Nerve fibers showing immunoreactivities for thyrosine hydroxylase and dopamine-beta-hydroxylase re-appear in the guinea pig uvea after sympathectomy

Recovery of sympathetic nerve function after lumbar sympathectomy is slower in the hind limbs than in the torso

Local sympathetic denervation by surgical sympathectomy is used in the treatment of lower limb ulcers and ischemia, but the restoration of cutaneous sympathetic nerve functions is less clear. This study aims to explore the recovery of cutaneous sympathetic functions after bilateral L_2–4 sympathectomy. The skin temperature of the left feet, using a point monitoring thermometer, increased intraoperatively after sympathectomy. The cytoplasm of sympathetic neurons contained tyrosine hydroxylase and dopamine β-hydroxylase, visualized by immunofluorescence, indicated the accuracy of sympathectomy. Iodine starch test results suggested that the sweating function of the hind feet plantar skin decreased 2 and 7 weeks after lumbar sympathectomy but had recovered by 3 months. Immunofluorescence and western blot assay results revealed that norepinephrine and dopamine β-hydroxylase expression in the skin from the sacrococcygeal region and hind feet decreased in the sympathectomized group at 2 weeks. Transmission electron microscopy results showed that perinuclear space and axon demyelination in sympathetic cells in the L₅ sympathetic trunks were found in the sympathectomized group 3 months after sympathectomy. Although sympathetic denervation occurred in the sacrococcygeal region and hind feet skin 2 weeks after lumbar sympathectomy, the skin functions recovered gradually over 7 weeks to 3 months. In conclusion, sympathetic functional recovery may account for the recurrence of hyperhidrosis after sympathectomy and the normalization of sympathetic nerve trunks after incomplete injury. The recovery of sympathetic nerve function was slower in the limbs than in the torso after bilateral L_2–4 sympathectomy.

GAP-43 mRNA and calcitonin gene-related peptide mRNA expression in sensory neurons are increased following sympathectomy

Sympathectomy has been shown to result in an increased density of fibers immunoreactive for sensory peptides in peripheral targets innervated by both sensory and sympathetic neurons, providing evidence for functional interactions between sympathetic and sensory systems. These findings provided the background for examining the hypothesis that axonal outgrowth is induced from sensory neurons following sympathectomy. We examined the expression of GAP-43 mRNA, a specific marker for axonal outgrowth, in cervical (C3, C7, C8) and thoracic (T1, T2) dorsal root ganglia (DRG) of the rat following bilateral removal of the superior cervical ganglion, to assess whether the described increases in peptidergic afferent fibers reflected axonal outgrowth. In situ hybridization was used with 35S labeled riboprobes complementary to GAP-43 mRNA, and to calcitonin gene-related peptide (CGRP) mRNA, a marker for a major subset of thin-fiber sensory neurons. The density of GAP-43 mRNA nearly doubled by 18 h following sympathectomy and reached a threefold increase by 3 days. By 45 days following surgery, the GAP-43 mRNA level was still nearly twice that of normal animals, CGRP immunoreactivity was also examined: the density of fibers in the iris and cornea of sympathectomized animals was considerably greater from two weeks to 45 days following surgery, than in sham-operated controls. Concomitantly, there was a slight but significant increase in CGRP mRNA expression in T1 and C3 DRG 14 days postsympathectomy. Quantitative computerized image analysis demonstrated that GAP 43 mRNA expression in sympathectomized animals was 1.5 times greater in medium-sized DRG neurons and almost fourfold greater in small DRG neurons than in control rats. These results indicate that sympathetic denervation elicits axonal outgrowth in the population of sensory neurons that give rise to the small unmyelinated and thinly myelinated axons of peripheral nerves.

Intestinal ganglioneuromatosis: mucosal and transmural types. A clinicopathologic and immunohistochemical study of six cases

Six cases of intestinal ganglioneuromatosis (GN) included in this study reveal the occurrence of two morphologic patterns. Transmural GN was characterized by neural hyperplasia in all layers of the bowel wall with predominant involvement of the myenteric plexus. It was found in three patients affected by multiple endocrine neoplasia IIb. Mucosal GN, having predominant involvement of the mucosa without concomitant hyperplasia of the myenteric plexus, was associated with von Recklinghausen's disease, adenocarcinoma of the colon, and multiple adenomas with megacolon in one case each. Clinicopathologic correlations and review of the literature suggest that mucosal GN might represent a distinct entity with a lower morbidity rate than the transmural variant. Immunohistochemical stains reveal considerable heterogeneity. S-100 protein, neuron-specific enolase, and synapto-physin immunostaining followed the distribution of the nervous hyperplasia in the different intestinal layers as identified morphologically and allowed precise determination of the proliferating cells. Increased reactivity for vasoactive intestinal polypeptide, opioid peptides leu-enkephalin and met-enkephalin, and substance P was present in all cases with transmural involvement; mucosal GN showed normal reactivity for opioid peptides and focal increased staining for substance P (one case) and vasoactive intestinal polypeptide (two cases) in the lamina propria. Mild increased immunoreactivity for tyrosine hydroxylase was present in the myenteric plexus of four out of four cases. Histochemical determination of acetylcholinesterase, performed in one case of transmural type, demonstrated hyperplasia of parasympathetic fibers and neurons. Electron microscopic study of another case suggested the presence of several neurotransmitters. These results indicate that the physiopathology of GN is related to a complex hyperplasia of several peptidergic, cholinergic, and probably adrenergic nerve fibers instead of a selective overgrowth of one type of nerve fiber.