Ornithine decarboxylase stimulation in rat ovary by luteinizing hormone

In normal albino rats with a 4-day estrous cycle, the activity of ovarian ornithine decarboxylase undergoes a transitory rise on the evening of proestrus and only at that time. The response could be elicited by the administration of either luteinizing hormone or human chorionic gonadotrophin. When antiserum to luteinizing hormone was injected at 2 p.m. on the day of proestrus, the induction of ornithine decarboxylase was blocked, an indication that the enzyme is under luteinizing hormone control. The strategic positioning of the induction of ornithine decarboxylase between the normal release of luteinizing hormone and ovulation impties that putrescine is associated with the ovulatory process, and opens a new avenue of research on the control of ovulation.