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PubMedDate not supplied

Experimental American trypanomiasis in rats: sympathetic denervation, parasitism and inflammatory process.

Tissue parasitism, inflammatory process (histologic methods) and sympathetic denervation (glyoxylic acid-induced histofluorescence for demonstration of catecholamines) were studied in the heart (atrium and ventricle) and the submandibular gland of rats infected with the Y strain of Trypanosoma cruzi. In the heart paralleling intense parasitism and inflammatory process, the sympathetic denervation started at day-6 of infection and at the end of the acute phase (day 20) practically no varicose nerve terminals were found in both myocardium and vessels. In the submandibular gland, in spite of the rarity of amastigote pseudocysts and the scarcity of inflammatory foci, slight to moderate (days 13-15 of infection) or moderate to severe denervation (day 20) was found. At day 120 of infection both organs exhibited normal pattern of sympathetic innervation and only the heart showed some inflammatory foci and rare pseudocysts (ventricle). Our data suggest the involvement of circulating factors in the sympathetic denervation phenomena but indicate that local inflammatory process is, at least, an aggravating factor.

Animals↗
PubMedDate not supplied

Muscle biopsies show that FES of denervated muscles reverses human muscle degeneration from permanent spinal motoneuron lesion.

This paper presents biopsy analyses in support of the clinical evidence of muscle recovery induced by a new system of life-long functional-electrical-stimulation (FES) training in permanent spinal-motoneuron-denervated human muscle. Not earlier than 1 year after subjects experienced complete conus cauda lesion, their thigh muscles were electrically stimulated at home for several years with large skin surface electrodes and an expressly designed stimulator that delivered much longer impulses than those presently available for clinical use. The poor excitability of long-term denervated muscles was first improved by several months of twitch-contraction training. Then, the muscles were tetanically stimulated against progressively increased loads. Needle biopsies of vastus lateralis from long-term denervated subjects showed severe myofiber atrophy or lipodystrophy beginning 2 years after spinal cord injury (SCI). Muscle biopsies from a group of 3.6- to 13.5-year denervated subjects, who underwent 2.4 to 9.3 years of FES, show that this progressive training almost reverted long-term muscle atrophy/degeneration.

Adult↗
PubMed1987

Opioid neuronal denervation in Gilles de la Tourette syndrome.

Increased striatal dopaminergic functions with heightened postsynaptic receptor sensitivity has been proposed to underlie the major clinical symptoms of Tourette's syndrome (TS). The beneficial response of the majority of TS patients to haloperidol supports the hyperdopaminergic pathophysiological concept of TS. However, in 5 recently encountered TS patients, haloperidol failed to ameliorate self-injurious behavior (SIB) while the opiate antagonist, naloxone, attenuated SIB, implicating deranged endorphinergic mechanisms in the pathophysiology of this disorder. Brain damage is commonly associated with partial neuronal denervation, denervation supersensitivity and neuronal habituation (Cannon's Law). While the motor tics of TS possibly reflect neuronal denervation of striatal dopaminergic neurons. SIB may represent opioid denervation with alterations in opioid receptor sensitivity possibly involving striato-limbic-hypothalamic circuits. The effect of naloxone on SIB in TS could thus be explained on the basis of a modulatory effect of this drug on opioid receptor sensitivity.

Brain↗
PubMed2003

Myostatin expression in age and denervation-induced skeletal muscle atrophy.

Myostatin is hypothesized to regulate skeletal muscle mass and to be a potential target for therapeutic intervention in sarcopenia. To clarify whether myostatin is invariably associated with sarcopenia, this study examined the levels of expression of myostatin mRNA and protein in Sprague Dawley rats during aging- and denervation-induced sarcopenia. The level of myostatin mRNA in the gastrocnemius decreased progressively with age being 9, 34 and 56% lower at 6, 12 and 27 months, respectively, compared with mRNA levels at 1.5 months. In contrast, two low molecular mass isoforms of myostatin protein identified by Western blotting increased progressively with age. With denervation, myostatin mRNA was 31% higher on day 1 but by 14 days after sciatic neurectomy when the muscle had atrophied 50%, myostatin expression decreased 34% relative to the sham operated limb. Western analysis of the denervated gastrocnemius showed that myostatin protein levels varied in parallel with mRNA. These disparate patterns of expression of myostatin during age- and denervation-induced atrophy suggest that the regulation of myostatin is complex and variable depending on whether the atrophy is slowly or rapidly progressive.

Journal Article↗
PubMed1988

Effect of hypothermia on the twitch and tetanic contractions of denervated rat diaphragm muscle under isotonic conditions.

Effect of hypothermia was studied on the twitch and tetanic contractions of the chronically denervated rat diaphragm muscles under isotonic conditions. The muscles were denervated for 15-20 days and the temperature was lowered from 35 degrees C to 15 degrees C. The results showed that hypothermia and chronic denervation had very little effect on the isotonic contraction parameters since these were found to be unaltered at all temperatures except at 15 degrees C. It is suggested that denervation has no significant effect on the contractile component of our experimental muscles.

Journal Article↗
PubMed1989

Effects of hypertension and sympathetic denervation on cerebral blood flow in newborn pigs.

To investigate the potential role of sympathetic nerves in preventing pronounced increases in cerebral blood flow, we evaluated the effects of abrupt hypertension on the cerebral circulation of newborn pigs with intact cerebral sympathetic innervation and after cerebral sympathetic denervation. Epinephrine infusion was used to induce abrupt increases in mean (+/- SEM) arterial pressure (innervated pigs, 62 +/- 3 mm of Hg to 115 +/- 3 mm of Hg; denervated pigs, 71 +/- 4 mm of Hg to 132 +/- 4 mm of Hg) that remained increased for the 3 minutes of the study. Abrupt hypertension increased blood flow to all brain regions. In denervated pigs, the increased flow to the cerebrum was prolonged, compared with that in pigs with intact sympathetic innervation. Differences between pigs of the innervated and denervated groups were not apparent, with respect to blood flow to any other region (caudate region, brain stem, cerebellum). In newborn pigs, sympathetic nerves may attenuate hypertension-induced increases in blood flow to the cerebrum, but do not appear to affect flow to the rest of the brain.

Animals↗
PubMed1989

An attempt to prevent or delay denervation changes in rat muscles.

A number of drugs which are known to affect lysosomes and their enzyme activities were used in an attempt to inhibit or delay the onset of denervation changes in rat muscles. The following parameters were used: the occurrence of fibrillations in electromyographs; diameters of muscle fibers; acid phosphatase activity; acetylcholinesterase activity and distribution in end plates. Differences between denervated and non-denervated limbs were evaluated and compared in the different treatment groups. The various parameters were differently affected by the different drugs. Chloroquin, thiouracil and streptomycin appeared to be more effective than other treatments in the inhibition of denervation changes.

Animals↗
PubMed1988

[Experimental cerebral vasospasm induced by oxyhemoglobin and the sympathetic nervous system (Part 2): An investigation into denervation supersensitivity].

UNLABELLED: The pathological mechanism of cerebral vasospasm following subarachnoid hemorrhage has not been well clarified until now. There have been reports that denervation supersensitivity in cerebral vessels occurring after subarachnoid hemorrhage may possible play a role in the appearance of cerebral vasospasm. On the other hand, we have accepted that oxyhemoglobin (Oxy-Hb) is an important spasmogenic substance. In the present study, we investigated the effect of chemical denervation (reserpine or 6-hydroxydopamine: 6-OHDA) and surgical denervation (bilateral superior cervical ganglionectomy: SCG) on the constrictive sensitivity of cat basilar arteries to noradrenaline (Nor) and oxyhemoglobin (Oxy-Hb) in situ. METHOD: Adult cats were anesthetized with intramuscular pentobarbital and maintained on a respirator through a tracheostomy. By the transclival approach, the basilar artery was exposed. A cannula was then inserted into the subarachnoid space, and through it, Oxy-Hb and Nor were injected. The sequential changes in caliber of the basilar artery were measured using photography. SCG was done 7 days before the application of Nor or Oxy-Hb and 14 days before application of Oxy-Hb. Pretreatment with reserpine was done as follows: 1 mg/kg of reserpine was injected subcutaneously once each day for 2 days. On the following day, the sensitivity of the basilar arteries to Nor or Oxy-Hb was assessed. Pretreatment with 6-OHDA was done as follows: 5 mg of 6-OHDA was dissolved in 1.0 ml of artificial CSF, and then injected into the cisterna magna. Seven days later, Nor or Oxy-Hb was applied. RESULTS: Pretreatment with reserpine tended to increase the vasoconstriction induced by 10(-7)-10(-4) M of Nor and the constriction induced by 10(-3) M of Nor was increased statistically (P less than 0.05). Cisterna magna injection of 6-OHDA tended to increase the vasoconstriction induced by Nor. SGG tended to increase the vasoconstriction induced by 10(-7)-10(-4) M of Nor and at a dose of 10(-3) M of Nor, the constriction of the basilar arteries was increased statistically (P less than 0.05). However, pretreatment with reserpine, 6-OHDA and SCG did not increase the vasoconstriction induced by Oxy-Hb. These results lead us to suggest that denervation supersensitivity does not participate in the vasoconstriction induced by Oxy-Hb.

Animals↗
PubMed1983

Pancreatic intraductal pressure: II. Effects of autonomic denervation.

The effects of autonomic denervation, local anaesthesia, and electrical stimulation on pancreatic intraductal pressure were studied in a group of dogs. Pressure studies were performed via a catheter placed in the distal pancreatic duct and by a transsphincteric route. Periampullary application of lidocain produced a decrease in the distal pancreatic duct pressure. Bilateral vagal section resulted in a significant pressure decrease while celiac ganglion plexus denervation produced additional pressure decreases. Electrical stimulation of the ampullary region resulted in a significant pressure increase. With transsphincteric pressure studies, bilateral vagotomy did not produce a significant pressure change, while celiac plexus denervation and pancreatic duct perfusion with lidocainin resulted in a moderate decrease in pressure. Electrical stimulation of the completely denervated perampullary region resulted in a significant pressure increase. These results suggest that the autonomic nervous system may affect the pancreatic ductal pressure, via its action on the sphincter mechanism of the main papilla, as well as on the ductal system. Local duodenopancreatic reflexes may play an additional role in controlling pancreatic duct pressure.

Animals↗
PubMed1994

[Magnetic resonance imaging in denervated muscle. A preliminary study].

Ten patients with various forms of peripheral neuropathy and spinal radiculopathy were examined with MRI using a low-field permanent magnet (0.2 T) and spin echo (SE)/inversion recovery (IR) sequences, with an adequate inversion time to suppress healthy muscle signal. In acute denervation MR sensitivity was low on both sequences; in subacute denervation the damaged muscle was more intense than the healthy muscle only on IR sequences. MRI adequately depicted fatty infiltration in chronic denervation. In conclusion, MRI is a promising tool for mapping and noninvasively monitoring denervated motor units in skeletal muscles, whose role is currently complementary to that of electromyography.

Acute Disease↗
PubMed1993

[The effect of electroacupuncture on the function of the partially denervated bladder in rabbits].

Experiments were done with male rabbits (2.5-3.0 Kg). The postganglionic fibers from bilateral pelvica ganglia to the bladder were excised partially and resulted in reversible retention urine. The pressure-volume curve of bladder and volume of residual urine was measured at the third day, sixth day, thirteenth day, twentieth day and twenty-seventh day after the operation of denervation and compared with preoperation respectively. The rabbits were divided into two groups at random. In electroacupuncture group, immediately after the operation of denervation, the intradermal needles were implanted in derma of bilateral "Subcortex" auriculopoint. Before each measurement electroacupuncture at these points and bilateral "Shenshu" (somatic point) was given for 10 minutes. In control group, the operation of denervation was undergone as well but did not be implanted the needle and given electroacupuncture. The results showed that, before the operation a smooth or slowly uniform rising wave appeared on the pressure-volume curve of bladder and only a peak repeated on this background at an instant every injecting water. But after the operation, due to losing of control of parasympathetic nerve partially the pressure-volume curve of bladder appeared ascending step wave evidently after every injecting water. The bladder volume and the residual urine increased evidently. The differences between before and after the operation were statistically significant (P < 0.05). It showed that, after denervating partially the adaptation of the rabbits' bladder was decreased. But on the third day and the sixth day after operation the residual urine decreased more evident in electroacupuncture group than in control group (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Points↗
PubMed1995

[Clinical response of different colonic segments to chemical denervation: an experimental study].

An experimental study in rats with chemical myenteric plexus destruction of different segments of large intestine is presented. Forty Wistar rats weighing 200-250 g were used. Four groups of ten animals each were made. Group I: control; group II: myenteric denervation of 4 cm segment of rectosigmoid; group III: myenteric denervation of 4 cm segment of descending colon; group IV: myenteric denervation of 4 cm segment of transverse colon. Myenteric denervation was produced by serosal application of 0.1% benzalconium chloride during 30 minutes. Animals were evaluated by clinical parameters (survival, weight change, food intake, nutritional state), radiological (barium enema) and histomorphometry. Group IV showed the greatest mortality, nutritional deterioration and colonic obstruction while the results of group II are similar to control group.

Animals↗
PubMed1995

Regional sympathetic denervation after myocardial infarction: a follow-up study using [123I]MIBG.

Previous studies in dogs have shown that experimental infarction produces myocardial sympathetic denervation not only in the infarcted area, but also in a region apical to the infarction. In these dogs MIBG myocardial scintigraphy detected denervation but returned to normal in a few months at which time reinnervation was shown to have occurred. Myocardial sympathetic denervation was studied with MIBG scintigraphy in ten patients after their first acute transmural myocardial infarction; scans were repeated at 4 months, one year and 30 months to follow the time course of possible reinnervation. Except during the first 48 hours following the infarction, no therapy except for antiaggregants was administered to the patients; during this follow-up period no cardiac events were seen. One week after infarction, comparison of MIBG images with perfusion scans revealed that the denervated area was larger than the infarcted area; no difference in MIBG uptake by the infarcted myocardium was found during the 30 months follow-up.

3-Iodobenzylguanidine↗
PubMed1998

[Cardiac sympathetic denervation after aortic surgery in a patient with thoracic dissecting aneurysm: a case report].

We experienced a case of a 60 year-old man with cardiac sympathetic denervation after aortic graft replacement of ascending aorta for a dissecting aneurysm (Debakey type II). Fourteen years after pheochromocytomectomy (paraganglioma), the patient developed a severe chest pain, and admitted to the hospital for the diagnosis of dissecting aneurysm. CT scan with contrast enhancement revealed thrombosed dissecting aneurysm in the region of ascending aorta to aortic arch. Graft replacement was undergone on the same day. 123I-MIBG imaging 20 days after the operation showed severely attenuated myocardial uptake (heart to mediastinum ratio 1.19), although the MIBG imaging before the operation showed normal myocardial uptake (heart to mediastinum ratio 1.55). Heart rate variability analysis in Holter ECG showed that the power of the low frequency (LF), that of the high frequency (HF) and L/H ratio were severely decreased. MIBG and heart rate variability analysis indicated that cardiac sympathetic and parasympathetic nerve were denervated. This is the first report of cardiac sympathetic denervation after aortic vascular surgery. Clinical significance of cardiac sympathetic denervation after aortic vascular surgery is uncertain, and further investigation will be required.

3-Iodobenzylguanidine↗
PubMed1997

Sensory and motor denervation influence epidermal thickness in rat foot glabrous skin.

Denervation in man often results in shiny, dry, thin skin. A previous study has shown that the epidermis of glabrous skin in the rat becomes approximately 40% thinner within 1 week following sciatic nerve transection, but which nerve fiber type or types influence epidermal thickness is unknown. In this study, we compared the effects on the epidermis of selective sensory, motor, and sympathetic denervation. Protein gene product 9.5 and calcitonin gene-related peptide immunocytochemical staining were used to determine the extent of denervation of epidermis, dermis, and sweat glands in the footpads. Epidermal thickness of the glabrous plantar skin of the foot was measured. To verify the specificity and reliability of each animal model, the relevant regions of the peripheral nervous system were examined by light or electron microscopy or both. Epidermal thickness decreased significantly following sciatic nerve transection (58% of control, P < 0.05) and dorsal root ganglionectomy (59%; P < 0.05). The thickness also decreased following lumbar ventral rhizotomy (61%; P < 0.01), destruction of lumbar spinal motor neurons (66%; P < 0.05), and botulinum toxin-induced paralysis of the tibialis anterior and gastrocnemius muscles (70%; P < 0.05). A slight decrease followed dorsal rhizotomy (84%; P < 0.01). In contrast, no significant alterations in epidermal thickness were detected following sham operation and sympathectomy. Epidermal thinning was paralleled by reductions in the amounts of transcripts for glyceraldehyde-3-phosphate dehydrogenase and beta-actin. These results suggest that selective loss of both sensory and motor fibers to the hind limb can contribute to reducing epidermal thickness in rat foot glabrous skin.

Actins↗
PubMed1991

Posterior cricoarytenoid muscle denervation.

Vocal fold paralysis most commonly results from injury to the recurrent laryngeal nerve. The length of time required for denervation atrophy would be useful in planning reinnervation procedures. Given the absence of long-term data on the status of the canine posterior cricoarytenoid muscle following denervation, this study was undertaken. The results indicate that muscle atrophy does not occur for at least 1 year following denervation.

Animals↗
PubMed1998

Regulation of prothrombin, thrombin receptor, and protease nexin-1 expression during development and after denervation in muscle.

Prothrombin, thrombin receptor (ThR), and protease nexin-1 (PN-1) mRNA levels in mouse muscle were quantified using competitive reverse transcriptase-polymerase chain reaction during development and after denervation to examine the possible role of thrombin in activity-dependent synapse elimination at the neuromuscular junction. The results showed that the levels of prothrombin and ThR were maximal at birth and decreased by two orders of magnitude by postnatal day 20 (P20). The level of PN-1 mRNA was fairly constant during development except for a 4-fold to 5-fold downregulation at P10 and P15, the periods of maximal synapse elimination at the rodent neuromuscular junction. The expression of prothrombin mRNA in muscle at birth was 41-fold and 22-fold lower than those of ThR and PN-1, respectively, and the level of difference between prothrombin and PN-1 reached almost three orders of magnitude at adulthood. Denervation of adult muscle resulted in a reversal of the relative expression levels of the three genes. There were rapid 8-fold and 10-fold increases in prothrombin and ThR mRNA, respectively, and a 2-fold decrease in PN-1 mRNA. The changes in mRNA levels of the three genes after denervation indicated that these genes were regulated in a innervation-dependent manner and that nerve activity may play an important regulatory role in the expression of prothrombin, ThR, and PN-1. The concurrent regulation of prothrombin and ThR suggests that thrombin-mediated cellular activities in muscle may be affected via the activation of ThR. An elevated level of local thrombin or thrombin-like activity might result from the decreased inhibitory activity of PN-1 during the period of peak synapse elimination in muscle development.

Amyloid beta-Protein Precursor↗
PubMed1996

Rapid activity-dependent sprouting of optic fibers into a local area denervated by application of beta-bungarotoxin in goldfish tectum.

The retinotectal projection is known to be capable of extensive long-term expansion of connections, but it is not known how fast such changes can occur or what triggers sprouting of terminals. We studied sprouting of optic fibers into an area denervated by local microinjection of beta-bungarotoxin (beta-BTX), a specific presynaptic neurotoxin with phospholipase A2 activity that destroys nerve terminals at the neuromuscular junction. After injection of 0.1 pmol of beta-BTX, the optic terminals fired spontaneously with decreasing amplitude and became silent within 1 to 2 h. Outside the injection zone, the retinotectal map was normal, so the silent zone was associated with a scotoma in the visual field. Horseradish peroxidase (HRP) staining of the entire optic nerve showed a denervated region at the injection site with beaded, degenerating fibers at its edge. Between 3 and 9 days later, optic units were recorded within the injection zone whose receptive fields lay just outside the scotoma in the visual field, indicating that intact surrounding terminals had sprouted into the area. These sprouts made functional connections, as indicated by field potential recordings and current source-density analysis. At this time, HRP staining also demonstrated retinal innervation within the injection zone. By 12 days, normal maps with no scotoma were recorded and HRP staining was normal at the injection site, indicating that the beta-BTX-damaged fibers had regenerated to reclaim their tectal sites. The results show that the retinotectal projection of goldfish is very dynamic, since intact optic fibers can sprout into adjacent vacant postsynaptic territory within 2 to 3 days, much faster than previously reported. In a final experiment, we showed that this sprouting is activity-dependent, since it could be prevented by blocking retinal activity with intraocular tetrodotoxin (TTX) during the first 2 days postinjection, even though TTX block of activity does not block regeneration in this system. One possible mechanism for this rapidly triggered sprouting is that arachidonic acid liberated by beta-BTX acts as a sprouting factor to attract surrounding healthy fibers into the denervated region but requires activity at the terminals to be effective.

Animals↗