Effect of catalpol on glycemic metabolism in hyperglycemic Alzheimer disease rat model

Zhang Qi; Gao Feng; Liu Qian; Liu Qianqian; Sun Qiushuang; Yang Juanzhen; Wang Jinhong

doi:10.3760/j.issn.1673-4777.2018.06.016

Abstract：Objective To observe the effect of catalpol on glycemic metabolism in hyperglycemic Alzheimer disease(AD) rat model.Methods Fifty Sprague Dawley rats were randomly divided into normal control group (n =10),hyperglycemia group (n =10),hyperglycemic AD model group (n =9),catalpol group (n =9) and pioglitazone group(n =6).Y-maze test was performed before injection and on the 7th,14th day after injection of β-amyloid fragment 25-35 (Aβ25-35).Body weight,blood glucose and serum insulin were detected before injection and on the 3rd,9th,15th day after injection of Aβ25-35.Contents of insulin and insulin-like growth factor(IGF-1)in brain homogenate were tested by enzyme-linked immunosorbent assay;expressions of insulin and IGF-1 were observed through immunohistochemical staining and western blotting.Results Learning index in hyperglycemic AD model group was significantly lower than that in normal control group on the 7th,14th day after injection of Aβ25-35(P ＜0.01).Iearning index in catalpol group and pioglitazone group was significantly higher than that in hyperglycemic AD model group(P ＜0.01).Blood glucose level in catalpol group was significantly lower than that in hyperglycemia AD model group on the 9th,15th day after injection of Aβ25-35 [(10.4 ± 2.1) mmol/L vs (17.4 ±0.9) mmol/L,(7.9 ± 0.5) mmol/L vs (19.2 ± 0.8) mmol/L] (P ＜ 0.05).Serum insulin level in catalpol group and pioglitazone group was significantly lower than that in hyperglycemic AD model group on the 15th day after injection of Aβ25-35 [(14.8 ± 1.7),(15.1 ± 1.7) mIU/L vs (17.2 ± 1.4) mIU/L] (P ＜ 0.05).Levels of insulin and IGF-1 in brain homogenate in hyperglycemic AD model group were significantly lower than those in normal control group;levels of insulin and IGF-1 in brain homogenate in catalpol group and pioglitazone group were significantly higher than those in hyperglycemic AD model group [(14.93 ± 0.37),(15.06 ±0.26)mIU/Lvs (13.70 ±0.54)mIU/L;(6.13 ±0.11) × 105,(6.42 ±0.15) × 105 ng/L vs (3.44 ±0.19) × 105 ng/L] (P ＜ 0.05).Pathological images showed positive staining of insulin and IGF-1 in cytoplasm of cortical neurons;hyperglycemic AD model group showed cell cytoplasmic reduction and positive staining reduction compared with normal control group;insulin and IGF-1 positive staining increased in catalpol group and pioglitazone group.Electrophoretic results showed that expressions of insulin and IGF-1 in hyperglycemic AD model group were significantly lower than those in normal control group;expressions of insulin and IGF-1 in catalpol group and pioglitazone group were significantly higher than those in hyperglycemic AD model group.Conclusion Catalpol regulates the glucose metabolism in hyperglycemic AD rats.