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Differential Turnover Rates of D 1 Dopamine Receptors in the Retina and in Distinct Areas of the Rat Brain
Author(s) -
Giorgi O.,
Pibiri M. G.,
Biggio G.
Publication year - 1991
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1991.tb08216.x
Subject(s) - nucleus accumbens , striatum , substantia nigra , receptor , endocrinology , medicine , dopamine receptor , dopamine , chemistry , biology , biochemistry , dopaminergic
The present study was designed to examine the steady‐state density and the turnover rates of D 1 dopamine (DA) receptors in the striatum, nucleus accumbens, substantia nigra, and retina of the rat. The turnover rates were measured by monitoring the repopulation kinetics of D 1 DA receptors labelled with [ 3 H]SCH 23390 after the irreversible inactivation induced by a single dose of N ‐ethoxycarbonyl‐2‐ethoxy‐ 1, 2‐dihydroquinoline (10 mg/kg s.c.). The repopulation of D 1 DA receptors could be described adequately in all the neural tissues investigated by a theoretical model that assumes a constant rate of receptor production (i.e., zero order) and a rate of degradation that is dependent on the receptor density at any time (i.e., first order). The quantitative analysis of the experimental data using this theoretical model revealed significant regional differences in the rates of receptor production and degradation. Thus, the receptor production rates determined in the nucleus accumbens and striatum (8.03 and 9.96 fmol/mg of protein/h, respectively) were four‐ to sixfold larger than those measured in the substantia nigra (1.80 fmol/mg of protein/h) and retina (1.50 fmol/mg of protein/h). On the other hand, the receptor degradation rates in the striatum, nucleus accumbens, and retina (0.0093 h −1 , 0.0110 h −1 , and 0.0123 h −1 , respectively) were 2.6–3.5‐fold larger than the receptor degradation rate in the substantia nigra (0.0035 h −1 ).