Nothias F, Salin P, Peschanski M, Chesselet M F
INSERM CJF 91-02, Faculté de Médecine, Créteil, France.
Brain Res Mol Brain Res. 1993 Nov;20(3):245-53. doi: 10.1016/0169-328x(93)90047-s.
The goal of the present study was to determine whether alterations in neuronal morphology and connections in thalamic grafts were accompanied by changes in the expression of mRNA encoding glutamic acid decarboxylase (GAD), the key enzyme in the synthesis of GABA, the normal neurotransmitter of neurons of the thalamic reticular nucleus. Cell suspensions of rat fetal tissue containing both thalamic reticular nucleus and ventrobasal primordia were transplanted into the excitotoxically lesioned somatosensory thalamus of adult rats. Levels of messenger RNA (mRNA) encoding GAD (Mr 67,000; GAD67) were measured 7 days to 4 months following transplantation via quantitative in situ hybridization with 35S-radiolabeled antisense RNAs. Expression of GAD67 mRNA in the thalamic reticular nucleus was analyzed in parallel in rat pups between 0 and 30 days postnatally, and in adult animals. As already observed with immunohistochemistry, transplanted neurons of the thalamic reticular nucleus did not group in specific clusters but rather mingled with unlabeled (putatively ventrobasal) neurons. Levels of labelling for GAD67 mRNA per neuron increased over time and reached adult levels during the third week post-grafting, i.e. 2 weeks after the theoretical birthdate of the neurons (grafted at embryonic days 15-16). Similar values were observed and a plateau was reached at similar time points during normal ontogeny. The results suggest that, in contrast to morphology and size of the neuronal cell bodies, gene expression of GAD67 develops normally despite the ectopic location of neurons of the thalamic reticular nucleus in the somatosensory thalamus, the abnormal connectivity and the lack of segregation from non-GABAergic neurons.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究的目的是确定丘脑移植体中神经元形态和连接的改变是否伴随着编码谷氨酸脱羧酶（GAD）的mRNA表达的变化，GAD是γ-氨基丁酸（GABA）合成中的关键酶，而GABA是丘脑网状核神经元的正常神经递质。将含有丘脑网状核和腹侧基底原基的大鼠胎儿组织细胞悬液移植到成年大鼠经兴奋性毒素损伤的体感丘脑中。在移植后7天至4个月，通过与35S放射性标记的反义RNA进行定量原位杂交，测量编码GAD（分子量67,000；GAD67）的信使RNA（mRNA）水平。同时分析出生后0至30天的幼鼠以及成年动物丘脑网状核中GAD67 mRNA的表达。正如免疫组织化学所观察到的，丘脑网状核的移植神经元没有聚集在特定的簇中，而是与未标记的（推测为腹侧基底的）神经元混合在一起。每个神经元的GAD67 mRNA标记水平随时间增加，并在移植后第三周达到成年水平，即神经元理论出生日期（在胚胎第15 - 16天移植）后的2周。在正常个体发育过程中，在相似的时间点观察到相似的值并达到平台期。结果表明，与神经元细胞体的形态和大小不同，尽管丘脑网状核神经元在体感丘脑中位置异位、连接异常且与非GABA能神经元缺乏分离，但GAD67的基因表达仍正常发育。（摘要截断于250字）
