Decline in striatal dopamine D1 and D2 receptor activation in aged F344 rats.
Aging differentially affects receptor function. In the present electrophysiological study we compared neuronal responsiveness to locally applied dopamine D1 and D2 receptor agonist in the striatum of female Fischer 344 rats aged 3 and 26-27 months. In a subgroup of the old rats, the nigrostriatal dopamine bundle was destroyed unilaterally with 6-hydroxydopamine (6-OHDA) to assess receptor plasticity in response to denervation. Spontaneous firing rate of striatal neurons was higher in aged compared to young rats. Higher doses of the D1 agonist SKF 38393 or the D2 agonist quinpirole were required to elicit a 50% change in firing rate in aged compared to young rats. No difference with SKF 38393 or quinpirole was detected between 6-OHDA denervated and control (nonlesioned) striatum in aged rats. Supersensitivity to D2 agonists has been reported following 6-OHDA lesions in young rats. These observations suggest that D2 receptors in aged rat striatum might not be as plastic as in younger rats.
Gould
T J
TJ
Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262, USA.
Strömberg
I
I
Bickford
P C
PC
D000375:Aging / Q000502:physiology*; D000818:Animals; D004298:Dopamine / Q000172:deficiency / Q000502:physiology; D018491:Dopamine Agonists / Q000494:pharmacology*; D004594:Electrophysiology; D005260:Female; D007150:Immunohistochemistry; D017072:Neostriatum / Q000187:drug effects* / Q000254:growth & development*; D016627:Oxidopamine; D051381:Rats; D011916:Rats, Inbred F344; D017447:Receptors, Dopamine D1 / Q000187:drug effects*; D017448:Receptors, Dopamine D2 / Q000187:drug effects*; D012399:Rotation; D013239:Stereotyped Behavior / Q000187:drug effects / Q000502:physiology; D013563:Sympathectomy, Chemical
D018491:Dopamine Agonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D016627:Oxidopamine; D004298:Dopamine