Age-related changes in dopamine, LHRH and somatostatin in the rat hypothalamus.

The distribution of dopamine, somatostatin and LHRH was examined in young and aged male rats of the Fisher 344 strain. Dopamine histofluorescence and peptide immunocytochemical staining were performed together in each animal by the use of a stimultaneous visualization technique. Comparative analysis or rats at 3, 12, 20, and 30 months of age revealed a general decrease in somatostatin and LHRH in the median eminence; dopamine fluorescence intensity also was depressed in the median eminence although dopaminergic perikarya of the arcuate nucleus of the hypothalamus appeared to increase in intensity with age. The age-related decline in median eminence LHRH may point to a central locus of reproductive senescence in the rat.