CELL-SPECIFIC DIFFERENTIAL EXPRESSION OF NA-CHANNEL BETA-1-SUBUNIT MESSENGER-RNA IN THE OLFACTORY SYSTEM DURING POSTNATAL-DEVELOPMENT AND AFTER DENERVATION()
S. Sashihara et al., CELL-SPECIFIC DIFFERENTIAL EXPRESSION OF NA-CHANNEL BETA-1-SUBUNIT MESSENGER-RNA IN THE OLFACTORY SYSTEM DURING POSTNATAL-DEVELOPMENT AND AFTER DENERVATION(), The Journal of neuroscience, 16(2), 1996, pp. 702-713
Activity-dependent mechanisms have been implicated in olfactory system
development but, although such activity requires ion channels, few re
ports have described their expression in the olfactory system. We inve
stigated the developmental and denervation-induced regulation of the N
a+-channel beta 1 subunit (Na beta 1) in rat olfactory bulb (OB) and p
iriform cortex (PC). In situ hybridization shows that Na beta 1 mRNA e
xpression is upregulated developmentally, but with different time cour
ses in mitral, tufted, and pyramidal cells. In mitral cells, label was
detected at postnatal day 4 (P4) and gradually increased to P14. Tuft
ed cells were devoid of Na beta 1 mRNA before P14, when most cells exp
ressed adult levels. In pyramidal cells of PC, Na beta 1 expression wa
s not detectable clearly until P14, with maximal expression at P28. To
examine the regulation of Na beta 1 mRNA, we surgically deafferented
the OB at P30 and compared the effects on Na beta 1 with those for Na-channel alpha-subunit (Na alpha) mRNAs. Within 5 d of surgery, the Na
beta 1 and Na alpha II signals within tufted cells disappeared almost
completely. Na beta 1 and Na alpha II expression was decreased in mit
ral cells to low-to-moderate levels. In pyramidal cells, Na beta 1 mRN
A expression was decreased moderately without significant changes in N
a alpha II mRNA. Deafferentation had no detectable effects on Na alpha
I or III mRNAs in either OB or PC. These data indicate that Na beta 1
mRNA is expressed differentially in subpopulations of cells in the ol
factory system during development and after deafferentation and sugges
t that the expression of Na beta 1 is regulated independently of Na al
pha mRNAs via cell-specific and pathway-specific mechanisms.