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Science 23 June 1972:
Vol. 176. no. 4041, pp. 1331 - 1332
DOI: 10.1126/science.176.4041.1331
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Articles

Melanophore Stimulating Hormone: Release Inhibition by Ring Structures of Neurohypophysial Hormones

Victor J. Hruby 1, Clark W. Smith 1, Sister Annette Bower 2, and Mac E. Hadley 2

1 Department of Chemistry, University of Arizona, Tucson 85721
2 Department of Biological Sciences, University of Arizona

Tocinamide and tocinoic acid, ring structures of oxytocin, are potent inhibitors of the release of melanophore stimulating hormone from the rat and hamster pituitary in vitro. Tocinamide is effective at concentrations as low as 10-14M on the mammalian pituitary. These peptides do not affect release of the hormone on the frog (Rana pipiens) pars intermedia, but they do inhibit release in the bullfrog (Rana catesbeiana) and the toad (Bufo marinus). The specificity of the peptides on inhibition of the hormone is demonstrated by the fact that oxytocin, lysine vasopressin, and pressinoic acid and pressinamide (ring structures of the vasopressins) do not show such inhibitory activity. Hypothalamic extracts of either the frog (Rana pipiens) or the rat inhibit release of the hormone from pituitaries of either species. The inhibitory effects of tocinamide and tocinoic acid, like that of hypothalamic extracts, are reversible.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Hypothalamic Regulatory Hormones: At least nine substances from the hypothalamus control the secretion of pituitary hormones.
A. V. Schally, A. Arimura, and A. J. Kastin (1973)
Science 179, 341-350
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