DOWN-REGULATION OF NA-RNA IN OLFACTORY-BULB TUFTED CELLS FOLLOWING DEAFFERENTIATION( CHANNEL MESSENGER)

UNILATERAL naris cauterization blocks odorant access to ipsilateral ol factory receptor cells and results in functional deafferentation of th e olfactory bulb (OB). We used naris cauterization on postnatal day 2 (P2) to study the effects of deafferentation on the expression of Nachannel subunits in OB. In situ hybridization at P18 showed that expre ssion of Na+ channel alpha II and beta I mRNA was dramatically downreg ulated in tufted cells, while signals in mitral cells showed no detect able changes. Our observations suggest that during critical periods of development in some neurons, Na+ channel expression may be modulated by physiological activity. The differential response in the tufted and mitral cells may reflect varying degrees of dependence on afferent in put or fundamental differences in cell properties.