between 9 and 15 h. Although the maximal expression of proceptive and receptive components as well as minimal rejection of the male occurs around 12 h after delivery, females may show lordosis in response to mounting between 6 to 18 h postpartum [71,115]. In accordance, studies in semi-natural environments show that most PPE rats leave the nest and mate approximately 10 h after parturition [72,73,116]. However, if females deliver close to the onset of the dark phase, then PPE is delayed to the second postpartum day, stressing the interaction between circadian and delivery-related signals in its control [103,113].…”

“…The general expression of sexual behavior of PPE rats as well as the structure and efficiency of mating do not differ from those observed in the sexual interaction of late proestrus cycling females. Copulatory time in semi-natural environments, however, has been reported to be reduced during PPE either by decreasing the number of intromissions [72] or by reducing inter-intromission intervals [116]. The similarity in the behavioral profile of PPE and cycling females may respond to similar changes in sexual steroids levels-estrogen peak followed by progesterone peak-that precede both behavioral estrus.…”

Gonadotropin-inhibitory hormone as a regulator of social interactions in vertebrates

“…Inhibition of the estrous cycle in lactating rats is mainly attributed to inhibition of GnRH-I and LH secretion (Fox and Smith, 1984). Female rats experience a postpartum estrus in which they ovulate within 24 h of parturition (Hedricks and McClintock, 1985). Estrus and ovulation are delayed for approximately 20 days in lactating rats that suckle more than six pups.…”

Variable mode of estrus affects female decision for multiple mating

“…Taken these together, one might expect different mating strategies of females mating in each mode of estrus. Indeed, it has been shown that females in PPE devote less time to mating than females in CE (Gilbert et al 1980;Hedricks and McClintock 1985;Witt et al 1990;delBarco-Trillo and Ferkin 2007). However, whether females in PPE and CE differ in their propensity to remate and differ in mate assessment efforts has not been investigated.…”