To determine the psychophysiological correlates of hormonal response during sexual activity, systolic blood pressure (SBP), anal electromyography (EMG), and anal photoplethysmography (APG) were monitored continuously throughout testing in 13 women and 10 men. Each subject completed two or more tests of self-stimulation to 5 min beyond orgasm. Blood samples were obtained continuously for measurement of oxytocin (OT) levels. In both men and women, very high positive correlations were observed between the percentage change in levels from baseline through orgasm of: OT and SBP; OT and EMG intensity prior to and during orgasm; APG and EMG. The number of anal contractions and duration of orgasm were also highly correlated. Two patterns of orgasm were defined by the presence or absence of a quiescent period between orgasmic contractions. EMG and APG amplitudes correlated with the pattern of orgasm. Subjective orgasm intensity correlated significantly with increased levels of OT in multiorgasmic women only. The positive correlations between measures are consistent with a possible functional role for OT in human sexual response.
Oxytocin in Postpartum Depression
Researchers at the University of Basel, Switzerland, measured oxytocin levels in 73 healthy pregnant women. Sixteen reported previous episodes of major depression that had ended at least two years before they joined the study.
Blood samples to measure oxytocin were taken during the third trimester of pregnancy. The women were given written screening tests to assess their risk of depression during pregnancy and again within two weeks of giving birth.
Overall, 14 women were determined to be at risk for postpartum depression based on their test scores. The risk of depression was not different between mothers who were breastfeeding and those who were not. Lower oxytocin levels before birth were associated with a greater risk of postpartum depression.
Skrundz, M. Neuropsychopharmacology, online, May 11, 2011
Gunther Meinlschmidt, PhD, assistant professor of psychology, University of Basel, Switzerland.
Carmichael, M.S. et al, Plasma oxytocin increases in the human sexual response.
J. Clin. Endocrinol. Metab. 1987/64 (1) / 27 – 31