The secretory patterns of growth hormone in pregnant and hysterectomized ewes

This work was undertaken to determine the secretory patterns of GH during p regnancy and to evaluate the effect. if any, of hysterectomy during early p regnancy on subsequent secretion of GH in ewes. The concentrations of GH we re determined in the plasma of jugular blood samples collected at 15-min in tervals during a 6-h period on days 20, 40, 60, 80, 100 and 120 post-mating , and three times per week between days 29 and 120 post-mating from 5 pregn ant ewes and from 5 ewes from which the gravid uterus was removed on day 30 post mating. A pulse analysis program (Pulsar) was used to analyse the sec retory patterns of GH in individual profiles of the serial sampling period. In the two groups of ewes, peripheral concentrations of GH fluctuated in a n episodic manner during the frequent blood sampling of any stage of the po st-mating period examined. The overall GH concentrations, the basal GH conc entrations, the frequency and the amplitude of GH pulses remained fairly st able between days 20 and 120 post-mating in the two groups of ewes, The par ameters of GH secretion were not different between the two groups of ewes. The secretory patterns of GH, as determined in plasma of blood collected th ree times per week between days 29 and 120 post-mating were also not differ ent between the two groups of ewes. In conclusion, results of this study show that (i) the pulsatile secretion of GH does not change as pregnancy advances, and (ii) hysterectomy performe d during early pregnancy does not subsequently affect the secretory pattern s of GH, These findings suggest that the gravid uterus and/or the fetoplace ntal unit secretory products are unlikely to be involved in the control of GH secretion during pregnancy in the ewe.