Opioidergic control of luteinizing hormone secretion in the female rabbit: influence of age on the response to naloxone

To examine the role of opioid neurons on luteinizing hormone (LH) secretion in the female rabbit, we determined LH release at timed intervals after naloxone administration to rabbits aged 25-150 days. The LH response to naloxone (10 mg/kg) was not significantly elevated until day 43 when LH rose 76-113% above basal levels at 40-80 min. In 56-day-old females the corresponding increase was 160% at 15 min and in 65- to 67-day-olds it was 154%. …