FAT PAD-SPECIFIC COMPENSATORY MASS INCREASES AFTER VARYING DEGREES OFLIPECTOMY IN SIBERIAN HAMSTERS

Long day-housed Siberian hamsters show compensatory mass increases in inguinal (I) white adipose tissue (WAT) after epididymal WAT pad (EWAT ) removal (x) but do not increase EWAT mass after IWATx. This study te sted whether EWAT is specifically unresponsive to IWATx or whether EWA T lacks responsiveness to body fat deficits in general. We also tested whether the compensatory mass increases that occur after side-specifi c body fat removal are unilateral or bilateral. Therefore EWAT and/or IWAT was removed unilaterally or bilaterally. The compensatory changes in WAT mass by the intact fat pads were measured 12 wk later. EWAT di d not compensate for removal of its contralateral mate. Retroperitonea l WAT and IWAT showed greater compensatory mass increases ipsilateral to the side of fat pad removal when EWAT or IWAT pads were removed uni laterally but not after removal of larger amounts of body fat. These r esults suggest the following: I)in general, the greater the lipectomy- induced lipid deficit, the greater is the relative fat pad mass compen sation; 2) the restoration of body fat content after lipectomy may inv olve mechanisms that can detect the side of the lipid deficit and enha nce fat deposition on this side; and 3) EWAT does not show compensator y mass increases after lipectomy.