含GABA_A受体α_6亚单位mRNA神经元在大鼠脑内的生后发育

用原位杂交组织化学方法观察了大鼠小脑皮质和耳蜗核中含ＧＡＢＡＡ受体α６亚单位ｍＲＮＡ神经元的生后发育过程。结果发现小脑在生后发育中，杂交信号在生后第５ｄ最早出现于内颗粒层，在生后第２１ｄ达到高峰并持续至成年期。但在外生发展始终未见到阳性信号。在耳蜗核中，α６亚单位ｍＲＮＡ到生后第７ｄ方出现，其表达水平在此后的阶段内迅速增加，从生后第１４ｄ开始，杂交信号的增强趋于缓慢，至生后第３ｗ达到成年水平。α６亚单位ｍＲＮＡ在小脑及耳蜗核的生后发育早期即有较强表达，提示其与上述两个系统的成熟过程有关。

EXPRESSION OF GABA_A RECEPTOR α_6 SUBUNIT mRNA IN THE DEVELOPING RAT BRAIN

It is well known that γ-aminobutyric acid_A receptor(GABA_A-R)represents the target structure of GABA. Recently,many subunits of the GABA_A-R have been found in the vertebrate brain by molecular cloning analysis.Their localization and function have also been studied. But much less is known about the α_6 subunit.So,the expression of α_6 subunit mRNA in the developing rat brain was examined by in situ hybridization histochemistry. SD rats at different postnatal (P) ages were used.Sections (10￣ 15 μm)were incubated with the specific probe labeled at 3'end withα-￣(35)S]dATP and examined by emulsion autoradiography. In the developing cerebellum,α_6 mRNA became detectable at P_5 and increased rapidly until P_(14).Then it increased grsdualy and reached adult levels at P_(21).In contrast, the neurons in the cochlear nuclei were not labeled until P_7.The number and labeling intensity of these labeled neurons increased during the following period and achieved adult levels at the third postnatal week. Our results indicated that, in rat , the expression of α_6 gene in both cerebellar and cochlear granule cells may be a reflection of their common origin. α_6 mRNA expression coincided with the maturation of the granule cells of the cerebellum and cochlear nuclei, suggesting that it might play an important role in the development of these regions.