title: Oxytocin and HPA stress axis reactivity in postpartum women.
abstract: BACKGROUND
  Lactation is thought to buffer stress reactivity via oxytocin (OT). Dysregulation of the HPA axis has been reported in women with postpartum depression (PPD). The co-occurrence of PPD and lactation failure suggests that abnormalities in OT signaling may play a role in PPD. We hypothesized that abnormal OT signaling is implicated in dysregulated HPA axis reactivity among postpartum women with mood symptoms. In a prospective perinatal cohort, we tested associations between OT levels during breastfeeding and stress reactivity.
  
  
  METHODS
  We recruited 52 pregnant women who intended to breastfeed, among whom 47 underwent a standardized stressor, the Trier Social Stress Test (TSST), at 8 weeks postpartum. 39 were breastfeeding at time of TSST. We assessed mood symptoms using validated instruments and defined as symptomatic women with EPDS ≥ 10 and/or Spielberger ≥ 34. Following IV placement for blood draws, women breastfed their infants and then underwent the TSST. Mothers' hormone responses were quantified.
  
  
  RESULTS
  Among symptomatic breastfeeding women (N=11; asymptomatic N=28), we found lower OT levels during breastfeeding (p<0.05) and higher CORT levels (p<0.05) both during breastfeeding and the TSST, as compared to asymptomatic breastfeeding women. In a mixed effects model examining CORT reactivity by symptom group and OT AUC, we observed a paradoxical response in symptomatic breastfeeding women during the TSST (group × time × OT AUC p<0.05); higher OT AUC was associated with higher CORT.
  
  
  CONCLUSIONS
  In all breastfeeding women, the surge of OT during feeding appears to buffer subsequent stress-induced CORT secretion. However, in symptomatic breastfeeding women, we found a positive correlation between OT AUC and CORT, instead of the expected negative correlation, which we found among asymptomatic women.
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7160, United States. Electronic address: elizabeth.q.cox@gmail.com.
authors.forename: E Q
authors.initials: EQ
authors.lastname: Cox
authors.affiliation: Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7160, United States.
authors.forename: A
authors.initials: A
authors.lastname: Stuebe
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7160, United States.
authors.forename: B
authors.initials: B
authors.lastname: Pearson
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7160, United States.
authors.forename: K
authors.initials: K
authors.lastname: Grewen
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7160, United States.
authors.forename: D
authors.initials: D
authors.lastname: Rubinow
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7160, United States.
authors.forename: S
authors.initials: S
authors.lastname: Meltzer-Brody
mesh_terms: D000328:Adult; D001007:Anxiety / Q000378:metabolism / Q000523:psychology; D001942:Breast Feeding; D016022:Case-Control Studies; D015331:Cohort Studies; D003863:Depression / Q000378:metabolism; D019052:Depression, Postpartum / Q000378:metabolism* / Q000523:psychology; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D007774:Lactation / Q000378:metabolism* / Q000523:psychology; D008137:Longitudinal Studies; D010121:Oxytocin / Q000378:metabolism*; D010913:Pituitary-Adrenal System / Q000378:metabolism*; D049590:Postpartum Period; D011446:Prospective Studies; D013315:Stress, Psychological / Q000378:metabolism* / Q000523:psychology; D055815:Young Adult
chemical_list: D010121:Oxytocin; D006854:Hydrocortisone
keywords: Cortisol; HPA axis; Lactation failure; Oxytocin; Pospartum depression