Melanotropin bioassays

In vitro and in vivo comparisons

Ana Maria de L Castrucci, Mac E. Hadley, Victor J Hruby

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

A reflectance method was utilized to compare the in vitro responses in three species of frogs (Rana pipiens, R. berlandieri forrei, and R. catesbeiana) and a lizard (Anolis carolinensis) to α- and β-melanotropins (α- and βp-MSH). The integumental chromatic response of the three ranid species was identical, in that α-MSH was about 2 times more potent than βp-MSH. The melanotropins were equipotent in the lizard skin bioassay. A remarkable feature of the Anolis skin assay is that skins from this lizard can be utilized repeatedly many times in one day with an extremely high degree of precision. The reflectance method was also used to determine the in vivo potencies of α-MSH and βp-MSH in the frog, R. pipiens. Surprisingly, the melanotropins were more active in the in vivo assay than in the in vitro bioassay. The darkening response of the frogs to α-MSH was reversed by 6 hr, but the response to βp-MSH persisted for more than 8 hr. When α-MSH was incubated in frog serum, the melanotropic activity was almost totally abolished by 30 min, whereas the melanotropic activity of βp-MSH was evident much longer (4 hr) in the presence of the serum. In light of the observation that the melanotropic activity of α-MSH is rapidly lost by incubation in frog serum, it is unclear why the hormone was more active as measured in vivo and why the darkening response in vivo persisted so long.

Original languageEnglish (US)
Pages (from-to)104-111
Number of pages8
JournalGeneral and Comparative Endocrinology
Volume55
Issue number1
DOIs
StatePublished - 1984

Fingerprint

melanocyte-stimulating hormone
Melanocyte-Stimulating Hormones
Biological Assay
frogs
bioassays
skin (animal)
lizards
Rana pipiens
Anura
reflectance
Lizards
Anolis carolinensis
Lithobates catesbeianus
Anolis
assays
hormones
In Vitro Techniques
Skin
Serum
color

ASJC Scopus subject areas

  • Endocrinology

Cite this

Melanotropin bioassays : In vitro and in vivo comparisons. / Castrucci, Ana Maria de L; Hadley, Mac E.; Hruby, Victor J.

In: General and Comparative Endocrinology, Vol. 55, No. 1, 1984, p. 104-111.

Research output: Contribution to journalArticle

Castrucci, Ana Maria de L ; Hadley, Mac E. ; Hruby, Victor J. / Melanotropin bioassays : In vitro and in vivo comparisons. In: General and Comparative Endocrinology. 1984 ; Vol. 55, No. 1. pp. 104-111.
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