Variations in oxytocin, vasopressin and neurophysin concentrations in the bovine ovary during the oestrous cycle and pregnancy

Abstract

Bovine ovaries were obtained from the abattoir and corpora lutea were classified as: (1) early luteal phase (approximately Days 1-4); (2) mid-luteal phase (Days 5-10); (3) late luteal phase (Days 11-17); (4) regressing (Days 18-20) and (5) pregnant (Days 90-230). In addition, preovulatory follicles and whole ovaries without luteal tissue were collected. Concentrations of oxytocin, vasopressin, bovine neurophysin I and progesterone were measured in each corpus luteum by radioimmunoassay. Progesterone and neurophysin I levels increased from Stage 1 to Stage 2, plateaued during Stage 3 and declined by Stage 4. Oxytocin and vasopressin concentrations increased from Stage 1 to Stage 2 but declined during Stage 3 and were low (oxytocin) or undetectable (vasopressin) in follicles, whole ovaries and pregnancy corpora lutea. Therefore the concentrations of both peptide hormones were maximal during the first half of the cycle and declined before those of progesterone. The high concentration of oxytocin within the corpus luteum coupled with the presence of bovine neurophysin I suggests that oxytocin is synthesized locally.

Association between neuropeptide oxytocin and male infertility

“…Additionally, there are some controversial issues regarding the interaction between OT and FSH, LH. Some early studies have shown that OT can inhibit the release of LH and FSH [25], whereas other reports have not [26,27]. In this research, OT plasma concentration was not correlated with that of LH and FSH.…”

Luteotropic Mechanisms in the Bovine Corpus Luteum: Role of Oxytocin, Prostaglandin F₂ _α, Progesterone and Noradrenaline

“…Thus, the increase of the OT concentrations in bovine CL from the early to the mid-luteal phase ( Fig. 1) is maintained only by the stimulation of a post-translational oxytocinneurophysin process [15][16][17][18]. The terminal enzyme in the post-translating processing of oxytocinneurophysin is peptidyl glycine α-amidating mono-oxygenase (PGA) [13,17].…”

Diagnostic précoce de gravidité chez la vache grâce à l'observation de l'éjection du lait induite par l'ocytocine lutéale

“…C'est la progestérone qui, jusqu'à maintenant, a été l'unique «révélateur» de l'activité lutéale par les variations de sa concentration dans le plasma sanguin (Terqui et André, 1982;Humblot et Thibier, 1984;Kishimoto et al, 1987) et dans le lait (Laing et Heap, 1973;Heap et al, 1976;Hoffman et al, 1976;Cox et al, 1978;Booth et al, 1979;Thibier, 1980;Laitinen et al, 1985;Sauer et al, 1986;Stanley et al, 1986; Van de Wiel et Koops, 1986 (Humblot et al, 1987). Par ailleurs, malgré leur apparente simplicité, les kits EIA peuvent parfois exiger des temps de réaction de 20!0 min pour que la lecture soit interprétable (Tainturier et al, 1988 (Mialot, 1988) (Wathes et al, 1984;Ivell et al, 1985).…”