IBN-9412699 Willis Samson The best way to assess the physiological role of a neuropeptide hormone in an intact animal is to remove that neuropeptide from the system and observe the effect on the physiology of the animal. This study involves the use of a novel method, developed by this investigator, in which the cytotoxin plant lectin, ricin A chain, is conjugated to the hormone oxytocin. Using this technique the effects of oxytocin on the regulation of reproductive hormones will be studied. One very important part of the study will be to demonstrate the ability of ligand-ricin conjugates to kill specific receptor-bearing neuronal populations in vivo. Previous studies by this group have shown that intracerebroventricular injections of oxytocin-ricin A locked the secretion of luteinizing hormone (LH) during the estrus cycle. In this study, the in vivo mechanism of action of oxytocin (OT)-ricin A chain in disrupting luteinizing hormone (LH) secretion in the estrogen and progesterone-primed ovariectomized rat will be determined. The goal is to examine possible direct communications of oxytocin-containing cells with containing LH releasing hormone and, more generally, to examine the roles of peptide hormones in the central nervous system control of reproductive function.
