EXPRESSION OF PREPRODYNORPHIN mRNA IN THE RAT NUCLEUS CAUDALIS

采用原位杂交定量分析技术，观察了低强度和高强度电刺激三叉神经初级传入后尾侧核神经元前脑啡肽原mRNA的表达。在这两个强度的刺激主要增强了这种mRNA的表达在板层I和II神经元的尾侧核。高、低强度刺激后1、2h表达增强，并持续到刺激结束后24h。原位杂交定量分析表明，该基因表达的增加似乎主要是由于该mRNA表达强度的增加。与我们以前的报道相比，在初级传入的低强度刺激后，前脑啡肽原mRNA的表达呈双模式增加，这种增强主要是由于在初级传入的低强度刺激后，结果表明，刺激三叉神经初级传入后，尾侧核神经元中前强啡肽原mRNA的表达与前脑啡肽原mRNA的表达以不同的方式增加，提示在尾侧核中，前强啡肽原和前脑啡肽原两种阿片肽基因的表达受初级传入的不同调节。

The expression of preproenkephalin mRNA was examined using techniques for quantitative analysis of in situ hybridization in nucleus caudalis neurons following electrical stimulation of trigeminal primary afferents at the low and high intensities. Stimulation at both intensities principally enhanced the expression of this mRNA in laminae I and II neurons of the nucleus caudalis. The enhancement of the expression was found at one and two hours after the stimulation of high and low intensities, respectively, and was continued until 24 hour at the end of stimulations. Quantitative analysis of in situ hybridization revealed that the increment in the expression of this gene appears to be mainly due to an increase in the intensity of expression of this mRNA.Compared with our previous reports in which the expression of preproenkephalin mRNA was enhanced in a bimodial temporal pattern after stimulation at the low intensity of the primary afferents and this enhancement were mainly due to increase in the number of the positive neurons, the present result for the expression of preprodynorphin mRNA indicate that the expression of this mRNA in nucleus caudalis neurons are increaced in different manner from that of preproenkephalin mRNA following stimulation of trigeminal primary afferents, suggesting that in the nucleus caudalis the expression of two opioid peptide genes, preprodynorphin and preproenkephalin, are differentially regulated by primary afferents.