Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DENERVATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed2004

[The study on the regeneration of skeletal muscles after denervation].

OBJECTIVE: To study the degeneration and regeneration of skeletal muscle after denervation. METHODS: Denervation was carried out in gastrocnemius muscles in 30 adult BALB/C mice by cutting the sciatic nerve. The gastrocnemius muscles were removed at 1, 2, 4, 8, 12, 16 weeks after denervation, respectively. Specimens were processed for histological study and immunohistochemical technique. RESULTS: Muscle fiber atrophy followed by degerneration and regeneration was observed in the early period of denervation. Fusion of the regenerated muscle cells with each other followed by degeneration of the cells and growth of fibro-connective tissue were observed in the later stage. The expression of myoglobin and actin decreased in 1-4 weeks after denervation. The postive expression of the proteins was observed in some 8 weeks' cells and in many degenerated 12-14 weeks' muscle cells. CONCLUSION: Degeneration and regeneration may coexisted in the denervated muscles. The regenerated muscle cells can't fully develop due to the deficit of nerve regulation and degenerate again. The regenerated muscle cells will melt each other and can't develop to mature muscle fiber in the later stage.

Animals↗
PubMed2004

A new ovarian denervation technique and it's effect on sexual cycle, conception rates and offspring numbers in rats.

OBJECTIVES: A novel denervation technique of ovarian was used in rats to investigate its effects on sexual cycle, pregnancy rates and offspring numbers. SETTING AND DESIGN: A total of 34 female albino rats were included. Animals were divided into 3 groups. METHODS: In group 1, ovaries were bilaterally denervated. Animals in group 2 underwent sham operation and group 3 comprised of controls. Sexual cycles in animals were followed by vaginal irrigations. Gestations were determined with parturition of rats. RESULTS: Results indicated that in denervated rats, frequency of estrus decreased and period of estrus increased resulting in a decrease in conception rates and offspring numbers when compared to control rats. MAIN FINDINGS: Although the results were consistent with previous denervation techniques, the operational procedure described herein is simpler and requires no sophisticated equipment, suggesting this to be a method of choice in reproductive physiology studies. CONCLUSION: In this study, we denervated the ovary with a technique other than classical in which the tissues except vascular structures over ovarian suspensory ligament were excised. We found that, estrus count decreased, duration of sexual cycle increased, conception rates and the offspring numbers reduced. This is thought to be a result of blockage of ovarian neural control due to denervation.

Animals↗
PubMed2006

Histological evidences of reparative and regenerative effects of beta-adrenoceptor agonists, clenbuterol and isoproterenol, in denervated rat skeletal muscle.

The aim of this study was to determine the contribution of beta-adrenoceptor activation in the reconstruction of the structural and functional organization of denervated skeletal muscle. beta-agonists, clenbuterol (1.2 mg/kg body weight) and isoproterenol (2 mg/kg body weight), administration (daily oral administration; maximum 7 days) to normal innervated rats as well as denervated animals caused muscle hypertrophy. An increase in mean fiber diameter confirmed this stimulated growth both in normal innervated and denervated rat gastrocnemius muscle. Examination of muscle nuclei from treated but normal innervated rat gastrocnemius exhibited features like large size, active nucleoplasm and an increase in their number per fiber cross section and per mm mean fiber length indicating towards an elevated biosynthetic activity in tissue in the presence of beta adrenoceptor agonists. Administration of drugs to normal innervated animals resulted in an emergence of central muscle nuclei. The hyperactive and enlarged muscle nuclei ultimately organized themselves into unusually elongated nuclear streaks. beta agonist treatment to denervated rats resulted in amelioration of atrophic state of tissue characterized by hypertrophy of muscle fibers thus lending to a restoration of structural organization of tissue. Bizarre shapes of nuclei in denervated muscle tend to recover to that characteristic to normal innervated muscle in presence of clenbuterol and isoproterenol hydrochloride. All observations were confirmed by administering butoxamine, a beta-adrenoceptor antagonist along with beta-agonists. The results suggests that both clenbuterol and isoproterenol hydrochloride are capable of mimicking normal innervation functions in skeletal muscle and thus play important role in the structural and functional reorganization of tissue. Amelioration of denervation atrophy in rat gastrocnemius in the presence of beta-agonists supports this.

Adrenergic beta-Agonists↗
PubMed1991

The relationship between renal sympathetic nerve activity and arterial pressure after selective denervation of baroreceptors and chemoreceptors.

The relationship between an acute increase in arterial pressure and renal sympathetic nerve activity produced in rats under chloralose anesthesia after carotid and sinoaortic denervation was analyzed by quantifying the nerve activity associated with arterial pressure changes. After sinus denervation there was no change in arterial pressure (125 +/- 2.3 vs 124.6 +/- 5 mmHg, N = 6), but the renal sympathetic nerve activity (10.8 +/- 0.9 vs 8.0 +/- 1.1 bars s-1 cycle-1, N = 6) was significantly decreased. In spite of this, baroreflex control of renal sympathetic nerve activity was the same as during the control period. After sinoaortic denervation, there were simultaneous increases in arterial pressure (from 124 +/- 2.3 to 188 +/- 6 mmHg, N = 6) and renal sympathetic nerve activity (from 10.8 +/- 0.9 to 13.7 +/- 2.9 bars s-1 cycle-1) with marked attenuation of the baroreflexes. Spectral analysis of arterial blood pressure after sinus denervation showed a shift of a 1-Hz peak to 0.7 Hz, probably related to a decrease in respiratory frequency. The results suggest that after sinoaortic denervation the acute increase in arterial pressure is only due to aortic denervation.

Animals↗
PubMed1991

Hyperpolarization of denervated skeletal muscle by lemakalim and its antagonism by glybenclamide and tolbutamide.

Innervated skeletal muscles are endowed with K+ channels activatable by K+ channel openers. It is of interest to know whether the denervation-induced depolarization is due to a deficiency of such a K+ channel. In denervated mouse diaphragm, lemakalim, a K+ channel opener, effectively hyperpolarizes membrane and reduces membrane resistance, spontaneous activity as well as twitch force reversibly. Reductions of transmembrane K+ gradient diminish the lemakalim-induced hyperpolarization. In voltage-clamped fiber, lemakalim induces a long-lasting outward current. A current clamp experiment suggests a reversal potential of around -90 mV. On innervated diaphragm, lemakalim hyperpolarizes membrane and increases conductance if the muscle is predepolarized by anodal current. Lemakalim, however, is much less effective in overcoming the depolarization caused by crotamine, which activates Na+ channel. The effects of lemakalim are not attenuated by blockades of membrane Na+, Ca++ and Cl- permeabilities. Glybenclamide and tolbutamide, blockers of ATP-regulated K+ channel, antagonize the effects of lemakalim at low concentrations and produce slight membrane hyperpolarizations in denervated muscle, but marked membrane depolarizations in innervated muscle at higher concentrations. Cs+ depolarizes both innervated and denervated diaphragms and reduces the hyperpolarizing effect of lemakalim. The results suggest that lemakalim hyperpolarizes denervated muscle via glybenclamide sensitive K+ channels. It is inferred that a reduction of membrane K+ conductance rather than an increase of Na+ or Ca++ conductance contributes to the denervation-induced depolarization.

Animals↗
PubMed1990

Electrophysiological analysis of adrenergic neurotransmission and its modulation by chronic denervation in canine saphenous veins.

The present experiments were undertaken to investigate the electrophysiological responses of the canine saphenous vein evoked by perivascular nerve stimulation, norepinephrine or selective alpha adrenergic agonists before and after chronic sympathetic denervation. Unilateral sympathectomy was performed from T12 to L9 in adult female dogs. After 3 to 5 weeks, the denervated saphenous veins were removed. Innervated saphenous veins were obtained from unoperated dogs. In innervated but not in denervated veins, electrical stimulation generated excitatory junction potentials and a slow depolarization. The slow depolarization was inhibited by rauwolscine or phentolamine, but not by prazosin, whereas excitatory junction potentials were not inhibited by alpha adrenergic blockers. Exogenously applied norepinephrine caused a depolarization of the membrane that was inhibited by rauwolscine but not by prazosin. The selective alpha-1 adrenergic agonist, phenylephrine, and the selective alpha-2 adrenergic agonist, UK 14,304, caused depolarization. In denervated veins, the threshold concentrations of norepinephrine or UK 14,304 required to depolarize the smooth muscle cell membrane were reduced. Responses to phenylephrine were not affected by denervation. These results indicate that in the canine saphenous vein norepinephrine, whether added exogenously or released from sympathetic nerves, causes predominant depolarization by activating alpha-2 adrenergic receptors. Denervation augments selectively the electrical response to alpha-2 adrenergic stimulation.

Adrenergic alpha-Agonists↗
PubMedDate not supplied

Effects of various drugs on denervation changes in rat muscles.

The effects of drugs, known to affect lysosomal enzyme activities on denervated gastrocnemius muscles of rats were studied. The drugs used were: amiodarone, chloroquine, cortisone, streptomycin and trypan blue. The parameters investigated included changes in fibrillations in electromyographs, morphometric evaluations of muscle atrophy and replacement, and light and electron microscopic analysis of morphological changes and of histochemical acid phosphatase activity. All drug treatments reduced the intensity and frequency of fibrillations. Acid phosphatase spillage was best inhibited by trypan blue. Progressive muscle fiber atrophy with massive aggregation of mitochondria at the cell periphery occurred in denervated fibers. Atrophy was expressed both in loss of muscle weight and in reduction of average muscle fiber diameter. Administration of all the drugs resulted in slowing down of muscle weight loss, particularly 30 days after denervation. All drugs induced slowing down of the loss in average fiber diameter on day 3 after denervation, while on day 10 only cortisone and amiodarone still exerted this effect. A similar transitory slowing of denervation changes was observed in estimations of replacement of muscle by collagen and adipose tissue. Only the effect of trypan blue and amiodarone persisted on day 10. The results indicate that drugs known to inhibit lysosomal enzyme activity may slow down the denervation-derived muscle atrophy to a certain extent, but the effects are transitory.

Acid Phosphatase↗
PubMedDate not supplied

[Cyclic nucleotide levels, adenylate cyclase activity and membrane potential of the gastrocnemius muscle fibers following denervation in adult and old rats].

The denervation-induced changes of cyclic nucleotide concentrations adenylate cyclase activity and resting membrane potential were studied in gastrocnemius muscle of adult and old rats. Under conditions of denervation alterations in resting membrane potential and in adrenaline-stimulated adenylate cyclase activity had a biphasic character in the muscle studied: resting membrane potential was increased and the adenylate cyclase activity was decreased following 30 min denervation, while the opposite effect was observed after 2 weeks denervation. The denervation did not alter cGMP concentration. In old animals more pronounced changes of cAMP level were found in denervated gastrocnemius muscle.

Adenylyl Cyclases↗
PubMed1987

Denervation augments alpha-2 but not alpha-1 adrenergic responses in canine saphenous veins.

Experiments were performed in order to determine the influence of sympathetic denervation on alpha-1 and alpha-2 adrenergic responses in canine saphenous veins. In female dogs anesthetized with sodium pentobarbital, the left lumbar sympathetic chain was excised from L1 to L7. After a 3- to 5-week period, the left (denervated) and right (innervated) saphenous veins were removed, cut into rings and suspended for isometric tension recording in organ chambers filled with modified Krebs-Ringer bicarbonate solution. Denervation reduced significantly the norepinephrine content of the venous rings and the contractile responses evoked by the indirect sympathomimetic amine, tyramine. The contractile responses evoked by exogenous norepinephrine were augmented by denervation under control conditions (16.7-fold shift in concentration-effect curve) and also after inhibition of neuronal and extraneuronal uptake and beta adrenoceptors (3.8-fold shift in curve). Denervation increased the contractile responses evoked by the alpha-2 adrenergic agonist, UK 14,304 (5-fold shift in concentration-effect curve), but not those produced by the alpha-1 adrenergic agonist, phenylephrine. The selective augmentation of alpha-2 adrenergic responses by denervation may reflect the preferential innervation of alpha-2 adrenoceptors in the canine saphenous vein.

Animals↗
PubMed1986

Denervation-induced supersensitivity to calcium of chemically skinned smooth muscle of the guinea-pig vas deferens.

Chronic denervation of the smooth muscle of the guinea-pig vas deferens results in postjunctional supersensitivity. A partial membrane depolarization contributes to the enhanced sensitivity. However, there is evidence that supersensitivity results in part from cellular alterations other than membrane potential changes. In the present study we investigated the possibility that changes in the sensitivity of the contractile proteins may contribute to the phenomenon. The approach was to evaluate the concentration-response relationship for calcium of "skinned" preparations of guinea-pig vas deferens. The tissues were chemically skinned with either triton X-100 or saponin. Concentration-response curves for calcium were constructed 1 week after postganglionic denervation of one of a pair of vasa deferentia. The curve for denervated tissues was shifted significantly to the left of control (1.5-fold at the level of the EC50). In addition to supersensitivity, denervated skinned preparations exhibited a faster rate of contraction. The phenothiazine compounds trifluperazine, fluphenazine and chlorpromazine relaxed skinned muscles which were contracted with calcium. The relaxation was concentration-dependent, and was less pronounced in denervated vasa deferentia than in controls. These results suggest that increased sensitivity of the contractile proteins may contribute to denervation-induced supersensitivity of smooth muscle, and further that this may be related to a change in the activity or amount of calmodulin.

Animals↗
PubMed1993

Mechanical response of lizard skeletal muscles to disuse: II. Effect of short-term denervation.

The gastrocnemius muscles of Uromastix hardwickii were used to determine the effects of the absence of neural influence on them. For this purpose, the muscles were denervated for 7 days and were used to record isometric twitch and tetanus. The contraction parameters thus obtained from the denervated muscles were then compared with their own controls. The isometric tensions and time dependent tension parameters were significantly lower in the denervated muscles. The time dependent parameters, peak duration in twitch and duration of active state in twitch were however, found to be unaffected by short-term denervation with the exception of twitch/tetanus half relaxation time ratio, which was significantly higher in the denervated muscles. The denervation effects observed on the mechanical contraction behaviour of the gastrocnemius muscle have been discussed in terms of electrical excitation, excitation-contraction coupling and cross bridge interaction.

Animals↗
PubMed1993

Wrist denervation procedures in the treatment of Kienböck's disease.

In almost all papers on wrist denervation, indications for denervation in Kienböck's disease has been mentioned without exact data. A detailed analysis of our clinical data on 61 patients proved the positive effect with respect to pain relief. In the 47 patients in which the denervation was combined with other procedures, such as radial shortening, ulnar lengthening, lunate excision, and replacement by silicone or tendon, pedicled pisiform transposition, and STT arthrodesis, a very high rate of patients (76%) had no complaints or pain only with heavy manual work. Of these treated patients, 88% were very or remarkably satisfied. About the same success rate was found in cases in which the denervation was applied as a single procedure. The extent of denervation was different; therefore, it can be concluded that partial or complete denervation has its value as an additional or single procedure in the treatment of Kienböck's disease, especially in the advanced stages (Decoulx's stages III and IV).

Denervation↗
PubMed1996

Effects of denervation on acetylcholine receptor clusters on frog cardiac ganglion neurons as revealed by quantitative laser scanning confocal microscopy.

We examined the effects of denervation on clusters of nicotinic acetylcholine receptors (AChRs) on autonomic neurons in the frog heart using immunofluorescence techniques and laser scanning confocal microscopy. We showed previously that normally innervated neurons have both large, brightly stained AChR clusters and small, dim AChR clusters. A majority (80%) of the large/bright AChR clusters are located at synaptic sites, whereas the small/dim clusters are distributed widely over the cell surface. Here, we use image analysis to identify these two classes of clusters on images generated from stacks of optical sections through neuronal cell bodies and to examine the effects of denervation on their number, size, and brightness (pixel intensity). Denervation reduces the number of large/ bright AChR clusters per cell to < 10% of sham-operated values and increases the number of small/dim clusters per cell by two- to threefold. These changes occur at 4 d of denervation, the earliest time examined, and are sustained for 6 weeks. The size of large/bright AChR clusters is decreased compared with sham-operated controls, and their brightness is unchanged. The size of small/dim AChR clusters is unchanged by denervation, but their brightness is increased. Denervation results in a shift in the contribution of each AChR cluster class to the total measurable AChR pool-from one dominated by large/bright clusters to one dominated by small/dim clusters. These results show that the nerve terminals on cardiac ganglion neurons appear to exert a continual and reversible influence on the organization of the postsynaptic membrane.

Animals↗
PubMed1993

Changes in bone formation during experimental tooth movement after denervation of the rabbit inferior alveolar nerve.

The effects of nerve fibers on bone formation during tooth movement were examined using eight rabbits with denervation of inferior alveolar nerve (IAN). IAN on one side for all the animals was denervated and and sham operation was performed on the other side of denervation. The distance of tooth movement on the denervated and sham operated sides was very similar and 1.20 +/- 0.17 and 1.24 +/- 0.12 (mean +/- S.D. mm), respectively. From the fluorescent observations, the denervated and sham operated sides in the animals without tooth movement i.e. control group showed similar morphology. The animals with tooth movement i.e. experimental group showed significant new bone formation than the control group. However, the amount of new bone formation on the denervated side was less than the sham operated side. It was suggested that the nerve fibers might play some roles on bone formation during the tooth movement.

Alveolar Process↗
PubMed1998

Cell trafficking, mediator release, and articular metabolism in acute inflammation of innervated or denervated isolated equine joints.

OBJECTIVES: To describe the acute cellular response, inflammatory mediator release, and effect on chondrocyte metabolism of interleukin 1 beta (IL-1 beta) in isolated innervated or denervated equine metacarpophalangeal joints. ANIMALS: One metacarpophalangeal joint of 24 adult horses. PROCEDURES: The metacarpophalangeal joint was isolated for 6 hours in a pump-perfused, auto-oxygenated, innervated or denervated metacarpophalangeal joint preparation. Isolated joints were assigned to 4 groups: control, control-denervated, inflamed, and inflamed-denervated, and inflammation was induced by intra-articular injection of IL-1 beta. Synovial fluid was collected for cytologic examination and determination of IL (IL)-1 beta, (IL-6), prostaglandin E2 (PGE2), and substance P (SP) values. Synovial membrane was immunostained with SP and nerve-specific enolase (NSE) antibodies. Cartilage was collected for determination of proteoglycan (PG) synthesis and degradation. RESULTS: IL-1 beta induced significant neutrophilic leukocytosis in synovial and synovial membrane. IL-1 beta concentration and returned to baseline by 5.5 hours, but IL-6 concentration significantly increased throughout the study. Total SP content was significantly higher in inflamed joints. There was a significant increase in 24- and 48-hour PG degradation in inflamed innervated joints. CONCLUSION: Cellular response to IL-1 beta was rapid and sustained; joint clearance of IL-1 beta was rapid, and endogenous production of IL-1 beta did not follow. The IL-6 and PGE2 concentrations significantly increased, and SP content was increased in association with inflammation but not denervation. A degradative response of cartilage of IL-1 beta was observed, and was enhanced by innervation. This model was useful for investigation of the articular response to acute inflammation and the influence of denervation in modulating this response.

Animals↗
PubMed1998

[Macroscopic and histologic analysis of the rat prostate after denervation].

OBJECTIVE: To determine the role of autonomic innervation in the preservation of the prostate gland structure, we analyzed the gross and histological features of the rat prostate submitted to denervation by resection of the pelvic ganglia. METHODS: The study comprised 80 male Sprague-Dawley rats aged 3 months; 42 were anesthetized and resection of the right pelvic ganglia was performed via laparotomy. Thirty days thereafter they were sacrificed. Gross and microscopic analyses of the right ventral lobe were performed. Computerized morphometric analyses of the areas occupied by the lumen, epithelial and stromal compartments, the height of the epithelium and the vascular pattern were performed. The results were compared with those obtained from the 38 ventral lobes of rats of the same age that had not undergone denervation. RESULTS: Gross examination of denervated rat ventral lobe demonstrated atrophy and weighted 36% less (p < 0.001). Histological analysis of the compartments showed 27.9% were epithelial, 48.3% stromal and 51.8% glandular--epithelial and lumen--for the control group versus 14.8% (p < 0.001), 55.7% and 44.4% (not significant), respectively, for the denervated group. Denervated rat epithelial height measured 39.7% less. No differences in the vascular pattern were found. CONCLUSIONS: Resection of the rat pelvic ganglia, thereby inducing near-total vesico-prostatic denervation, causes structural and functional changes in the rat prostate compatible with atrophy. The observed changes were a reduction in weight and volume, as well as in the height and surface area of the secretory epithelium.

Animals↗
PubMed1998

Chronically denervated rat Schwann cells respond to GGF in vitro.

C-erbB receptor/neuregulin signalling plays a significant role in Schwann cell function. In vivo, Schwann cells up-regulate expression of c-erbB receptors in the first month after injury, but receptor expression is down-regulated with time to levels that are not detectable immunohistochemically. The inability of chronically denervated Schwann cells to respond adequately to signals derived from regenerating axons may be one reason why delayed repair of an injured peripheral nerve frequently fails. We have examined the effects of GGF on denervated Schwann cells in vitro. A modified delayed dissociation technique was used to obtain adult rat Schwann cells from the distal stumps of transected sciatic nerves which had been acutely (7 days) or chronically (2-6 month) denervated. We found that in vitro denervated Schwann cells invariably expressed p75NTR and c-erbB receptors. There was a progressive decrease in total cell yield and the percentage of cells with Schwann cell phenotype (p75NTR and/S-100 or/laminin or /GFAP or/c-erbB positive); proliferation rate; migratory potential; and expression of the cell adhesion molecules N-CAM and N-cadherin, with increasing time of denervation. Addition of GGF2 had a significant stimulatory effect upon Schwann cell proliferation and migration, and an increased proportion of Schwann cells expressed N-CAM and N-cadherin, suggesting that these responses were mediated via GGF/c-erbB signalling. Our results support the view that it may be possible to manipulate chronically denervated Schwann cells so that they become more responsive to signals derived from regrowing axons.

Animals↗
PubMed2003

Brain-derived neurotrophic factor-, neurotrophin-3-, and tyrosine kinase receptor-like immunoreactivity in lingual taste bud fields of mature hamster after sensory denervation.

Unlike lingual taste buds in most mammals, fungiform buds on the anterior tongue of mature hamster survive sensory denervation. The role of the neurotrophin ligands, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), and their respective tyrosine kinase (Trk) receptors, TrkB and TrkC, in denervated taste buds is not known. The present report investigates changes in the degree of gemmal cell immunoreactivity (IR) (i.e., number of immunoreactive cells/bud profile) and density of nerve fiber-IR of these markers in unilaterally denervated mature hamsters. The fungiform bud field after chorda tympani/lingual nerve resection is compared with the nerve-dependent, posterior tongue foliate and circumvallate bud fields after glossopharyngeal nerve resection. Four weeks post lesion, the number of denervated fungiform buds matched that on the unoperated side, whereas denervated foliate and circumvallate bud counts decreased by 72% and 38%, respectively. In taste buds that survived on the posterior tongue, the degree of foliate bud cell BDNF-, NT-3-, and TrkB-like IR, and circumvallate bud cell BDNF- and NT-3-like IR, significantly decreased compared with the unoperated side. In contrast, for anterior tongue fungiform bud cells, the degree of neurotrophin- and receptor-like IR was relatively less affected: NT-3- and TrkB-like IR were unchanged; BDNF-like IR, although significantly decreased, was also maintained. Moreover, TrkB-like fiber IR was essentially eliminated within and surrounding fungiform buds. Hence, NT-3-, BDNF-, and TrkB-like IR in fungiform gemmal cells may reflect an autocrine capacity promoting survival. Because TrkC-like IR in bud cells is absent (i.e., immunonegative), and sparse in fibers intragemmally and perigemmally, NT-3 may also bind to bud cell TrkB so as to sustain fungiform gemmal cell viability post denervation.

Animals↗