Abstract
Studies have been carried out to characterize the increase in cyclic adenosine monophosphate (AMP) which occurs in the rabbit superior cervical ganglion in response to electrical stimulation of the preganglionic nerve fibers. The cyclic AMP content of the ganglion increased about 2-fold in response to preganglionic stimulation. This effect could be mimicked by the application of carbachol or bethanechol, agents capable of activating muscarinic receptors. The increase in cyclic AMP brought about either by preganglionic stimulation or by the cholinergic agonists was potentiated in the presence of substances which inhibit phosphodiesterase, was reduced by atropine or by apha adrenergic antagonists and was unaffected by hexamethonium or by the beta adrenergic antagonist. MJ 1999. The data support the interpretation that the increase in cyclic AMP, which follows electrical stimulation of the preganglionic nerve fibers, occurs in the postganglionic nerve cells, probably in response to dopamine released from a dopaminergic interneuron. The results are compatible with the hypothesis that cyclic AMP mediates dopaminergic transmission in the ganglion and thereby modulates the responsiveness of the postganglionic neurons to excitatory activity in the principal, monosynaptic, excitatory pathway.
Footnotes
- Received May 31, 1973.
- Accepted October 5, 1973.
- © 1974 by The Williams & Wilkins Co.
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