Roles of nitric oxide as a vasodilator in neurovascular coupling of mouse somatosensory cortex.
Neural activities trigger regional vasodilation in the brain. Diffusible messengers such as nitric oxide (NO) and prostanoids are considered to work as vasodilators in neurovascular coupling. However, their roles are still controversial. In the present study, cortical images of neural activities and vasodilation were recorded through the intact skull of C57BL/6 mice anesthetized with urethane. Flavoprotein fluorescence responses elicited by vibratory hindpaw stimulation were followed by darkening of arteriole images reflecting vasodilation in the somatosensory cortex. Vasodilation was also observed in light reflection images at the wavelength of 570 nm in the same mice. We perfused the surface of the cortex under the skull with 100 microM N(G)-nitro-l-arginine (l-NA), an inhibitor of NO synthase (NOS), and 10 microM indomethacin, an inhibitor of cyclooxygenase (COX). These drugs suppressed vasodilation without changing flavoprotein fluorescence responses. A mixture of l-NA and indomethacin almost completely eliminated vasodilation. In mice lacking neuronal NOS (nNOS), activity-dependent vasodilation was significantly suppressed compared with that in littermate control mice, while that in mice lacking cytosolic phospholipase A2 alpha (cPLA2alpha) was unchanged. These results indicate that NO works as a vasodilator in neurovascular coupling of the mouse somatosensory cortex.
Kitaura
Hiroki
H
Department of Neurophysiology, Brain Research Institute, Niigata University, Asahi-machi, Chuo-ku, Niigata 951-8585, Japan.
Uozumi
Naonori
N
Tohmi
Manavu
M
Yamazaki
Maya
M
Sakimura
Kenji
K
Kudoh
Masaharu
M
Shimizu
Takao
T
Shibuki
Katsuei
K
D000818:Animals; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005420:Flavoproteins; D005456:Fluorescent Dyes; D054513:Group IV Phospholipases A2 / Q000235:genetics / Q000378:metabolism; D006940:Hyperemia / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology; D010812:Physical Stimulation; D013003:Somatosensory Cortex / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D052246:Cyclooxygenase 2 Inhibitors; D005420:Flavoproteins; D005456:Fluorescent Dyes; D019335:Nitroarginine; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D054513:Group IV Phospholipases A2