Evidence for loss of brain [3H]spiroperidil and [3H]ADTN binding sites in rabbit brain with aging.

[3H]Spiroperidol and [3H]2-amino-6,7-dihydroxyl-1,2,3,4,-tetrahydronaphthalene hydrochloride (ADTN) binding were measured in various central nervous system regions of 5 month and 5.5 year old rabbits. In striatum, young animals had a 38% higher number of [3H]spiroperidol binding sites and a 140% higher number of [3H]ADTN binding sites than did the older animals. In frontal cortex and anterior limbic cortex there were respectively 42% and 26% more [3H]spiroperidol binding sites in the young animals. There was no change in the binding site number or affinity for [3H]spiroperidol in retina with aging. Pharmacological characterization demonstrated that [3H]spiroperidol binds to a dopamine receptor in striatum and to a serotonin receptor in cortex.