Surgical Removal of Perirenal and Epididymal Adipose Tissue Decreases Serum Leptin Concentration and Increases Lipogenic Enzyme Activities in Remnant Adipose Tissue of Old Rats

Abstract

Background: The rate of lipogenesis and gene expression of lipogenic enzymes in white adipose tissue (WAT) of rats decreases with age. Previously, we showed the inverse relationship between serum leptin concentration and lipogenic enzymes activities in WAT of ageing rats. Based on those results, we postulated that leptin could play some role in the downregulation of lipogenic enzyme genes expression in WAT of old rats. Objective: To further test this hypothesis, in the present paper we examined the effect of surgical removal of perirenal and epididymal WAT on serum leptin concentration and lipogenic enzymes activities in remnant adipose tissue of old rats. Methods: One-year-old rats, which display a high serum leptin concentration and low lipogenic enzyme activities in WAT, were subjected to surgical removal of the perirenal and epididymal WAT. Two months after the surgery, the serum leptin concentration and lipogenic enzyme activities in remnant WAT were compared to the serum leptin concentration and lipogenic enzyme activities measured in adipose tissue collected during the surgery. Results: WAT removal resulted in an approximately 6-fold decrease of serum leptin concentration and about a 2-fold increase of lipogenic enzyme activities in remnant adipose tissue. Conclusions: These results indicate that interventions designed to reduce abdominal adipose tissue mass can change the lipogenic activity of remnant adipose tissue. Additionally, leptin could be one of the factors contributing to the downregulation of the genes expression of lipogenic enzymes during ageing in rats.

Transplantation or removal of intra-abdominal adipose tissue prevents age-induced glucose insensitivity

“…Consistent with no change of total fat, removal of EWAT in the present study did not alter leptin concentrations, and this is consistent with a previous report (30). There was an apparent transient increase of leptin at 4 wks post-transplantation, but it was gone by 8 wks, consistent with reports that measured leptin after 10 (24) or 12 wks (39).…”

The gender- and fat depot-specific regulation of leptin, resistin and adiponectin genes expression by progesterone in rat

“…Collectively, the results presented above indicate that WAT of females expressed progesterone receptor at higher level in inguinal versus retroperitoneal WAT, whereas in males, all main WAT depots displayed low or undetectable levels of progesterone receptor. Moreover, these results indicate that progesterone receptor in WAT, similarly as observed in other tissues [40], was downregulated by progesterone administration.…”

“…8). It has been shown that progesterone can diminish the level of its own receptor in main target organs [40]. Based on these observations we decided to measure the effect of progesterone administration on progesterone receptor mRNA and protein levels in inguinal and retroperitoneal WAT of female rats.…”

“…Based on these findings one can suppose that similar factors could be responsible for the observed increase of body weight. The lack of progesterone administration on the serum concentration of leptin and adiponectin despite significant increases of leptin and adiponectin gene expression in inguinal adipose tissue of female rats could be attributed to the fact that in females retroperitoneal, and in males retroperitoneal and epididymal WAT, are the main sources of the circulating leptin [39][40][41].…”

Up-regulation of orexigenic and down-regulation of anorexigenic neuropeptide gene expression in rat hypothalamus after partial lipectomy

“…Leptin down-regulates orexigenic and up-regulates anorexigenic neuropeptide gene expression (Korner et al, 2001;Takahashi and Cone, 2005). Both our previous studies (Nogalska et al, 2009) and the experiments conducted by other authors (Gabriely et al, 2002) showed that surgical removal of adipose tissue is reflected by a decrease in the amount of circulating leptin in rats. As the assessment of changes in orexigenic and anorexigenic neuropeptide gene expression in human hypothalamus after adipose tissue removal is not possible, we examined this phenomenon in an animal model.…”