Activity And Mechanism Of Fractions And Components Of LWDHD On Prevention And Treatment Diabetic Encephalopathy

Diabetic encephalopathy(DE), a kind of complications of diabetes with cognitive dysfunction as the main performance. Cross section of DE belongs to the Department of Neurology and Department of Endocrinology. The cognitive dysfunction of DE is formed by multiple factors and links. The pathogenesis of DE is complex, and the researches on DE have lagged behind. The most pathological mechanism of targeted drugs on DE including aldose reductase inhibitors, non-enzymatic glycosylation inhibitor, glutathione preparations and neurotrophic factor, still remain in the preclinical or clinical studies because of various reasons. Therefore, searching for development of new drugs on DE according to the pathogenesis has great significance.DE is a kind of diabetes complicated with dementia and amnesia in traditional Chinese medical science. The basic pathogenesis of diabetes is dryness-heat due to deficiency of yin. The pathological changes of viscera emphatically occur in lung, stomach and kidney, and kidney is the main disordered region. Therefore, nourishing kidney Yin is the basic treatment of diabetes. Liuwei dihuang decoction(LWDHD), a representative prescription for invigorating the kidney and nourishing Yin, is applied extensively as a basic recipe in treating diabetes in traditional Chinese medical science. Pharmacological studies have showed that LWDHD can increase the content of hepatic glycogen, reduce the activity of hepatic glucose-6-phosphatase, decrease the levels of blood glucose, blood lipid and free fatty acids, and scavenge free radicals. Moreover, LWDHD can significantly improve memory and cognitive ability, increase the reaction speed, has the prevention effect on the progressive and degenerative amnesia, and improve the intelligence, ability, memory ability of senile dementia patients. Therefore, based on the pathogenesis of diabetic encephalopathy, the effects of LWDHD on cognitive impairment and nervous pathological changes in DE were studies from improving the cognitive ability, antioxidant, anti-apoptosis, regulation of cholinergic nerve function and neurotrophic factor expression and other aspects. The results will provide scientific basis for the prevention and treatment of DE.The first chapter, screeing the effective components of LWDHD on improves cognitive impairment.the PPAR delta agonist screening model, PTP-1B inhibitor screening model, T/B lymphocyte proliferation model, subacute aging mice model and Yin deficiency model were first used to screen the active fraction of four extracts(total extract, water elution part, 30% alcohol elution part, 70% alcohol elution) in LWDHD and active components of nine compounds(Gallic acid, paeoniflorin, paeonol, Catalpol, loganin, morroniside, aucubin, 23-acetyl Alisma triptolide B, diosgenin). The results showed that: 1. paeonol, diosgenin, and aucubin significantly increased the content of PPAR δ; 2. paeonol, morroniside, loganin, 23-acetyl alisma triptolide B, paeoniflorin and aucubin had certain degree of inhibition of PTP-1B function; 3. paeonol and diosgenin promoted the proliferation of B cells; paeoniflorin and aucubin significantly promoted the proliferation of T cells; morroniside promoted the proliferation of T and B lymphocytes, and water washed fraction and the total extract also promoted the proliferation of T and B lymphocyte; 4. The ethanol-water fraction of LWDHD improved the cognitive abilities, scavenged free radical, reducing oxidative stress, decreased the content of Aβ in brain in D-galactose-induced aging mice, which had obvious anti-aging effect; 5. The ethanol-water fraction of LWDHD increased the growth rate of body weight, index numbers of thymus and spleen, reduced the activities of SOD and GSH-Px, increased MDA level, and decreased levels of serum c AMP, T3 and T4 and the ratio of c AMP/c GMP. Therefore, the ethanol-water fraction of LWDHD is the active fraction, and paeonol is the active components in LWDHD.The second chapter, the high fat diet plus low dose STZ injection preparation of DE rat model was adopted to study the effects of ethanol-water fraction of LWDHD(2.33 g/kg and 9.32 g/kg) on the behavior, the level of blood glucose, oxidative index detection, apoptosis of nerve cells, activities of Ch AT and Ach E, and expressions of BDNF, IGF-1 and other neurotrophic factor. The results showed that: in the water maze test, the escape latencies and explore distance were significantly shortened in ethanol-water fraction of LWDHD treated DE rats, and swimming time in the target quadrant and the platform traversing times were increased. Moreover, ethanol-water fraction of LWDHD significantly reduce the contents of blood glucose, increased the activities of CAT, Na~+-K~+-ATP, Ch AT and Ach E and level of GSH, and decreased the level of LPO and the activity of i NOS in DE rats. Immunohistochemical staining results showed that ethanol-water fraction of LWDHD could inhibit the neuron apoptosis, enhance the expressions of BDNF and IGF proteins in the cortex and DG region of hippocampus of DE rats. Congo red staining results demonstrated that ethanol-water fraction of LWDHD could reduce the Aβ deposition in the cortex and DG region of hippocampus of DE rats.The third chapter, according to screening results in the first chapter and the previous researches, more researches have showed that paeonol has protective effect on nerve injury, and has been used as a neuroprotective agent to reduce neurotoxicity. Therefore, we use the same method described in the second chapter to study the effect of paeonol on DE. The results showed: in the water maze test, paeonol(50 mg/kg and 100 mg/kg) significantly shortened the escape latency and explore distance, prolonged swimming time in the target quadrant, and increased the platform traversing times in DE rats. Moreover, paeonol significantly reduce the contents of blood glucose,AGEs and GSP, increased the activities of CAT, Na~+-K~+-ATP, Ch AT and Ach E and level of GSH, and decreased the level of LPO and the activity of i NOS in DE rats. Immunohistochemical staining results showed that paeonol could inhibit the neuron apoptosis, enhance the expressions of BDNF and IGF proteins, and reduce the expression of RAGE and NF-κB proteins in the cortex and DG region of hippocampus of DE rats. Congo red staining results demonstrated that paeonol could reduce the Aβ deposition in the cortex and DG region of hippocampus of DE rats.In summary, the ethanol-water fraction of LWDHD and paeonol may ameliorate the cognitive ability and hippocampal tissue disorder in DE rats by lowering blood sugar, anti-oxidant, regulating the cholinergic nerve function, anti-apoptosis, enhancing the expression of neurotrophic factors, reducing the deposition of Aβ and other ways. The preliminary results show that, the intervention of AGEs/RAGE/NF-κB pathway may be the mechanism of Paeonol on prevention and treatment of diabetes encephalopathy.