Direct effect on the ovary of the adrenergic blocking drug dibenzyline.

Abstract

Data are presented to show that the adrenergic blocking drug Dibenzyline (phenoxybenzamine hydrochloride, SK & F) blocks ovulation in laying hens not only when it is injected systemically (iv) at doses of 20 mg/kg but also when it is injected directly into the wall of the largest follicle (300 μg/follicle). The blocking effect of Dibenzyline can be overcome by injecting 2.5 mg of LH systemically (iv), which causes ovulation if the injection is made 4, 6, or 12 hr before expected ovulation, but the follicles become atretic if LH is injected 2 hr prior to ovulation. In distinct contrast, LH injected directly into the follicle wall following Dibenzyline blockade is unable to cause ovulation. However, if a mixture of FSH and LH, in which FSH predominates (150 μg FSH: 120 μg LH), is injected into the follicle wall, all the blocked follicles ovulate. These results raise questions concerning the nature of the ovulation-inducing hormone and raise the possibility that systemically injected hormones become complexed with other hormones or become otherwise altered before they act at the level of the end-organ in the traditionally expected manner. Preliminary data show that in rabbits intra-ovarian or intrafollicular injection of adrenergic blocking drugs also prevents local ovulation while other follicles in the same ovary or in the opposite ovary of the same animal ovulate normally. (Endocrinology85: 38, 1969)