Deep subcutaneous adipose tissue is the most metabolically active adipose depot in pregnant women- a preliminary study by ex-vivo analysis

Maternal obesity confers metabolic risk to both the mother and the offspring. The lipid metabolism of adipose tissue is directly linked to these metabolic consequences. This study aimed to better understand adipose tissue lipid metabolism in pregnant women by investigating the rate of lipolysis, adipocyte size, and the expression of the hormone-sensitive lipase (HSL) enzyme in different adipose depots. Approximately 4 g of adipose tissue (AT) was collected from each of 11 pregnant women (total samples, n = 33) during elective caesarean sections. Samples were obtained from superficial subcutaneous AT (sSAT), deep subcutaneous AT (dSAT), and visceral AT (VAT). Adipocytes were isolated by collagenase digestion. Cell size was measured using a fluorescent microscope and ImageJ software. Lipolysis was quantified via glycerol release (adjusted for cell number) using a commercial assay at baseline and after 60 min of isoproterenol stimulation. Total RNA extracted from AT was reverse transcribed to cDNA, and HSL gene expression relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was quantified by real-time PCR. Results were analyzed by categorizing the pregnant women into 3 groups as Normal weight (NW), Normal weight/Overweight (NW/OW) and Overweight (OW), considering the South Asian and Global body mass index (BMI) cut-off values. In NW/OW pregnant women group, the baseline lipolysis was significantly higher in dSAT compared to sSAT (P = 0.05) and VAT (P = 0.03) and was closer to stimulated lipolysis rates in both sSAT and VAT at 60 min in the same group, and to the baseline lipolysis of dSAT of overweight women. Deep subcutaneous adipose tissue (dSAT) was the most metabolically active depot in NW/OW and OW pregnant women. A preferable understanding of the distribution and metabolism of adipose tissue is important for prevention and control of maternal obesity related consequences.