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 physical injury in vivo, and after toxic insult in vitro and in vivo. The current immunocytochemical study aimed to monitor the neuropeptide status of neuronal cultures prepared from adult mouse dorsal root ganglia (DRG), and to ascertain whether changes occurred following treatments with 0.1-1 microM methylmercury (MeHg). Proportions of both substance P (SP) and calcitonin gene related peptide (CGRP) containing neurons increased significantly, and were maintained throughout the 24 h exposure period. In contrast the numbers of somatostatin (SOM)-ir neurons decreased. Substance P- and CGRP-ir neuron increases may be related to nociceptive responses, whereas the decreases in SOM containing neurons could reflect a differential loss in this subset of sensory neurons.