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Comparison of [ 3 H]WIN 35,428 Binding, a Marker for Dopamine Transporter, in Embryonic Mesencephalic Neuronal Cultures with Striatal Membranes of Adult Rats
Author(s) -
Valchar Martin,
Hanbauer Ingeborg
Publication year - 1993
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.1471-4159.1993.tb03174.x
Subject(s) - nomifensine , mazindol , dopamine transporter , dopamine uptake inhibitors , dopamine plasma membrane transport proteins , cytosol , binding site , chemistry , dopamine , biophysics , reuptake , membrane , biochemistry , biology , endocrinology , dopaminergic , enzyme , receptor , serotonin
In contrast to striatal membranes of adult rats, where high‐ ( K D1 = 34 n M ) and low‐ ( K D2 = 48,400 n M ) affinity binding sites for [ 3 H]WIN 35,428 are present, in primary cultures of ventral mesencephalon neurons (CVMNs) only low‐affinity binding sites were found ( K D = 336,000 n M ). The binding of [ 3 H]WIN 35,428 in CVMNs prepared from rat embryos was reversible, saturable, and located in cytosol. Although dopamine (DA) uptake blockers inhibited [ 3 H]DA uptake at nanomolar concentrations in CVMNs, the displacement of [ 3 H]WIN 35,428 binding in CVMNs by DA uptake inhibitors required 100‐8,000 times higher concentrations than were needed to displace [ 3 H]WIN 35,428 binding in striatal membranes. Piperazine derivatives, e.g., GBR‐12909, GBR‐12935, and rimcazole, inhibited [ 3 H]WIN 35,428 binding in CVMNs more effectively than did cocaine, WIN 35,428, mazindol, nomifensine, or benztropin. A positive correlation ( r = 0.779; p < 0.001) was found between drug affinities for the striatal membrane sites labeled by [ 3 H]WIN 35,428 and their abilities to inhibit DA uptake in CVMNs, whereas no correlation existed between the IC 50 values of drugs that inhibited [ 3 H]WIN 35,428 binding and [ 3 H]DA uptake in CVMNs. The cytosolic [ 3 H]WIN 35,428 binding sites may be a piperazine acceptor and may not be involved in the regulation of the DA transporter.