Lactation and Reactivity to Physical and Psychological Stress.
Final rept. 15 Sep 95-14 Sep 98,
MARYLAND UNIV COLLEGE PARK
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The purpose of this study was examine the behavioral and physiological responses of lactating versus nonlactating females to stressors, such as those that might be encountered in military life and to analyze in animal models the possible mechanisms that might account for differences between lactating and nonlactating females. Studies of basal cortisol levels, cognitive performance and reactivity to stressors were conducted in human subjects during late pregnancy and immediately postpartum in women that were lactating or bottle-feeding their infants. Analyses of blood and behavior from the human subjects revealed that lactating women had increased lymphocyte proliferation in response to a mitogenic challenge, but were less likely to respond to psychological stress. Research in rats revealed that lactating female rats show less fear behavior and are less hormonally reactive to stress than nonlactating females. Lactation did not affect acoustic startle responses in rats. Lactating rats have also had enhanced lymphocyte proliferation responses to mitogens. Studies with a new rodent model prairie voles have revealed that oxytocin a principle hormone of lactation, but not vasopressin, is capable of inhibiting the HPA axis.
- Medicine and Medical Research