Neuron numbers in locus coeruleus do not change with age in Fisher 344 rat.

Counts of neurons in locus coeruleus of Fisher 344 rats of ages from 12 to 32 months showed no loss with advancing age. Species comparisons of age changes in locus coeruleus neuron counts and measures of catecholamine systems suggested that the human and nonhuman primate locus coeruleus shows age changes and seen in rodent locus coeruleus. It is suggested that although rodent models of human aging have value under some circumstances, rodent and primate brain should not be considered equivalent with regard to phenomena related to noradrenergic mechanisms.