Increased expression of neuronal nitric oxide synthase (NOS) in visceral neurons after nerve injury

Abstract

The distribution of nitric oxide synthase immunoreactivity (NOS-IR) and the changes in this distribution after peripheral axotomy were examined in lumbosacral afferent and preganglionic neurons (PGNs) innervating the pelvic viscera of the male rat. The visceral neurons in L6-S1 and L1-L2 dorsal root ganglia (DRG) and in the spinal cord were identified by retrograde axonal transport following injection of Fluorogold (FG) into the major pelvic ganglion (MPG). Axotomy was performed by removing the MPG on one side 2–4 weeks prior to sacrificing the animals. A differential distribution of NOS-IR was detected in DRG cells at different segmental levels of control animals. Significantly greater numbers of NOS-IR cells were present in thoracic (T8, T10, T12; 30–44 cell profiles/section) and rostral lumbar DRGs (L1-L2; 3–15 NOS-IR cell profiles/section) compared to caudal lumbosacral (L5-S1) DRGs (0.2–0.7 cell profiles/section). A significant increase in the number of NOS-IR cells was detected in the L6-S1 DRG (p < or = 0.001; 11 NOS-IR cell profiles/section) but not in the L2 or L5 DRG ipsilateral to axotomy. In these ganglia, an average of 37.0 +/- 4.0% (L6) and 20.6 +/- 2.2% (S1), respectively, of FG-labeled pelvic afferent neurons were NOS-IR compared to 1.1 +/- 0.5% (L6) and 2.5 +/- 1.4% (S1) contralateral to the axotomy. Following axotomy, a significantly greater percentage of dye-labeled pelvic visceral afferents in the L1 and L2 DRG also exhibited NOS-IR in comparison to the contralateral side. Following axotomy, NOS-IR fibers were detected along the lateral edge of the dorsal horn extending from Lissauer's tract to the region of the sacral parasympathetic nucleus (SPN) on the ipsilateral side of the L6 and S1 spinal segments. These NOS-IR fibers were not detected in adjacent spinal segments (L4, L5, or S2). Axotomy also changed the numbers of NADPH-d-positive and NOS-IR cells in the region of the SPN in the L6 spinal segment. Contralateral to the axotomy 38.3 +/- 4.0% of PGNs in the L6 spinal segment were colabeled with NOS-IR; however, ipsilateral to axotomy, a significantly greater percentage (61.0 +/- 3.0%; p < or = 0.01) of PGNs exhibited NOS-IR. Axotomy did not alter the distribution of PGNs in the S1 segment exhibiting NOS-IR. These results indicate that NOS-IR in visceral afferent and PGNs is plastic and can be upregulated by peripheral nerve injury.

Sexually dimorphic gastrin releasing peptide system in the spinal cord controls male reproductive functions

“…Double ICC confirmed that GRP-containing fibers surrounded neurons expressing neuronal nitric oxide synthase (nNOS; Fig. 1m-u), a marker for autonomic preganglionic neurons 14 and an enzyme involved in erection and ejaculation 12 . Electron micrography demonstrated GRP-immunoreactive presynaptic boutons innervating nNOS-positive dendrites in these autonomic nuclei of the lumbosacral spinal cord (Fig.…”

Expression of corticotropin-releasing factor and CRF receptors in micturition pathways after cyclophosphamide-induced cystitis

“…Spinal cord segments were identified based on at least two criteria as follows: 1) the T 13 dorsal root ganglion (DRG) exits after the last rib and 2) the L 6 vertebra is the last moveable vertebrae followed by the fused sacral vertebrae. Segmentation was later confirmed by immunostaining the autonomic nucleus in the L 6-S1 spinal segments with neuronal nitric oxide synthase (nNOS) IR (64). Our previous work (64) demonstrated that all nNOS IR cells in the rat SPN were retrogradely labeled from the major pelvic ganglion and therefore represented preganglionic parasympathetic neurons.…”

“…Segmentation was later confirmed by immunostaining the autonomic nucleus in the L 6-S1 spinal segments with neuronal nitric oxide synthase (nNOS) IR (64). Our previous work (64) demonstrated that all nNOS IR cells in the rat SPN were retrogradely labeled from the major pelvic ganglion and therefore represented preganglionic parasympathetic neurons. Only spinal segments exhibiting nNOS IR in the autonomic nucleus were subsequently used in analysis, and all rats in the present study exhibited nNOS-immunoreactive cell bodies in the L6-S1 autonomic nucleus.…”

Nitric oxide synthase in the frog cerebellum: Response of Purkinje neurons to unilateral eighth nerve transection

“…NADPHd and NOS protein are inducible in term of de novo synthesis in traumatically injured neurons (Wu, 2000). After peripheral axotomy, NOS protein and NOS mRNA increase in some neuronal populations (Verge et al, 1992;Vizzard et al, 1995); moreover, NOS is up-regulated in axotomized motoneurons (Yu, 1994;Yu, 1997;Mü ller and Stoll, 1998;Ma et al, 2000).…”

“…In the mammal cerebellum, Purkinje cells normally do not contain NOS (Vincent, 1994;Blottner et al, 1995;Vincent, 1996), but a lesion can induce NADPHd in the perikaria (Blottner et al, 1995;Saxon and Beitz, 1996). Increased NOSi and NADPHd activity were described in dorsal root ganglia on the ipsilateral side to peripheral axotomy (Vizzard et al, 1995), from 3 days to 4 weeks. Similar results were obtained after electrolyte lesions of the nucleus basalis magnocellularis (Sabbatini et al, 1999).…”