Different subcellular localization of neurotensin-receptor and neurotensin-acceptor sites in the rat brain dopaminergic system.
The subcellular localization of neurotensin-receptor sites (NT2 sites) and neurotensin-acceptor sites (NT1 sites) was studied in rat caudate-putamen by isopycnic centrifugation in sucrose density gradients. [3H]Neurotensin binding to NT2 sites occurred as a major peak at higher sucrose densities, colocalized with [3H]dopamine uptake, and as a small peak at a lower density; whereas binding to NT1 sites occurred as a single large peak at an intermediate density. 6-Hydroxydopamine lesions of the median forebrain bundle resulted in a total loss of NT2 sites in the caudate-putamen but did not affect NT2 sites in the nucleus accumbens and the olfactory tubercle. NT1 sites were not affected. Kainic acid injections into the rat caudate-putamen led to a partial decrease of NT1 sites in this region 5 days later. After a few weeks they returned to normal. Therefore NT2 sites are probably associated with presynaptic nigrostriatal dopaminergic terminals in the caudate-putamen but not in the nucleus accumbens and the olfactory tubercle. A possible association of NT1 sites with glial cells is suggested.
Schotte
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A
Department of Biochemical Pharmacology, Janssen Research Foundation, Beerse, Belgium.
Rostène
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W
Laduron
P M
PM
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D002421:Caudate Nucleus / Q000378:metabolism / Q000648:ultrastructure; D002458:Cell Fractionation; D002500:Centrifugation, Isopycnic; D004298:Dopamine / Q000502:physiology*; D006892:Hydroxydopamines / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009496:Neurotensin / Q000378:metabolism*; D016627:Oxidopamine; D011699:Putamen / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D018028:Receptors, Neurotensin; D017981:Receptors, Neurotransmitter / Q000378:metabolism*
D006892:Hydroxydopamines; D018028:Receptors, Neurotensin; D017981:Receptors, Neurotransmitter; D009496:Neurotensin; D016627:Oxidopamine; D007608:Kainic Acid; D004298:Dopamine