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LACK OF EVIDENCE FOR AXONAL TRANSPORT OF D 1 AND D 2 RECEPTORS IN THE NIGRO‐STRIATAL PATHWAY OF THE RAT
Author(s) -
SAVASTA M.,
DUBOIS A.,
SCATTON B.
Publication year - 1988
Publication title -
fundamental and clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.655
H-Index - 73
eISSN - 1472-8206
pISSN - 0767-3981
DOI - 10.1111/j.1472-8206.1988.tb00651.x
Subject(s) - ketanserin , medial forebrain bundle , chemistry , spiperone , receptor , axoplasmic transport , biophysics , anatomy , medicine , endocrinology , neuroscience , dopamine , striatum , dopamine receptor , biology , 5 ht receptor , biochemistry , serotonin
Summary— The possibility that D 1 and D 2 dopamine receptors are axonally transported in the nigro‐striatal pathway has been investigated in the rat by placing a coronal knife cut (sparing the striato‐nigral pathway) through the medial forebrain bundle (MFB) and autoradiographically examining the density of D 2 (as labeled by [ 3 H]spiperone in the presence of ketanserin) and D 1 (as labeled by [ 3 H]SCH 23390) receptors. The efficacy of MFB transection has been assessed by measuring in parallel the binding of [ 3 ]ketanserin, a ligand that has been reported to be axonally transported in this bundle. At 12 h post‐transection, there was a minor accumulation of [ 3 H]spiperone binding on both sides of the transection. However, (+)butaclamol (1 μM) failed to displace the ligand build‐up at the knife cut, thus demonstrating the nonspecific nature of [ 3 H]spiperone accumulation. Similar results were observed at 24, 48, and 72 h after severing the MFB. MFB transection also failed to cause changes in specific [ 3 H]SCH 23390 binding at the knife cut at 12–72 h post‐surgery. In contrast, a dramatic accumulation of [ 3 H]ketanserin binding sites was observed rostral and caudal to the cut at 12 h post‐transection, attesting to the efficacy of the lesion. These results confirm the existence of both anterograde and retrograde transport of [ 3 H]ketanserin binding sites and suggest that D 1 and D 2 receptors are not axonally transported in fibers of the nigro‐striatal pathway.