Regulation by nerve growth factor of neuropeptide phenotypes in primary cultured sensory neurons prepared from aged as well as adult mice.

The present study investigated neuropeptide phenotypes of aged, as well as adult, mouse sensory neurons. Proportions of somatostatin (SOM), calcitonin gene related protein (CGRP) and neuropeptide Y (NPY) immunoreactive (ir)-neurons were lower in primary cultures from aged (2 years) mice than in those from adult (6 months) animals, but similar for substance P (SP) in the absence of exogenous nerve growth factor (NGF). Addition of NGF, significantly enhanced (P < 0.05) proportions of SP, NPY and CGRP ir-neurons in both adult and aged cultures, whereas SOM ir-neurons were not affected in either. Thus SP, CGRP, NPY and SOM phenotypes are retained in cultured aged DRG neurons and some phenotypes can remain sensitive to NGF regulation.