Homogenates of male rat hypothalami were fractionated by means of differential centrifugation, and α‐melanocyte‐stimulating hormone (α‐MSH) in the various fractions was quantified by radioimmunoassay. Of the total quantity of α‐MSH in the homogenate, 36% was recovered in the 11,500 g pellet and 31% sedimented between 11,500 and 105,000 g. α‐MSH was not detected in the 105,000 g supernatant fluid. When the 900 g supernatant fluid was fractionated on continuous sucrose density gradients at non‐equilibrium conditions, two populations of particles containing α‐MSH were observed. When fractionated at equilibrium conditions, the two populations were recovered in a single band. These sedimentation characteristics indicate that the particles that contain α‐MSH differ in size but are similar in density. After hypo‐osmotic shock, the large particles containing α‐MSH were not demonstrable, whereas the small particles appeared to be resistant to such treatment. In their sedimentation, the particles containing α‐MSH were indistinguishable from particles containing thyrotropin releasing hormone (TRH) but were separable from those that contained luteinizing hormone releasing hormone (LHRH). It is suggested that the large particles containing α‐MSH are synaptosomes.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Neurochemistry|
|State||Published - Oct 1977|
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience