[Effects of Moringa flavone on cognitive function and neuropathological indexes in diabetic encephalopathy rats]

To investigate the effect of Moringa flavone on cognitive impairment and neuropathological indexes in diabetic encephalopathy (DE) rats.

Sixty male Sprague-Dawley (SD) rats were divided into control group, model group, positive drug group, Moringa low-dose and high-dose groups according to the random number table method, with 10 rats in each group. Diabetic rat model was established by intraperitoneal injection of 25 mg/kg streptozotocin (STZ) after continuous feeding of high fat and high sugar diet for one week. Blood was collected from the tail vein after 72 hours, the mean value of twice random blood glucose was ≥ 16.67 mmol/L, and the continuous positive urine glucose showed that the diabetes model was successfully prepared. The control group was fed with conventional feed. After successful model establishment, the rats in the Moringa low and high dose groups were given 4.0 g/kg and 8.0 g/kg Moringa extract (Moringa flavone) by gavage everyday, the rats in the positive drug group were given piracetam 0.48 g/kg, and the rats in the model group and control group were given the same amount of normal saline once a day for 30 days. Morris water maze was used to evaluate the cognitive impairment of the rats. The hippocampus of the rats was harvested 12 hours after the last administration, and the advanced glycation end product receptor (RAGE) and nuclear factor-κB (NF-κB) were detected by immunohistochemistry. The contents of acetylcholinesterase (AChE), advanced glycation end product (AGE) and choline acetyl transferase (ChAT) were detected by enzyme linked immunosorbent assay (ELISA).

Compared with the control group, the escape latency and the exploration distance in model group were extended, target quadrant stay time was shortened, the levels of AChE and AGE in brain tissue were significantly increased, and ChAT level was significantly decreased. Morris water maze experiment showed that compared with the model group, in the Moringa low and high dose groups from the 3rd day, the escape latency (s: 35.07±7.21, 33.14±5.35 vs. 43.09±9.83, both P < 0.05) and the exploration distance (m: 8.32±4.23, 8.10±4.97 vs. 13.02±3.67) were significantly shortened (both P < 0.05). The target qauadrant stay time was extended (s: 35.12±3.12, 41.53±8.37 vs. 23.15±4.89, both P < 0.01). The results of ELISA showed that compared with the model group, the levels of AChE and AGE in brain tissue of the Moringa low and high dose groups were significantly decreased [AChE (U/L): 180.22±12.03, 142.67±20.56 vs. 205.27±25.14, AGE (μg/L): 439.10±25.19, 428.27±19.14 vs. 501.28±21.53, all P < 0.05], and the levels of ChAT were significantly increased (U/L: 51.95±5.27, 53.13±5.04 vs. 37.91±5.10, both P < 0.01). There were no significant differences in AChE, AGE or ChAT between the Moringa low and high dose groups. The results of immunohistochemistry showed that the number of RAGE and NF-κB positive cells in DG area of hippocampus increased significantly, and the average gray values of RAGE and NF-κB decreased significantly. Compared with the model group, the RAGE and NF-κB positive cells in the Moringa low and high dose groups were significantly reduced, and the average gray values of RAGE and NF-κB in hippocampus were significantly increased [RAGE (gray value): 110.46±10.04, 117.76±8.64 vs. 92.19±8.76, NF-κB (gray value): 109.40±8.93, 116.59±7.26 vs. 90.74±13.27, all P < 0.05]. There were no significant differences in the expressions of RAGE or NF-κB between the Moringa low and high dose groups.

Moringa flavonoids could obviously improve the cognitive dysfunction and memory ability of DE model rats, improve the pathological changes of hippocampus, and have a certain protective effect on brain.