Regulation of cerebral blood flow response to somatosensory stimulation through the cholinergic system: a positron emission tomography study in unanesthetized monkeys.
The effects of scopolamine, a muscarinic cholinergic receptor antagonist and physostigmine, a cholinesterase inhibitor, on the regional cerebral blood flow (rCBF) response to vibrotactile stimulation of the forepaw were studied in the brain of unanesthetized monkeys using 15O-labeled water and high resolution positron emission tomography. Before scopolamine administration, vibrotactile stimulation produced a significant increase in the rCBF response in the contralateral somatosensory cortex of the monkey brain. Intravenous administration of scopolamine at doses ranging from 1 to 500 microg/kg resulted in a dose-dependent reduction of the rCBF response. The rCBF response abolished by scopolamine (50 microg/kg) was recovered by administration of physostigmine (10 microg/kg). On the other hand, the regional cerebral metabolic rate of glucose (rCMRglc) response, measured with [18F]-2-fluoro-2-deoxy-D-glucose, to the same stimulation was unchanged by administration of either scopolamine and/or physostigmine. These results suggested that cholinergic mechanisms might be involved in regulation of the coupling between neuronal activity and rCBF response, not between the activity and rCMRglc response.
Tsukada
H
H
Central Research Laboratory, Hamamatsu Photonics K.K., Hamakita, Shizuoka, Japan. tsukada@crl.hpk.co.jp
Kakiuchi
T
T
Ando
I
I
Shizuno
H
H
Nakanishi
S
S
Ouchi
Y
Y
D000818:Animals; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D003847:Deoxyglucose / Q000031:analogs & derivatives / Q000378:metabolism; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D006439:Hemodynamics / Q000187:drug effects; D007091:Image Processing, Computer-Assisted; D008253:Macaca mulatta; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000502:physiology*; D010812:Physical Stimulation; D010830:Physostigmine / Q000494:pharmacology; D012601:Scopolamine / Q000494:pharmacology; D013003:Somatosensory Cortex / Q000502:physiology*; D014055:Tomography, Emission-Computed
D002800:Cholinesterase Inhibitors; D005462:Fluorine Radioisotopes; D018727:Muscarinic Antagonists; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose; D010830:Physostigmine; D012601:Scopolamine