Heterogeneity of Vascular Innervation in Hamster Cheek Pouch and Retractor Muscle

Abstract

The hamster cheek pouch and its retractor muscle have provided valuable insights into microvascular physiology of an epithelial tissue and striated muscle, respectively. Nevertheless, the innervation of these vascular beds has not been resolved. This study has investigated the nature of autonomic and sensory innervation of these vascular beds and has tested whether it varies within or between tissues. Multiple-labelling immunohistochemistry identified autonomic and peptide-containing sensory nerve fibres. Presumptive sympathetic vasoconstrictor axons with immunoreactivity (IR) for tyrosine hydroxylase (TH) and neuropeptide Y (NPY) innervated feed arteries and arterioles (but not veins or venules) of the retractor and anterior (muscular) cheek pouch; these axons were absent from the posterior (epithelial) region of the cheek pouch, as confirmed by catecholamine fluorescence. Presumptive autonomic vasodilator axons with IR for vasoactive intestinal peptide (VIP) consistently innervated feed arteries and proximal arterioles of the cheek pouch, but generally not those of the retractor muscle nor distal arterioles of either tissue. Sparse presumptive sensory axons with IR for calcitonin gene-related peptide (CGRP) and substance P were found near arterial and venous vessels in all regions of the cheek pouch and retractor muscle; CGRP-IR was also located in motor end plates associated with striated muscle fibres. Such regional differences in vascular innervation by autonomic and sensory neurons may selectively effect local and regional control of blood flow between and within vascular beds.

Neural control of muscle blood flow during exercise

“…A rich adventitial plexus of sympathetic nerve fibers surrounds feed arteries and extends throughout the arteriolar network, including its terminal branches (26,31,50). However, neither capillaries nor venules in skeletal muscle are directly innervated (26).…”

Remote arteriolar dilations caused by methacholine: a role for CGRP sensory nerves?

“…Therefore, additional pathways, such as nerves, may be involved, or the signal may be regenerated within the vessel wall as it moves from cell to cell. Because various neural innervations of elusive function (12) have been identified on the arterioles in the cheek pouch and because previous studies indicate that local anesthesia inhibits the vascular relaxation response to acetylcholine (23), this study was performed to determine whether there may be a role for neural mechanisms in the remote vasomotor signals generated by arteriolar muscarinic receptor stimulation.…”

A Novel Model of Pain Sensation Using Superfused Gastrosplenic Omentum Preparation of Anesthetized Rats

“…There are many reports indicating the presence of sensory nerve innervation on the arterioles: the paravascular pain receptors of the artery in the isolated rabbit ear (8), the epineural arterioles of the sciatic nerves (9), the sensory innervation of the trigeminal nerve blood vessels (10), the perivascular sympathetic nerve of the small intestine (11), autonomic and peptide-containing sensory nerve fibers in the hamster cheek pouch (12), and primary visceral afferents to the spleen of guinea pigs (13).…”