Research Supported by National Institute of Mental Health RO1 HD/DK37431

1. No Stress Un-Handled Stress Un-Handled 3.0 2.5 No Stress Handled Stress Handled 2.0 Serum CORT Levels (% of Basal) 1.5 N-HAN 120 * 1.0 H 100 UH 0.5 HAN 80 0.0 AM. Licking 15min 30min 90min 0min 60 * 40 20 0 Early Life Handling: Effect on Maternal Behavior and Impact on Hypothalamic Pituitary Axis (HPA) during Subsequent Pregnancy and Post-lactating PeriodChakrabarti A, Huang LD, Park J, Smith K, Juma A, Vazquez DMDepartment of PediatricsUniversity of Michigan, Ann Arbor, MI Abstract Methods Results The efficacy of maternal care in mitigating the long term consequences of prenatal stress in offspring is unclear. To investigate this aspect of development, females derived from high-licking mom handled group (H) were compared to females derived from a baseline (unhandled UH) group once they were adults. Figure 1 and 2, show increased maternal behavior in the female offspring that were derived from handled litters. Half of H and UH female offspring were stressed (S) with unpredictable stressors during pregnancy creating two experimental groups; Handled-Stress (S-H) and Unhandled- Stress (S-UH). These were compared to non-stressed handled (H-NS) and non-stress unhandled (UH-NS). Half of the mothers’ stress response to 30 min restraint was studied at the end of the last stress session during pregnancy (gestational day 19) and the other half were studied 1 week after pups were weaned from lactation. Results in figure 3 and 4 showed that the stressed groups regardless of infant handling history had a lower serum corticosterone levels compared to the NS groups during pregnancy. However, post-weaning the females handled as infants had a lower stress response when compared the unhandled groups. The blunted stress response observed in all pregnant stressed mothers is hypothesized to be the result of chronic unpredictable stress, while the post-weaning blunted response in handled females is consistent with previous data indicating decreased stress and anxiety response in adult male rats that were handled as infants. Therefore, results indicated that enhanced maternal care results in a limited stress response, but only under a non-pregnant physiological state. • Phase I • Commercially Purchased Females were mated (n=8) • At Birth: litters culled to 12 pups (6M:6F) • Daily Handling- 15 min daily, AM (cage temperature mantained at 35°C with heating pad) • Maternal Behavior Scored- 3x AM, 3x PM • As adults, female offspring were mated Phase II 2. Stress Response Female rats stressed during pregnancy have low CORT levels. Phase I HAN No Stress Un-Handled Stress Un-Handled HAN= 15 min/daily 7.5 UN-HAN No Stress Handled Stress Handled 5.0 (% of Basal) Serum CORT Levels Not-Stressed N-HAN= not handled 2.5 Stressed • Phase II • As adults, female offspring that were handled as infants were mated • Unpredictable Stressors done at AM and PM from pregnancy day 3 to 19 (E3-E19) • swim • predator odors (fox • crowding • Restraint • short term water deprivation • Questions: • What is the effect on the mothers’ • maternal behavior? • HPA responses to acute stress? Phase II Acute Restraint after 16 days of chronic stress 0.0 0min 15min 30min 90min Stressed (n=12) HAN Figure 3. Serum CORT response to restraint stress 16 days after chronic stress during pregnancy. Restraint is done on day 19 of pregnancy. Control (not-stressed) (n=12) HAN= 15 min/daily After lactation female rats handled as infants have a blunted stress response. N-HAN Stressed (n=12) Control (not-stressed) (n=12) N-HAN= not handled Acute Restraint Objectives & Hypothesis Figure 4. Serum CORT response to restraint stress after lactation period • Characterize the maternal behavior (pup licking) of female • rats that were handled daily for 14 days as infants • (2) Determine if female pups that had high-licking mothers • have a blunted response to stress (as measured by serum • CORT levels) during and after their first pregnancy • Hypotheses: • A. Mothers that were handled as infants will have higher • licking towards their own pups. • B. These pups, once adults, will have enhanced maternal • behavior and lower stress response during and after • pregnancy. Results Conclusion Phase I 1. Maternal Behavior Our data is in agreement with the literature that supports that perinatal handling causes inter-generational transfer of increased maternal care in female rats.[1][2] The blunted stress response observed in the stressed non-handled mothers is hypothesized to be the result of exhaustion of the HPA system commonly is seen after chronic unpredictable stress. This is consisted with the General Adaptive Syndrome proposed by Selye in 1956 [3]. The post-weaning response is indicative of altered brain circuits conducive to a decreased HPA response in the mothers that received high levels of maternal care as infants. Therefore, our preliminary results indicate that high maternal care results in a limited stress response, but only under a non-pregnant physiological state. In follow-up studies, it will be pertinent to ascertain the extent of corticosterone elevation in the H-S and UH-S females chronically stressed during pregnancy from day to day as a result of the stressors being performed. It is possible that the pregnant females that were handled as infants may have a different (blunted) response to unpredictable stress in the initial days of the stress paradigm. This may be favorable to the development of the offspring. In addition, we would like to investigate whether the offspring derived from mothers subjected to prenatal unpredictable stress have altered anxiety behavior along with the propensity to seek drugs. The anxiety behavior of the female offspring is being analyzed. Handling during infancy increases licking behavior in female rats. * 75 Non Stress Stress 50 • Selected References : • Champagne, F., Meany, M. J. (2001). Like mother, like daughter: evidence for non-genomic transmission of parental behavior and stress responsivity. Progress in Brain Research, 133, 287-302. • Champagne, F. A. (2008). Epigenetic mechanisms and the transgenerational effects of maternal care. Frontiers in Neuroendocrinology, 29, 386-397. • Selye, H. (1936). A syndrome produced by diverse nocuous agents. Nature, 138, 32-34. • Meddle, S. L., Bishop, V. R., Gkoumassi, E., van Leeuwan, F. W., Douglas, A. J. (2007). Dynamic changes in oxytocin receptor expression and activation at parturition in the rat brain. Endocrinology, 148, 5095-5104. • Campbell, A. (2008). Attachment, aggression and affiliation: the role of oxytocin in female social behavior. Biopsychology, 77, 1-10. • Olazabal, D. E., Young, L. J. (2006). Oxytocin receptors in the nucleus accumbens facilitate "spontaneous" maternal behavior in adult female prairie voles. Neuroscience,141,559-568. • Lonstein, J. S. (2005). Reduced anxiety in postpartum rats requires recent physical interactions with pups, but is independent of suckling and peripheral sources of hormones. Hormones and Behavior, 47, 241-255. • Amico, J. A., Mantella, R. C., Vollmer, R. R., Li, X. (2004). Anxiety and stress responses in female oxytocin defcient mice. Journal of Neuroendocrinology, 16, 319-324. • Smith, J., Seckl, J., Evans, A., Costall, B., & Smythe, J. (2004). Gestational stress induces post-partum depression-like behaviour and alters maternal care in rats. Psychoneuroendocrinology, 29, 227-244. • Meaney, M. J. (2001) Maternal care, gene expression, and the transmission of individual differences in stress reactivity across generations. Annual Review of Neuroscience, 24,116101192. S. The development of infants’ circadian rest activity rhythm and mothers’ rhythm. Physiol. Behav 2002, 77:91-98. AM. Licking 25 A. 0.0 Handled Unhandled Handled Unhandled Figure 1. Licking Behavior of mothers whose pups were handled daily compared to mothers whose pups were not handled. Figure 2. Licking Behavior in mothers that were handled as infants. Stress is given during pregnancy to a sub-group of mothers from each Handled and Unhandled groups. Research Supported by National Institute of Mental Health RO1 HD/DK37431