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PubMed1988

Maintenance by glycyl-L-glutamine in vivo of molecular forms of acetylcholinesterase in the preganglionically denervated superior cervical ganglion of the cat.

The 24-hr intracarotid infusion of plasma-treated glycyl-L-glutamine (3 microM) produced significant enhancement of the monomeric G1 and tetrameric G4 forms of acetylcholinesterase of the cat superior cervical ganglion 48 hr after denervation, in comparison with denervated, noninfused controls. No significant effect of glycyl-L-glutamine could be demonstrated 4 or 6 days after denervation. These findings are consistent with the conclusion, drawn from a previous in vitro study, that glycyl-L-glutamine acts at a stage prior to the aggregation of the G1 form into higher polymers to maintain the acetylcholinesterase content of denervated ganglia. It is proposed that the dipeptide may regulate the transcription of the DNA for acetylcholinesterase to its corresponding mRNA.

Acetylcholinesterase↗

PubMed1998

Nonmyogenic factors bind nicotinic acetylcholine receptor promoter elements required for response to denervation.

Nicotinic acetylcholine receptors (AChRs) belong to a class of muscle proteins whose expression is regulated by muscle electrical activity. In innervated muscle fiber, AChR genes are transcriptionally repressed outside of the synapse, while after denervation they become reexpressed throughout the fiber. The myogenic determination factors (MDFs) of the MyoD family have been shown to play a central role in this innervation-dependent regulation. In the chicken AChR alpha-subunit gene promoter, two E-boxes that bind MDFs are necessary to achieve the enhancement of transcription following muscle denervation. However, the deletion of promoter sequences located upstream to these E-boxes greatly impairs the response to denervation (Bessereau, J. L., Stratford- Perricaudet, L. D., Piette, J., Le Poupon, C. and Changeux, J. P. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 1304-1308). Here we identified two additional cis-regulatory elements of the alpha-subunit gene promoter that cooperate with the E-boxes in the denervation response. One region binds the Sp1 and Sp3 zinc finger transcription factors. The second region binds at least three distinct factors, among which we identified an upstream stimulatory factor, a b-ZIP-HLH transcription factor. We propose that among MDF-responsive muscle promoters, a specific combination between myogenic and nonmyogenic factors specify innervation-dependent versus innervation-independent promoters.

Adenoviridae↗

PubMed1998

Expression and trans-synaptic regulation of P2x4 and P2z receptors for extracellular ATP in parotid acinar cells. Effects of parasympathetic denervation.

Trans-synaptic regulation of muscarinic, peptidergic, and purinergic responses after denervation has been reported previously in rat parotid acinar cells (McMillian, M. K., Soltoff, S. P., Cantley, L. C., Rudel, R., and Talamo, B. R. (1993) Br. J. Pharmacol. 108, 453-461). Characteristics of the ATP-mediated responses and the effects of parasympathetic denervation were further analyzed through assay of Ca2+ influx, using fluorescence ratio imaging methods, and by analysis of P2x receptor expression. ATP activates both a high affinity and a low affinity response with properties corresponding to the recently described P2x4 and the P2z (P2x7)-type purinoceptors, respectively. Reverse transcription-polymerase chain reaction analysis reveals mRNA for P2x4 as well as P2x7 subtypes but not P2x1, P2x2, P2x3, P2x5, or P2x6. P2x4 protein also is detected by Western blotting. Distribution of the two types of ATP receptor responses on individual cells was stochastic, with both high and low affinity responses on some cells, and only a single type of response on others. Sensitivity to P2x4-type activation also varied even among cells responsive to low concentrations of ATP. Parasympathetic denervation greatly enhanced responses, tripling the proportion of acinar cells with a P2x4-type response and increasing the fraction of highly sensitive cells by 7-fold. Moreover, P2x4 mRNA is significantly increased following parasympathetic denervation. These data indicate that sensitivity to ATP is modulated by neurotransmission at parasympathetic synapses, at least in part through increased expression of P2x4 mRNA, and suggest that similar regulation may occur at other sites in the nervous system where P2x4 receptors are widely expressed.

Adenosine Triphosphate↗

PubMed1996

Molecular cloning of the rat NADH:ubiquinone oxidoreductase subunit and its up-regulation in the facial muscle after denervation: detected by means of differential display.

The differential display method was applied to identify gene expression which is especially up-regulated in the rat denervated skeletal muscle. Total RNA from normal and denervated facial muscles was isolated, amplified by PCR using certain primers, and separated by electrophoresis on polyacrylamide gel. PCR products which were apparently higher in the operated than in the control side were cut out from the gel and subsequently sequenced. One of the cDNA fragments obtained in the present study showed about 80% identity in nucleotide sequence and about 84% identity in amino acid sequence to one of the NADH: ubiquinone oxidoreductase (complex I) subunits from the bovine heart mitochondria (813). Complex I, the first and largest enzyme of the mitochondrial respiratory chain, transfers electrons from NADH to ubiquinone-10 (UQ-10). B13 is a 13 kDa subunit; deficiency of which causes incomplete or incorrect assembly of a functional complex I, resulting in one of the types of human mitochondrial myopathy. Northern blot analysis and in situ hybridization histochemistry confirmed that rat B13 mRNA expression was up-regulated after denervation and was distributed throughout whole muscle cell body. These findings suggest that up-regulation of the rat B13 mRNA expression after denervation plays an important role in the effective electron transfer from NADH to UQ-10 in skeletal muscle cells, resulting in restriction of lipid peroxidation and biological tissue damage.

Amino Acid Sequence↗

PubMed1986

Expression of several adhesive macromolecules (N-CAM, L1, J1, NILE, uvomorulin, laminin, fibronectin, and a heparan sulfate proteoglycan) in embryonic, adult, and denervated adult skeletal muscle.

Levels of the neural cell adhesion molecule N-CAM in muscle are regulated in parallel with the susceptibility of muscle to innervation: N-CAM is abundant on the surface of early embryonic myotubes, declines in level as development proceeds, reappears when adult muscles are denervated or paralyzed, and is lost after reinnervation (Covault, J., and J. R. Sanes, 1985, Proc. Natl. Acad. Sci. USA, 82:4544-4548). Here we used immunocytochemical methods to compare this pattern of expression with those of several other molecules known to be involved in cellular adhesion. Laminin, fibronectin, and a basal lamina-associated heparan sulfate proteoglycan accumulate on embryonic myotubes after synapse formation, and their levels change little after denervation. L1, J1, nerve growth factor-inducible large external protein, uvomorulin, and a carbohydrate epitope (L2/HNK-1) shared by several adhesion molecules are undetectable on the surface of embryonic, perinatal, adult, or denervated adult muscle fibers. Thus, of the molecules tested, only N-CAM appears on the surface of muscle cells in parallel with the ability of the muscle cell surface to accept synapses. However, four antigens--N-CAM, J1, fibronectin, and a heparan sulfate proteoglycan--accumulate in interstitial spaces near denervated synaptic sites; regenerating axons traverse these spaces as they preferentially reinnervate original synaptic sites. Of particular interest is J1, antibodies to which block adhesion of central neurons to astrocytes (Kruse, J., G. Keihauer, A. Faissner, R. Timpl, and M. Schachner, 1985, Nature (Lond.), 316:146-148). J1 is associated with collagen and other fibrils in muscle and thus may be an extracellular matrix molecule employed in both the central and peripheral nervous systems.

Animals↗

PubMed1986

Molecular forms of N-CAM and its RNA in developing and denervated skeletal muscle.

The neural cell adhesion molecule (N-CAM) is present in both embryonic and perinatal muscle, but its distribution changes as myoblasts form myotubes and axons establish synapses (Covault, J., and J. R. Sanes, 1986, J. Cell Biol., 102:716-730). Levels of N-CAM decline postnatally but increase when adult muscle is denervated or paralyzed (Covault, J., and J. R. Sanes, 1985, Proc. Natl. Acad. Sci. USA., 82:4544-4548). To determine the molecular forms of N-CAM and N-CAM-related RNA during these different periods we used immunoblotting and nucleic acid hybridization techniques to analyze N-CAM and its RNA in developing, cultured, adult, and denervated adult muscle. As muscles develop, the extent of sialylation of muscle N-CAM decreases, and a 140-kD desialo form of N-CAM (generated by neuraminidase treatment) is replaced by a 125-kD form. This change in the apparent molecular weight of desialo N-CAM is paralleled by a change in N-CAM RNA: early embryonic muscles express a 6.7-kb RNA species which hybridizes with N-CAM cDNA, whereas in neonatal muscle this form is largely replaced by 5.2- and 2.9-kb species. Similar transitions in the desialo form of N-CAM, but not in extent of sialylation, accompany differentiation in primary cultures of embryonic muscle and in cultures of the clonal muscle cell lines C2 and BC3H-1. Both in vivo and in vitro, a 140-kD desialo form of N-CAM and a 6.7-kb N-CAM RNA are apparently associated with myoblasts, whereas a 125-kD desialo form and 5.2- and 2.9-kb RNAs are associated with myotubes and myofibers. After denervation of adult muscle, a approximately 12-15-fold increase in the levels of N-CAM is accompanied by a approximately 30-50-fold increase in N-CAM RNA, suggesting that N-CAM expression is regulated at a pretranslational level. Forms of N-CAM and its RNA in denervated muscle are similar to those seen in perinatal myofibers.

Animals↗

PubMed1984

Denervation supersensitivity in skeletal muscle: analysis with a cloned cDNA probe.

Motor neurons regulate the acetylcholine sensitivity of the muscles they innervate: denervated muscle fiber become "supersensitive" to acetylcholine, due to insertion of newly synthesized acetylcholine receptors (AChRs) in the plasma membrane. We used hybridization analysis with a cloned cDNA specific for AChR alpha-subunit to compare the abundance of AChR mRNA in innervated and denervated adult mouse muscles. Within 3 d of denervation, levels of AChR mRNA increased 100-fold; levels of actin mRNA changed little. The increase in AChR mRNA level was sufficiently large and rapid to account for denervation supersensitivity.

Actins↗

PubMed1990

Effect of liver denervation on compensatory changes in food intake, body composition and hepatic enzyme induction after food restriction in rats.

The mechanisms involved in the recovery of body fat and liver metabolism after food restriction and refeeding are not understood. This study's aim was to determine the need for hepatic neural input for the compensatory changes in food intake, body composition and hepatic lipogenic enzymes seen upon realimentation after energy restriction. Rats underwent total surgical hepatic denervation or had sham operations. One group of sham-operated and denervated rats was fed a semipurified diet ad libitum; a second group was restricted to 40% ad libitum levels for 7 d, then given free access to food during a 2-d refeeding period. Body fat content and body fat recovery rate from below "set point" were not altered by hepatic denervation. These observations do not rule out liver involvement because blood-borne factors communicating energy status information to the central nervous system could be released from the liver. The activities of hepatic enzymes--glucose-6-phosphate dehydrogenase, malic enzyme and citrate cleavage enzyme--were stimulated at least twofold by restriction and refeeding when compared to ad libitum feeding. Hepatic denervation had no effect on basal enzyme levels in ad libitum-fed animals or on elevated enzyme activity induced by refeeding after food restriction. This study clearly demonstrates that hepatic innervation is not essential for energy balance and body composition regulation. The induction of lipogenic enzymes by food restriction and refeeding does not depend on central nervous system input to the liver.

ATP Citrate (pro-S)-Lyase↗

PubMed1993

Hepatic denervation alters the transition from the fed to the food-deprived state in conscious dogs.

The hepatic nerves can modulate hepatic glycogenolysis and glycogenesis and thus might be expected to be involved in the response of the animal to the transition from the fed to the food-deprived state. Therefore the arterial concentrations and net hepatic balance of glucose and its metabolites, as well as the hepatic glycogen concentrations, were compared in hepatic-innervated and -denervated dogs 18, 24 and 42 h after their usual daily meal. Arterial concentrations of glucose, alanine, lactate and glycerol; net hepatic balances of glucose, alanine and glycerol; and glycogen concentrations were similar in hepatic-innervated and -denervated dogs at each time investigated. Net hepatic balances of lactate (with negative values indicating uptake) in hepatic-innervated and -denervated dogs, respectively, were: 18 h, 4.1 +/- 4.3 vs. -4.3 +/- 3.6 mumol.kg-1 x min-1; 24 h, 4.8 +/- 3.6 vs. -6.7 +/- 1.7 mumol.kg-1 x min-1 (P < 0.05); 42 h, -7.0 +/- 2.0 vs. -6.8 +/- 1.0 mumol.kg-1 x min-1. Based on changes in net hepatic lactate balance, the denervated liver responds more rapidly to food deprivation than the innervated liver, but the metabolic state of the liver appears similar by 42 h after a meal.

Alanine↗

PubMed1993

Upstream sequences of the myogenin gene convey responsiveness to skeletal muscle denervation in transgenic mice.

Myogenin, as well as other MyoD-related skeletal muscle-specific transcription factors, regulate a large number of skeletal muscle genes during myogenic differentiation. During later development, innervation suppresses myogenin expression in the fetal hind limb musculature. Denervation of skeletal muscle reverses the effects of the nerve, and results in the reactivation of myogenin expression, as well as of other embryonic muscle proteins. Here we report that myogenin upstream sequences confer tissue- and developmental-specific expression in transgenic mice harboring a myogenin/chloramphenicol acetyltransferase (CAT) reporter construct. Using in situ hybridization to analyze serial sections of E12.5 embryos, we found colocalization of CAT and endogenous myogenin transcripts in the primordial muscle of the head and limbs, in the intercostal muscle masses, and in the most caudal somites. Later in development, we observed that the expression of the transgene and endogenous myogenin gene continued to be restricted to skeletal muscle but decreased shortly after birth; a period that coincides with the innervation of secondary myotubes. Furthermore, denervation of the mouse hind limbs induced a 10-fold accumulation of CAT and endogenous myogenin transcripts by 1 day after sciatic nerve resection; a 25-fold increase was observed by 4 days after denervation. Interestingly, we observed that the accumulation of CAT enzyme activity lagged considerably with respect to the increase in CAT transcripts. Our results indicate that the cis-acting elements that temporally and spatially confine transcription of the gene during embryonic development, and that mediate the responses to innervation and denervation of muscle, lie within the upstream sequences analyzed in these studies.

Animals↗

PubMed2002

Effects of aging and denervation on the expression of uncoupling proteins in slow- and fast-twitch muscles of rats.

We investigated the effects of aging and denervation on the gene expression of uncoupling proteins (UCPs) in slow-twitch soleus and fast-twitch gastrocnemius muscles. In a comparison between the control limbs of 6- and 24-month-old rats, the mRNA levels of UCP3, heart-type fatty acid binding protein (HFABP), and glucose transporter-4 (GLUT4) were considerably lower in the gastrocnemius muscles of the older rats, whereas no significant differences in the mRNA levels of those genes as well as UCP2 and cytochrome oxidase subunit IV (COX-IV) were observed in the soleus muscles of young and old rats. The UCP3 and COX-IV protein levels were also reduced considerably in the aged gastrocnemius muscles with atrophy. Denervation of the sciatic nerve caused an increase in UCP3 mRNA levels in both muscles, but the regulation of other genes contrasted between the two types of skeletal muscles. In spite of the increased mRNA level, a remarkable reduction in UCP3 protein was found in the denervated gastrocnemius muscles. These results indicate that the effects of aging and denervation on the gene expression of UCPs, HFABP, GLUT4, and COX-IV are different between the muscle types. The reduction in the mitochondrial UCP3 and COX proteins in aged fast-twitch muscles may have a negative effect on energy metabolism and thermogenesis in old animals.

Aging↗

PubMed1990

Characterization of C-protein isoforms expressed in developing, denervated, and dystrophic chicken skeletal muscles by two-dimensional gel electrophoresis.

C-Proteins in developing, denervated, and dystrophic chicken skeletal muscles were examined by means of two-dimensional (2D) gel electrophoresis in combination with immunoblotting. In this analysis, the electrophoresis system which was devised by Hirabayashi (Anal. Biochem. 117, 443-451, 1981) provided excellent resolution; three C-protein variants, one fast-type (Cf) and two slow-types (CS3 and CS4) with different Mrs and pIs, were distinguished on a 2D gel. In the neonatal breast muscle, both Cf and CS3 were detected, but during postnatal development, CS3 disappeared from this muscle and Cf became only the C-protein isoform in the adult muscle. In posterior latissimus dorsi (PLD) muscle, both Cf and CS3 were similarly detected at the neonatal stage, but CS3 was replaced by CS4 as this muscle developed. When the breast and PLD muscles were denervated or suffered from muscular dystrophy, both CS3 and CS4 were co-expressed in these muscles in addition to Cf. These results definitely show that the C-protein isoform pattern varies during development and degeneration of chicken skeletal muscles, and in addition the dystrophic or denervated muscle differs from the neonatal muscle with regard to C-protein isoform expression. We suggest that chicken skeletal muscle degenerating due to denervation or muscular dystrophy does not simply recapture the nature of the neonatal muscle, but shifts in a somewhat different direction.

Aging↗

PubMed1997

Occurrence of capillaries with fenestrae in the intrinsic laryngeal muscles of the guinea pig after unilateral denervation.

Capillaries in the posterior cricoarytenoid and the arytenoid muscles of the guinea pig were examined by electron microscopy 3 days after transection of unilateral recurrent laryngeal nerve. The denervated posterior cricoarytenoid muscle had neuromuscular junctions (NMJs) lacking terminal axons, while in the unpaired arytenoid muscle, normal and denervated NMJs coexisted among muscle fibres being seemingly normal. Capillaries in both muscles were almost of the continuous type. However, approximately 10% of capillaries around the denervated NMJs and among some muscle fibres in both muscles, often had a small number (< 10) of fenestrae bridged by a single-layered diaphragm. The untreated normal muscles contained only continuous capillaries. These findings suggest that denervation may induce the fenestrated changes of intramuscular capillaries.

Animals↗

PubMed1997

Venous air embolism and selective denervation for torticollis.

Selective denervation to relieve severe torticollis requires surgery with the patient in the sitting position. Nerve stimulation is used to guide the procedure; therefore, patients undergo general anesthesia without muscle relaxation. Because of the risk of venous air embolism (VAE), monitoring with precordial Doppler and a multiorifice right atrial catheter has been recommended. To document the incidence of VAE and, thus, the effectiveness of monitors to detect it, consecutive patients who underwent selective peripheral denervation for torticollis between June 1993 and July 1994 were studied retrospectively, and those who underwent the procedure between August 1994 and February 1996 were studied prospectively. No VAE was documented in the retrospective group (n = 31). In the prospective group (n = 69), precordial Doppler detected one episode of VAE that lasted < 20 s and had no clinical sequelae. The incidence of complications from right atrial catheter insertion was 8% (carotid puncture, hematoma, inability to cannulate) but with no permanent sequelae. We conclude that VAE is infrequent and self-limited in association with selective denervation for torticollis. While monitoring with precordial Doppler for patients undergoing denervation for torticollis is indicated, the use of a right atrial catheter is of limited value because of associated complications and increased operating room time and cost.

Adult↗

PubMed1990

Electrophysiological study of the denervated orbicularis oculi muscle in dogs.

This study investigated the electrophysiology of the denervated orbicularis oculi muscle and its clinical application. Orbicularis oculi muscle denervation was achieved by complete transection of the seventh nerve in ten dogs. The parameters studied were the electrical requirements needed to cause a minimal perceptible contraction (twitch) and a complete eyelid closure (blink). Twitch and blink curves were generated. The findings are summarized as follows: (1) Minimum intensities for direct twitch of denervated orbicularis oculi muscle were significantly lower than intensities of normal orbicularis oculi muscle twitch (p less than 0.01) when long stimulus duration (5 to 400 ms) was used. (2) Minimum intensities for direct blink of denervated orbicularis oculi muscle were not significantly different from stimulus intensities for blink of normal orbicularis oculi muscle if long stimulus duration (5 to 400 ms) was used. Twitch and blink curves could be used to clinically follow the orbicularis oculi muscle movement return after operations performed in patients affected by lagophthalmos.

Animals↗

PubMed1998

Perceptual significance of somatosensory cortical reorganization following peripheral denervation.

The functional significance of reorganization in somatosensory cortex following peripheral denervation has not been thoroughly addressed. In this paper, two distinct hypotheses dealing with this issue are discussed. The first is the hypothesis of functional respecification. This influential view suggests that sets of partially deafferented cortical neurons, which respond to new peripheral inputs and acquire new receptive fields, undergo corresponding changes in perceptual meaning. Excitation of these neurons by stimulation of their novel receptive fields is thought to result in a change in referral of sensation from the original (now denervated) skin fields to the newly acquired skin fields. The second hypothesis is that of functional conservation. This equally plausible alternative is that sets of partially deprived neurons, although they respond to novel peripheral inputs, retain their original perceptual meaning. Excitation of these neurons by stimulation of their new receptive fields is thought to evoke sensation formerly mediated by those neurons, and hence is still projected to the original, now denervated skin regions or phantom. Behavioral evidence strongly suggests that cortical reorganization after peripheral denervation does not result in major functional respecification, but that the original perceptual function mediated by those neurons is preserved.

Animals↗

PubMedDate not supplied

Fibrillation potential amplitude after denervation.

Fibrillation potentials have been reported to decline in amplitude with time after denervation. The use of maximum fibrillation potential amplitude to determine the relative acuity of axonal loss ("old" v "new/recurrent") has been advocated but with conflicting endorsements as to the appropriate benchmark amplitude, i.e., 100 microV compared with 250 microV. This investigation uses computer simulations to examine the rate of fibrillation potential amplitude decline expected given known values for muscle fiber size atrophy and conduction velocity slowing over time after denervation. Factors that affect the amplitude and potentially lead to erroneous interpretations in the clinical scenario of partially denervated muscle tissue are discussed. The use of fibrillation potential maximum amplitude criteria to determine the age of lesion onset in both totally and partially denervated muscle is fraught with technical and pathophysiological hazards of interpretation and must be considered cautiously, if at all, in clinical practice.

Animals↗

PubMed1997

Denervation promotes the development of cancer-related lesions in the gastric remnant.

Innervation of the gastric mucosa plays an important role in its defense mechanism. In a previous study, gastrectomy with denervation promoted tumorigenesis in the gastric body in rats after administration of a carcinogenic agent. In this study we investigated the induced gastric mucosal changes from the viewpoint of mucin histochemistry. Gastrectomy with denervation promoted the development of intestinal metaplasia, dysplasia, and carcinoma in the gastric body. Proliferating cell nuclear antigen labeling indexes as a marker for cell kinetics were significantly elevated in the denervated group. Analysis of mucin histochemistry by staining with paradoxical concanavalin A (PCA) and galactose oxidase-Schiff (GOS), which are markers for expression of the gastric phenotype, revealed that these mucins were positive in submucosal adenocystic proliferation and carcinoma at the anastomotic site. Conversely, in the gastric body these mucins disappeared with progression of dysplasia, and carcinoma cells contained neither PCA- nor GOS-positive mucins. These results suggest that there are two different processes of carcinogenesis in the gastric remnant, depending on the location, and that denervation of the remnant gastric mucosa promotes the development of cancer-related lesions in the gastric body.

Animals↗