Local Ovarian Effects of Catecholamines on Human Chorionic Gonadotropin-Induced Ovulation in the Rabbit

Alpha-adrenergic blockage by dibenzyline is postulated to interfere with follicular rupture by preventing functional intervention of smooth muscle fibers in the ovary by delaying or inhibition of ovulation in rabbits induced by HCG.

Abstract

Observations were made on the local effects of the adrenergic drugs norephinephrine (1 mcg per kg weight) dibenzyline (.25 mg/kg) isoproterenol (1 mcg/kg) and propranolol (.1 mcg/kg) on HCG (Human Chorioic Gonadotropin) induced ovulation in 91 rabbits. All the rabbits received 50 I.U. of HCG and were operated on in identical fashion. Control animals received 1 ml of normal saline and showed 10 hours after HCG administration a mean number of 11.6 follicles per rabbit. There were 6.7 hemorrhagic and 4.9 mature follicles respectively. The test animals were divided into 2 groups; one group received the adrenergic agents 10 hours after HCG administration via injection into the abdominal aorta. The mean number of total follicles per rabbit was 10.1 for norepinephrine 11.3 for dibenzyline 7.9 for iso-proterenol and 10 for propanolol. Hemorrhagic follicles per rabbit were: 6.7 for norepinephrine 3.0 for dibenzyline 7.9 for isoproterenol and 10 for propranolol. The mean number of mature follicles per rabbit were: 3.5 for norepinephrine 8.3 for dibenzyline 2.3 for isoproterenol and 4.6 for propranolol. In the 10-hour post-HCG group the norepinephrine-injected group showed no significant difference from controls in either the number of mature follicles or hemorrhagic follicles. The dibenzyline-injected group showed a significant increase in mature follicles decrease in hermorrhagic follicles and delay or inhibition of ovulation compared with the controls. Isoproterenol was associated with a significant decline in the mean number of mature follicles compared with controls and with propanolol-injected animals. Propanolol-injected rabbits showed no significant difference from controls in either mature or hemorrhagic follicles. The second test group had norepinephrine or dibenzyline injected 7 hours post-HCG and ovarian morphology was followed up to 10 hours. Norepinephrine produced no change in either mature or hemorrhagic follicles compared with controls. Dibenzyline was injected in two dosages 7 hours after HCG: .25 mg/kg and 1.0 mg/kg. Ovarian morphology was followed up to 60 hours after injection and showed an increase in the number of mature follicles and a decrease in the number of hemorrhagic follicles. It appeared to delay the time of ovulation. The effects of d ibenzyline appear to be more profound when it is administered closer to HCG administration. Systemic administration (via the marginal ear vein) of dibenzyline resulted in minimal effects. Alpha-adrenergic blockage by dibenzyline is postulated to interfere with follicular rupture by preventing functional intervention of smooth muscle fibers in the ovary.