The purpose of the study was to investigate whether the small fiber-evoked dorsal root reflex (DRR) can be obtained by electrical stimulation of the peripheral nerve in rats. Fifty-one DRRs were recorded from different kinds of fiber filaments in the proximal ends of the cut L(5) dorsal root following electrical stimulation of the sural nerve. According to the kind of afferent fibers in the sural nerve associated with the DRRs from dorsal root, these DRRs were divided into five different types: A(alphabeta) fiber-evoked A(alphabeta).DRR (A(alphabeta)- A(alphabeta).DRR), A(betadelta) - A(delta ).DRR, A(betadelta)-C.DRR, A(alphabetadelta)-C.DRR and C-C.DRR. The results obtained show that the DRR can be obtained from either A-fibers (including A(delta )-fibers) or C-fibers of dorsal root filaments by stimulation of the sural nerve. It is therefore suggested that either A(delta ).DRR or C.DRR can be used as a validity index of presynaptic inhibition of the thin primary afferent terminals for investigation of the modulation mechanisms of peripheral effectors.
Afferent Pathways ; Animals ; Electric Stimulation ; Female ; Male ; Nerve Fibers, Myelinated ; physiology ; Nerve Fibers, Unmyelinated ; physiology ; Rats ; Rats, Sprague-Dawley ; Reflex ; physiology ; Spinal Nerve Roots ; physiology ; Sural Nerve ; physiology

OBJECTIVETo explore the regeneration of mechanical sensory fibers after free nerve transplantation.

METHODNeuroelectrophysiological technique (single nerve fiber recording) was used to test the regeneration rate of mechanical sensory fibers, the proportion of rapidly and slowly adapting receptors, the stimulating thresholds of regenerated mechanoreceptors and conduction velocity of regenerated fibers. The regeneration pattern of the mechanoreceptors after free nerve transplantation to the rabbit reconstructed penis was also analyzed.

RESULTS9 months after operation, the number of regenerated mechanical sensory fiber was almost normal. The regenerated rapidly adapting receptors had a higher proportion with higher mature degree than the regenerated slowly adapting receptors. 9 months after nerve transplantation the stimulating thresholds of regenerated mechanoreceptors and conduction velocity of regenerated fibers remained below normal.

CONCLUSIONAfter free nerve transplantation to the rabbit reconstructed penis, the function of both rapidly and slowly adapting sensory nerve fiber partially recovered, but in different extent.

Animals ; Ganglia, Sensory ; physiology ; Male ; Mechanoreceptors ; physiology ; Nerve Fibers ; transplantation ; Nerve Regeneration ; Penis ; surgery ; Rabbits

OBJECTIVETo develop a system for automatically controlling carotid sinus pressure in the study on baroreceptors.

METHODSThe preparation containing carotid sinus with parts of the connected vessels and carotid sinus nerve (CS-CSN) were isolated and perfused. A critical pressure controlling component (PRE-U, Hoerbiger, Deutschland) dictated by a computer was integrated into the system to clamp the intrasinus pressure. The pressure command and the relevant intrasinus pressure were compared to evaluate the validity of the pressure controlling system.

RESULTSA variety of sinus pressure-controlling patterns, including pulsation, ramp and step pressures, could be achieved accurately by using the system, and the pressure-dependent discharge activities of sinus nerve were confirmed.

CONCLUSIONThis system for clamping carotid sinus pressure could realize multiple pressure-controlling patterns and is a useful and flexible pressure controlling method that could applied in the study on mechano-electric transduction of baroreceptors.

Animals ; Blood Pressure ; Carotid Sinus ; innervation ; physiology ; Nerve Fibers ; physiology ; Pressoreceptors ; physiology ; Rabbits

OBJECTIVETo investigate the asymmetry of fibers in the posterior limb of the internal capsule with diffusion tensor imaging.

METHODSTwenty-nine volunteers (right-handers: 20, left-handers: 9) were enrolled in this study. All the data were obtained using a 1.5 tesla scanner (Signa EXCITE II. GE Medical Systems). The parameters including apparent diffusion coefficient (ADC), fractional anisotropy (FA) and eigenvalue lambda1, lambda2, lambda3 were acquired from the posterior limb of the internal capsule in both hemisphere of brain, and paired t-test was used for statistical differences between the hemisphere.

RESULTSNo differences of ADC and lambda1 were found among the right-handers, but FA in the internal capsule of left hemisphere was larger than that in the right (0.72+/-0.03 compared with 0.70 +/-0.04, P=0.001), and lambda2, lambda3 in the left was lower than that in the right [(4.39+/-0.32 compared with 4.50+/-0.33)x10(-3) mm(2)/s, P=0.016 and (2.19 +/-0.34 compared with 2.29 +/-0.40)x10(-3) mm(2)/s, P=0.024, respectively]. In contrast to the results among the right-handers, all parameters in the left-handers showed no statistical differences.

CONCLUSIONThe fibers in the posterior limb of the internal capsule of left hemisphere might be well sheathed with myelin among right-handers.

Adult ; Diffusion Magnetic Resonance Imaging ; methods ; Female ; Humans ; Internal Capsule ; physiology ; Male ; Nerve Fibers, Myelinated ; physiology

Measurement of motor nerve conduction velocity(MNCV) of the median and peroneal nerves was performed in 79 normal fullterm newborn infants and children up through the age of 329 weeks. They were divided into eight groups by age. The following study was undertaken to obtain the mean +/- S.D. and the regression equation of Y (MNCV) on X (age). The MNCV values of each group were compared with those of normal adults.
Child ; Child, Preschool ; Human ; Infant ; Infant, Newborn ; Median Nerve/physiology ; Motor Neurons/physiology* ; Nerve Fibers/physiology ; Neural Conduction* ; Peroneal Nerve/physiology

BACKGROUNDIndirect traumatic optic neuropathy (TON) is an acute injury of the optic nerve associated with severe visual dysfunction, which may be a result of secondary mechanical injury and vascular disorder of the optic nerve due to trauma. We analyzed the natural course of axonal loss and blood flow disturbances in patients with indirect TON to find a possible therapeutic window.

METHODSA cohort of 54 patients with indirect TON recruited between October 2008 and October 2010 at Beijing Tongren Hospital was retrospectively analyzed. The patients were divided into no light perception group (NLP) and better than NLP (btNLP) group. Specifically, the thickness of the retinal nerve fiber layer (RNFL) measured by spectral domain optical coherence tomography (SD-OCT), and hemodynamic parameters of the ophthalmic artery (OA), central retinal artery (CRA) and posterior ciliary artery (PCA) were determined.

RESULTSTwo weeks after injury, there was a statistically significant decrease in the thickness of RNFL in the btNLP group as compared with the fellow control eyes (P < 0.05). In contrast, in the NLP group, RNFL thickness slightly increased for 2 weeks following injury, then overtly reduced after 4 weeks (P < 0.05). Peak systolic velocity (PSV) of CRA was significantly decreased 4 weeks after injury (P < 0.05) in both the NLP group and btNLP group (P < 0.05). The thickness of RNFL in the NLP group was negatively correlated with PSV of CRA after 1 week of injury (P < 0.05, r = -0.962).

CONCLUSIONSSD-OCT is a useful supplement in detecting the axonal loss in TON. The dynamic change of the thickness of RNFL appears to correlate with the hemodynamic disturbances in the natural course of TON. The first 2 weeks following an injury is critical and should be considered as the therapeutic window for TON patients.

Adult ; Female ; Humans ; Male ; Middle Aged ; Nerve Fibers ; physiology ; Optic Nerve ; physiology ; Optic Nerve Injuries ; physiopathology ; Retinal Neurons ; physiology ; Retrospective Studies ; Tomography, Optical Coherence

We investigated the adrenergic sensitivity of afferent fibers in the L4 dorsal roots of rats with a unilateral ligation of the L5-L6 spinal nerves. About 12% of nociceptive fibers on the affected side were excited by sympathetic stimulation or by intra-arterial injection of norepinephrine which did not affect A beta-fiber activity. Sympathetic excitation of nociceptive fibers was suppressed by alpha 1-antagonist prazosin, while it was unaffected by alpha 2-antagonist yohimbine. Most of these fibers were excited by intra-arterial injection of alpha 1-agonist phenylephrine, without being affected by an injection of alpha 2-agonist clonidine. Sympathetic excitation was blocked by lidocaine applied near the receptive fields of recorded fibers. The results suggested that some nociceptors remaining intact after partial nerve injury become sensitive to sympathetic activity by the mediation of alpha 1-adrenoceptors in the peripheral endings.
Animal ; Male ; Nerve Fibers/physiology* ; Nociceptors/physiology* ; Norepinephrine/pharmacology ; Pain/physiopathology* ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, alpha-1/physiology*

The character of the membrane of fiber can be simulated by nonpower RC network on condition that the offset of distance between the transmembrane potential of unmyelinated nerve fiber and the resting potential of nerve fiber cell is small enough. Thus, it is possible to found the successive cable equation with external stimulation under subthreshold linear state. So far, most scholars use time-domain analysis method. In this paper are reported the method of integral transform and the analytical expression of cable equation under the stimulation of point electrical source firstly. And at the same time, computer-aided simulation of transmembrane potential of nerve fiber and analysis of the possibility of activating action potential are presented.
Action Potentials ; physiology ; Computer Simulation ; Electric Stimulation ; Humans ; Membrane Potentials ; physiology ; Models, Neurological ; Nerve Fibers, Unmyelinated ; physiology

The classical cable function has been used to represent the response of peripheral nerves stimulated by external parallel electric field. It can not describe the excitation of peripheral nerves stimulated by perpendicular electric field. In this paper, responses of the nodes of Ranvier to transverse-field are deeply investigated by mathematic simulation and in-vitro experiments. The paper demonstrates that, under perpendicular electric field stimulation, the responses evoke a two-stage process including an initial polarization and the actual change of the transmembrane potential. It is the net inward current along a radial direction of the node of Ranvier that causes the peripheral nerve excitation. Based on the two-stage process, a novel model is introduced to describe peripheral nerves stimulated by transverse-field, and the classical cable function is modified. The new model and the improved cable function are verified by several in-vitro experiments. They can be used to represent peripheral nerves responses by arbitrary electric field stimulation.
Animals ; Bufo bufo ; Electric Conductivity ; Electric Stimulation ; Electromagnetic Fields ; Electrophysiology ; Membrane Potentials ; Models, Biological ; Nerve Fibers ; physiology ; Peripheral Nerves ; physiology ; Ranvier's Nodes ; physiology ; Sciatic Nerve ; physiology

Spinal cord injury (SCI) is frequently companied by necrosis and apoptosis of oligodendrocytes (OLs), which contributes to demyelination of myelinated nerve fibers and their electrophysiological defects. This pathological demyelination often results in sensory or motor deficits. Here, we first focus on the microenvironment changes after SCI that cause OLs' death, then discuss the major mechanism of endogenous oligodendrocytogenesis and axonal remyelination, and finally summarize current therapies targeting OLs protection and replacement.
Animals ; Apoptosis ; physiology ; Cell Death ; physiology ; Humans ; Necrosis ; pathology ; Nerve Fibers, Myelinated ; pathology ; Nerve Regeneration ; physiology ; Oligodendroglia ; pathology ; Spinal Cord ; physiopathology ; Spinal Cord Injuries ; pathology ; physiopathology ; therapy