Afferent Pathways ; anatomy & histology ; Animals ; Female ; Ganglia, Spinal ; anatomy & histology ; Neurons, Afferent ; Rats ; Rats, Sprague-Dawley ; Urinary Bladder ; innervation

BACKGROUND AND OBJECTIVES: Fos, the protein product of c-fos gene, has been known to be rapidly expressed in neurons following various external and internal stimuli and this protein expression has been used as a neural activation marker in many fields. This experiment was performed to examine the afferent pathway of the lateral semicircular canals following sinusoidal acceleration. MATERIALS & METHODS: To stimulate the lateral semicircular canals, animals received rotary stimulation for 90 minutes with 2.0Hz sinusoidal acceleration. Thirty minutes after stimulation, the subjects were sacrificed and their brainstems were processed for immunohistochemistry to detect Fos expression. RESULTS: Fos proteins were strongly expressed in the superior, dorsal medial vestibular and inferior vestibular nuclei. However, there was no expression in the lateral and ventral portion of medial vestibular nuclei. CONCLUSION: This finding suggested that the afferent pathway from peripheral vestibular end-organ can be successfully mapped by detection of Fos expression and Fos is an useful neural activity marker in the vestibular system.
Acceleration* ; Afferent Pathways ; Animals ; Brain Stem* ; Genes, fos ; Immunohistochemistry ; Neurons ; Semicircular Canals ; Vestibular Nuclei*

Diseases and injuries to the nervous system can lead to a devastating chronic pain condition called neuropathic pain. We review changes that occur in the peripheral nervous system that may play a role in this disease. Common animal models for neuropathic pain involve an injury to one or more peripheral nerves. Following such an injury, the nerve fibers that have been injured exhibit many abnormal properties including the development of spontaneous neural activity as well as a change in the expression of certain genes in their cell body. Recent data indicate that adjacent, uninjured nerve fibers also exhibit significant changes. These changes are thought to be driven by injury-induced alterations in the milieu surrounding the uninjured nerve and nerve terminals. Thus, alteration in neural signaling in both injured and uninjured neurons play a role in the development of neuropathic pain after peripheral nerve injury.
Animals ; Disease Models, Animal ; Nerve Fibers ; pathology ; Neuralgia ; physiopathology ; Neurons, Afferent ; cytology ; Peripheral Nerve Injuries ; physiopathology

OBJECTIVETo trace the segmental distribution of somatic sensory neurons of the skin and dorsal nerve in the rabbitś penis.

METHODSThe experiment was performed on 8 adult male rabbits with the nerve tracing method of retrograde axonal transport of horseradish peroxidase (HRP), which was injected into the dermis around the penis and the dorsal nerve of the penis. The rabbits were sacrificed five days later to harvest the spinal cord segments and the dorsal root ganglia of lumbosacral segments for histological study.

RESULTSThe HRP tracing showed that a number of labeled HRP positive neurons appeared in spinal ganglia (S2 - S4) in all the rabbits, and distributed segmentally. The counts of the positive neurons different segments were: S2 (215.0 +/- 10.2) , S3 (242.2 +/- 8.3) and S4 (109.7 +/- 8.4) respectively, with statistically significant difference between the two groups.

CONCLUSIONThe rabbit's sensory nerve fibers in both the skin and the dorsal nerve of the penis are rooted in the S2-S4 segments of spinal ganglia, which distribute regularly.

Animals ; Anterior Horn Cells ; anatomy & histology ; Biomarkers ; Male ; Neurons, Afferent ; Neurons, Efferent ; Penis ; innervation ; Rabbits ; Random Allocation ; Skin ; innervation

Migraine is a neurological disorder characterized by recurrent and disabling severe headaches. Although several anticonvulsant drugs that block voltage-dependent Na⁺ channels are widely used for migraine, far less is known about the therapeutic actions of carbamazepine on migraine. In the present study, therefore, we characterized the effects of carbamazepine on tetrodotoxin-resistant (TTX-R) Na⁺ channels in acutely isolated rat dural afferent neurons, which were identified by the fluorescent dye DiI. The TTX-R Na⁺ currents were measured in medium-sized DiIpositive neurons using the whole-cell patch clamp technique in the voltage-clamp mode. While carbamazepine had little effect on the peak amplitude of transient Na⁺ currents, it strongly inhibited steady-state currents of transient as well as persistent Na⁺ currents in a concentration-dependent manner. Carbamazepine had only minor effects on the voltage-activation relationship, the voltage-inactivation relationship, and the use-dependent inhibition of TTX-R Na⁺ channels. However, carbamazepine changed the inactivation kinetics of TTX-R Na⁺ channels, significantly accelerating the development of inactivation and delaying the recovery from inactivation. In the current-clamp mode, carbamazepine decreased the number of action potentials without changing the action potential threshold. Given that the sensitization of dural afferent neurons by inflammatory mediators triggers acute migraine headaches and that inflammatory mediators potentiate TTX-R Na⁺ currents, the present results suggest that carbamazepine may be useful for the treatment of migraine headaches.
Action Potentials ; Animals ; Anticonvulsants ; Carbamazepine* ; Headache ; Kinetics ; Migraine Disorders ; Nervous System Diseases ; Neurons* ; Neurons, Afferent ; Rats ; Sodium Channels ; Trigeminal Ganglion*

In this study, the expressions of growth hormone secretagogue receptor type 1a (GHS-R1a) in the rat dorsal root ganglion (DRG) and nodose ganglion (NG) were investigated by using immunohistochemistry and in situ hybridization. The results clearly showed the presence of GHS-R1a mRNA and GHS-R1a-positive neurons in the rat DRG and NG. GHS-R1a was also co-localized with calcitonin gene-related peptide (CGRP) in some DRG and NG neurons, indicating the existence of subpopulations of the visceral afferents. The extrinsic primary afferent visceroceptive DRG and NG neurons from the stomach were identified by retrograde tracing fluorogold and stained for GHS-R1a and CGRP. Some neurons both positive for CGRP and GHS-Rla were labled by fluorogold. Our results not only demonstrate the expression of GHS-R1a in the vagal afferents but also provide the first and direct morphological evidence for its presence in the spinal visceral afferents, and gherin might have a modulatory role in the visceral afferent signaling.
Afferent Pathways ; Animals ; Calcitonin Gene-Related Peptide ; metabolism ; Ganglia, Spinal ; cytology ; Immunohistochemistry ; Neurons, Afferent ; cytology ; Nodose Ganglion ; cytology ; Rats ; Receptors, Ghrelin ; metabolism ; Stomach ; innervation

OBJECTIVETo explore the patterns of innervation of cervical facet joints and determine the pathways from facet joints to dorsal root ganglions (DRGs) in order to clarify the causes of diffuse neck pain, headache, and shoulder pain.

METHODSForty-two male-Sprague-Dawley rats, weighing 250-300 g, were randomly divided into three groups: Group A (n=18), Group B (n=18), and Group C (n=6). Under anesthesia with intraperitoneal pentobarbital sodium (45 mg/kg body weight), a midline dorsal longitudinal incision was made over the cervical spine to expose the left cervical facet joint capsule of all the rats under a microscope. The rats in Group A underwent sympathectomy, but the rats in Group B and Group C did not undergo sympathectomy. Then 0.6 microlitre 5% bisbenzimide (Bb) were injected into the C1-2, C3-4 and C5-6 facet joints of 6 rats respectively in Group A and Group B. The holes were immediately sealed with mineral wax to prevent leakage of Bb and the fascia and skin were closed. But in Group C, 0.9% normal saline was injected into the corresponding joint capsules. Then under deep re-anesthesia with intraperitoneal pentobarbital sodium (45 mg/kg body weight), C1-C8 left DRGs in all rats and the sympathetic ganglions in Group B were obtained and the number of the labeled neurons was determined.

RESULTSNeurons labeled with Bb were present in C1-C8 DRGs in both Group A and Group B, and sympathetic ganglions in Group B. In the C1-2 and C3-4 subgroups, labeled neurons were present from C1 to C8 DRGs, while in C5-6 subgroups they were from C3 to C8. The number of Bb(+) neurons after sympathectomy was not significantly different in the injected level from that without sympathectomy. But in the other levels, the number of Bb(+) neurons after sympathectomy was significantly less than that without sympathectomy.

CONCLUSIONSThe innervation of the cervical facet joints is derived from both sensory and sympathetic nervous system, and DRGs are associated with sympathetic ganglions through nerve fibers outside the central nerve system.

Animals ; Cervical Vertebrae ; innervation ; Ganglia, Spinal ; cytology ; Ganglia, Sympathetic ; cytology ; Male ; Neurons, Afferent ; cytology ; Rats ; Rats, Sprague-Dawley

The vanilloid receptor type-1 (VR1) is a nonselective cation channel activated by capsaicin and can be act as mediator of chemical and physical stimuli that elicit pain. The presence of VR1 in the dorsal root, trigeminal and nodose ganglia has been firmly established, but it unclear in the mouse intestinal wall. The distribution of VR1 receptors in mouse afferent neurons innervating the intestinal tract was investigated by immunohistochemistry. Also small and large intestines were dual-labelled with antibody for VR1 and marker for interstitial cells of Cajal (c-kit). VR1-immunopositive cells were localized on fine fibers in myenteric plexus and expressed weakly myenteric ganglia. The majority of VR1-immunopositive fibers are not colocalized with or apposed to c-kit positive interstitial cells of Cajal. Also electrophysiologically capsaicin had no effect on cultured interstitial cells of Cajal. It is concluded that VR1-immunoreactive intestinal nerves are mainly distributed in myenteric plexus of murine intestinal wall, and vanillod may be not directly related to interstitial cells of Cajal in regulation of intestinal motility.
Animals ; Capsaicin ; Ganglia ; Gastrointestinal Motility ; Immunohistochemistry ; Interstitial Cells of Cajal ; Intestines ; Mice* ; Myenteric Plexus* ; Neurons, Afferent ; Nodose Ganglion ; Spinal Nerve Roots

The vanilloid receptor type-1 (VR1) is a nonselective cation channel activated by capsaicin and can be act as mediator of chemical and physical stimuli that elicit pain. The presence of VR1 in the dorsal root, trigeminal and nodose ganglia has been firmly established, but it unclear in the mouse intestinal wall. The distribution of VR1 receptors in mouse afferent neurons innervating the intestinal tract was investigated by immunohistochemistry. Also small and large intestines were dual-labelled with antibody for VR1 and marker for interstitial cells of Cajal (c-kit). VR1-immunopositive cells were localized on fine fibers in myenteric plexus and expressed weakly myenteric ganglia. The majority of VR1-immunopositive fibers are not colocalized with or apposed to c-kit positive interstitial cells of Cajal. Also electrophysiologically capsaicin had no effect on cultured interstitial cells of Cajal. It is concluded that VR1-immunoreactive intestinal nerves are mainly distributed in myenteric plexus of murine intestinal wall, and vanillod may be not directly related to interstitial cells of Cajal in regulation of intestinal motility.
Animals ; Capsaicin ; Ganglia ; Gastrointestinal Motility ; Immunohistochemistry ; Interstitial Cells of Cajal ; Intestines ; Mice* ; Myenteric Plexus* ; Neurons, Afferent ; Nodose Ganglion ; Spinal Nerve Roots

OBJECTIVETo study the distribution character of the trigeminal sensory afferent fibers in rat's trigeminal sensory root (RxV) and to explore the possibility of selectively injury of the pain afferent fibers.

METHODSThe retrograde tracer fluorogold (FG) was injected into trigeminal spinal subnucleus and pontine nucleus respectively. After 7 days survival, the rats were sacrificed and the RxV was removed and sectioned. The distribution of FG at RxV was studied under fluorescent microscope and its character was analyzed.

RESULTSAfter being introduced into trigeminal spinal rostral nucleus, the FG could be observed at the lateral portion on the sections of RxV. The fibers were small and concentrated. The interpolaris subnucleus and caudal subnucleus injection group also showed small and concentrated fibers in the lateral portion of RxV, but the distribution area was larger than that of the rostral subnucleus group. While being injected into trigeminal pontine nucleus, the FG positive axons could be found in the ventral, medial and central portion of the RxV cross sections. These fibers were thicker and more scattered compared to those projecting into trigeminal spinal nucleus.

CONCLUSIONThe fibers relating to transporting pain sensory concentrate at a certain area of rat' s RxV, which indicate that selectively injury of the pain afferent fibers of RxV should be possible.

Animals ; Fluorescent Dyes ; Male ; Neurons, Afferent ; physiology ; ultrastructure ; Rats ; Rats, Wistar ; Staining and Labeling ; Trigeminal Ganglion ; physiology ; ultrastructure ; Trigeminal Neuralgia