Number Of Sensory Nerve Fibers Research Articles

Differences in Damage to CGRP Immunoreactive Sensory Nerves After Two Lumbar Surgical Approaches

Immunohistochemical study. To evaluate invasive surgical approaches by analyzing the number of sensory nerve fibers at 2 back muscle sites in rats and humans and the number of injured nerve fibers innervating these 2 sites after muscle injury in rats. SUMMARY OF BACKGROUND DATA.: Several minimally invasive approaches have recently become popular in the treatment of lumbar spine disorders. Minimally invasive surgery (MIS) is not invasive to back muscle and is thought to reduce low back pain. Muscle damage has been generally evaluated by magnetic resonance imaging (MRI); however, damage to sensory nerve fibers in and around back muscle that is directly related to pain has apparently not been explored. Human muscle at L4-L5 was obtained from the paraspinous process (during a midline approach) and from paraspinal back muscle (during a Wiltse paraspinal approach) (n = 10 each). The muscle was sectioned and immunostained for calcitonin gene-related peptide (CGRP). To detect dorsal root ganglion (DRG) neurons innervating back muscle in rats, Fluoro-Gold (FG) was applied to the same 2 sites on the lower back muscle at L4-L5 (only application, n = 12; application of FG + muscle injury, n = 12). DRGs were harvested and immunostained for CGRP and activating transcription factor-3 (ATF-3: marker for nerve injury). The numbers of FG-labeled CGRP-immunoreactive or FG-labeled ATF-3-immunoreactive DRG neurons innervating the 2 sites were counted and compared. CGRP-immunoreactive sensory nerve fibers were found at the 2 sites. The average number of CGRP-immunoreactive sensory nerve fibers in muscle obtained in a midline approach was significantly higher than that in muscle obtained in a Wiltse paraspinal approach (P < 0.01). The numbers of FG-labeled CGRP- and ATF-3-immunoreactive DRG neurons innervating paraspinous process muscle were significantly greater than those innervating paraspinal back muscle in rats (P < 0.01). There are more CGRP-immunoreactive sensory nerve fibers and DRG neurons innervating muscle in the midline approach area than in the Wiltse paraspinal approach area in humans and rats. There are more ATF-3-immunoreactive DRG neurons innervating muscle in the midline approach area than in the Wiltse paraspinal approach area after muscle injury in rats. This result may show the differences in sensory nerve injury during the 2 surgical approaches.

Anatomical and electrophysiological comparison of the sensory innervation of bronchial and tracheal parasympathetic ganglion neurons

Anatomical and electrophysiological techniques were used to examine differences in the level of sensory nerve terminals localized in parasympathetic ganglia in guinea pig trachea and bronchus. We quantified substance-P-immunoreactive nerve terminal profiles within the ganglia and the amplitude of capsaicin-sensitive depolarization (slow excitatory postsynaptic potential or sEPSP) evoked by vagus (bronchial) or recurrent (tracheal) nerve-stimulation. Substance-P-immunoreactive axon profiles per intrinsic tracheal neuron were fewer in number than per bronchial ganglion neuron. The average amplitude and duration of the capsaicin-sensitive sEPSPs were similar in tracheal and bronchial ganglion neurons. Furthermore, capsaicin evoked a nearly equal depolarization of bronchial and tracheal ganglion neurons. The sEPSPs were reduced in both areas by a selective neurokinin-3 receptor antagonist, SR142801. These results demonstrate that although the number of sensory nerve fibers in tracheal ganglia are significantly less than those in the bronchus, this did not translate to an obvious physiological difference in sEPSP amplitude.

Functional Components of the Greater Superficial Petrosal Nerve

SummaryThe normal greater superficial petrosal nerve of the cat averages 2193 axons and of these, 1625 are myelinated and 568 are without myelin sheaths. A single intact nerve of the dog held 3487 nerve fibers, which were divided into 2299 myelinated and 1188 unmyelinated axons.An average of 597 sensory nerve fibers remains in the greater superficial petrosal nerve of the cat after its motor axons have been eliminated. Of this average number of sensory nerve fibers, 461 are myelinated and 136 are unmyelinated. The deefferented petrosal nerve of one dog contained 960 sensory axons and 664 of these were myelinated while 296 were without myelin sheaths.It is estimated that the greater superficial petrosal nerve of the cat has an average of approximately 1596 motor nerve fibers and these are divided into 1164 myelinated and 432 unmyelinated nerve fibers. The greater superficial petrosal nerve of the dog contained 2527 motor axons and 1635 of these were myelinated and 892 were unmyelinated.It is evident, there...