To investigate the ameliorative effect and mechanism of short-acting exenatide on diabetic cognitive dysfunction.
METHODS
2
Spontaneously diabetic
db
/
db
mice were randomly divided into model group (normal saline) and exenatide group (50 μg/kg), with
db
/
m
mice as the normal control group (normal saline), with 8 mice in each group. Mice in each group were subcutaneously injected with corresponding drugs or normal saline twice daily for 8 consecutive weeks. Body weight and fasting blood glucose were measured at a fixed time every week. Cognitive function was evaluated by Morris water maze test. The levels of oxidative st
, cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) were detected in hippocampus tissue of mice. The hippocampal neuronal HT22 cells of mice were divided into control group (25 mmol/L glucose), high glucose group (125 mmol/L glucose), high glucose+exenatide group (125 mmol/L glucose+20 nmol/L exenatide), high glucose+exenatide+H89 (PKA inhibitor) group (125 mmol/L glucose+20 nmol/L exenatide+10 μmol/L H89), and high glucose+H89 group (125 mmol/L glucose+10 μmol/L H89). After 48 h of intervention with corresponding solutions/culture medium, the levels of oxidative stress indicators, cAMP and PKA, the activities of mitochondrial respiratory enzymes Ⅱ and Ⅳ, and the phosphorylation level of dynamin-related protein 1 (Drp1) were measured.
RESULTS
2
Animal experiments showed that compared with the normal control group, the model group exhibited significantly increased body weight, fasting blood glucose and MDA level in the hippocampus (
P
<0.05), as well as significantly prolonged escape latency (
P
<0.05); swimming speed significantly slowed down, the time spent in the target quadrant, the number of platform crossings, and the levels of SOD, GSH, cAMP and PKA in the hippocampus were significantly decreased (
P
<0.05). Compared with model group, all the above indicators (except for swimming speed) in the exenatide group were significantly reversed (
P
<0.05). Cell experiments showed that compared with high glucose group, the high glucose+exenatide group had significantly decreased MDA level (
P
<0.05), and significantly increased levels of SOD, GSH, cAMP and PKA, the activities of mitochondrial respiratory enzymes Ⅱ and Ⅳ, and phosphorylation level of Drp1 (
P
<0.05). Compared with high glucose+exenatide group, the above indicators in the high glucose+exenatide+H89 group were significantly reversed (
P
<0.05).
CONCLUSIONS
2
Short-acting exenatide can activate the cAMP/PKA pathway, promote Drp1 phosphorylation, and increase the activities of mitochondrial respiratory enzymes, thereby maintaining mitochondrial stability, reducing oxidative stress injury, and ultimately improving diabetic cognitive dysfunction.
关键词
Keywords
references
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