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Neuropeptides contained in peripheral cardiovascular nerves
Summary
Cardiovascular nerves contain neuropeptides like substance P and vasoactive intestinal peptide (VIP). These nerves, particularly substance P sensory nerves, are not essential for baroreceptor reflexes.
Area of Science:
- Neuroscience
- Cardiovascular Biology
- Pharmacology
Background:
- Neuropeptides, including substance P, vasoactive intestinal peptide (VIP), neuropeptide Y, and enkephalin, are present in mammalian cardiovascular nerves.
- Evidence also suggests the presence of gastrin-releasing peptide and neurotensin in some cardiovascular nerves.
Purpose of the Study:
- To investigate the distribution and function of various neuropeptides within the cardiovascular system.
- To determine the role of substance P-containing sensory nerves in baroreceptor reflexes.
Main Methods:
- Immunohistochemical localization of neuropeptides in cardiovascular tissues.
- Pharmacological manipulation using capsaicin to assess the role of substance P nerves.
- Assessment of baroreceptor reflex function following capsaicin treatment.
Main Results:
- Substance P nerves are widespread, with highest density in large arteries, and can be selectively degenerated by capsaicin.
- Degeneration of substance P nerves did not impair baroreceptor reflexes.
- VIP nerves are prominent in cerebral and uterine arteries, as well as arteries of erectile and secretory tissues.
- Neuropeptide Y is co-localized with noradrenaline and depleted by reserpine or 6-hydroxydopamine.
- Enkephalin nerves are found in limited small arterial beds.
Conclusions:
- Cardiovascular innervation involves a diverse array of neuropeptides with distinct distributions.
- Substance P-containing sensory nerves are not critical for the baroreceptor reflex mechanism.
- Further research is needed to elucidate the specific roles of VIP, neuropeptide Y, and enkephalin in cardiovascular regulation.