Relative quantitation of monoamine histofluorescence in young and old non-human primates

The relative content of monoamines within identified brain stem neurons in 4 and 20-year old monkeys (Macaca nemestrina) was determined with microspectrofluorometric techniques. Intraneuronal monoamine content was found to decrease with age in the locus coeruleus, substantia nigra and raphe and was found to be reduced further in the locus coeruleus by the presence of lipofuscin granules. These data indicate that intraneuronal monoamine content is reduced in the aged macaque.