Changes in substance P and calcitonin gene-related peptide binding in the dorsal horn of rat spinal cord following pronase-induced deafferentation

Quantitative receptor autoradiography was used to evaluate potential altera tions in substance P (SP) and calcitonin gene-related peptide (CGRP) bindin g in the L4 spinal segment of rats following unilateral poisoning of the sc iatic nerve with pronase. Ten days after pronase-induced deafferentation th ere was a significant increase in SP and CGRP binding in the superficial (I -II) and deeper (II-IV) laminae of the dorsal horn ipsilaterally. Densitome tric measurements revealed a 50% return towards normal values for SP bindin g by 90 days postpronase injection in all laminae examined, while the densi ty of CGRP binding showed a partial return towards normal values for lamina e III-IV only. These differential responses may be indicative of the mechan isms underlying pronase-induced peripheral neuropathy.