The present study was conducted to investigate the effect of the ketogenic diet supplemented with mealworm oil on oxidative stress and cognivite ability in scopolamine-induced dementia rats. As experimental animals, male rats of Sprague Dawley species were used, and the experimental diets were divided into CD group (control diet), KD group (ketogenic diet), SKD group (scopolamine administration + ketogenic diet), CMO group (control + mealworm oil diet), and SMO group (scopolamine administration + mealworm oil diet). Ten animals were put in each group and bred for seven weeks. The effect of ketogenic diet supplemented with mealworm oil on oxidative stress and cognitive function in white rats is summarized as follows:

1. Dietary intake and weight gain were not significantly different among all groups, but feed intake was higher in the CD group. There was no difference in brain weight based on organ weight per 100 g of body weight, and the KD group showed significantly lower weight than the CD group in height. Liver weight showed highest value in the SMO group and the lowest value in the CMO group (p<0.05).

2. In the Morris water maze experiment for cognitive ability and behavioral analysis, when the experiment was conducted and the time to find the last escape zone was measured, there was no significant difference in time between each group. The SKD group shortened the escape time the most to 3.55 seconds, and the KD group to 1.82 seconds. Thus, there was no significant difference due to mealworm oil supply. In the passive avoid test, when the last retention time was measured, the passive avoidance response was slow in the group fed with the ketogenic diet, and the retention time significantly increased in the CMO group and the SMO group (p<0.05).

3. Malondialdehyde, a lipid peroxide, showed higher concentration in the KD group than in the CD group, and the lipid peroxide concentration increased by the ketogenic diet was significantly lowered in the dementia-inducing group SKD and SMO. Brain tissue of the KD group showed the highest lipid peroxide concentration, and the CMO and the SMO groups showed significantly lowest lipid peroxide concentration (p<0.05). Nitric oxide production capacity was significantly lower in the KD, SKD, CMO, and SMO groups compared to the CD group in serum (p<0.05), and there was no difference among the groups. Brain tissue of the KD group showed a lower NO scavenging ability than the CD group (p<0.05), and the SKD, CMO, and SMO groups showed a similar trend comparable to that of the normal CD group.

4. Superoxide dismutase activity showed a high tendency in the SKD group in the serum, and the KD group showed a high activity in the brain tissue (p<0.05). TAC in serum was highest in the SKD group and the lowest in the CD group (p<0.05). Brain tissue of the CD and SKD groups showed the highest antioxidant activity, and the CMO and SMO groups showed the lowest level (p<0.05). Catalase activity in serum was highest in the KD and SKD groups, and the brain tissue of the SKD group showed the highest activity and the CD group showed the lowest activity. Glutathione peroxidase activity was highest in the CD group and the lowest in the KD group in serum, with significant highest concentration in the SKD group brain tissue (p<0.05). Glutathione S-transferase activity was not significantly different among all groups in serum, and in the brain tissue, with the KD group showing high activity (p<0.05).

5. Among the memory-related factors, acetylcholinesterase activity showed high activity in the CD group in serum and the lowest activity in the SKD group (p<0.05). Brain tissue of the KD and SMO groups showed significantly higher activity than the CD group, and the SKD group showed the lowest activity (p<0.05). Serum acetylcholine content was highest in the CD group and lowest in the KD group. Brain tissue was highest in the KD group and lowest in the SKD group. Among the amyloid β content in brain tissue, the content of A-beta 1-42 was the highest in the SKD group administered with scopolamine and the lowest in the CD group. The content of A-beta 1-40 was also highest in the SKD group, but lowest in the CMO group (p<0.05).

6. Among the hematological components, GOT and GPT activities were highest in the KD group and lowest in the CMO group (p<0.05). Serum protein and globulin concentrations were highest in the CMO group and lowest in the KD group. The albumin concentration was highest in the CMO group and lowest in the CD group (p<0.05). For serum lipid content, total cholesterol was lowest in the CMO group and HDL-cholesterol was significantly higher in the CMO group (p<0.05). Total lipid in liver tissue was highest in the CD group and phospholipid was highest in the KD group. Brain tissue phospholipids were highest in the SMO group (p<0.05). There were no significant differences in hemoglobin and hematocrit levels and glucose levels.

As a result of studying the antioxidant effect and the effect on memory due to the ketogenic diet, it is thought that the ingestion of mealworm oil will have a positive effect on the protective effect of oxidative stress. A ketogenic diet containing mealworm oil showed effects on antioxidant activity, lipid peroxide production, and memory-related factors, but it did not appear to have a significant effect on scopolamine-induced memory impairment. Therefore, the current study on mealworm oil as a dietary supplement is insufficient, and the present study is a basic experiment on mealworm oil for mild cognitive impairment.