Neuronal nitric oxide has a role as a perfusion regulator and a synaptic modulator in cerebellum but not in neocortex during somatosensory stimulation—An animal PET study

• Published in: Neuroscience research 2002-10, Vol.44 (2), p.155-165
• Main Authors: Hayashi, Takuya, Katsumi, Yukinori, Mukai, Takahiro, Inoue, Manabu, Nagahama, Yasuhiro, Oyanagi, Chisako, Yamauchi, Hiroshi, Shibasaki, Hiroshi, Fukuyama, Hidenao
• Format: Article
• Language: English
• Subjects: Animals; Brain Mapping; Cat; Cats; Cerebellum - diagnostic imaging; Cerebellum - drug effects; Cerebellum - physiology; Cerebral blood flow; Cerebral glucose metabolism; Cerebrovascular Circulation - drug effects; Cerebrovascular Circulation - physiology; Electric Stimulation; Energy Metabolism - drug effects; Energy Metabolism - physiology; Enzyme Inhibitors - pharmacology; Functional Laterality - physiology; Glucose - metabolism; Indazoles - pharmacology; Male; Neurons - diagnostic imaging; Neurons - drug effects; Neurons - physiology; Neurovascular coupling; Nitric oxide; Nitric Oxide - metabolism; Nitric Oxide Synthase - antagonists & inhibitors; Nitric Oxide Synthase - metabolism; Somatosensory Cortex - diagnostic imaging; Somatosensory Cortex - drug effects; Somatosensory Cortex - physiology; Synapses - drug effects; Synapses - metabolism; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Tomography, Emission-Computed; Up-Regulation - drug effects; Up-Regulation - physiology
• ISSN: 0168-0102; 1872-8111
• DOI: 10.1016/S0168-0102(02)00122-0

To clarify a role of neuronal nitric oxide in neurovascular coupling, we performed cerebral blood flow (CBF) and cerebral metabolic rate of glucose (CMR glc) measurements with positron emission tomography in somatosensory-stimulated cats using a specific neuronal nitric oxide synthase inhibitor, 7-nitroindazole (7-NI). The effect on flow–metabolism coupling were tested by global and regional-specific changes on CBF and CMR glc, and the regional-specific effect was estimated both by regions of interest (ROI) and voxel-based (VB) analysis using globally-normalized CBF and CMR glc changes. The electrical somatosensory stimulation in the unilateral forepaw elicited coupled increase in CBF and CMR glc in the contralateral somatosensory cortex (7%) and the ipsilateral cerebellum (8%). 7-NI induced 20% decrease in global CBF both during rest and activation, but not in global CMR glc at simulation. Both ROI and VB analysis showed that 7-NI induced an increase in CMR glc (13%) in the ipsilateral cerebellum compared to control under vehicle alone, but it was accompanied by only 8% increase in CBF, suggesting uncoupling of flow-metabolism while it induced any perturbations in the contralateral somatosensory cortex. These observations suggest that neuronal nitric oxide has an important role for a mediator of regional neurovascular coupling as well as synaptic modulator in the cerebellum, but less so in the neocortex.