To investigate the pattern of expression of osteopontin (OPN) in tissues of the central nervous system (CNS) responding to peripheral immunological stimulation, the expression of OPN was studied in the spinal cord of rats with experimental autoimmune neuritis (EAN). In this model system, the sciatic nerves and spinal nerve roots are the target organs of EAN and the spinal cord is a remote organ that may be indirectly affected. OPN was constitutively expressed in some astrocytes adjacent to the pia mater and neurons in normal rats. In rats with EAN, OPN was increased in the same cells and in some inflammatory cells, including macrophages in the subarachnoid space. Expression of CD44, a receptor of OPN, was weak in normal spinal cord tissue and increased in the entire spinal cord parenchyma in rats with EAN, as well as in inflammatory cells. These findings suggest that inflammatory cells as well as reactive astrocytes are major sources of OPN and CD44 in the spinal cord of rats with EAN. Further study is needed to elucidate the functional role of OPN in the spinal cord affected by EAN.
Animals ; Antigens, CD44/metabolism ; Astrocytes/metabolism ; Ectodysplasins ; Female ; Immunohistochemistry ; Macrophages/metabolism ; Membrane Proteins ; Neuritis, Autoimmune, Experimental/*metabolism ; Neuroglia/metabolism ; Neurons/metabolism ; Osteopontin ; Rats ; Rats, Inbred Lew ; Sciatic Nerve/metabolism ; Sialoglycoproteins/*metabolism ; Spinal Cord/*metabolism ; Spinal Nerve Roots/metabolism

OBJECTIVESTo investigate the significance of c-fos oncogene morphogenetic protein's locational expression, and the correlativity between nerve transmitters calcitonin gene-related peptide (CGRP) expression and nerve root's functional change using the animal model of the chronic compressive injury in the nerve root.

METHODSThe animal model of chronic compressive injury of the nerve root was established by transplanting autogenous cancellous bone into the intervertebral foramen. During different injury phase (1, 2, 4, 8, 12, 24 weeks after operation), the functional status of the nerve root was determined under the monitoring of evoked potential, and the expression changes of c-fos oncogene morphogenetic protein and nerve transmitter CGRP were detected using in situ hybridization technique and their expression intensity was determined using automatic image analytic instrument respectively.

RESULTSOne week after operation, the c-fos expression strengthened in both anterior and posterior root fiber obviously. Two to four weeks after operation, the expression of the posterior root fiber weakened than the anterior root fiber. After 12 weeks, the anterior root fiber expression turned down obviously, however the posterior root fiber expression backed up slightly compared with that of the 8 weeks. By the time of 24 weeks after operation, the expression enhancement in all roots disappeared. CGRP expression increased obviously at the site of compressive axon of both anterior and posterior root. The expression of the posterior root axon and ganglion cell was higher than that of the anterior root axon. CGRP expression was diminished in the second week than the first week, and that was especially obvious in the posterior root and ganglion cell. But 4 weeks after operation, the expression enhanced once more, and that was more obvious inside the anterior root axon. Eight weeks after operation, the expression intensity attained the high peak. Twelve weeks after operation, the expression started the slow-moving descent.

CONCLUSIONSThe expression of c-fos gene protein is beneficial to localize the damaged part of certain nerve. During chronic injury, the degeneration of posterior root sensory fiber is earlier than the anterior root motor fiber. The expression of CGRP strengthened when the nerve fiber degenerated by the harmful stimulation, and the expression intensity is positively related with pain. That suggests when the nervous tissue is hurt, the information of warning and regulation should be sent out to our body.

Animals ; Calcitonin Gene-Related Peptide ; metabolism ; Cats ; Disease Models, Animal ; Female ; In Situ Hybridization ; Male ; Proto-Oncogene Proteins c-fos ; metabolism ; Radiculopathy ; metabolism ; physiopathology ; Spinal Nerve Roots ; physiopathology

OBJECTIVESTo determine the effect of destroying capsaicin-sensitive primary afferents (CSPA) fibers on paw withdrawal mechanical threshold (PWMT) induced by the direct compression of L5 nerve root with autologous disc.

METHODSThe procedure used autologous disc of the rats from the coccygeal intervertebral discs to apply direct pressure to the L5 dorsal root. PWMT was measured at the different time points post-surgery and pre-surgery. The changes in spatial expression pattern of c-fos protein in the spinal cord were also determined at 3 weeks when PWMT decreased to the peak.

RESULTSThe pretreatment with capsaicin produced a complete prevention of mechanical hyperalgesia induced by disc compression. The direct compression of L5 nerve root produced an obvious expression of fos-like immunoreactivity neurons in the dorsal horn of the spinal cord, which was significantly decreased by pretreatment with capsaicin.

CONCLUSIONSThe study shows that CSPA fibers, which mainly terminated in superficial layers of dorsal horn, may play a key role in mechanical hyperalgesia in the new sciatica model.

Afferent Pathways ; physiopathology ; Animals ; Capsaicin ; pharmacology ; Disease Models, Animal ; Hyperalgesia ; physiopathology ; Intervertebral Disc Displacement ; complications ; Male ; Pain Threshold ; drug effects ; Proto-Oncogene Proteins c-fos ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sciatica ; etiology ; metabolism ; physiopathology ; Spinal Nerve Roots ; metabolism

OBJECTIVETo establish an artificial somatic-autonomic reflex arc in rats and observe the following distributive changes of neural fibers in the bladder.

METHODSAdult Sprague-Dawley rats were randomly divided into three groups: control group, spinal cord injury (SCI) group, and reinnervation group. DiI retrograde tracing was used to verify establishment of the model and to investigate the transport function of the regenerated efferent axons in the new reflex arc. Choline acetyltransferase (ChAT) in the DiI-labeled neurons was detected by immunohistochemistry. Distribution of neural fibers in the bladder was observed by acetylcholine esterase staining.

RESULTSDiI-labeled neurons distributed mainly in the left ventral horn from L3 to L5, and some of them were also ChAT-positive. The neural fibers in the bladder detrusor reduced remarkably in the SCI group compared with the control (P < 0.05). After establishment of the somatic-autonomic reflex arc in the reinnervation group, the number of ipsilateral fibers in the bladder increased markedly compared with the SCI group (P < 0.05), though still much less than that in the control (P < 0.05).

CONCLUSIONThe efferent branches of the somatic nerves may grow and replace the parasympathetic preganglionic axons through axonal regeneration. Acetylcholine is still the major neurotransmitter of the new reflex arc. The controllability of detrusor may be promoted when it is reinnervated by the pelvic ganglia efferent somatic motor fibers from the postganglionic axons.

Acetylcholinesterase ; biosynthesis ; Anastomosis, Surgical ; Animals ; Autonomic Fibers, Preganglionic ; physiology ; Cholinergic Fibers ; metabolism ; Immunohistochemistry ; Motor Neurons ; cytology ; metabolism ; Nerve Regeneration ; physiology ; Neural Pathways ; cytology ; metabolism ; Rats ; Rats, Sprague-Dawley ; Reflex ; physiology ; Spinal Cord Injuries ; physiopathology ; Spinal Nerve Roots ; surgery ; Urinary Bladder ; innervation ; physiology ; surgery ; Urinary Bladder, Neurogenic ; surgery