Expression of the sodium channel transcripts Nav1.8 and Nav1.9 in injured dorsal root ganglion neurons of interferon-γ or interferon-γ receptor deficient mice

Changes in the dorsal root ganglion (DRG) expression of the sodium channels Nav1.8 and Nav1.9 may contribute to injury-induced hyperexcitability and pain. Interferon (IFN)-γ receptor −/− mice display a reduced pain-related behavior after nerve injury as compared to wild-type mice (NeuroReport 8 (1997) 1311). To elucidate a possible role for IFN-γ in the regulation of sodium channels, we have studied the DRG mRNA expression of Nav1.8/Nav1.9 in IFN-γ- or IFN-γ receptor-deficient mice. In both types of mice, nerve damage induced a downregulation of Nav1.8 as well as Nav1.9. The magnitude of this reduction was similar to that observed in wild-type animals. These results indicate that the downregulation of Nav1.8/Nav1.9 in damaged DRG neurons is not influenced by IFN-γ. Thus, the reduced pain-related behavior of nerve-injured IFN-γ receptor null mice is not due to differential changes in the regulation of Nav1.8/Nav1.9 mRNA. [Copyright &y& Elsevier]