NA-1 SUBUNIT MESSENGER-RNA - DIFFERENTIAL EXPRESSION IN RAT SPINAL SENSORY NEURONS( CHANNEL BETA)

The brain Na+ channel beta 1 subunit (Na beta 1) mRNA has recently bee n localized within rat central nervous system where it is expressed at differing levels in different types of neurons. In the present study, we have studied the expression pattern of Na beta 1 mRNA in rat dorsa l root ganglion (DRG) neurons using non-radioactive in situ hybridizat ion histochemistry. Na beta 1 mRNA is differentially expressed in adul t DRG, with higher levels in intermediate-to-large (> approximately 25 mu m in diameter) DRG neurons than in small (< 25 mu m) DRG neurons. This cell body size-related Na beta 1 mRNA expression is consistently observed beginning at postnatal day 4 and continues throughout develop ment to adulthood. The present results indicate that (i) Na beta 1 mRN A is expressed in neurons in the peripheral nervous system and (ii) Na beta 1 gene expression is differentially regulated in DRG neurons in relation to their cell body sizes.