Nerve growth factor regulates VR-1 mRNA levels in cultures of adult dorsal root ganglion neurons

Nerve growth factor (NGF) regulates the nociceptive properties including sensitivity to capsaicin of a subset of dorsal root ganglion neurons, which express the high-affinity NGF receptor, trkA. Capsaicin sensitivity co-localizes with the expression of a cloned capsaicin receptor, vanilloid receptor type 1 (VR-1), which displays properties similar to the native capsaicin response. To determine whether VR-1 mRNA levels are regulated by NGF, VR-1 mRNA levels and the ability to respond to capsaicin by release of the neuropeptide calcitonin gene related peptide (CGRP) were measured as a function of NGF concentration in cultures of adult dorsal root ganglion neurons. NGF treatment increased both VR-1 mRNA expression and capsaicin evoked release of CGRP. These effects were inhibited by treatment with the trkA inhibitor k252a.