The developmental effects of exposure to various doses of buprenorphine, methadone, or water during the perinatal period were studied in the rat. Rats were exposed to buprenorphine (0.3, 1.0, or 3.0 mg/kg/day), methadone (9 mg/kg/day), and/or water prenatally, postnatally, or both pre- and postnatally, via maternally implanted osmotic minipumps. Fetal and maternal mortality and morbidity were a...

Oxytocin secretion is important for the normal progress of parturition in the rat. We tested the hypotheses that contractions of the uterus before pup delivery activate oxytocin neurons, and that they do so via a noradrenergic projection. In anesthetized 22-day (term) pregnant rats, i.v. oxytocin pulses enhanced both uterine contractile activity and the firing rate of oxytocin and vasopressin n...

There is a complex collection of neuroendocrine function during the postpartum period. Prolactin (PRL) released by suckling stimulus and its PRL receptors (PRL-R) in the central nervous system (CNS) are involved in hyporesponsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in lactating mammals including rodents and humans. It is not clear how long it takes to reestablish the attenuated...

Mammalian mothers provide water to their young via milk. Rodent mothers reclaim much of this water by licking the anogenital areas of their pups, stimulating reflexive urination, and consuming the pups' urine. Male rodents do not provide milk (hence water) to the young, but in some species male parents may nevertheless lick their pups. We determined the amount of water transfer from pups to mot...

The ventral tegmental area (VTA) plays a critical role in motivated behavior. However, it remains unclear whether intact VTA function is necessary for motivated behavior to seek contexts repeatedly paired with natural stimuli and/or pharmacological stimuli. In the present study, conditioned place preference (CPP) was induced with highly salient natural or drug stimuli attributed with strong inc...

Individual differences in maternal behavior in rodents are associated with altered physiology and behavior in offspring across their lifespan and across generations. Offspring of rat dams that engage in high frequencies of high-arched-back nursing and pup-licking (High-LG) show attenuated stress responses compared to those engaging in lower frequencies (Low-LG). Selective breeding also produces...

Paternal care during early development influences pup survivorship in the monogamous and biparental California mouse, Peromyscus californicus. Moreover, paternal pup retrievals impact development of adult offspring aggression and the neuropeptide vasopressin, yet little is known about the underlying mechanisms of these developmental changes. Because testosterone can increase arginine vasopressi...

In cooperatively breeding animals, in which nonbreeding subordinates assist in rearing offspring born to dominants, breeders and helpers may be in conflict over their respective contributions to offspring care and selection may favour breeders that use aggression to elevate the work rates of helpers. We tested the prediction that dominant female meerkats, Suricata suricatta, should increase agg...

Fathers play a substantial role in infant care in a small but significant number of mammalian species, including humans. However, the neural circuitry controlling paternal behavior is much less understood than its female counterpart. In order to characterize brain areas activated by paternal care, male California mice were separated from their female mate and litter for 3 h and then exposed to ...