Aged F344 rats exhibit an increased proportion of dopamine agonist-excited striatal neurons.
In order to study age-related differences in striatal electrophysiological activity in freely-moving animals, multi-wire electrode arrays were chronically implanted in the striatum of young (6-8 months) and aged (24-26 months) Fischer 344 rats. After recording baseline activity, d-amphetamine (D-AMPH; 1.0 mg/kg) and apomorphine (APO; 0.5 mg/kg) were administered to the two age groups. For both the D-AMPH and APO series, the percentage of striatal neurons that increased firing rates as a result of the DA agonists was 19% higher in the old animals than in the young animals. In addition, D-AMPH increased the firing rates of D-AMPH-excited neurons to a greater extent in the old animals than in the young animals. While the rate-increasing effects of APO did not differ significantly as a function of age, its effects were slightly greater in the old animals as well. These results suggest that age-related decreases in nigrostriatal DA function may result in alterations in the way in which the striatum integrates corticostriatal and nigrostriatal inputs to influence motor function.
Stanford
John A
JA
Department of Anatomy & Neurobiology, The University of Kentucky Chandler Medical Center, Lexington 40536-0098, USA. jastan2@pop.uky.edu
Gash
Clelland R
CR
Gerhardt
Greg A
GA
D000375:Aging / Q000502:physiology*; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D003913:Dextroamphetamine / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D004567:Electrodes, Implanted; D004594:Electrophysiology; D008297:Male; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D011916:Rats, Inbred F344
D018491:Dopamine Agonists; D018765:Dopamine Uptake Inhibitors; D001058:Apomorphine; D003913:Dextroamphetamine