POSTPARTUM HYPOGONADOTROPHINISM: EVIDENCE FOR INCREASED OPIOID INHIBITION

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Abstract
To investigate a proposed role for endogenous opioids in the inhibition of LHRH-gonadotropin release in the postpartum hypogonadotropic state, LH [luteinizing hormone] and FSH responses to naloxone infusion (1.6 mg/h for 2 h) and to a pulse of LHRH (10 .mu.g) were measured in 5 non breast-feeding women. Sequential studies were made at 4 intervals during the first 25 days postpartum. LH and FSH responses to naloxone were absent on Day 10 postpartum, but significnat increments were observed in all studies performed between Days 13-25 postpartum. The relative increments of FSH and LH during naloxone varied as the puerperium progressed; a 3-fold greater release of FSH than LH was found on Day 13-15 while the reverse was observed on Day 25. The intermediate days (17-20) yield an equal response. There was a positive linear correlation between the LH and FSH responses to naloxone infusion and to LHRH. Apparently, the hypogonadotropinism of the puerperium is due at least in part to increased opioid inhibition of LHRH secretion.