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The cerebrovascular parasympathetic innervation
1Department of Neurology, Keio University, Tokyo, Japan.
Cerebrovascular and Brain Metabolism Reviews
|January 1, 1993
Summary
Parasympathetic nerves, identified by choline acetyltransferase and vasoactive intestinal polypeptide (VIP), regulate cerebral blood flow. Stimulation of these nerves causes vessel relaxation, impacting cerebrovascular tone.
Area of Science:
- Neuroscience
- Vascular Biology
- Autonomic Nervous System
Background:
- Parasympathetic innervation of cerebral vessels was poorly understood compared to sympathetic innervation.
- Recent studies have begun to elucidate the sources, pathways, and functions of cerebrovascular parasympathetic nerves.
Purpose of the Study:
- To map the cerebrovascular parasympathetic innervation in mammals.
- To investigate the role of parasympathetic nerves in regulating cerebral blood flow and tone.
Main Methods:
- Histochemistry using choline acetyltransferase and vasoactive intestinal polypeptide (VIP) markers.
- Retrograde tracer techniques and selective denervation in animal models (rat, cat, monkey).
- Biochemical assays for acetylcholine (ACh) in pial arteries and pharmacological studies on isolated arteries.
Main Results:
- Parasympathetic nerve fibers containing ACh and VIP were identified in cerebral vessels.
- ACh demonstrated high-affinity uptake, local synthesis, and release in pial vessels.
- ACh and VIP induced relaxation of isolated pial arteries, dependent on endothelial function and receptor stimulation.
- Stimulation of parasympathetic nerves increased cerebral blood flow, mimicking local ACh and VIP administration.
Conclusions:
- Parasympathetic nerves play a significant role in regulating cerebral vascular tone.
- Acetylcholine and VIP are key neurotransmitters mediating parasympathetic effects on cerebral vessels.
- Further research is needed to understand the pathophysiological relevance of this innervation.