Functional brain mapping based on changes in local cerebral blood flow (ICBF) or glucose utilization (ICMRglc) induced by functional activation is generally carried out in animals under anesthesia, usually α-chloralose because of its lesser effects on cardiovascular, respiratory, and reflex functions. Results of studies on the role of nitric oxide (NO) in the mechanism of functional activation of ICBF have differed in unanesthetized and anesthetized animals. NO synthase inhibition markedly attenuates or eliminates the ICBF responses in anesthetized animals but not in unanesthetized animals. The present study examines in conscious rats and rats anesthetized with α-chloralose the effects of vibrissal stimulation on ICMRglc and ICBF in the whisker-to-barrel cortex pathway and on the effects of NO synthase inhibition with NG-nitro-L-arginine methyl ester (L-NAME) on the magnitude of the responses. Anesthesia markedly reduced the ICBF and ICMRglc responses in the ventral posteromedial thalamic nucleus and barrel cortex but not in the spinal and principal trigeminal nuclei. L-NAME did not alter the ICBF responses in any of the structures of the pathway in the unanesthetized rats and also not in the trigeminal nuclei of the anesthetized rats. In the thalamus and sensory cortex of the anesthetized rats, where the ICBF responses to stimulation had already been drastically diminished by the anesthesia, L-NAME treatment resulted in loss of statistically significant activation of ICBF by vibrissal stimulation. These results indicate that NO does not mediate functional activation of ICBF under physiological conditions.
|Number of pages
|Proceedings of the National Academy of Sciences of the United States of America
|Published - Jun 19 2001
- Cerebral glucose utilization
- Functional brain imaging
- Whisker-to-barrel cortex pathway
ASJC Scopus subject areas