EFFECTS OF HIPPOCAMPAL KAINIC ACID LESIONS ON STRIATOLIMBIC DOPAMINE D-1-LIKE, D-2-LIKE, AND D-4-LIKE RECEPTORS

Changes in D-1-, D-2- and D-4-like dopamine receptor binding in rat ca udate-putamen, nucleus accumbens and hippocampus mere examined by quan titative in vitro receptor autoradiography after unilateral injections of kainic acid into hippocampus to degenerate local intrinsic neurons and remove hippocampal-striatal projections. Radioligands were: [H-3] SCH-23390 for D-1-like (D-1/D-5) receptors, [H-3]nemonapride alone for D-2-like (D-2/D-3/D-4) receptors and with 300 nM S[-]-raclopride and other masking agents for D-4-like receptors. Kainic acid injections pr oduced massive local hippocampal losses of D-1-like (75%), D-2-like (7 7%) and D-4-like (79%) receptor binding but did not significantly alte r D-1-, D-2- or D-4-like receptor density in caudate-putamen or nucleu s accumbens, Most D-1-, D-2- and D-4-like receptors in rat hippocampus evidently arise on intrinsic postsynaptic neurons whereas none mas de tected on presynaptic terminals of hippocampal-striatal afferents inne rvating the striatal complex. (C) 1998 IBRO. Published by Elsevier Sci ence Ltd.