Sex-specific susceptibility to type 2 diabetes mellitus and preventive effect of linalyl acetate

Aims: Biological, psychosocial and lifestyle risk factors interact in the development of type 2 diabetes mellitus (T2DM). To date, the effects of sex, chronic stress (CS) and high-fat diet (HFD) on T2DM and the ability of linalyl acetate (LA) to prevent T2DM have not been determined. This study therefore explored the differential effects of CS and HFD on T2DM, as well as the ability of LA to prevent T2DM development, in male and female rats. Main methods: T2DM was induced in rats by feeding an HFD and placing them under immobilization stress for 2 h/day for 3 weeks. Low-dose streptozotocin was administered on day 15, and LA was administered for 3 weeks. Key findings: Fasting blood sugar (FBS) increased in HFD-fed male, but not female, rats. CS further increased FBS in HFD-fed rats, whereas CS alone did not alter FBS. The homeostatic model assessment-insulin resistance (HOMA-IR) showed results similar to FBS. Serum corticosterone levels markedly increased only in HFD-fed male rats exposed to CS. Pancreas nuclear factor kappa B (NF-kappa B) levels were higher in HFD-fed male rats exposed to CS than in control rats although there were no sex differences. LA 10 mg/kg significantly reduced FBS, serum insulin, HOMA-IR, and serum corticosterone levels in HFD-fed male rats exposed to CS. LA 10 mg/kg also tended to reduce NF-kappa B in the pancreas and significantly increased mitochondrial membrane potential (MMP) in the liver. Significance: Male rats are vulnerable to T2DM induced by CS and HFD, and LA can prevent T2DM in these rats not only by reducing insulin resistance and corticosterone levels but by increasing MMP in the liver.