Experience with younger siblings facilitates maternal responsiveness in pubertal norway rats

Abstract

The latency of maternal behavior (MB) onset induced by cohabitation with pups (sensitization) increases in female and male Long-Evans rats from 24 days of age (1-2 day latency) to 42 days of age (4-5 day latency). This decline in maternal responsiveness at Day 42 did not occur in 50% of rats ("responders") which lived with their dam and younger siblings (conceived during the postpartum estrus) for either 4 or 11-18 days after their birth. In contrast to cessation of suckling at about Day 25 postpartum in the absence of a 2nd litter, when a 2nd litter was born greater than Day 26 or less than Day 26 postpartum, suckling continued for a mean of 32 and 35.5 days, respectively (and up to Day 40). Also, time spent suckling during the 10 days following the birth of the 2nd litter was more than five times as great if the 2nd litter was born with little or no delay (less than Day 26). The offspring from the 1st litter spent about 80% of the diurnal observation time in proximity to the dam and younger siblings, and instances of nurturance (retrieving, crouching, licking) toward the young littermates were observed. However, the only dam-litter interaction significantly related to subsequent maternal responsiveness by 1st litter offspring was a positive relation between the prior incidence of aggression by mothers towards juveniles and sensitization latency.

Effects of experience on the parental responses of male Mongolian gerbils

“…The results of the present experiment are also consistent with results of previous work showing (a) that female rats exposed, as adolescents, to neonatal pups show shorter latencies to induction of maternal behavior than do those lacking such adolescent experience (Moretto, Paclik, & Fleming, 1986;Stern & Rogers, 1988), and (b) that prairie voles with alloparenting experience display higher levels of parental care in their first reproductive effort than do control animals lacking such experience (Wang & Insel, 1996).…”

Ontogeny of the transition from killer to caregiver in dwarf hamsters (Phodopus campbelli) with biparental care

“…Variables manipulated were species and subject sex. There was no evidence of a sex difference in alloparental responsiveness even though, in weanling Norway rats, males become maternal faster than females tested at 24 days of age (Stern & Rogers, 1988) and males retrieve pups more frequently than female juveniles (Gray & Chesley, 1984). Similarly, juvenile prairie voles are more likely to behave alloparentally if they are male rather than female (Roberts et al, 1998).…”

“…Since juvenile alloparental experience might affect development and later parental behavior (Lonstein & De Vries, 2001;Stern & Rogers, 1988), no animals had alloparental experience as juveniles. Each was then presented with 1 unrelated, anesthetized stimulus pup in the standard pup-displacement test.…”

Comparison of the “Nursing” and Other Parental Behaviors of Nulliparous and Lactating Female Rats

“…It is unlikely that feral virgin female rats would have either no experience with young pups until adulthood (Calhoun, 1963;Davis and Hall, 1951;Gilbert, Burgoon, Sullivan, and Adler, 1983;Gray and Chesley, 1984;Stern and Rogers, 1988) or repeated access as adults to another female's litter (Calhoun, 1963). The sensitization paradigm is therefore an unnatural, but potentially useful, model to examine nonhormonal factors regulating maternal behavior.…”