title: Dexamethasone enhances level of GAP-43 mRNA after nerve injury and facilitates re-projection of the hypoglossal nerve.
abstract: Application of dexamethasone was found to induce an enhanced expression level of mRNA encoding the growth associated protein (GAP-43) after peripheral nerve injury. Following hypoglossal nerve axotomy, a dexamethasone releasing pellet (1.5 mg released in 3 weeks) was placed near the transected nerve. GAP-43 mRNA was detected in the hypoglossal nucleus by non-radioactive in situ hybridization histochemistry using an alkaline phosphatase-labeled oligonucleotide probe. A significant elevation of GAP-43 mRNA level was observed 2 weeks after the transection in dexamethasone treated animals. This induction was not observed in the dorsal motor nucleus of vagus which expresses moderately high levels of GAP-43 mRNA even without nerve injury. Although dexamethasone did not alter the maximum level of GAP-43 mRNA in the hypoglossal nucleus after nerve injury, it prolonged the period in which the mRNA expression remained elevated. This may be due to post-transcriptional effect by the glucocorticoid. Dexamethasone treatment also caused a slight facilitation of reprojection. This may be due to the enhancement of GAP-43 mRNA level by the glucocorticoid.
authors.affiliation: Department of Neuroanatomy, Osaka University Medical School, Japan.
authors.forename: G L
authors.initials: GL
authors.lastname: Yao
authors.forename: H
authors.initials: H
authors.lastname: Kiyama
mesh_terms: D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology*; D019922:GAP-43 Protein; D015870:Gene Expression / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology; D007002:Hypoglossal Nerve / Q000502:physiology*; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D009412:Nerve Fibers / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009434:Neural Pathways / Q000502:physiology; D016900:Neurofilament Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration; D013997:Time Factors
chemical_list: D019922:GAP-43 Protein; D005938:Glucocorticoids; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; D012333:RNA, Messenger; D003907:Dexamethasone