Effects of Apilarnil on Type 2 Diabetes-Induced IRS-1/PI3K/Akt Mediated Insulin Resistance in Male Rats

Abstract

Diabetes is one of the most important chronic and metabolic health problems seen as an epidemic of the 21st century. The incidence of diabetes is gradually increasing, and different methods are used to treat it. Apitherapy products such as honey, propolis, royal jelly, and bee venom can be used as an alternative to treat diabetes and reduce symptoms. One of these apitherapy products is Apilarnil, which has not yet become popular. The hypolipidemic, hepatoprotective, androgenic, anabolic, and immune system enhancing properties of Apilarnil indicate that it may be effective in the treatment of type 2 diabetes or in reducing the symptoms. The study aimed to determine the therapeutic effect of Apilarnil on insulin resistance and the possible underlying mechanism. In the study, 40 8 week-old male Wistar albino rats were used. The rats were divided into 5 groups as Control, Diabetes, Diabetes + Api1 (125 mg/kg/day lyophilized Apilarnil), Diabetes + Api2 (250 mg/kg/day lyophilized Apilarnil) and Diabetes + Api3 (500 mg/kg/day lyophilized Apilarnil). Each group consisted of 8 rats. Apilarnil doses were administered by oral gavage with 1 mL of distilled water, 5 days in a week, during the last 6 weeks. The levels of Nrf2, NF-κB, TNF-α, total IRS-1, p-IRS-1, PI3K p85, total Akt, p-Akt, IL-1B, and GLUT4 proteins were determined in target tissues by Western blotting. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (TC), and triglyceride (TG) levels were detected in the serum. Serum superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), and insulin levels were determined by the ELISA method. According to the data obtained in the study, the application of Apilarnil, compared to the diabetes group, balanced some findings, but did not demonstrate a fully antidiabetic effect.

1

Effect of Apilarnil on body weight change (A) and feed consumption (B) in rats. *p < 0.05, **p < 0.01 and ***p < 0.001 indicate difference compared to control group, ###p < 0.001 indicate difference compared to diabetes group.

2

Effect of Apilarnil on glucose tolerance (A) and area under the curve (B) in rats. ***p < 0.001 indicates a difference compared to the control group, +p < 0.05. ++p < 0.01 and +++p < 0.001 indicate a difference compared to the Diabetes + Api3 group.

3

Effect of Apilarnil on blood glucose level (mg/dL) in rats. ***p < 0.001 indicates a difference compared to the control group, +p < 0.05 and ++p < 0.01 indicate a difference compared to the Diabetes + Api3 group.

4

Effect of Apilarnil on serum fasting insulin level (A), HOMA-IR index (B), HOMA-β index (C) and insulin sensitivity index (D) in rats. ****p < 0.0001 indicates difference compared to the control group.

5

Effect of Apilarnil on liver (A), pancreas (B) and visceral fat (C) weights in rats. *p < 0.05, **p < 0.01 and ***p < 0.001 indicate differences compared to the control group.

6

Effects of Apilarnil on serum alanine aminotransferase (ALT, A), aspartate aminotransferase (AST, B) triglyceride (TG, C), low-density lipoprotein (LDL, D), high-density lipoprotein (HDL, E) and total cholesterol (TC, F) levels in rats. *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001 Compared to the control group; +p < 0.05, ++p < 0.01, +++p < 0.001 Compared to the diabetes group; #p < 0.05 Compared to the diabetes + Api1 group.

7

Effect of Apilarnil on serum catalase (CAT, A), superoxide dismutase (SOD, B), glutathione peroxidase (GSH-Px, C) and malondialdehyde (MDA, D) levels in rats. ***p < 0.001 and ****p < 0.0001 indicate differences compared to the control group.

8

Effect of Apilarnil on liver Nrf2 (A), NF-κB (B), TNF-α (C), total IRS-1 (D), p-IRS-1 (E), total Akt (F), p-Akt (G), and PI3K p85 (H) protein expression levels (J) in rats. β-Actin was used as a loading control. Data are organized according to the percentage of the control group. *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001 indicate differences compared to the control group. The full blots of liver protein expression levels are presented in Figure S1 in the Supporting Information.

9

Effect of Apilarnil on muscle total IRS-1 (A), p-IRS-1 (B), total Akt (C), p-Akt (D), PI3K p85 (E), and GLUT4 (F) protein expression levels (G) in rats. β-Actin was used as a loading control. Data are organized according to the percentage of the control group. ****p < 0.0001 indicates difference compared to the control group. The full blots of muscle protein expression levels are presented in Figure S2 in the Supporting Information.