Rat brain melanin at different ages and after various treatments

Melanin was measured by a spectrophotofluorometric method in the brains of albino rats from birth to 20 months of age. The concentration of brain melanin increased from Day 1 until adult levels were reached at 1 month. Between 1 and 20 months of age no significant differences were found in brain melanin. Daily injections of alpha-MSH, MIF-I, melatonin, or diluent did not consistently alter the concentration of brain melanin and a high (40%) protein diet did not appear to increase it. After concurrent injections of alpha-MSH and theophylline, an initial elevation of the level of melanin in the brain of newborn rats was found beginning at Day 8 but by age 1 month the values had returned to control levels. The results show that the largest changes in the concentrations of melanin in the brains of rats occur with age during the first month after birth.