Postnatal development of autonomic and sensory innervation of thoracic hairy skin in the rat. A histochemical, immunocytochemical, and radioenzymatic study.
Histochemical, immunocytochemical, and radioenzymatic techniques were used to examine the neurotransmitter-related properties of the innervation of thoracic hairy skin in rats during adulthood and postnatal development. In the adult, catecholamine-containing fibers were associated with blood vessels and piloerector muscles, and ran in nerve bundles throughout the dermis. The distribution of tyrosine hydroxylase (TH)-immunoreactive (IR) fibers was identical. Neuronal fibers displaying neuropeptide Y (NPY) immunoreactivity were seen in association with blood vessels. Double-labeling studies suggested that most, if not all, NPY-IR fibers were also TH-IR and likewise most, if not all, vessel-associated TH-IR fibers were also NPY-IR. Calcitonin gene-related peptide (CGRP)-IR fibers were observed near and penetrating into the epidermis, in close association with hair follicles and blood vessels, and in nerve bundles. A similar distribution of substance P (SP)-IR fibers was evident. In adult animals treated as neonates with the sympathetic neurotoxin 6-hydroxydopamine, a virtual absence of TH-IR and NPY-IR fibers was observed, whereas the distribution of CGRP-IR and SP-IR fibers appeared unaltered. During postnatal development, a generalized increase in the number, fluorescence intensity, and varicose morphology of neuronal fibers displaying catecholamine fluorescence, NPY-IR, CGRP-IR, and SP-IR was observed. By postnatal day 21, the distribution of the above fibers had reached essentially adult levels, although the density of epidermal-associated CGRP-IR and SP-IR fibers was significantly greater than in the adult. The following were not evident in thoracic hairy skin at any timepoint examined: choline acetyltransferase activity, acetylcholinesterase histochemical staining or immunoreactivity, fibers displaying immunoreactivity to vasoactive intestinal peptide, cholecystokinin, or leucine-enkephalin. The present study demonstrates that the thoracic hairy skin in developing and adult rats receives an abundant sympathetic catecholaminergic and sensory innervation, but not a cholinergic innervation.
Schotzinger
R J
RJ
Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio.
Landis
S C
SC
D000320:Adrenergic Fibers / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D005260:Female; D006197:Hair / Q000254:growth & development / Q000294:innervation*; D008297:Male; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D009478:Neuropeptide Y / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D051381:Rats; D011917:Rats, Inbred Lew; D011919:Rats, Inbred Strains; D012867:Skin / Q000254:growth & development / Q000294:innervation*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D009478:Neuropeptide Y; D009479:Neuropeptides; D014446:Tyrosine 3-Monooxygenase