Maternal Behavior Anne Neumann PSY 890 Psychopharmacology
Maternal Behavior • Any behavior that contributes directly to the survival of offspring that have left the body of the female (Nelson, 2005) • Sensitization/ concaveation: process whereby continuous exposure to young pups can induce maternal responsiveness in non-lactating female rodents (Rosenblatt, 1967)
Endocrine control of MB • Moltz et al. (1970): • Ovariectomized nulliparous female rats were injected SC with EB over days 1-11, P over days 6-9 and Prol on days 9 and 10 • Control females: EB+P, P+Prol, EB + Prol, no hormones • Females that received EB + P + Prol regimen had the shortest latencies to onset of MB (48 hours) • Females in the EB and P group showed moderate stimulation of MB (3 days) • Females in P + Prol and EB + Prol groups did not differ from untreated females
Neuroanatomy of maternal behavior • VNO → accessory olfactory bulbs → lateral olfactory tract → medial nuclei of amygdala → stria terminalis → BNST/ MPOA
Neurochemistry of MB • Oxytocin • Opioids • Prolactin/Dopamine
Oxytocin and MB • Pedersen & Prange (1979): ICV oxytocin facilitates MB in virgin rats. • Fahrbach et al (1986): Oxytocin could facilitate MB, only in females tested in a novel environment. • Reducing oxytocin neurotransmission (oxytocin inhibitors, antagonists, lesions of PVN) inhibits onset of MB.
Oxytocin and MB Pedersen et al. (1982)
Oxytocin Insel & Harbaugh (1989)
Oxytocin receptor • Oxytocin receptor: membrane-bound G-protein coupled receptor that along with the 3 vasopressin receptors form the OT-AVP receptor family • Oxytocin receptors: in uterus, kidney, and brain • Facilitation of MB requires increase in central rather than peripheral oxytocin. • Oxytocin’s effects require estrogen priming.
Oxytocin Numan & Insel (2003)
Opioids and MB • Both the content of β-endorphin in the MPOA and the density of 3H-nalaxone binding are decreased during day 12 of lactation relative to day 12 of pregnancy. • Parallel increases were found in ovariectomized females treated with both E and P relative to ovariectomized nontreated females. Hammer & Bridges (1987)
Opioids and MB • Bridges & Grimm (1982): Morphine prevented the onset of maternal behavior and opiate receptor antagonist naloxone blocked morphine effects. • Rubin & Bridges (1984): Morphine blocked maternal behavior in sensitized ovariectomized females, when placed into the MPOA, but not VMH. • Mann, Kinsley, & Bridges (1991): Morphine effects are mediated via the μ-receptor: ICV administration of β-endorphin or DAGO reduced maternal behavior for 1-3 hours, whereas other opioid agonists (DPDPE (δ), U50488H (κ)) failed to disrupt MB
Prolactin and MB • Acute administration of prolactin has never been shown to induce rapid-onset MB. • Lack of selective, high-affinity antagonists for prolactin receptors to decrease prolactin function
Prolactin and MB Numan & Insel (2003)
References • Bridges, R.S. & Grimm, C.T. (1982). Reversal of morphine disruption of maternal behavior by concurrent treatment with the opiate antagonist naloxone. Science, 218, 166-168. • Hammer, R.P. & Bridges, R.S. (1987). Preoptic area opioids and opiate receptors increase during pregnancy and decrease during lactation. Brain Research, 420, 48-56. • Insel, T.R. & Harbaugh, C.R. (1989). Lesions of the hypothalamic paraventricular nucleus disrupt the initiation of maternal behavior. Physiology and Behavior, 45, 1033-1041. • Moltz, H., Lubin, M., Leon, N., Numan, M. (1970). Hormonal induction of maternal behavior in the ovariectomized nulliparous rat. Physiology & Behavior, 5, 1373-1377. • Numan, M. & Insel, T.R. (2003). The neurobiology of parental behavior. Springer: New York • Pedersen, C.A., Ascher, J.A., Monroe, Y.L., Prange, A.J. Jr (1982). Oxytocin induces maternal behavior in virgin female rats. Science, 216, 648-649. • Pedersen, C.A., Caldwell, J.D., Walker, C., Ayers, G. & Mason, G.A. (1994). Oxytocin activates the postpartum onset of rat maternal behavior in the ventral tegmental area and medial preoptic areas. Behavioral Neuroscience, 108, 1163-1171. • Pedersen, C.A. & Prange Jr., A.J. (1979). Induction of maternal behavior in virgin rats after intracerebroventricular administration of oxytocin. Proceedings of the National Academy of Sciences of the United States of America, 76, 6661-6665. • Thompson, A.C. & Kristal, M.B. (1996). Opioid stimulation in ventral tegmental area faciliates the onset of maternal behavior in rats. Brain Research, 743, 184-201.