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ObjectiveTo explore the amelioration of cognitive dysfunction in diabetes mellitus （DM） by Jianpi Qinghua prescription （JPQH） based on type 2 diabetes （T2DM） model rats. MethodFifty healthy male Wistar rats of SPF grade were randomly divided into control group （n=10） and experimental group （n=40）. The rats in the control group were fed conventionally， while those in the experimental group were fed on a high-sugar， high-fat diet for six weeks and administered with streptozotocin （STZ） for the induction of the DM model. The model rats were randomly divided into model group， sitagliptin group （1.2 g·L-1）， pioglitazone group （0.8 g·L-1）， and JPQH group （1.3 g·mL-1）， with 10 rats in each group. After six weeks of drug intervention， the changes in body weight， blood glucose， and other related indexes of each group were recorded. Enzyme-linked immunosorbent assay （ELISA） was performed to detect the levels of tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， and interleukin-6 （IL-6） in the peripheral blood and brain. The Morris water maze test was used to evaluate the cognitive function in rats. Hematoxylin-eosin （HE） staining was used to observe the pathological morphology of the hippocampal CA region. The amyloid β-protein 40 （Aβ40） level was detected by immunohistochemistry. The protein expression of t-tau and p-tau in hippocampal neurons of rats was detected by Western blot. ResultCompared with blank group， the body weight of model group was significantly decreased （P<0.05）， blood glucose level was significantly increased （P<0.01）， inflammatory cytokines TNF-α and IL-1β were increased （P<0.05）， learning and spatial ability were significantly decreased （P<0.01）， the arrangement of hippocampal cells was loose and disordered， and the intercellular space was significantly increased. The number of cells decreased significantly， and the expression of Aβ40 increased significantly. and increased t-tau and p-tau protein content in the hippocampus （P<0.01）. Compared with model group， the JPQH group showed reduced blood glucose （P<0.01）， decreased TNF-α and IL-1β levels in the peripheral blood and cerebrospinal fluid （P<0.05）， a downward trend of IL-6 without a statistical difference， improved learning and spatial memory ability （P<0.01）， densely arranged cells in the hippocampal CA1 area， increased cell number， reduced Aβ40 expression， and decreased p-tau protein expression （P<0.05）. ConclusionJPQH can prevent cognitive dysfunction in DM by reducing inflammatory factor levels， decreasing neurotoxicity caused by Aβ40 deposition， and inhibiting hyperphosphorylation of tau protein in DM rats.
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Objective To investigate the influence of blood glucose fluctuation on ser202 phosphorylation sites of tau protein( p-Tau) in hippocampus of diabetic rats; to explore the possible mechanism of blood glucose fluctuation impacting on tau protein hyperphosphorylation. Methods Healthy male Sprague Dawley rats were randomly divided into normal control group ( NC group ) and diabetes group. After diabetic rats model was established, all the diabetic rats were randomly divided into diabetic continuous hyperglycemia group (DC group) and diabetic blood glucose fluctuant group ( DF group). Rats in DF group were given glucose solution intraperitoneal injection twice at regular time everyday. 30 minutes after each intraperitoneal injection, insulin subcutaneously injections were given. Rats in the NC group and DC groups were given the same volume of saline subcutaneous injection. Specimens were collected in 8 weeks, the levels of p-Tau and total tau in rat hippocampus were detected by immunohistochemical staining and Western blotting. The immunoreactive positive products were analyzed by image analysis system. Glycogen synthase kinase-3β(GSK-3β) mRNA was detected by realtime PCR. Results (1) Blood glucose fluctuation of rats in DC and DF group were greater than NC group. And the mean blood glucose, standard deviation of mean blood glucose (SDBG), and large amplitude of glycemic excursion (LAGE) levels were increased significantly compared to NC group, the difference has statistical significance ( all P < 0. 05). Compared with DC group, SDBG and LAGE levels of DF group were higher (both P<0. 05). HbA1C and insulin levels were no difference (P>0. 05). (2) Compared with NC group, the hippocampal p-Tau level of DC group and DF group were increased (P < 0. 05 ); Compared with DC group, the hippocampal p-Tau expression of DF group was increased ( P <0. 05). Compared with DC group, a higher hippocampal GSK-3β mRNA level was found in DF group ( P <0. 05). Conclusions On the basis of diabetes animal model, giving glucose solution intraperitoneal injection and insulin subcutaneously injection 30 minutes later twice at regular time everyday could establish experimental model of diabetic blood glucose fluctuation. Blood glucose fluctuation may aggravate the diabetic rats hippocampal p-Tau. The possible mechanism seems to be an up regulation of the GSK-3β.
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Objective To investigate the influence of blood glucose fluctuation on ser202 phosphorylation sites of tau protein( p-Tau) in hippocampus of diabetic rats; to explore the possible mechanism of blood glucose fluctuation impacting on tau protein hyperphosphorylation. Methods Healthy male Sprague Dawley rats were randomly divided into normal control group ( NC group ) and diabetes group. After diabetic rats model was established, all the diabetic rats were randomly divided into diabetic continuous hyperglycemia group (DC group) and diabetic blood glucose fluctuant group ( DF group). Rats in DF group were given glucose solution intraperitoneal injection twice at regular time everyday. 30 minutes after each intraperitoneal injection, insulin subcutaneously injections were given. Rats in the NC group and DC groups were given the same volume of saline subcutaneous injection. Specimens were collected in 8 weeks, the levels of p-Tau and total tau in rat hippocampus were detected by immunohistochemical staining and Western blotting. The immunoreactive positive products were analyzed by image analysis system. Glycogen synthase kinase-3β(GSK-3β) mRNA was detected by realtime PCR. Results (1) Blood glucose fluctuation of rats in DC and DF group were greater than NC group. And the mean blood glucose, standard deviation of mean blood glucose (SDBG), and large amplitude of glycemic excursion (LAGE) levels were increased significantly compared to NC group, the difference has statistical significance ( all P < 0. 05). Compared with DC group, SDBG and LAGE levels of DF group were higher (both P<0. 05). HbA1C and insulin levels were no difference (P>0. 05). (2) Compared with NC group, the hippocampal p-Tau level of DC group and DF group were increased (P < 0. 05 ); Compared with DC group, the hippocampal p-Tau expression of DF group was increased ( P <0. 05). Compared with DC group, a higher hippocampal GSK-3β mRNA level was found in DF group ( P <0. 05). Conclusions On the basis of diabetes animal model, giving glucose solution intraperitoneal injection and insulin subcutaneously injection 30 minutes later twice at regular time everyday could establish experimental model of diabetic blood glucose fluctuation. Blood glucose fluctuation may aggravate the diabetic rats hippocampal p-Tau. The possible mechanism seems to be an up regulation of the GSK-3β.
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Alzheimer ’ s disease ( AD ) is characterized by pro-gressive loss of memory and other cognitive functions .With re-cent discoveries , activation of silent mating-type information reg-ulator 2 homolog 1 ( SIRT1 ) could attenuate the cognitive dys-function of AD via reducing amyloid-βaggregation and tau pro-tein phosphorylation , inhibiting inflammatory reaction , and regu-lating synaptic plasticity .This review aims to highlight the in-volvement of these new discoveries of SIRT 1, and Akt/protein kinase B(PKB) signaling pathways, for their potential therapeu-tic effect against AD .
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Aim To investigate the effects of ginsenoside(GS) on phosphorylation of tau protein,microtubule,cellular apoptosis and its related factors in cellular model of Alzheimer disease(AD) induced by the protein phosphatase 1 and 2A inhibitor okadaic acid(OA).Methods The human neuroblastoma cell line SK-N-SH cells were cultured with GS for 24 h,the culture medium was changed,and then incubated with OA 10 nmol?L-1 for 6 h.The changes of cell morphology were observed by inverted microscope.The laser confocal microscopy was used to observe the microtubule changes.Western blot was applied to determine the expression of phosphorylation of tau protein,and apoptosis-regulating factors Bcl-2,Bax and Caspase-3.The changes of apoptotic cells were observed by TUNEL method.Results The normal SK-N-SH cells spread well.OA-treated cells showed that the cell axons and the microtubules were broken and decreased under the inverted microscope and laser confocal microscope.Preincubation of GS demonstrated the significantly protective effects against the morphologic damage induced by OA.In OA-treated group,the phosphorylation of tau protein at Ser-199/202 and Ser-404 sites was higher than that in normal group,and the non-phosphorylation of tau protein at the same sites was lower;Incubation of GS at the dose of 50 mg?L-1 and 100 mg?L-1 with the cells decreased the phosphorylation of tau protein Ser-199/202 and Ser-404 sites.GS group at the dose of 50 mg?L-1 and 100 mg?L-1 decreased the expression of at non-phosphorylation of tau protein at the Ser202 site.The apoptotic cells were not found in normal group.The number of apoptotic cells were obviously increased.the expression of Bax and caspase-3 significantly enhanced,and Bcl-2 expression decreased in the OA-treated model group.GS significantly decreased the apoptotic cell number of nerve cells,inhibited the expression of Bax and caspase-3.Conclusion GS can protect the nerve cells from pathological change induced by OA.Maybe because it can inhibit the hyperphosphorylation of tau protein and protect the nerve cells from apoptosis,thus GS may have potential to treat Alzheimer disease.