GROWTH-ASSOCIATED PROTEIN-43 (GAP-43) MESSENGER-RNA IS UP-REGULATED IN THE RAT SUPERIOR CERVICAL-GANGLIA AFTER PREGANGLIONIC TRANSECTION

Growth-associated protein 43 (GAP-43) is a growth-associated protein w hich is synthesised in high amounts in neurons during neuronal outgrow th. In a previous study we have shown that GAP-43 immunoreactivity is increased in neurons in superior cervical ganglia (SCG) and in nerve t erminals in the irides after preganglionic denervation. We have now ex amined changes in GAP-43 mRNA using in situ hybridisation. GAP-43 mRNA was seen to be constitutively expressed by principal neurons of the r at superior cervical ganglion. Expression was increased further by sec tion of the cervical sympathetic trunk, reaching a maximum (increased by about 30%) 3 days after decentralisation. The increased GAP-43 prot ein seen after decentralisation thus appears to be due to an upregulat ion of GAP-43 mRNA in the adrenergic neurons. The results imply that G AP-43 expression in the SCG is under presynaptic control, acting at le ast partly by control of mRNA levels. (C) 1998 Elsevier Science Irelan d Ltd. All rights reserved.