The objective of the study was to measure the concentration of adiponectin in plasma, its mRNA expression and the expression of the adiponectin receptors AdipoR1 and AdipoR2 in subcutaneous adpipose tissue (ST) of women with various levels of fat in their organism. A further objective of the study was to determine to what extent the stated parameters correlate with obesity as defined by BMI (body mass index) and how it can be affected by a very low calorie diet (VLCD).
Patient sample: The sample of 70 women was divided into groups by BMI: patients with class 3 obesity (BMI > 40 kg.m(-2), n = 25), patients with class 1 and 2 obesity (BMI 30-40 kg.m(-2), n = 15), overweight patients (BMI 25-30 kg.m(-2), n = 10) and a normal healthy control group (BMI 20-25 kg.m(-2), n = 20). In the case of 14 women with class 3 obesity, the parameters were measured before and after a three-week diet with an energy content of 2200 kJ (550 kcal)/day (VLCD).
Method: Plasma concentrations of adiponectin were measured using an ELISA kit (LINCO Research, USA). Subcutaneous adipose tissue was taken using biopsy. RNA was isolated using a MagNA Pure Compact RNA Isolation Kit (Tissue) (Roche, SRN). The gene expression of adiponectin, AdipoR1 and AdipoR2 was determined using the real-time PCR (RT-PCR) method on a ABI Real-Time PCR 7500 instrument (Applied Biosystems, USA) with TaqMan Gene Expression Assays hydrolisation probes. beta-2-mikroglobulin (beta2M) was used as an endogenous control, to which the data was normalised.
Results: The circulatory concentration of adiponectin, its mRNA expression and the mRNA expression of AdipoR1 in ST correlate negatively with BMI (r = -0.524, p < 0.001; r = -0.460, p < 0 001; p = -0.354, p = 0.004). The expression of AdipoR2 in ST did not correlate with BMI. The VLCD reduced weight by 9% but did not affect the plasma concentration of adiponectin or the rate of its expression, or the expression of AdipoR1 and AdipoR2.
Conclusion: Our results show that not only the circulatory concentration of adiponectin but also its mRNA expression and the expression of AdipoR1 in ST are significantly lower in obese women compared to a control group and may contribute to the development of metabolic complications in obesity.