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ENHANCEMENTOF CALCITONINGENE-RELATEDPEPTIDE LEVELS IN RAT SENSORYNEURONS INDUCEDBY DEGENERATION OF MOTOR NERVE FIBERS
MASAHIKOSAKAGUCHI,YOKO INAISHI,YASUHIROKASHIHARA,AND MOTOY KUNO,
National Institute for Physiological Sciences, Okazaki 444, Japan. Since calcitonin gene-related peptide (CGRP) in rat soleus muscle virtually disappears after chronic section of the sciatic nerve, its CGRP is of neural origin.
When degeneration of sensory
fibers was induced by removing the lumbar dorsal root ganglia (DRG),the CGRP content of the soleus muscle decreased to 5% of the normal level.
In contrast, degeneration of motor nerve
fibers induced by sectioning the lumbar ventral roots increased the CGRP content of the muscle. Moreover, chronic section of the lumbar ventral roots on one side enhanced CGRP expression in the lumbar DRG on both sides.
While the serum level of nerve growth factor (NGF) in normal rats was
below the detection limit (< 10 pg/ml), the serum sampled 10 days after section of the lumbar ventral roots contained about 50 pg/ml of NGF. chronically infused NGF.
CGRP levels of the lumbar DRG increased by
These resultssuggest that NGF newly synthesized in Schwann cells around
degenerating motor nerve fibers causes up-regulation of CGRP expression in DRG cells.
EXPRESSION OF NEUROMODULIN (GAP-431 mRNA JN TJfIERAT EYPOGLOSSAL NUCLEUS K&LOWING A NERVE TRANSECTION OR CRUSH OF HYPOGLOSSAL NERVE DFMONSTRATED BY NON-RADIOACTIVE IN SZTU HYBRIDIZATION IXISTOCEEMISTRY.
Neuromodulin (GAP-43) is a calmodulin binding protein which is localized in axonal growth cone and suggested to associate with axon growth, synaptogenesis, and regenerationby regulating local cahnodulin concentration. In present study, we examined the gene regulation of the neummodulm following the nerve injury by the non-radioactive in situ hybridization histochemistry where an alkaline phosphatase labelled oligodeoxynucleotide probe was used. The unilateralXII nerve was injured by transection or crush, and the change of neuromodulin mRNA level in the hypoglossal motoneurons was observed. Both the tmnsection and crush injmy resulted in a dramaticincrease of neuromodulm mRNA expression in an ipsilateralhypoglossal nucleus, whereas the mRNA level in the contralateralhypoglossal nucleus was no more than that observed in unopen&d amimals. The increases of the neuromodulin mRNA were substantial during the first three days after the operation, and the high level of the gene expression were, then, sustained for 2-3 weeks. Thus, the neummodulin could be important for the hy-poglossal motoneurons to regenerate or recover from such nerve injury.
PLASTICITY OF THE SYMPATHETIC NERVE FIBERS INNERVATING THE RAT CEREBRAL ARTERIES AFTER REMOVAL OF THE UNILATERAL SUPERIOR CERVICAL GANGLION. YOSHIAKI NOJYO', NOBUAKI TAMAMAKI', ---I AND YUJI HANDA* Dewartment of 'Anatomy _and *Neurosurgery, Fukui Medical School, Matsuoka-cho, Fukui 910-11 Japan. In order to study the plasticity of the sympathetic nerve fibers in rats whose unilateral superior cervical ganglion (SCG) had been removed, the contralateral intact sympathetic fibers were anterogradely labeled with WGA-HRP and the reinnervating axons and terminal plexus were traced on the cerbral arteies. Experimental conditions were (1) the age of ganglionectomy (1 day to 16 weeks old), (2) the length of survival time after ganglionectomy (1 to 16 weeks), and (3) the decentralization of contralateral SCG. In the experiments of (2) and (3) a ganglionectomy was done at the age of 4 weeks. All operative procedures were done under Nembutal anesthesia. The outgrowth and reinnervation of sympathetic nerve fibers on the denervated cerebral arteries were seen as early as 1 week, and the re‘innervating nerve fibers gradually expanded on the circle of Willis by 8 weeks. In young rats reinnervation was confined within the circle of Willis, but in the infant rats reinnervating fibers reached the branches of cilcle of Willis, such as the middle cerebral artery. The sites and routes of nerve sprouting were characterized as follows; anterior and posterior communicating arteries, ethomoidal artery, and interdural space of skull base. In rats of old age and decentralization outgrowth and reinnervation was strongly compressed.