Postnatal appearance of luteinizing hormone-releasing hormone (LHRH)-like material in the pineal gland of the rat.

Immunoreactive luteinizing hormone-releasing hormone (LHRH)-like material has been demonstrated in the pineal gland of the adult rat. The objective of the present study was to examine the ontogenetic development of this LHRH-like substance in the rat pineal with the peroxidase-antiperoxidase (PAP) method of Sternberger. LHRH-like immunoreactive material was not observed in pineal glands of newborn rats. The amount of material increased progressively from the 6th-12th day of postnatal development. On day 12, the amount of LHRH-like immunoreactivity was consistent and comparable in all pineal glands of male and female animals examined.