Regional differences in mechanisms of cerebral circulatory response to neuronal activation.
Vibrissal stimulation raises cerebral blood flow (CBF) in the ipsilateral spinal and principal sensory trigeminal nuclei and contralateral ventroposteromedial (VPM) thalamic nucleus and barrel cortex. To investigate possible roles of adenosine and nitric oxide (NO) in these increases, local CBF was determined during unilateral vibrissal stimulation in unanesthetized rats after adenosine receptor blockade with caffeine or NO synthase inhibition with N(G)-nitro-L-arginine methyl ester (L-NAME) or 7-nitroindazole (7-NI). Caffeine lowered baseline CBF in all structures but reduced the percent increase during stimulation only in the two trigeminal nuclei. L-NAME and 7-NI lowered baseline CBF but reduced the percent increase during stimulation only in the higher stations of this sensory pathway, i.e., L-NAME in the VPM nucleus and 7-NI in both the VPM nucleus and barrel cortex. Combinations of caffeine with 7-NI or L-NAME did not have additive effects, and none alone or in combination completely eliminated functional activation of CBF. These results suggest that caffeine-sensitive and NO-dependent mechanisms are involved but with different regional distributions, and neither fully accounts for the functional activation of CBF.
Gotoh
J
J
Laboratory of Cerebral Metabolism, National Institute of Mental Health, Bethesda, Maryland 20892-4030, USA.
Kuang
T Y
TY
Nakao
Y
Y
Cohen
D M
DM
Melzer
P
P
Itoh
Y
Y
Pak
H
H
Pettigrew
K
K
Sokoloff
L
L
D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000098:blood supply / Q000166:cytology / Q000502:physiology; D014278:Trigeminal Nuclei / Q000098:blood supply / Q000166:cytology / Q000502:physiology; D014738:Vibrissae / Q000294:innervation / Q000502:physiology; D014851:Wakefulness
D000697:Central Nervous System Stimulants; D004791:Enzyme Inhibitors; D007191:Indazoles; D009569:Nitric Oxide; D002110:Caffeine; D019001:Nitric Oxide Synthase; D005947:Glucose; C080122:7-nitroindazole; D019331:NG-Nitroarginine Methyl Ester