Cyclic Nucleotides
The production of cyclic nucleotides may be influenced by neurotransmitters
and anesthetics, and cyclic
nucleotides may serve as second messengers in altering neurotransmission. The effect
of anesthetics on cyclic adenosine monophosphate (cAMP) content varies with the species
and tissues examined.[74]
Most studies demonstrate
an increase in brain cAMP content of rodents during the administration of volatile
anesthetics, with the magnitude of the increase varying among species and among brain
regions.[74]
In contrast, levels of cyclic guanosine
monophosphate (cGMP) in brain are decreased by volatile agents.[75]
Nitric oxide activates guanylyl cyclase to form cGMP, and nitric oxide production
can be enhanced by excitatory neurotransmitters. It has been suggested that volatile
anesthetics decrease brain cGMP by interfering with the neuronal nitric oxide-cGMP
pathway.[75]
Such alterations in brain cyclic nucleotide
content may chemically alter (e.g., through phosphorylation) macromolecules that
are important in neurotransmission.
