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INTRODUCTION: Apelin could be one of the last protective defenses before developing obesity-related disorders, including insulin resistance, type 2 diabetes, and hypertension, which can be modified by dietary intake. The present study investigated the association of habitual intake of total fatty acids (TFAs), saturated-, monounsaturated-, polyunsaturated FAs, n-3, and n-6 FAs with Apelin expression in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). METHODS: We obtained VAT and SAT from 168 participants (64 nonobese and 104 obese) who had undergone open abdominal surgery. Dietary intake information was gathered with a valid and reliable food frequency questionnaire. The mRNA expression of the Apelin gene was analyzed by real-time PCR. RESULTS: Apelin serum levels were increased in the obese subjects compared to the nonobese group (p = 0.016). The SAT and VAT Apelin mRNA levels were significantly elevated in the obese participants compared to the nonobese ones (p < 0.05). Based on BMI status, only obese subjects indicated a positive association between SAT and VAT Apelin expression and TFA intake (p < 0.001). However, this association was observed between SAT and VAT Apelin gene expression and polyunsaturated fatty acid (PUFA) and n-3 FA intakes in both obese and nonobese groups (p < 0.05). CONCLUSION: High Apelin gene expression was associated with TFA intake in obese subjects in both fat tissues. However, habitual intake of PUFA and n-3 FA was associated with Apelin gene expression in obese and nonobese individuals. Our results indicate a determinative role of the quality and quantity of FA intake on adipose tissue.

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Background: Peroxisome proliferator-activated receptor gamma (PPARγ) has recently been studied for its potential influence on the functional response of the human body to exercise. We aimed to investigate the association of habitual physical activity (PA) with PPARγ mRNA level in the visceral and subcutaneous adipose tissues (VAT and SAT) in non-obese and obese non-diabetic adults. Methods: VAT and SAT were obtained from 95 individuals, including 40 non-obese (BMI<30kg/m2) and 55 obese (BMI≥30kg/m2) who underwent elective abdominal surgery (Tehran, Iran, 2012-2015). The assessment of habitual PA was performed by a valid and reliable International PA Questionnaire-long form, and the metabolic equivalent of task (MET) was evaluated. Real-time quantitative reverse transcriptase-PCR evaluated the PPARγ expression in VAT and SAT. Results: PPARγ expression in both VAT (1.18 vs. 0.37 fold change, P<0.001) and SAT (2.07 vs. 0.29 fold change, P=0.004) among obese subjects was higher than the non-obese group. After controlling for age, sex, and total energy in-take, a positive association was found between total METs and PPARγ expression in both VAT and SAT among obese participants (ß=0.22, P=0.007 and ß=0.12, P<0.001, respectively). Among obese participants, there was a direct association between leisure time-related METs with VAT PPARγ expression (ß=0.05, P=0.026). Moreover, in this group, an association was observed between occupation-related METs with PPARγ in both fat tissues (ß=0.11, P=0.002 and ß=0.17, P=0.013, respectively), and household work-related METs with SAT PPARγ (ß=0.21, P=0.011). Conclusion: High PA as an indispensable part of a healthy lifestyle may exert its beneficial effect by regulating PPARγ expression.

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BACKGROUND: Peroxisome proliferator-activated receptor gamma (PPARγ) is a promising therapeutic molecule. Epigenetic mechanisms, including non-coding RNAs, regulate the expression level of the PPARγ gene. OBJECTIVE: We aimed to examine the PPARγ expression in non-diabetic individuals in four body mass index (BMI) categories and its association with miR-34a and miR-143 expression. METHODS: Visceral and subcutaneous adipose tissues (VAT and SAT) samples were collected from patients undergoing bariatric or elective open abdominal surgeries. The subjects (mean age: 42±14.8 years) included 18 normal-weight, 19 overweight, 18 obese, and 19 morbidly obese individuals. The RNAs levels were determined by quantitative real-time PCR. RESULTS: The PPARγ expression was significantly upregulated in both adipose depots of the morbidly obese subjects compared to the normal group. SAT PPARγ level was significantly increased in the obese group compared to the normal-weight group (P<0.01); this increase was also significant in the SAT of morbidly obese subjects compared to the overweight cases (P=0.02). Differences in the regulation of PPARγ expression in both SAT and VAT were significant between the four groups (P<0.05). While miR-143 was overexpressed in the SAT of obese and morbidly obese individuals compared to the normal-weight group, the pairwise comparison showed no significant difference in the miR-34a expression of SAT between the four BMI groups (P>0.01). After controlling for the confounding factors, the expression of VAT PPARγ was directly associated with the miR-34a level in the normal-weight group (ß=0.311, P=0.010). A negative association was observed between the VAT PPARγ expression and miR-34a expression in obese cases (ß = - 0.594, P=0.039). CONCLUSION: The results also confirmed the regulatory function of microRNAs in the PPARγ expression and adipogenesis.

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BACKGROUND: Adipose tissue (AT) is a passive reservoir for energy storage and an active endocrine organ responsible for synthesizing bioactive molecules called adipokines. Omentin is known as an anti-inflammatory adipokine that can modulate insulin sensitivity. The present study aimed to investigate the relationship between omentin mRNA expression and glucose homeostasis of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in non-diabetic adults. METHODS: VAT and SAT adipose tissues were collected from 137 adults aged ≥ 18 years hospitalized for abdominal surgery. Before surgery, preoperative blood samples were taken from the participants to measure fasting plasma glucose, insulin, and triglyceride. BMI, HOMA-IR, HOMA-B, and QUICKI were calculated. Insulin levels were measured with Mercodia kits using enzyme-linked immunosorbent assay (ELISA). In order to obtain omentin mRNA expression, real-time PCR was performed. RESULTS: Overall, 91 (66.4%) subjects were healthy [without insulin resistance (IR)], and 46 (33.6%) participants were with IR. In healthy and IR subjects, omentin gene expression was 1.04 and 2.32, respectively in VAT, and 3.06 and 1.30, respectively, in SAT (P > 0.05). After controlling for age and BMI, linear regression analysis indicated a significant positive association of SAT omentin expression with insulin concentration (ß = 0.048; 95% CI 0.009, 0.088, P = 0.017) and HOMA-IR (ß = 0.173; 95% CI 0.023, 0.323, P = 0.014). Moreover, a negative association of SAT omentin expression with HOMA-B (ß = - 0.001; 95% CI 0.002, - 0.001, P < 0.001) was observed. CONCLUSION: This study's finding confirms a direct association between IR with omentin mRNA levels in SAT. Besides, the indicator of insulin sensitivity had an inverse association with omentin gene expression in SAT. This aspect of research suggests that omentin secretion from SAT has a strong link with insulin regulation.

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BACKGROUND: Apelin is an adipokine with an intermediatory role in obesity and insulin resistance, which can be modified by dietary intake. AIMS: In this study, we aimed to determine the association of the plasma fatty acid composition with apelin plasma concentration and gene expression in visceral (VAT) and subcutaneous (SAT) adipose tissues. METHODS: In this cross-sectional study, we recruited 179 patients aged 19-75 years who were candidates for elective surgery. Through the surgery, SAT and VAT were collected to measure apelin gene expression. Anthropometric measurements, fasting blood samples, and dietary intakes were collected before surgery. Free fatty acids (FFAs) in fasting whole plasma were measured using gas chromatography with flame ionization detection. Linear regression models were used to estimate standardized ß (STZ ß) showing the association of individual and total FFAs with apelin gene expression after adjustment for potential confounding variables. RESULTS: In multivariable analysis, we observed a significant positive association of total plasma free fatty acids (FFAs) (STZ ß = 0.241, P = 0.006), saturated fatty acid (SFA) (STZ ß = 0.336, P < 0.001), and monounsaturated fatty acid (MUFA) (STZ ß = 0.313, P < 0.001) concentrations with apelin gene expression from VAT after controlling for age, sex, body mass index, homeostatic model assessment for insulin resistance (HOMA-IR), physical activity, and energy intake. In the SFA family, there was a direct association with plasma concentration of myristic acid (STZ ß = 0.372, P < 0.001), pentadecanoic acid (STZ ß = 0.252, P = 0.002), and heptadecanoic acid (STZ ß = 0.407, P < 0.001) with apelin mRNA expression in VAT. There was no significant association between FFAs and apelin plasma concentration and SAT mRNA levels. CONCLUSIONS: In conclusion, circulating plasma FFAs, SFA, and MUFA had a positive association with apelin gene expression in VAT. It seems that plasma fatty acid composition may regulate apelin gene expression in VAT.

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Quantitative reverse transcription polymerase chain reaction (qRT-PCR) in thyroid tumors require accurate data normalization, however, there are no sufficient studies addressing the suitable reference genes for gene expression analysis in malignant and normal thyroid tissue specimens. The purpose of this study was to identify valid internal control genes for normalization of relative qRT-PCR studies in human papillary thyroid carcinoma tissue samples. The expression characteristics of 12 candidate reference genes (GAPDH, ACTB, HPRT1, TBP, B2M, PPIA, 18SrRNA, HMBS, GUSB, PGK1, RPLP0, and PGM1) were assessed by qRT-PCR in 45 thyroid tissue samples (15 papillary thyroid carcinoma, 15 paired normal tissues and 15 multinodular goiters). These twelve candidate reference genes were selected by a systematic literature search. GeNorm, NormFinder, and BestKeeper statistical algorithms were applied to determine the most stable reference genes. The three algorithms were in agreement in identifying GUSB and HPRT1 as the most stably expressed genes in all thyroid tumors investigated. According to the NormFinder software, the pair of genes including 'GUSB and HPRT1' or 'GUSB and HMBS' or 'GUSB and PGM1' were the best combinations for selection of pair reference genes. The optimal number of genes required for reliable normalization of qPCR data in thyroid tissues would be three according to calculations made by GeNorm algorithm. These results suggest that GUSB and HPRT1 are promising reference genes for normalization of relative qRT-PCR studies in papillary thyroid carcinoma.

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The purpose of the study was to investigate the association of leptin gene expression in visceral and subcutaneous adipose tissues with habitual fatty acid intake and its subtypes in adults. Visceral and subcutaneous adipose tissues were gathered from 97 participants aged ≥ 20, who had undergone elective abdominal surgery. Dietary fatty acid intakes including total fatty acids (TFA), saturated fatty acid (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), n-3, n-6, and n-9 fatty acids were collected using a valid and reliable food-frequency questionnaire (FFQ). The leptin gene expression in visceral and subcutaneous adipose tissues was measured by Real-Time PCR. After controlling for body mass index (BMI) and insulin, energy-adjusted dietary intake of SFA was positively and MUFA and n-3 fatty acids were negatively associated with subcutaneous and visceral adipose tissues leptin gene expression. Besides, a significant negative association of PUFA, n-6, and n-9 fatty acids with leptin mRNA from visceral adipose tissue were observed. In order to better interpretations of the results, the participants were allocated two groups including non-obese (BMI < 30kg/m2) and obese subjects (BMI ≥ 30kg/m2). Among non-obese participants, the SFA had positive and PUFA had negative association with leptin gene expression in both adipose tissues. Furthermore, in obese participants, n-3, n-6, and n-9 fatty acids had a negative association with visceral leptin gene expression. Habitual intake of SFA, MUFA, and n-3 fatty acids were associated with leptin gene expression in visceral and subcutaneous adipose tissues, suggesting an important role of quality and quantity of fatty acids intake in adipose tissue to regulate leptin expression.

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