Endothelin receptors in kainic acid-induced neural lesions of rat brain.
Seven days after an intracerebroventricular injection of 0.8 microgram kainic acid, a time of neural tissue-repair after damage, we applied our receptor autoradiographic method to examine changes in the endothelin receptors in kainic acid-induced neural lesions of the rat brain. There were belt-shaped areas with the de novo expressed [125I]endothelin-1 binding sites in the damaged hippocampus CA1, CA3, and CA4 subfields. We also noted a homogeneous zone with a low binding-density, the area sandwiched by the belt-shaped areas. In a "remote" area corresponding anatomically to the deep soma layer of the piriform cortex plus lateral parts of amygdaloid complex we noted a well-defined area with "punched hole-figure" of low density [125I]endothelin-1 binding sites. The lesion was surrounded by areas rich in binding sites. The de novo expressed [125I]endothelin-1 binding sites were characterized endothelin B receptor. Microglia were present in the area with "punched hole-figure" and in the hippocampus pyramidal cell layer with neuronal death. In contrast to microglia, astrocytes were rich with hypertrophia in kainic acid-induced neural lesions anatomically corresponding to areas with the de novo endothelin B receptor. Taken together with the present observations of microscopic evidence of cellular distribution, we suggest that the de novo expressed endothelin B receptor was carried by astrocytes aggregating in neural lesions. In light of our findings, the possibility that astrocytes can be activated by the endothelin B receptor in response to neural tissue repair after damage to neurons would have to be considered.
Sakurai-Yamashita
Y
Y
Department of Pharmacology, Nagasaki University School of Medicine, Japan.
Niwa
M
M
Yamashita
K
K
Kataoka
Y
Y
Himeno
A
A
Shigematsu
K
K
Tsutsumi
K
K
Taniyama
K
K
D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism; D007608:Kainic Acid / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects*; D011869:Radioligand Assay; D051381:Rats; D011921:Rats, Inbred WKY; D017466:Receptors, Endothelin / Q000378:metabolism*
D017466:Receptors, Endothelin; D007608:Kainic Acid