Matesic D, Attardi B, Dellovade T, Pfaff D, Germak J
Department of Pediatrics and Human Development, Michigan State University, East Lansing 48824, USA.
J Neuroendocrinol. 1997 Jun;9(6):467-78. doi: 10.1046/j.1365-2826.1997.00596.x.
The immortalized neuronal cell line, GT1-7, has been shown to secrete LHRH in a pulsatile manner and to possess many other characteristics of hypothalamic LHRH neurons in vivo, and thus provides a potential model system for studying biochemical and physiological mechanisms regulating LHRH secretion. In the present study, two morphologically and functionally distinct types of cells have been identified in GT1-7 cultures and each type purified to over 95% homogeneity. One type (N cells) appeared more neuronal with extended neurites and somewhat rounded cell perikarya, while the other type (G cells) had flatter cell perikarya that contained filopodia but no neurites. Growth properties of the two cell types also differed. The doubling time for proliferation of N cells was nearly two-fold shorter than that for G cells and N cells displayed 'piling up' whereas G cells exhibited contact inhibition. Functionally, N cells, but not G cells, were dye-coupled as measured by a fluorescence photobleaching assay. While both cell types expressed LHRH, N cells released significantly higher levels of LHRH into the culture media and exhibited more intense LHRH immunostaining. The two cell types also showed differences in immunostaining for other proteins. N cells, unlike G cells, immunostained positive for neuron-specific enolase (NSE), whereas G cells, unlike N cells, stained immunopositive for vimentin. Both cell types expressed SV-40 T antigen protein, indicating that they were derived from the same transgenic mouse hypothalamic tumour. The physiological significance of these two cell types in GT1-7 cultures remains to be determined, but elucidation of their morphological and biochemical properties is intended to contribute to better understanding and application of this experimentally important neuroendocrine cell line.
永生化神经元细胞系GT1-7已被证明以脉冲方式分泌促性腺激素释放激素（LHRH），并在体内具有下丘脑LHRH神经元的许多其他特征，因此为研究调节LHRH分泌的生化和生理机制提供了一个潜在的模型系统。在本研究中，在GT1-7培养物中鉴定出两种形态和功能不同的细胞类型，并且每种类型均纯化至超过95%的同质性。一种类型（N细胞）看起来更具神经元特征，有延伸的神经突和略呈圆形的细胞体，而另一种类型（G细胞）的细胞体更扁平，含有丝状伪足但没有神经突。两种细胞类型的生长特性也不同。N细胞增殖的倍增时间比G细胞短近两倍，N细胞表现出“堆积”现象，而G细胞表现出接触抑制。在功能上，通过荧光光漂白测定法测量，N细胞而非G细胞是染料偶联的。虽然两种细胞类型都表达LHRH，但N细胞向培养基中释放的LHRH水平明显更高，并且表现出更强的LHRH免疫染色。两种细胞类型在其他蛋白质的免疫染色方面也存在差异。与G细胞不同，N细胞对神经元特异性烯醇化酶（NSE）免疫染色呈阳性，而与N细胞不同，G细胞对波形蛋白免疫染色呈阳性。两种细胞类型均表达SV-40 T抗原蛋白，表明它们源自同一只转基因小鼠下丘脑肿瘤。GT1-7培养物中这两种细胞类型的生理意义仍有待确定，但阐明它们的形态和生化特性旨在有助于更好地理解和应用这一在实验上很重要的神经内分泌细胞系。
