OVARIAN MODULATION OF LIPOPROTEIN-LIPASE ACTIVITY IN WHITE ADIPOSE-TISSUE OF GROUND-SQUIRRELS

Golden-mantled ground squirrels [Spermophilus lateralis] were ovariectomized (OVX) or sham-OVX during the weight gain phase of the circannual body weight cycle. Other squirrels, OVX or sham-OVX during the weight loss phase, were s.c. implanted with estradiol-filled or empty Silastic capsules. The mass of several fat pads as well as adipose tissue lipoprotein lipase (LPL) activity were determined at autopsy. Ovariectomy at either phase of the annual cycle was without effect on body weight. LPL activity of the parametrial fat pad was increased in OVX as compared to sham-OVX squirrels. Fourteen days of estradiol treatment during the weight loss phase decreased the mass and LPL activity of the retroperitoneal fat depot but did not affect these parameters in perirenal adipose tissue. Although estradiol exerts different or opposite effects on body mass and food intake of rats and ground squirrels, ovariectomy and estrogen treatment affect LPL activity in a similar fashion in both species.