Sustained increase in adrenergic activity in gerbil striatum following transient ischemia.
We investigated the changes in striatal monoaminergic functions, focusing on the release and metabolism, in a cerebral ischemic model induced by a 5-min bilateral occlusion of the carotid arteries (BOCA) and reperfusion in anesthetized gerbils. In the microdialysis study, the striatal extracellular level of dopamine (DA) markedly increased (144-fold) immediately after BOCA. Although norepinephrine (NE) and 5-hydroxytryptamine (5-HT) could not be detected in the dialysates throughout the baseline period, they increased to detectable levels after BOCA. On the contrary, the tissue contents of NE and 5-HT decreased or tended to decrease up to 4 hr following reperfusion. Striatal DA contents did not show any changes in the early period after ischemia-reperfusion and slightly increased at 4 hr or later. Tissue contents of 3-methoxytyramine (3-MT), a metabolite of DA by catechol-O-methyltransferase (COMT), increased 0 and 5 min after reperfusion. Normethanephrine (NMN), which is a metabolite of NE by COMT, also increased not only 5 min after but also up to 4 hr after ischemia-reperfusion, indicating a sustained increase in NE release. These results suggested that the neuronal activity of NE, which is supposed to exert a protective effect on ischemic damage, was enhanced for a longer period than that of DA after transient ischemia.
Izumi
J
J
Department of Pharmacology, School of Medicine, Showa University, Tokyo, Japan.
Inagaki
M
M
Kiuchi
Y
Y
Matsumoto
M
M
Yamazaki
Y
Y
Morioka
D
D
Usami
S
S
Oguchi
K
K
D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism*; D002545:Brain Ischemia / Q000201:enzymology / Q000378:metabolism*; D002394:Catechol O-Methyltransferase / Q000502:physiology; D003342:Corpus Striatum / Q000201:enzymology / Q000378:metabolism*; D004195:Disease Models, Animal; D005849:Gerbillinae; D008297:Male; D008995:Monoamine Oxidase / Q000502:physiology; D015424:Reperfusion
D015306:Biogenic Monoamines; D008995:Monoamine Oxidase; D002394:Catechol O-Methyltransferase