H-Pro-Leu-Gly-NH2, a potentinhibitor of melanocyte stimulating hormone (MSH) release [MSH-release inhibiting factor (MIF)], was labeled with 14C-leucine or 3H-proline and injected i.v. into rats. H-Pro-14C-Leu-Gly-NH2 was found to have a half-life of approximately 9 min and to be distributed in a space greater than that of the plasma volume. Relatively little radioactivity and no intact H-Pro-Leu-Gly-NH2 could be found in the urine 1 h afte.r administration. 3H- and 14C-labeled-H-Pro-Leu-Gly-NH2 accumulated in the pineal, pituitary, kidney, liver, and adrenals; the elevated tissue to plasma ratio in the pineal, along with the identification of unchanged H-Pro-Leu-Gly-NH2 there, suggests the possibility of a direct influence of the hypothalamus upon the pineal gland.
- Labeled MIF
- MSH-release-inhibiting factor (MIF)
- Metabolites of MIF
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Endocrine and Autonomic Systems
- Cellular and Molecular Neuroscience