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At least 109 records · Page 6Linked to original sources
PubMed2001

Is the postganglionic sympathetic neuron zinc-enriched? A stop-flow nerve crush study on rat sciatic nerve.

Axonal transport of endogenous zinc ions in the rat sciatic nerve was studied by a stop-flow/nerve crush technique combined with zinc selenide autometallography (ZnSeAMG) at light and electron microscopic levels. Distinct accumulations of ZnSeAMG grains were detected, in particular proximal but also distal to the crushes, 1.5 h after the operation, and the amounts of zinc ions increased further in the following 3-8 h. Ultrastructurally, ZnSeAMG grains were located predominantly in unmyelinated axons. The data suggest that a subpopulation of sciatic nerve axons contains and transports zinc ions both antero- and retrogradely, indicating that the second neuron in the sympathetic nervous system is zinc enriched (ZEN).

Animals↗
PubMed1994

Comparative study of microepineural suture, microepineural suture-aided CO2 laser, and laser only anastomoses in rat sciatic nerves.

The cut sciatic nerves of 33 rats were anastomosed by three different methods under the operation microscope; microepineural suture technique, CO2 laser technique, and laser-aided microepineural suture technique. On histologic examination at the end of 3 months postoperatively, in the CO2 laser and suture-aided CO2 laser groups, the degrees of inflammation, fibrosis, and Schwann cell vacuolar degeneration were significantly higher than in the microepineural suture anastomosis group. At the end of 3 months sciatic nerve function was absent in 3 of 11 rats anastomosed by only CO2 laser, however, sciatic nerve functions were found to be normal in the other two groups.

Anastomosis, Surgical↗
PubMed2002

An alternative video footprint analysis to assess functional loss following injury to the rat sciatic nerve.

The rat sciatic nerve is a well-established animal model for the study of recovery from peripheral nerve injuries. Footprint analysis is the most widely used non-invasive method of measuring functional recovery after injury in this model. We describe a new, alternative video analysis of standing (or static footprint video analysis) to assess functional loss following injury to the rat sciatic nerve, while the animal is standing or at periodic rest on a flat transparent surface. We found that this alternative video analysis is technically easier to perform than the corresponding footprint video analysis while walking, but still preserves all advantages of video versus conventional ink track method: i.e. few non-measurable footprints, better repeatability, high accuracy and more precise quantification of the degree of functional loss after sciatic nerve injury in the rat.

Animals↗
PubMed2000

Identification of differentially expressed genes in dorsal root ganglia following partial sciatic nerve injury.

Partial sciatic nerve injury, a model of neuropathic pain, elicits a variety of neurochemical, electrophysiological and neuroanatomical changes in primary sensory neurons. We have used the technique of messenger RNA differential display to identify genes with altered expression in these neurons which may contribute to the development of aberrant sensation following such peripheral nerve damage. This approach identified 14 distinct complementary DNA clones, representing transcripts with increased ipsilateral expression in L4/5 dorsal root ganglia, two weeks after unilateral partial ligation of the rat sciatic nerve. Both Zucker diabetic fatty rats and their lean counterparts were used in this study but none of the transcripts identified showed an induction that was confined to one of the two groups. The majority of the clones did not show significant sequence similarity to previously reported genes and therefore may represent novel messenger RNA sequences or, alternatively, unknown regions of partially characterised messenger RNAs. Two of the clones represented transcripts for the known proteins muscle LIM protein and acidic epididymal glycoprotein, neither of which had previously been associated with expression in the nervous system. Reverse transcriptase-polymerase chain reaction analysis and in situ hybridization confirmed that the messenger RNA expression of both muscle LIM protein and acidic epididymal glycoprotein was induced in an ipsilateral-specific manner. Their localisations, examined with in situ hybridization in L5 dorsal root ganglia, were limited in each case to a sub-population of neuronal profiles. Those neuronal profiles that demonstrated muscle LIM protein hybridization were distributed across the profile size range, whereas the distribution of acidic epididymal glycoprotein-positive profiles appeared to be skewed towards smaller profiles. The induction of muscle LIM protein and acidic epididymal glycoprotein in dorsal root ganglia may play an important functional role in the adaptive response of primary sensory neurons following partial sciatic nerve injury.

Animals↗
PubMed2000

Video analysis of standing--an alternative footprint analysis to assess functional loss following injury to the rat sciatic nerve.

The rat sciatic nerve is a well-established animal model for the study of recovery from peripheral nerve injuries. Footprint analysis is the most widely used non-invasive method of measuring functional recovery after injury in this model. We describe a new alternative video analysis of standing (or static footprint video analysis) to assess functional loss following injury to the rat sciatic nerve, during animal standing or periodic rest on a flat transparent surface. We found good correlation between video recording during standing and dynamic ink track footprint parameter measurements for both 1-5 and injured 2-4 toe spreads only. Reproducibility for these three parameters was also better using the video method. Uninjured 2-4 toe spread by video showed a poor correlation and similar reproducibility as compared with ink. However, both print length parameters measured by video had poorer correlation and greater variability, particularly the print length factor (PLF) was weakly correlated with that determined by ink. Contribution of the footprint factors on the estimated functional loss has also changed in conditions during standing. It was most prominent for the 1-5 toe spread factor (TSF), near marginal for the 2-4 or intermediary toe spread factor (ITF), and weak, statistically insignificant for the PLF. Thus, the introduction of a new functional loss index, or so-called static sciatic index (SSI), and its estimating formula was mandatory. Moreover, using a simple ratio of injured/uninjured 1-5 video toe spread as a substitute for the SSI, we could achieve considerable simplification of the method without any significant loss of accuracy. Our video analysis of standing is technically easier to perform than the corresponding footprint video analysis during walking, but still preserves all advantages of video versus conventional ink track method, i.e. there are few non-measurable footprints, better repeatability, high accuracy and more precise quantification of the degree of functional loss after sciatic nerve injury in the rat.

Animals↗
PubMed1997

A common epineural sheath for the nerves in the popliteal fossa and its possible implications for sciatic nerve block.

Sciatic nerve block in the popliteal fossa is associated with a highly variable success rate. Frequently, anesthesia is profound in the distribution of both the tibial (TN) and common peroneal nerves (CPN), although the response to nerve stimulation or paresthesia is obtained in the distribution of one division of the nerve. However, anesthesia in the distribution of only one division of the nerve is also a common occurrence under apparently identical clinical circumstances. Looking for a possible role of a common epineural sheath in these phenomena, we injected dye into the epineural sheath of the tibial nerve in 10 cadaver legs and observed its spread within the sheath. Injections of 15 mL and 30 mL of the dye resulted in a proximal spread of 147 +/- 34 mm and 172 +/- 50 mm, respectively, from the injection point 10 cm below the popliteal fossa crease. In a majority of the legs, the dye reached the division of the sciatic nerve in the popliteal fossa, bathing both the TN and CPN. Gross inspection and histologic examination of the sciatic nerve specimens revealed a common epineural sheath enveloping the TN and CPN. The presence of the common epineural sheath and its characteristics may have important clinical implications for sciatic nerve blockade in the popliteal fossa.

Humans↗
PubMed2002

Enhanced rate of nerve regeneration and directional errors after sciatic nerve injury in receptor protein tyrosine phosphatase sigma knock-out mice.

The receptor protein tyrosine phosphatase sigma (PTPsigma) is a member of the mammalian leukocyte common antigen-related (LAR) family. Its expression is developmentally regulated in neuronal tissues. The Drosophila homolog of the mammalian LAR family of phosphatases (DLAR) controls axon guidance during Drosophila embryogenesis. We have demonstrated previously that mice deficient in PTPsigma have CNS and peripheral nervous system abnormalities. The sciatic nerve in the PTPsigma(-/-) mice demonstrates an increased number of small diameter fibers and slower nerve conduction velocities compared with PTPsigma(+/+) or PTPsigma(+/-) controls. To study whether peripheral nerve regeneration is affected by PTPsigma activity, we assessed nerve regeneration in the PTPsigma(-/-) mouse after three standard models of sciatic nerve injury. We report that after sciatic nerve crush injury, nerve regeneration was significantly faster in the PTPsigma(-/-) animals, as determined by histologic, electrophysiologic, and neuromuscular testing. After sciatic nerve transection with immediate microsurgical repair or allografting, PTPsigma(-/-) nerve fibers demonstrated errors in directional growth compared with controls. We propose that PTPsigma regulates the axonal regeneration rate and guidance of regenerating fibers.

Action Potentials↗
PubMed1995

Low-affinity nerve growth factor receptor expression in sciatic nerve during P2-peptide induced experimental allergic neuritis.

Northern blot, immunocytochemistry, and single nerve fiber immunostaining were used to determine the expression of low-affinity nerve growth factor (NGF) receptor (p75NGFR) in the peripheral nervous system of Lewis rats during the course of experimental allergic neuritis (EAN) induced with 100 micrograms of 'SP26' synthetic peptide, corresponding to residues 53-78 of bovine P2 myelin protein. This severe reversible polyneuropathy, characterized by extensive multifocal demyelination in nerve roots, and axonal degeneration within sciatic nerve, represents a useful tool to investigate Schwann cell gene expression in these different pathological conditions. Our results showed that both p75NGFR mRNA and protein were induced within sciatic nerve by day 18 and 23 after 'SP26' immunization. By this time, however, p75NGFR was not detectable in roots of cauda equina. These data demonstrate that, during EAN induced by immunization with 100 micrograms of 'SP26', p75NGFR is up-regulated in Schwann cells and in nerve fibers distally along the nerve. This suggests that the induction of the receptor in sciatic nerve during P2-peptide EAN is related to the loss of axonal contact by Schwann cells.

Animals↗
PubMedDate not supplied

Locating the target nerve and injectate spread in rabbit sciatic nerve block.

BACKGROUND AND OBJECTIVES: The purpose of this study is to determine how close the needle tip is placed to the target nerve using a nerve stimulator and to determine how far the injectate spreads in percutaneous nerve blocks. METHODS: Twenty-four sciatic nerves of New Zealand white rabbits were located with a 2-dimensional needle manipulator and a nerve stimulator (pulse width: 100 micros for group I, 250 micros for group II). The stimulation current required to elicit a motor response for each insertion depth of the needle and the nerve-needle distance at which the required current reached the minimum were measured. Another 10 sciatic nerves were located manually using a nerve stimulator and neurolyzed with a mixed solution of 5% phenol and Indian ink (100 microL). RESULTS: The nerve-needle distance was in the range of -1.2 mm to +2.8 mm in group I (1.1 +/- 0.9 mm [mean +/- standard error] in absolute value) and -0.2 mm to +4.8 mm (2.2 +/- 1.7 mm [mean +/- standard error] in absolute value) in group II (positive values signify the center of the beveled surface is past the nerve), when the stimulation current reached the minimum (average minimum current: 0.47 mA in group I, 0.37 mA in group II). Indian ink spread over a significant distance (25.4 +/- 0.5 mm [mean +/- standard error]; range, 19-31 mm) longitudinally within the perineural tissue, and axonal degeneration was observed linearly at the peripheral portion of the nerve fascicle in a similar pattern as Indian ink spread. CONCLUSIONS: The target nerve was located within 5 mm from the needle with less than 0.5-mA stimulation current. The injectate spread to more than 20 mm on average even when a small volume (100 microL) of the injectate was injected in rabbit sciatic nerves.

Animals↗
PubMed1999

Hydro-jet cutting: a method for selective surgical dissection of nerve tissue. An experimental study on the sciatic nerve of rats.

The aim of this study was to answer the question: is it possible to save motor nerves when dissecting tissue with the hydro-jet dissector? In order to study the influence of the hydro-jet on motor nerves the function of the sciatic nerves of 10 Wistar rats was evaluated. The sciatic nerves were dissected bilaterally and only the left one was exposed to the hydro-jet. The water-jet emerged from a nozzle with a diameter of 0.1 mm and was applied to the nerve for 2, 5 or 10 s and with jet pressures of 80, 85 and 90 bar, respectively. After the operation the animals were observed for 5 months in order to monitor the degree of limping using a scale with 10 clinical grades of function. Five months postoperatively the animals were sacrificed and the sciatic nerves were studied by light and electron microscopy. It was found that hydro-jet pressures of 80 bar and exposure times of 2 s had already lead to irreversible damage to the sciatic nerve. Therefore further studies with lower pressures or shorter exposure times are required before considering hydro-jet cutting for parotid gland surgery. It must be confirmed as harmless to motor nerves before applying this method in humans.

Animals↗
PubMed1997

Reinnervation of denervated muscle by transplantation of fetal spinal cord to transected sciatic nerve in the rat.

When motor neurons in the spinal cord are destroyed, regeneration of motor axons and muscle reinnervation cannot be expected. We attempted reinnervation of the denervated muscle, i.e. motor unit reconstruction, using transplantation of the fetal spinal cord to the peripheral nerve. The sciatic nerve of an adult rat was resected for 20 mm, and a cavity was prepared using an autologous femoral vein at the distal stump of the nerve. The fetal spinal cord was then transplanted into the venous cavity. After 3-6 months, no voluntary muscle contraction was observed due to the absence of communication with the central nervous system. However, reinnervation of the muscles via the sciatic nerve by the transplanted spinal neurons was demonstrated electrophysiologically and histochemically. This suggested that a motor unit can be reconstructed by fetal spinal cord transplantation even if the original motor neurons in the spinal cord are not available.

Animals↗
PubMed1983

Rabbit sciatic nerve as a model for studying ganglioside metabolism in regenerating nerve.

The rabbit sciatic nerve contains a sufficient amount of gangliosides for chemical analyses. We have developed a method by which the dorsal root ganglion of L-7 can easily be injected with a radiolabeled precursor of ganglioside biosynthesis. We have used this to demonstrate that gangliosides are synthesized in dorsal root ganglia and then transported into peripheral nerve. Sialyltransferase-I activity is present in dorsal root ganglia, lumbosacral trunk, and sciatic nerve. This model is now well characterized for studies on ganglioside metabolism in degenerating and regenerating peripheral nerve.

Animals↗
PubMed1985

The long-term excitability of myelinated nerve fibres in the transected frog sciatic nerve.

The long-term excitability and the ionic currents in the nodes of Ranvier were studied in the severed frog sciatic nerve and the unoperated contralateral control nerve. After unilateral nerve section, compound action potentials of the nerve bundles and action potentials of single myelinated nerve fibres remained normal in amplitude and duration in either sciatic nerve for more than 38 days when frogs were kept at 11 degrees C. During this period the resting potentials averaged about -75 mV. Under voltage-clamp conditions Na currents and K currents in transected single myelinated nerve fibres also appeared normal in their kinetics, and in their peak amplitudes. These results indicate that the Na- and K-channel densities are quantitatively unchanged after the nerve transection, up to several weeks. The excitability of the severed sciatic nerve, expectedly, depends strongly on the time course of Wallerian degeneration. When frogs were kept at room temperature, the nerve excitability remained normal for only about 8-10 days, due to the faster Wallerian degeneration; whereas at 4 degrees C it was maintained for more than 84 days, as long as the myelinated nerve fibres did not degenerate. Together, these findings demonstrate that Na channels, K channels, and Na-K pumps are continuously present for several weeks in the transected nerve before nerve degeneration. It is surmised that either, (a) these proteins are extremely stable in the transected myelinated nerve fibres, or (b) they are supplied locally by Schwann cells, an open question recently posed by Chiu, Schrager & Ritchie (1984). In either event, the myelinated nerve fibres do not require cell bodies to provide a significant amount of new channels and pumps in order to retain their long-term excitability.

Action Potentials↗
PubMed1995

Effects of nerve growth factor on crushed sciatic nerve regeneration in rats.

The effects of nerve growth factor (NGF) on crushed sciatic nerve regeneration were studied in 30 rats, with 60 bilateral nerves. The nerves were crushed at a site 6 mm distal to the sciatic notch by the standard technique and 3 mm wide crush injuries were created. Then 2.1 microliters of normal saline in the control groups and an equal volume of NGF solution (containing 1 microgram of NGF) in the NGF-treated groups was injected into the crush sites and followed for 12, 28, and 56 days, respectively. At the end of the observation, electrophysiological evaluation was carried out; then samples 10 mm distal to the crush site were removed and prepared for histological and morphometric studies. Evoked muscle action potential (MAP) was recorded in 50% of the NGF-treated group at 12 days but not in the control group; the difference was statistically significant (P < 0.05). The motor nerve conduction velocity (MNCV) was increased in NGF-treated groups compared with control groups at 28 and 56 days (P < 0.05). Morphometrically, significantly more regenerated myelinated fibers (RMFs) were seen at 12 days, and larger diameter RMFs were found at 12, 28, and 56 days in NGF-treated groups than in control groups. These results indicate that topically applied NGF stimulates nerve regeneration and promotes function recovery in crushed rat sciatic nerves.

Action Potentials↗
PubMed1986

Fiber composition of the rat sciatic nerve.

The rat sciatic nerve originates from the spinal segments L4-L6. It is unifascicular at the trochanter; 5-7 mm distally, the nerve splits into two and then into four fascicles. The tibial portion gives rise to the tibial and the sural nerves, and the peroneal portion gives rise to the peroneal nerve and a cutaneous branch that perforates the lateral hamstring muscles to innervate the proximolateral face of the calf. The number and type of the axons in these branches were determined in light and electron micrographs of normal nerves, and after de-efferentation or sympathectomy. Deafferentation was technically not feasible because spinal ganglia and ventral roots were supplied by the same vascular plexus. The tibial nerve contained 1,000 motor and 3,500 myelinated afferent axons, 3,700 sympathetic axons, and 5,400 unmyelinated afferent axons. The peroneal nerve contained 600 motor and 1,300 myelinated afferent axons, 1,100 sympathetic axons and 3,000 unmyelinated afferent axons. The sural nerve contained 1,100 myelinated and 2,800 unmyelinated afferent axons; in addition, there were 1,500 unmyelinated sympathetic axons. The cutaneous branch consisted of 400 myelinated and 1,800 unmyelinated afferent axons. Thus, the entire sciatic nerve at midthigh is composed of about 27,000 axons; 6% are myelinated motor axons, 23% and 48% are myelinated and unmyelinated sensory axons, respectively, and 23% are unmyelinated sympathetic axons. The techniques used did not demonstrate sympathetic axons in the cutaneous branch and did not reveal the few motor axons contained in the sural nerve.

Adrenergic Fibers↗
PubMed1989

Lipid metabolism during early stages of Wallerian degeneration in the rat sciatic nerve.

We examined changes in biosynthetic capacity of sciatic nerve during the early stages of Wallerian degeneration, utilizing a model that permits exclusion of nonresident cells from degenerating nerve. Sciatic nerve segments were placed in either 5-microns pore (allowing infiltration of nonresident cells) or 0.22-microns pore (excluding nonresident cells) Millipore diffusion chambers and then implanted in the peritoneal cavity of the same 32-34-day-old rat. At times up to 7 days postsurgery, nerve segments from the chambers, as well as control segments from the contralateral sciatic nerve, were removed and their capacity to incorporate radioactive precursors into lipids and proteins assayed in vitro. In nerve segments from both the 0.22- and 5-microns pore chambers, incorporation of [14C]acetate into total lipids was decreased relative to control by 50% at 12 h postsurgery and by 85% at day 3. This decreased incorporation of [14C]acetate reflects primarily decreased de novo synthesis of cholesterol and of fatty acyl residues incorporated into glycerolipids and sphingolipids. There was a preferentially decreased synthesis of cerebrosides and cholesterol (components enriched in myelin) relative to other lipids, while cholesterol esters and free fatty acids (products of membrane degradation) accounted for a greater proportion of the greatly reduced levels of total lipid label. In contrast to [14C]acetate, incorporation of [3H]glycerol into lipids was increased up to fourfold, relative to control, 1 day after nerve transection.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗