Lower body adipose tissue removal decreases glucose tolerance and insulin sensitivity in mice with exposure to high fat diet

Abstract

MT Foster (2015) Lower body adipose tissue removal decreases glucose tolerance and insulin sensitivity in mice with exposure to high fat diet, Adipocyte, 4:1, 32-43, DOI: 10.4161/21623945.2014 It has been postulated that the protective effects of lower body subcutaneous adipose tissue (LBSAT) occur via its ability to sequester surplus lipid and thus serve as a "metabolic sink." However, the mechanisms that mediate this protective function are unknown thus this study addresses this postulate. Ad libitum, chow-fed mice underwent Shamsurgery or LBSAT removal (IngX, inguinal depot removal) and were subsequently provided chow (Chow; typical adipocyte expansion) or high fat diet (HFD; enhanced adipocyte expansion) for 5 weeks. Primary outcome measures included glucose tolerance and subsequent insulin response, muscle insulin sensitivity, liver and muscle triglycerides, adipose tissue gene expression, and circulating lipids and adipokines. In a follow up study the consequences of extended experiment length post-surgery (13 wks) or pre-existing glucose intolerance were examined. At 5 wks postsurgery IngX in HFD-fed mice reduced glucose tolerance and muscle insulin sensitivity and increased circulating insulin compared with HFD Sham. In Chow-fed mice, muscle insulin sensitivity was the only measurement reduced following IngX. At 13 wks circulating insulin concentration of HFD IngX mice continued to be higher than HFD Sham. Surgery did not induce changes in mice with pre-existing glucose intolerance. IngX also increased muscle, but not liver, triglyceride concentration in Chow-and HFD-fed mice 5 wks post-surgery, but chow group only at 13 wks. These data suggest that the presence of LBSAT protects against triglyceride accumulation in the muscle and HFD-induced glucose intolerance and muscle insulin resistance. These data suggest that lower body subcutaneous adipose tissue can function as a "metabolic sink."

A Systematic Scoping Review of Surgically Manipulated Adipose Tissue and the Regulation of Energetics and Body Fat in Animals

“…Several studies have reported on the potential anatomical location‐specific effects of specific adipose depots. No significant differences in adipose regrowth based on the location of excised fat pads were observed in PPAR‐γ knockout mice , Sprague Dawley rats , C57BL/6J mice , wild‐type or ob/ob mice , Wistar rats , Osborne‐Mendel rats , and Gold‐mantled ground squirrels , which was consistent with other studies .…”

“…Overall, C57BL/6J mice with WAT or BAT removed had inconclusive results (e.g., some subgroups had lipectomized animals with either a lower BW or no significant changes in BW) . Similarly, C57BL/6J ob/ob mice had no changes in BW or had mixed results.…”

“…Therefore, changes in BW in most rat studies in the long term (or at termination) were not significantly different compared with baseline weight, with the exception of a few studies (12,(27)(28)(29)(30). Overall, C57BL/6J mice with WAT or BAT removed had inconclusive results (e.g., some subgroups had lipectomized animals with either a lower BW or no significant changes in BW) (31)(32)(33)(34)(35)(36)(37). Similarly, C57BL/6J ob/ob mice had no changes in BW (38) or had mixed (39)(40)(41) results.…”

“…In contrast, results varied for Syrian and Siberian hamsters, in which some had no change (42,44,46,50,51,53,54,71), were increased (43,52,53), were decreased (48), or were inconclusive (percent BF was not reported) (45,47,49). Surgical manipulations of WAT and BAT in mice led to decreased BF in experimental animals (36,37,41,61), whereas other studies reported inconclusive results or no observed changes (31)(32)(33)(34)(35)38,39,60,(62)(63)(64)(65)(66)(67)72,73). BAT removal resulted in increased BW at termination in Manchester mice (58).…”

“…Several studies have reported on the potential anatomical location-specific effects of specific adipose depots. No significant differences in adipose regrowth based on the location of excised fat pads were observed in PPAR-γ knockout mice (61), Sprague Dawley rats (13,14), C57BL/6J mice (31,33), wild-type or ob/ob mice (39), Wistar rats (19,23), Osborne-Mendel rats (8), and Gold-mantled ground squirrels (55), which was consistent with other studies (16,17). In summary, BF at termination in lipectomy studies (summarized in Table 1) had no change (n = 23), increased (n = 5), decreased (n = 4), were inconclusive (n = 12), or were mixed (n = 2) when comparing total BF measures at baseline to termination.…”