Biological, chromatographical, and radioimmunological evidence for a melanotropin-like peptide in the central nervous system of Locusta migratoria.
Our recent immunocytochemical study has demonstrated the existence of alpha-melanocyte stimulating hormone (alpha-MSH)-like material in the locust central nervous system. The aim of the present study was to further characterize alpha-MSH in the locust brain by its biological effect on frog skin and by high-pressure liquid chromatography in combination with radioimmunological and biological detection methods. Parallel radioimmunoassay (RIA) curves of crude nervous tissue extracts coupled with bioactivity in a very specific bioassay suggest similarity between the locust alpha-MSH-like substance and synthetic alpha-MSH. The highest concentration of alpha-MSH immunoreactive material in the central nervous system was found in the optic lobes, where alpha-MSH immunoreactive cell bodies are localized, as was previously shown by immunocytochemistry. High concentrations of alpha-MSH immunoreactive material were also detected in the thoracic ganglia of the locust ventral nervous system. The application of locust brain extracts to gel permeation HPLC resulted in a similar elution profile of the bioactive and immunologically active substances, both coeluting with synthetic alpha-MSH. As is the case for vertebrate brain material, reverse-phase HPLC revealed four alpha-MSH immunoreactive peaks. One of the peaks coelutes with monoacetyl-alpha-MSH and other RIA-positive material elutes at times close (but not identical) to the methionine sulfoxide forms of alpha-MSH. Peak three, however, elutes in a very different position from desacetyl-alpha-MSH. Peaks are absent in the position of desacetyl-alpha-MSH. Similarity between the locust alpha-MSH-related substance and authentic alpha-MSH is discussed.
Schoofs
L
L
Zoological Institute of the University (KUL), Leuven, Belgium.
Jégou
S
S
Tonon
M C
MC
Huybrechts
R
R
Vaudry
H
H
De Loof
A
A
D000818:Animals; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D006110:Grasshoppers / Q000032:analysis*; D009074:Melanocyte-Stimulating Hormones / Q000032:analysis*; D011863:Radioimmunoassay
D009074:Melanocyte-Stimulating Hormones