Abstract
Insulin-like growth factor-I (IGF-I) plays an important role in bulbo-epithelial interactions in the olfactory system. Translocation of TRPV2 (also known as VRL1 and GRC) to the plasma membrane is augmented by IGF-I. In this study, we explore the effect of IGF-I on the mouse olfactory sensory neurons (OSNs) via TRPV2 by measuring intracellular calcium levels in isolated OSNs by fluorecence microscopy with Fluo4-AM, a calcium indicator. The increase of intracellular calcium levels in OSNs was induced by the application of IGF-I (25 ng/ml), which was inhibited in the presence of SK&F 96365 (20μM). The increase of intracellular calcium levels was induced by 1 mM of 2-aminoethoxydiphenyl borate (2APB), an activator of TRPV1/2/3, which was also inhibited by SK&F 96365. The intracellular calcium levels were not elevated by the application of both IGF-I and 2APB when calcium ion was eliminated from extracellular solution. Immunohistochemistry revealed IGF-I receptor and TRPV2 were co-localized on mouse olfactory epithelium. These data suggest that TRPV2 contributes the elevation of intracellular calcium level in response to IGF-I in OSNs. [J Physiol Sci. 2007;57 Suppl:S98]
