Felts P A, Yokoyama S, Dib-Hajj S, Black J A, Waxman S G
Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.
Brain Res Mol Brain Res. 1997 Apr;45(1):71-82. doi: 10.1016/s0169-328x(96)00241-0.
The expression of sodium channel alpha-subunit mRNAs I, II, III, NaG, Na6 and hNE (PN1) was examined in developing (E17-P30) hippocampus, cerebellum, spinal cord and dorsal root ganglia using non-isotopic in situ hybridization cytochemistry. The results showed distinct patterns of expression for each of the sodium channel mRNAs with maturation of the nervous system. In the hippocampus, sodium channel mRNA I was not detected at any developmental time, while mRNA II showed increasing hybridization signal between E17 and P30. Sodium channel mRNA III was more prevalent at late embryonic and early postnatal times, and was barely detectable at P30. The transcript for NaG showed transient expression between P2 and P15, being expressed at low levels at E17 and not being detectable at P30. Sodium channel mRNA Na6 exhibited a high level of expression between E17 and P15 in the hippocampal formation, with an attenuation of the signal by P30. hNE (PN1) mRNA was not detected in the hippocampus at any time examined. In the cerebellum, sodium channel mRNA I was not detected at E17 or P2, but became detectable in Purkinje cells at P15 and continued to show a low level of expression in these cells at P30. mRNA I was not detected at any time examined in granule cells of the cerebellum. Sodium channel mRNA II exhibited increasing expression in the developing cerebellum, and showed increasing signal in Purkinge cells beginning on P2 and granule cells on P15. Sodium channel mRNA III was down-regulated with development in the cerebellum, although mRNA III was readily detected at E17, it was not detected in any layers of the cerebellum by P15. NaG mRNA showed a peak of expression at P2, and was present at low levels at E17 and P15 and not detectable at P30. Na6 mRNA was highly expressed in the E17 cerebellum; this mRNA was present at high levels in Purkinje cells throughout development, although in granule cells the signal was attenuated at P15-P30. Sodium channel hNE (PN1) mRNA was not detected in the cerebellum at any time in development. In the spinal cord, sodium channel mRNA I showed increasing expression beginning at P2 and was highly expressed, particularly in ventral motor neurons, by P30. Sodium channel II mRNA was detected at all stages of development in the spinal cord; in contrast, mRNA III was detected at E17 and P2, but showed very low levels of expression by P30. NaG mRNA exhibited a transient expression in spinal cord at P2, but was not detectable at E17 and P30. Na6 mRNA was detectable at very low levels at E17 and became highly expressed at P2, prior to a reduction of the signal at P15 and P30. hNE (PN1) mRNA was not detected in the spinal cord at any time in development. In the dorsal root ganglia, sodium channel I mRNA hybridization signal was detected in DRG neurons at P2, with slightly increased levels at P15 and P30. Sodium channel II mRNA exhibited a relatively constant, moderate level of expression at all developmental ages. Sodium channel III mRNA was highly expressed in DRG neurons at E17 but was down-regulated with further development so that it was not detectable by P30. NaG mRNA was strongly expressed by some DRG neurons at all stages of development from E17 to P30; in general the level of NaG labelling was greater in larger neurons than in smaller neurons. Na6 mRNA showed increasing expression with development in DRG neurons; at E17, low levels of Na6 mRNA were detected and by P15 to P30 high levels of expression were present in some neurons. hNE (PN1) mRNA was present in DRG neurons at P2, and was up-regulated with further development so that by P30 hNE (PN1) was expressed in all DRG neurons sizes. These results demonstrate that sodium channel alpha-subunit mRNAs I, II, III, NaG, Na6 and hNE (PN1) exhibit distinct spatial and temporal patterns of expression in nervous tissue, and suggest that the expression of the sodium channel alpha-subunits is differentially regulated. (ABSTRACT TRUNCATED)
采用非同位素原位杂交细胞化学技术，检测了发育中（胚胎17天至出生后30天）海马、小脑、脊髓和背根神经节中钠通道α亚基mRNA I、II、III、NaG、Na6和hNE（PN1）的表达。结果显示，随着神经系统的成熟，每种钠通道mRNA都呈现出独特的表达模式。在海马中，任何发育时期均未检测到钠通道mRNA I，而mRNA II在胚胎17天至出生后30天之间杂交信号增强。钠通道mRNA III在胚胎后期和出生后早期更为普遍，在出生后30天时几乎检测不到。NaG转录本在出生后2天至15天之间短暂表达，在胚胎17天时低水平表达，出生后30天时未检测到。钠通道mRNA Na6在海马结构中胚胎17天至出生后15天之间高水平表达，出生后30天时信号减弱。在任何检测时间，海马中均未检测到hNE（PN1）mRNA。在小脑中，胚胎17天或出生后2天时未检测到钠通道mRNA I，但在出生后15天时在浦肯野细胞中可检测到，并在出生后30天时在这些细胞中持续低水平表达。在小脑颗粒细胞的任何检测时间均未检测到mRNA I。钠通道mRNA II在发育中的小脑中表达增加，从出生后2天开始在浦肯野细胞中信号增强，在出生后15天在颗粒细胞中信号增强。钠通道mRNA III在小脑中随着发育而下调，尽管在胚胎17天时很容易检测到mRNA III，但到出生后15天时在小脑的任何层中均未检测到。NaG mRNA在出生后2天时表达达到峰值，在胚胎17天和出生后15天时低水平表达，出生后30天时未检测到。Na6 mRNA在胚胎17天的小脑中高表达；在整个发育过程中，该mRNA在浦肯野细胞中高水平存在，尽管在颗粒细胞中，出生后15天至30天时信号减弱。在发育的任何时间，小脑中均未检测到钠通道hNE（PN1）mRNA。在脊髓中，钠通道mRNA I从出生后2天开始表达增加，到出生后30天时高表达，尤其是在腹侧运动神经元中。在脊髓发育的所有阶段均检测到钠通道II mRNA；相反，mRNA III在胚胎17天和出生后2天时检测到，但到出生后30天时表达水平极低。NaG mRNA在脊髓出生后2天时短暂表达，但在胚胎17天和出生后30天时未检测到。Na6 mRNA在胚胎17天时以极低水平可检测到，在出生后2天时高表达，在出生后15天和30天时信号减弱之前。在发育的任何时间，脊髓中均未检测到hNE（PN1）mRNA。在背根神经节中，在出生后2天时在背根神经节神经元中检测到钠通道I mRNA杂交信号，在出生后15天和30天时水平略有增加。钠通道II mRNA在所有发育年龄均表现出相对恒定的中等水平表达。钠通道III mRNA在胚胎17天时在背根神经节神经元中高表达，但随着进一步发育而下调，因此到出生后30天时无法检测到。从胚胎17天到出生后30天的所有发育阶段，一些背根神经节神经元中NaG mRNA均强烈表达；一般来说，较大神经元中NaG标记水平比较小神经元中更高。Na6 mRNA在背根神经节神经元中随着发育表达增加；在胚胎17天时，检测到低水平的Na6 mRNA，到出生后15天至30天时，一些神经元中存在高水平表达。hNE（PN1）mRNA在出生后2天时存在于背根神经节神经元中，并随着进一步发育而上调，因此到出生后30天时，hNE（PN1）在所有大小的背根神经节神经元中均有表达。这些结果表明，钠通道α亚基mRNA I、II、III、NaG、Na6和hNE（PN1）在神经组织中呈现出独特的时空表达模式，并表明钠通道α亚基的表达受到差异调节。（摘要截断）
