The Effect of Oxytocin and Vasotocin upon Progesterone, Testosterone and Estradiol 17β-Secretion by the Luteal Cells from Cyclic Pigs

Summary

Porcine luteal cells were obtained from the corpora lutea on the 13th day of the estrous cycle. The cells were digested with 0.25% trypsin and suspended in the Medium 199 with an addition of 10% calf serum, at a concentration of 5 x 10⁴ cells/ml. The cells were incubated with or without 4 and 40 mi.u./ml of oxytocin, 10 and 100 ng/ml of arginine-vasotocin, 1 µg LH and 50 U/ml hCG. Levels of progesterone, testosterone and estradiol 11 β were determined with the radioimmunological method, following 6 h incubation.

It was found that progesterone secretion under the influence of oxytocine (4 mi.u./ml) was less than in the control group and in the group with LH. Similarly, arginine-vasotocin at a dose of 10 ng/ ml inhibited progesterone secretion (P < 0.05). Higher doses of these peptides had no suppressive effect on the luteal cells.

Oxytocin and arginine-vasotocin had no influence on testosterone secretion by luteal cells. However, these cells produced less (P < 0.05) estradiol 17β under the influence of oxytocine than of hCG. The results point to a direct effect of oxytocin and arginine-vasotocin on steroidogenesis in the corpora lutea of cyclic pigs.

Key words

Oxytocin - Vasotocin - Porcine luteal cells - Pigs