Distribution, half-life, and excretion of 14C- and 3H-labeled l-Proly-l-Leucyl-Glycinamide in the rat

T. W. Redding, A. J. Kastin, R. M.G. Nair, A. V. Schally

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)92-100
Number of pages9
Issue number2
StatePublished - 1973
Externally publishedYes


  • Half-life
  • Labeled MIF
  • MSH-release-inhibiting factor (MIF)
  • Metabolites of MIF
  • Prolyl-leucyl-glycinamide

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology
  • Endocrine and Autonomic Systems
  • Cellular and Molecular Neuroscience


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