谷氨酸单钠引起大鼠垂体性侏儒变化

新生大鼠受小剂量谷氨酸单钠(MSG)皮下注射后,生长迟缓。至100日龄时,体重、身长落后于对照组2S,达到侏儒诊断标准。各内脏相应减轻,但脑重与智能与对照组无显著差异。类似人类垂体性侏儒的临床表现。形态学观察,显示下丘脑弓状核核团缩小、神经细胞萎缩、变性、数目减少。垂体重量减轻,垂体前叶生长激素细胞数目减少。图象分析仪测定,该类细胞体积、面积明显缩,但免疫组织化学染色表明仍有合成生长激素的能力,证明小剂量MSG引起下丘脑弓状核损伤,生长激素释放因子(GRF)产生及释放减少,血中生长激素浓度下降,符合目前临床对某些垂体性侏儒的病因分析,模型可作为进一步研究人类垂体性侏儒的动物模型。

The Morphological Change of “Pituitary Dwarf” Induced by Monosodium Glutamate on Rats

Wister newborn male rats were divided into two groups, one group was administrated MSG(4g/kg)by s.c. every two days from the second day to the tenth after birth. Another group was gaven N.S. as control. At the hundredth day, the rats were decapitated. We found that the rats' body weight and length in experimental grounp reduced significantly as compared with those in control group. There was no difference between two groups on brain weight and intelligence, although the reduction of weight of viscera was obvious in experimental group. The nucleus arcuatus were apparently smaller and the number of neurone were obviously less than those in the control. The weights of piutitary glands in experimental group were as 55.8 per cent as those in control group. The result of immunohistochemistry revealed the presence of GH-secreting cell in the pituitary glands of rats treated with MSG, but the number and area of these cells measured by image analyser were smaller. According to these results, we consider that the damage of nucleus arcuatus induced by MSG obviously decreases the secretion of growth hormon releasing factor, therefore, the secretion of GH is insufficant in pituitary gland and the differentiation of GH-secreting cells can not be promoted. The conc- lusion is that the dwarfism model induced by MSG in rats is very similar to pituitary dwarf of human being,