The Effects Of Chronic Folate Deficiency On Glucose Metabolism And Cognitive Function In Mice

Background With the gradual development of society and the constantly improvement of people’s living standard.the incidence of type 2 diabetes(T2D)is increasing,some cross-sectional studies have confirmed that the level of folate in patients with T2 D is lower and further lowered in T2 D patients with cognitive dysfunction.However,whether chronic folate deficiency(CFD)can cause T2 D,and whether CFD is related to cognitive dysfunction caused by T2 D has not been studied.This paper will discuss the etiology of T2 D from the new perspective of folate deficiency,to provide a theoretical basis for the health education of folic acid supplementation and to provide new ideas for the etiology and prevention and treatment of T2 D.Objective The purpose of this study was to investigate whether CFD lead to T2 D in mice,to investigate the effect of CFD on weight and glucose metabolism,to investigate whether CFD promotes cognitive dysfunction and its relationship with T2 D,and to illuminate the longitudinal effects of CFD on glucose and lipid metabolism and cognitive function in mice.Methods Seven-week-old ICR mice were randomly divided into CFD group and control group,fed folate deficiency feed and standard control feed respectively.Mice were all raised to 32 weeks.The water intake,litter wet conditions and behaviors of mice were observed daily.Mice were weighed at 7:00 every Monday.The intraperitoneal glucose tolerance test(IPGTT)was done in 23 weeks of age.The intraperitoneal insulin tolerance test(IPITT)were done on age of 24 weeks.Behavioral experiments such as open field,elevated plus maze,and Morris water maze test were conducted in 31-32 weeks of age.Fasting blood glucose was measured in the morning the day after behavioral tests.Insulin sensitivity test was conducted and the liver tissues were then collected.p-Akt / Akt,the key parameter of liver insulin signal pathway was detected by Western blotting.Remaining mice were killed after anesthesia.Blood samples were collected for determination of serum folate,total homocysteine,free fatty acid(FFA),insulin,triglyceride(TG),total cholesterol(TC),high density lipoprotein(HDL)cholesterol,low density lipoprotein(LDL)cholesterol,and very low density lipoprotein(VLDL)cholesterol.Liver tissues and abdominal fat tissues were carefully collected and weighed.Liver and abdominal fat index(liver or abdominal fat pad weight / body weight*100%)were then calculated.The pathological changes of liver tissues were observed by immunohistochemistry.Lipid synthesis-related m RNAs,Acc1 and Fasn,and lipid transport related m RNA,Pparγ,Cd36 and Apo B were detected by RT-PCR.The hippocampal p-Akt / Akt and important protein of neuron degeneration PSD95 were detected by Western blotting.The m RNA levels of hippocampal cognitive-related synaptic protein,including PSD95,Drd5,Synj1,Syt1 were detected by RT-PCR.Results(1)CFD induced the decrease of serum folate levels and the increase of homocysteine levels in mice;(2)On age of 13 weeks,CFD induced obesity and obvious hepatic steatosis,elevated serum TG and increased serum VLDL in mice.CFD had no effect on serum FFA,TC and HDL levels.(3)CFD upregulated hepatic Acc1 and Fasn m RNA,down-regulated hepatic Cd36 and Apo B m RNA expression in mice(4)On age of 23 weeks,CFD caused glucose intolerance,decreased insulin sensitivity,elevated fasting blood glucose and decreased serum insulin levels,and decreased hepatic p-Akt /Akt protein ratio in mice;(5)On age of 32 weeks,in the open-field test,the number of grooming and the peripheral time in CFD group were increased.In elevated plus maze,open arm distance,open/total arm entries and open/total arm distance in CFD group were all decreased.In Morris water maze,the latency to reach platform was longer,the number of platform crossing within 60 s was reduced in mice of CFD group.(6)CFD induced decreased hippocampal p-Akt / Akt protein ratio and increased PDS95 protein levels.Drd5 and Synj1 m RNA levels in CFD group were significantly decreased.Conclusion CFD can cause lipid metabolism disorders and glucose metabolism disorders in mice,followed by cognitive dysfunction in middle-aged,CFD-induced cognitive dysfunction may be associated with hippocampal glucose metabolism disorders.