Regional differences in reappearance of D2-dopamine receptors in the rat caudate-putamen complex after irreversible inactivation.
The reappearance of D2-receptors in the striatum of the rat was studied by autoradiography after in vivo labeling with [3H]N-n-propylnorapomorphine ([3H]NPA) at various time intervals after the inactivation of dopamine receptors by intraperitoneal administration of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ). Within two days after inactivation the labeling had decreased to 18% of controls. Thereafter, the label reappeared and after 8 days or more reached levels of 80% of that of untreated controls. Autography showed that 4 h after EEDQ treatment no preferential labeling of the striatum can be seen. Five days after EEDQ a slight difference in labeling density between the medial and lateral striatum was detected, whereas after 18 days a prominent lateromedial gradient in silver grain density was seen, resembling the gradient seen without EEDQ treatment. This silver grain gradient is not paralleled by the density of medium-sized neuronal cell bodies. This suggests a difference in synthesis rate of receptors either in other cells than the medium-sized neuron or, alternatively, in otherwise indistinguishable medium-sized neurons. Five days after EEDQ treatment, clusters of silver grains in the lateral striatum were seen. These clusters have a diameter of 150-400 microns and are separated from each other at 200-500 microns. Each cluster may represent newly synthesized receptors of a single neuron (e.g. cholinergic or somatostatinergic interneuron).
Loopuijt
L D
LD
Department of Biological Psychiatry, University Psychiatric Clinic, Groningen, The Netherlands.
Sebens
J B
JB
Korf
J
J
D000818:Animals; D001058:Apomorphine / Q000031:analogs & derivatives / Q000378:metabolism; D001345:Autoradiography; D002421:Caudate Nucleus / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D009928:Organ Specificity; D011699:Putamen / Q000378:metabolism*; D011804:Quinolines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000096:biosynthesis* / Q000187:drug effects; D017448:Receptors, Dopamine D2; D012016:Reference Values; D014316:Tritium
D011804:Quinolines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D014316:Tritium; C009074:N-n-propylnorapomorphine; C000470:EEDQ; D001058:Apomorphine