title: Plasma oxytocin concentrations in cyclic mares and sexually aroused stallions.
abstract: An experiment was conducted to measure plasma oxytocin concentrations at 4 different stages of the estrous cycle in 11 pony mares. Plasma oxytocin concentrations (muU/ml +/- SE) were found to be higher (P<.01) on day 2 of estrous (39.8 +/- 12.5) and day 5 post-ovulation (33.1 +/- 12.0) than on day 10 (2.3 +/- 1.6) and day 15 post-ovulation (6.8 +/- 4.1). A second experiment was conducted to measure jugular plasma oxytocin concentrations before and after sexual arousal in six pony stallions. Oxytocin concentrations (muU/ml +/- SE) were higher (P<0.06) after sexual arousal (50.5 +/- 8.9) than before sexual arousal (23.8 +/- 2.9). These data suggest plasma oxytocin concentrations may be associated with ovarian function in mares and with sexual behavior in stallions.
authors.affiliation: Endocrine Research Unit, Michigan State University East Lansing, Michigan 48824 USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Burns
authors.forename: P
authors.initials: P
authors.lastname: Kumaresan
authors.forename: R H
authors.initials: RH
authors.lastname: Douglas