Differential turnover rates of D1 dopamine receptors in the brain and retina of adult and senescent rats.
The present study was designed to investigate the turnover rates of D1 dopamine receptors in the brain and retina of adult and aged rats. To this aim, we monitored the increase in the density of 3H-SCH 23390 binding sites after the administration of the irreversible antagonist N-ethoxycarbonyl-2-ethoxy-1,2 dihydroquinoline (EEDQ). The results indicate that, in aged rats, the production rate of D1 receptors decreases by 41% to 61% in the striatum, nucleus accumbens and substantia nigra, whereas a smaller reduction in the degradation rate of these receptors is observed (-21% to -40%). In contrast, the production rate of D1 receptors in the retina of aged rats remains unchanged, whilst the degradation rate decreases by 25%. These alterations in the rates of receptor production and degradation may account for the age-related decrease in the density of D1 dopamine receptors in the striatum, nucleus accumbens and substantia nigra as well as for the increase in the density of these receptors in the retina of aged rats.
Department of Experimental Biology, University of Cagliari, Italy.
O
O
Giorgi
M G
MG
Pibiri
R
R
Dal Toso
G
G
Toffano
G
G
Biggio
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001552:Benzazepines / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000494:pharmacology; D008297:Male; D011804:Quinolines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*
D001552:Benzazepines; D018492:Dopamine Antagonists; D011804:Quinolines; D017447:Receptors, Dopamine D1; C000470:EEDQ