Effect of intra-ovarian 6-hydroxydopamine on progesterone secretion in sheep

Effects of arterial infusions of adrenalin and acetylcholine on luteal secretion of progesterone and oxytocin in goats

The effects of close intra-arterial infusion of acetylcholine and adrenalin on ovarian secretion of progesterone and oxytocin were examined on Day 10 of the estrous cycle in goats (estrus = Day 0). Acetylcholine (15 micrograms/min) was without effect, but adrenalin (10 micrograms/min) significantly (P < 0.001) raised both progesterone and oxytocin concentrations in ovarian vein plasma. These results show that luteal hormone secretion is enhanced in the goat by beta-adrenergic stimulation and suggest that, as in the sheep and cow, there may be neuroendocrine involvement in the regulation of caprine luteal function.

Effect of adrenalin and propranolol on progesterone and oxytocin secretion in vivo during the caprine estrous cycle

The effects of jugular infusions of adrenalin and the beta-adrenergic receptor antagonist propranolol on plasma concentrations of progesterone and oxytocin were examined at 2 different stages of the caprine estrous cycle. Adrenalin (25 micrograms.kg-1h-1) significantly (P < 0.05) increased oxytocin secretion on Day 3 and Day 10 of the cycle (estrus = Day 0); progesterone concentrations were significantly (P < 0.05) elevated on Day 10 alone. Propranolol had no effect on progesterone secretion yet significantly (P < 0.05) reduced oxytocin concentrations on Day 3. These results suggest that there may be neuroendocrine involvement in the regulation of luteal oxytocin secretion in the goat.

Insensitivity of dispersed caprine luteal cells to β-adrenergic agonists and other putative transmitter substances

Adrenaline (10(-6)-10(-4)M), serotonin (10(-6)-10(-4)M), and several other potential steroidogenic agonists failed to enhance either basal or LH-stimulated progesterone production from dispersed caprine luteal cells from Day 10 of the estrous cycle. The caprine corpus luteum (CL) would appear to be more refractory to exogenous stimulation than either the ovine or bovine CL.