Melanin in the rat brain

Melanin was measured in various parts of the rat brain by a spectrophotofluorometric assay. This method could detect natural, Sepia melanin as well as melanin synthesized from L-DOPA. Contrary to published expectations of other investigators, measurable amounts of melanin were found in the brain of albino as well as pigmented rats. The highest concentrations of melanin occurred in the pons-medulla and midbrain, but all regions within the blood-brain barrier contained greater concentrations than samples from many other tissues in the body. No significant change in the melanin content was found after various endocrine manipulations such as removal of the pituitary, pineal, adrenals, thyroid, testes, or ovaries, exposure to constant illumination or darkness, and daily injection for 5 weeks of α-MSH, Pro-Leu-Gly-NH 2 (MIF-I) or melatonin. As expected, retinal tissue from black-hooded rats contained extremely high levels of melanin whereas that from albino rats contained no melanin. It is thought that the presence of melanin in the brain of albino and pigmented rats may have a function which is still unknown

EXTRAPIGMENTARY EFFECTS OF MELANOCYTE-STIMULATING HORMONE IN AMENORRHŒIC WOMEN

Highly purified melanocyte-stimulating hormone (M.S.H.) was administered to six women with secondary amenorrhœa. Menstrual bleeding occurred in five of the patients approximately 13 days later. Transient electroencephalographic changes and akathisia-like symptoms developed in at least three of the women. The aqueous-flare phenomenon and increased visual dark adaptation were not observed, but statistically significant changes occurred in the concentrations of several components of serum