OBJECTIVE: To investigate the effects of pueraria lobata total flavonoids on cognitive dysfunction and brain-derived neurotrophic factor（ BDNF） expression in hippocampus of type 2 diabetes mellitus（ T2 DM） rats.METHODS: Totally 100 Wistar rats were randomly divided into the control group

model group

piracetam group（ 10 mg/kg）

pueraria lobata total flavonoids low（ 20 mg/kg） and high（ 40 mg/kg） dose group

with 20 cases in each group. T2 DM rats were established in model group

piracetam group and each dose group of pueraria lobata total flavonoids. After successful modeling

rats were given corresponding drugs by gavage. The control group and the model group were given the same volume of normal saline by gavage

the volume of administration was 10 ml/kg

once a day

for 140 d. At the end of the experiment

the cognitive function of rats was evaluated by Morris water maze test;hematoxylin eosin（ HE） staining was used to observe the pathological changes of hippocampal neurons in rats; mRNA and protein levels of BDNF

interleukin-4（ IL-4）

interleukin-8（ IL-8） and tumor necrosis factor-α（ TNF-α） protein in hippocampus were detected. RESULTS:（ 1） The neuron cell structure in the hippocampus of the control group was normal; the neurons in the hippocampus of the model group were massively necrotic with obvious inflammatory cell infiltration; the necrosis of hippocampal neurons in the piracetam group and the low and high dose group of pueraria lobata total flavonoids decreased

and the neuronal cell structure was relatively complete.（ 2） The escape latency time in the model group were longer than that in the control group

the expression levels of IL-4

IL-8 and TNF-α protein in the model group were higher than those in the control group

while the times of passing through the original platform position

staying time in the original platform quadrant

BDNF mRNA and protein expression levels were lower than those in the control group

with statistically significant differences（ P < 0. 05）.（ 3） The escape latency time in the piracetam group and pueraria lobata total flavonoids low and high dose group were shorter than that in the model group

the expression levels of IL-4

IL-8 and TNF-α protein in the piracetam group and pueraria lobata total flavonoids low and high dose group were lower than those in the model group

while the times of passing through the original platform position

staying time in the original platform quadrant

BDNF mRNA and protein expression levels were higher than those in the model group

with statistically significant differences（ P < 0. 05）. The escape latency time in the pueraria lobata total flavonoids high dose group was shorter than that in the pueraria lobata total flavonoids low dose group

the expression levels of IL-4

IL-8 and TNF-α protein in the pueraria lobata total flavonoids high dose group were lower than those in the pueraria lobata total flavonoids low dose group

while the times of passing through the original platform

staying time in the original platform quadrant

BDNF mRNA and protein expression levels were higher than those in the pueraria lobata total flavonoids low dose group

with statistically significant differences（ P < 0. 05）.（ 4） The escape latency time in the pueraria lobata total flavonoids low dose group was longer than that in the piracetam group

the expression levels of IL-4

IL-8 and TNF-α protein in the pueraria lobata total flavonoids low dose group were higher than those in the piracetam group

while the times of passing through the original platform

staying time in the original platform quadrant

BDNF mRNA and protein expression levels were lower than those in the piracetam group

with statistically significant differences（ P < 0. 05）. The escape latency time

IL-4

IL-8

TNF-α protein expression levels

times of passing through the original platform

staying time in the original platform quadrant

BDNF mRNA and protein expression levels in the pueraria lobata total flavonoids high dose group were similar to those in the piracetam group（ P >0. 05）. CONCLUSIONS: The protective effects of pueraria lobata total flavonoids on cognitive dysfunction in T2 DM rats is related to the mechanism that the total pueraria lobata total flavonoids can promote the mRNA and protein levels of BDNF

reduce the expression levels of IL-4

IL-8 and TNF-α

and alleviate the insulin resistance and inflammation.