Chlorogenic acid ameliorates memory dysfunction via attenuating frontal lobe oxidative stress and apoptosis in diabetic rat model

Background/aim: Diabetes mellitus, characterized by hyperglycemia, causes various complications, one of which is memory dysfunction. The frontal lobe is known to be responsible for impaired memory function due to hyperglycemia and is associated with oxidative stress- mediated neuronal cell apoptosis. Chlorogenic acid (CGA) is reported to have neuroprotective effects. However, its effect on the frontal lobe in diabetes mellitus (DM) rats is not widely known. This research aimed to elucidate the effect of CGA on the mRNA expressions of SOD1, SOD2, p53, and Bcl-2 in the frontal lobe of DM rats. Materials and methods: Thirty male Wistar rats (2-month-old, 150-200 gBW) were randomly divided into six groups: C (control), DM1.5 (1.5-month DM), DM2 (2-month DM), CGA12.5, CGA25 and CGA50 (DM+CGA 12.5, 25, and 50 mg/kgBW, respectively). A single dose of streptozotocin (60 mg/kgBW) was intraperitoneally injected. Intraperitoneal CGA injection was administered daily for DM1.5 rats for 14 days. Path length was measured in the Morris water maze (MWM) probe test. After termination, the frontal lobes were carefully harvested for RNA extraction. Reverse transcriptase PCR was performed to examine the mRNA expression of SOD1, SOD2, p53, and Bcl-2. Results: The DM2 group demonstrated significant shorter path length on the MWM probe test and significantly lower mRNA expression of SOD1 and Bcl-2, compared to the C group. After CGA administration, the CGA25 group showed a significantly shorter path length than the C group. The CGA12.5 and CGA25 groups had significantly higher mRNA expression of SOD1 than the DM1.5 group. Compared to the DM1.5 and DM2 groups, SOD2 mRNA expression of the administration of all three CGA doses increased markedly. Furthermore, Bcl-2 mRNA expression was significantly increased in the CGA12.5 and CGA50 groups, compared with the DM2 group. Conclusion: Chlorogenic acid might improve memory function through upregulation of frontal lobes' SOD1, SOD2, and Bcl-2 mRNA expression in DM rats.