A role for testosterone in the maintenance of seasonally appropriate body mass but not in lipectomy-induced body fat compensation in Siberian hamsters.
The purpose of this study was to test whether serum testosterone (T) concentrations characteristic of reproductively active, long-day-housed Siberian hamsters are necessary for compensatory increases in nonexcised fat pads following removal of epididymal white adipose tissue (EWAT) and/or for the maintenance of seasonally appropriate body weights in these hamsters. Long-day-housed hamsters were castrated or left intact, sham or EWAT lipectomized, and given T or cholesterol (C) implants. All groups had ad libitum food access except for two castrated T-treated groups that were pair-fed to their C-treated counterparts to control for effects of T on food intake. C-treated castrates had decreased body weights compared with all other groups, suggesting a role of T in the maintenance of seasonally appropriate body mass. Since the T-treated hamsters pair-fed to these T-deficient animals exhibited seasonally appropriate body weights and fat pad masses, T does not appear to affect these parameters through the modulation of food intake. All fat pads of C-treated animals were smaller than those of ad libitum- or pair-fed, T-treated castrates; however, EWAT was the only fat pad that was smaller in the C-treated sham-lipectomized group than in gonad-intact sham-lipectomized hamsters. This result may indicate an enhanced sensitivity of EWAT to T. The effects of T on fat pad mass were not associated with proportionate changes in lipoprotein lipase activity, suggesting that the major effect of T on fat accumulation occurs through other mechanisms in this species. C-treated lipectomized hamsters compensated for the body fat deficit 8 weeks after lipectomy via statistically non-significant increases in retroperitoneal and inguinal WAT mass. This finding suggests that, whereas T is necessary for maintenance of seasonally-appropriate body weight, it is not necessary for fat pad compensation after EWAT lipectomy.
Mauer
M M
MM
Department of Biology, Georgia State University, Atlanta 30303, USA.
Bartness
T J
TJ
D000273:Adipose Tissue / Q000502:physiology*; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D006224:Cricetinae; D004435:Eating; D004822:Epididymis / Q000033:anatomy & histology / Q000201:enzymology; D015187:Lipectomy; D008071:Lipoprotein Lipase / Q000378:metabolism; D008297:Male; D009919:Orchiectomy; D009929:Organ Size; D017111:Phodopus; D012621:Seasons; D013737:Testis / Q000033:anatomy & histology; D013739:Testosterone / Q000097:blood / Q000494:pharmacology / Q000502:physiology*
D013739:Testosterone; D008071:Lipoprotein Lipase