Endocrine Abstracts

Background and aim: Apelin, as an adipokine, is encoded by the APLN gene. It is a key regulator in glucose and lipid metabolism and plays an important role in the pathogenesis of insulin resistance and type 2 diabetes. It seems that habitual dietary intake of carbohydrates including quality and quantity by chronic manipulating insulin concentration might have a distinguishing role in the prediction of apelin gene expression in adipose tissue, but there is no evidence in this regards. Thus, this study aimed to determine whether dietary quality and quantity of carbohydrates were associated with gene expression of apelin in subcutaneous and visceral adipose tissue.

Methods: In this cross-sectional study, 102 participants, aged more than 20-year-old, who underwent minor abdominal surgery with minimal impact on dietary intakes, were selected. Before the surgery, a reliable and validated semi-quantitative FFQ was completed to assess habitual dietary intake of total carbohydrate intake, glycemic index (GI) and glycemic load (GL). Then, the food items were also categorized based on their glycemic index and load into three different groups including high (≥70), medium (56-69) and low (≤55) glycemic index and high (≥20), medium (11–19) and low (≤10) glycemic load foods. To control the effect of energy intake, the residual method was used for all dietary exposures. The mRNA expressions of APLN were measured by SYBER-Green qPCR. Multivariable linear regression was performed, standardized β (STZβ) was reported, and age, body mass index (BMI), and sex were adjusted.

Results: Participants characterized by a mean age of 41.7±14.6 years, mean BMI of 35.2±10.7 kg/m². Among participants, 16.3% presented insulin resistance. The association between dietary GI and APLN expression was significant in visceral (STZβ=0.402, P<0.001) and subcutaneous (STZβ=0.477, P<0.001) adipose tissue after controlling for potential confounders. Furthermore, there was a significant association between dietary GL and apelin mRNA levels in both visceral (STZβ=0.224, P=0.029) and subcutaneous (STZβ=0.350, P=0.001) adipose tissue. APLN expression in visceral (STZβ=0.253, P=0.013) and subcutaneous (STZβ=0.255, P=0.014) adipose tissue was associated with intake of foods with higher GI index.

Conclusion: Higher dietary intake of GL, GI, high GI foods were positively associated with APLN gene expression of adipose tissues. It seems that when considering the effect of dietary carbohydrate intake on adipose tissue metabolism, the carbohydrate quality is more important than carbohydrate quantity.