title: Regulation of growth-associated protein 43 (GAP-43) messenger RNA associated with plastic change in the adult rat barrel receptor complex.
abstract: Plastic change occurs in the adult rat barrel receptor complex following peripheral deafferentation by removal of facial vibrissae (vibrissectomy) and can be prevented by prior depletion of brain norepinephrine. Growth-associated protein (GAP-43, B50, F1, pp46), a marker for synaptic reorganization, increases in the barrel cortex of adult rats following both peripheral and central deafferentation. Here we followed changes in GAP-43 mRNA expression in the barrel receptor system following vibrissectomy. Adult rats had unilateral total vibrissectomy with sparing of the central (C3) vibrissa. By in situ hybridization, GAP-43 mRNA first increased at 24h (9%, P < 0.05) in the ipsilateral trigeminal complex. Levels remained elevated (up to 25% of the unlesioned side) over the next 6 days, decreased to 88% at 7 days and returned to control levels at 14 days. Contralateral barrel cortex levels of GAP-43 mRNA increased by 14% at 4-5 days remained elevated through 7 days and returned to control levels by 14 days. Increased GAP-43 mRNA levels 6 days after vibrissectomy were reproduced by complete transection of the infraorbital nerve and were blocked by depletion of brain norepinephrine. No change occurred in ventrobasal thalamus GAP-43 mRNA at any time. Dot blot and Northern blot hybridizations of GAP-43 mRNA after vibrissectomy showed a 43% increase in the ipsilateral trigeminal complex and a 16% increase in the contralateral barrel cortex at 3 days and an 84% increase in ipsilateral trigeminal and 50% increase in contralateral barrel cortex GAP-43 mRNA at 6 days, respectively. Thus, deafferentation-induced plasticity in the barrel pathway depends upon norepinephrine and is associated with increase in both GAP-43 mRNA and protein suggesting that this may involve a structural change.
authors: Neurology Service, Department of Veterans Affairs Medical Center, E. Orange, NJ 07018.
authors: B E
authors: BE
authors: Levin
authors: A
authors: A
authors: Dunn-Meynell
mesh_terms: D000818:Animals; D003714:Denervation; D004292:Dominance, Cerebral; D019922:GAP-43 Protein; D005786:Gene Expression Regulation; D008125:Locus Coeruleus / Q000502:physiology; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D009473:Neuronal Plasticity; D009638:Norepinephrine / Q000502:physiology*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000378:metabolism*; D013788:Thalamus / Q000502:physiology; D014158:Transcription, Genetic; D014276:Trigeminal Nerve / Q000502:physiology*; D014738:Vibrissae / Q000293:injuries / Q000294:innervation*
chemical_list: D019922:GAP-43 Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D009638:Norepinephrine