Jin B K, Franzen L, Baker H
Cornell University Medical College, Burke Medical Research Institute, White Plains, New York 10605, USA.
Int J Dev Neurosci. 1996 Nov;14(7-8):971-82. doi: 10.1016/s0736-5748(96)00044-5.
Odorant deprivation, produced by unilateral naris closure, profoundly reduces tyrosine hydroxylase (TH) expression within intrinsic olfactory bulb dopamine neurons. The TH gene contains an AP-1 site, which interacts with the product of the immediate early gene, c-fos. c-Fos exhibits activity dependent regulation in the CNS. The hypothesis that odorant stimulation and deprivation might modify c-fos expression in TH neurons was tested in adult CD-1 mice, subjected to unilateral naris closure. After 2 months, naris closed and control mice were exposed to either clean air for 60 min or clean air for 60 min followed by 30 min of alternating exposure to 10% isoamyl acetate (1 min) and air (4 min). A parallel reduction occurred in TH and fos expression (both c-fos mRNA and fos-like immunoreactivity) in the glomerular layer of the odorant-deprived olfactory bulb. Odor stimulation induced a short-lived increase in c-fos mRNA and fos-like immunoreactivity in olfactory bulbs contralateral to naris closure. The increase in fos expression was region-specific in the glomerular layer but more diffuse in mitral and granule cell layers. In olfactory bulbs ipsilateral to naris closure, odor stimulation also induced c-fos mRNA expression in the mitral and granule cell layers and sparsely within limited periglomerular regions. Odor induced expression in mitral and granule cell layers may represent increased centrifugal activity acting on as yet unknown genes. These results suggest a correlation between c-fos mRNA expression and increased neuronal activity in the olfactory bulb which, in turn, acts to regulate TH expression in periglomerular neurons.
单侧鼻孔封闭导致的嗅觉剥夺，会显著降低嗅球内源性多巴胺能神经元中酪氨酸羟化酶（TH）的表达。TH基因包含一个AP-1位点，该位点与即早基因c-fos的产物相互作用。c-Fos在中枢神经系统中表现出活性依赖性调节。在成年CD-1小鼠中进行单侧鼻孔封闭，以检验嗅觉刺激和剥夺是否会改变TH神经元中c-fos的表达这一假说。2个月后，将鼻孔封闭的小鼠和对照小鼠暴露于清洁空气中60分钟，或先暴露于清洁空气中60分钟，然后交替暴露于10%异戊酸乙酯（1分钟）和空气（4分钟）30分钟。在嗅觉剥夺的嗅球的肾小球层中，TH和fos表达（c-fos mRNA和fos样免疫反应性）出现了平行下降。气味刺激在鼻孔封闭对侧的嗅球中诱导了c-fos mRNA和fos样免疫反应性的短暂增加。fos表达的增加在肾小球层具有区域特异性，但在二尖瓣和颗粒细胞层中更为弥散。在鼻孔封闭同侧的嗅球中，气味刺激也诱导了二尖瓣和颗粒细胞层以及有限的肾小球周围区域内稀疏的c-fos mRNA表达。气味诱导的二尖瓣和颗粒细胞层表达可能代表作用于未知基因的离心活动增加。这些结果表明，c-fos mRNA表达与嗅球中神经元活动增加之间存在相关性，进而调节肾小球周围神经元中TH的表达。
