AXOPLASMIC-TRANSPORT OF CALCITONIN-GENE-RELATED PEPTIDE IN RAT PERIPHERAL-NERVE AS A FUNCTION OF AGE

Calcitonin gene-related peptide (CGRP) has been implicated in the trop hic regulation of acetylcholine receptors and G(4) acetylcholinesteras e at the rat neuromuscular junction. Since these latter molecules exhi bit significant changes with advancing age, we examined the possibilit y that certain aspects of CGRP transport are also influenced by aging. Double nerve ligations and CGRP radioimmunoassay of 3-mm nerve segmen ts permitted the assessment of the peptide's apparent transport rates in sciatic nerves from 3-, 12-, and 24-month-old Fischer 344 rats. Res ults confirm that CGRP is conveyed by anterograde axoplasmic transport ; more importantly, they suggest that CGRP is also transported retrogr adely, but in smaller amounts and at slower rates. In addition, our fi ndings indicate that the apparent rates of CGRP transport in both dire ctions significantly decline with advancing age. These data are consis tent with the notion that changes in CGRP delivery may contribute to a ge-related changes in junctional acetylcholine receptors and acetylcho linesterase.