Gerhardt G A, Cass W A, Henson M, Zhang Z, Ovadia A, Hoffer B J, Gash D M
Department of Psychiatry, University of Colorado Health Sciences Center, Denver 80262, USA.
Neurobiol Aging. 1995 Nov-Dec;16(6):939-46. doi: 10.1016/0197-4580(95)02013-6.
Rapid (5 Hz) chronoamperometric recordings using Nafion-coated carbon fiber electrodes (30-90 microns o.d.) combined with pressure-ejection of potassium from micropipettes were used to investigate potassium-evoked overflow of dopamine (DA) in the striatum of young (5 to 10 years old) and middle-aged (19 to 23 years old) anesthetized rhesus monkeys. The potassium-evoked DA-like signals from the 19- to 23-year-old animals were significantly lower in amplitude than those recorded in the young animals. In addition, the temporal dynamics of DA signals in the caudate nucleus of middle-aged animals were faster, while the time courses of the signals recorded in the putamen of middle-aged monkeys were significantly longer as compared to the signals recorded from young animals. Moreover, home cage activity levels of the middle-aged animals were significantly lower. Taken together, these data support age-related changes in the output of DA from DA fibers in the striatum of middle-aged monkeys.
