Free Access
Reprod. Nutr. Dev.
Volume 42, Number 4, July-August 2002
Page(s) 381 - 392
Reprod. Nutr. Dev. 42 (2002) 381-392
DOI: 10.1051/rnd:2002033

Plasma levels of cortisol and oxytocin, and uterine activity after cervical artificial insemination in the ewe

Eric Houdeaua, Pierre Raynala, Pierre-Guy Marnetb, Guy Germainc, Pierre Mormèded, Bernadette Rossanoa, Régine Monneriea and Marie-Jeanne Prud'hommea

a  Laboratoire de Neurobiologie des Fonctions Végétatives, INRA, Jouy-en-Josas, France
b  Équipe Associée INRA/ENSAR de Recherches sur la Traite, Rennes, France
c  Unité de Physiologie Animale, INRA, Jouy-en-Josas, France
d  Unité de Neurogénétique et Stress, INSERM/INRA, Institut François Magendie, Bordeaux, France

(Received 30 April 2002; accepted 25 July 2002)

The objective was to compare in the ewe the effects of easy and difficult procedures for artificial insemination (AI) (as related to rapid or poor accessibility of the cervix, respectively) on plasma cortisol (CORT) and oxytocin (OT), and uterine motility. All AI were simulated using a catheter empty of semen to study genital and environmental stimuli only. In experiment 1, 40 ewes were sampled after AI, and whether it was an easy or difficult procedure was reported for each animal. While CORT concentrations rose to a similar amount in all ewes, whatever the AI procedure, a significant OT response occurred after a difficult procedure only ( n = 18) (17.4 $\pm$ 1.7 versus 12.7 $\pm$ 0.7 pg $\cdot$mL -1 before AI, p < 0.05). In experiment 2, uterine activity was monitored in 4 ewes using an implantable telemetric transmitter equipped with an intrauterine pressure catheter. An increased uterine activity occurred during 2 $\pm$ 1 min after an easy AI ( n = 5), whereas the evoked activity lasted for 15 $\pm$ 4 min after a difficult AI ( p < 0.001, n = 7). A similar long-lasting response occurred after OT administration (100 mIU, i.v.). We concluded that the increase in uterine motility after a difficult AI resulted from a reflex release of OT, and not to a "stress" effect.

Key words: artificial insemination / cortisol / oxytocin / uterine contractions / telemetry

Correspondence and reprints: Eric Houdeau

© INRA, EDP Sciences 2002