The abnormality of the central noradrenergic system in Alzheimer's disease has two cases: decrease or increase. The former is easy to be understood, because it is resulted from the outstanding forfeit of the noradrenergic neurons in the nucleus locus ceruleus (nLC); but the noradrenalin concentration does not change and enen increase, it seems to disagree with the loss of the noradrenergic neurons in the nLC. This article put emphasis on it, enumerated the related evidence and analyzed the possible causes. At present time, the drugs to increase noradrenalin is used mostly in clinic. This paper summarized it and put forth our own opinions.

Objective To investigate the influence of different decomposed combinations of Simiao Yong’ an Decoction ( four-ingredient health-restoring decoction ) on the extraction rates of liquiritin , hy-peroside and luteoloside .Methods The extraction rates of liquiritin , hyperoside and luteoloside were de-termined with HPLC using a SunfireTMC18 analytical column(4.6mm ×150mm,5μm) in decomposed for-mula of Simiao Yong ’ an Decoction.The mobile phase was composed of aqueous phosphoric acid (0.1%) and acetonitrile using anisocratic elution .The column temperature was 35℃.The flow rate was 1.0 mL/min while the detection wavelength was set at 276 nm(liquiritin)and 350 nm(hyperoside and luteoloside ) .The contents and the extraction rates of liquiritin , hyperoside and luteoloside from the origi-nal and dismantled formula were detected and analyzed .Results Compared with the single herb , the more ingredients it contained , the higher extraction rates of liquiritin , hyperoside and luteoloside .When the whole ingredients were stewed together , the extraction rates of these 3 components reached the peak . Conclusion The different decomposed SimiaoYong ’ an Decoction can significantly improve the extrac-tion rates of liquiritin , hyperoside and luteoloside , which indicated the validity and rationality of com-pound compatibility from the extraction rates of chemical compositions .