CHANGES IN NEUROPEPTIDE IMMUNOREACTIVITY IN CULTURED ADULT-MOUSE SENSORY NEURONS FOLLOWING METHYLMERCURY CHLORIDE TREATMENTS

Changes in the neuropeptide expression of sensory neurons, related to functional modulation, have been widely reported both following physic al injury in vivo [4,23], and after to,:ic insult in vitro and in vivo [7]. The current immunocytochemical study aimed to monitor the neurop eptide status of neuronal cultures prepared from adult mouse dorsal ro ot ganglia (DRG), and to ascertain whether changes occurred following treatments with 0.1-1 mu M methylmercury (MeHg). Proportions of both s ubstance P (SP) and calcitonin gene related peptide (CG RP) containing neurons increased significantly, and were maintained throughout the 2 4 h exposure period. In contrast the numbers of somatostatin (SOM)-ir neurons decreased. Substance P- and CGRP-ir neuron increases may be re lated to nociceptive responses, whereas the decreases in SOM containin g neurons could reflect a differential loss in this subset of sensory neurons. (C) 1998 Elsevier Science Ireland Ltd.