Floyd P. Kupiecki

Epididymal fat pad alterations in mice with spontaneous obesity and diabetes and with chemically induced obesity.

SummaryPathologic alterations have been found in the epididymal fat pad of five strains of spontaneously obese or diabetic mice and in one strain of normal mice made obese by a single injection of goldthioglucose. — Histologic abnormalities were observed in the epididymal fat pad of all obese and diabetic mice. These abnormalities were at first characterized by a remarkable growth of the individual fat cell. Later, coinciding with a weight loss of the pad, and in some instances discoloration, the pad became hypercellular. A variable number of macrophages, mast cells and fibroblasts were observed occupying the intercellular spaces and a few fat cells appeared to be diminishing in size. — Overt necrosis and foci of acute inflammatory reaction of the epididymal fat pad was only seen in 9 month old T-KK mice. — “Lean” KK mice, having at all times an underdeveloped epididymal fat pad, were free of the lesions mentioned above. — Prediction of the character and degree of the pathologic changes in the early stages could not be made by gross observation of the fat pad. Histologie methods appear to be necessary to ascertain the condition of the epididymal fat pad of mice having abnormal body weight or abnormal plasma insulin levels.

The Lipolytic System in Adipose Tissue of Toronto-KK and C57BL/KsJ Diabetic Mice. Adenylate Cyclase, Phosphodiesterase and Protein Kinase Activities

SummaryEpinephrine-stimulated lipolysis in epididymal fat pads of T-KK mice is low, compared to C57BL/6J controls, at 10–12 weeks and 8–9 months of age. Lipolysis in isolated fat cells is similarly unresponsive to epinephrine in 9–12 week old T-KK anddb mice, but cyclic AMP phosphodiesterase activity is normal. Basal adenyl cyclase activity in ghosts prepared from isolated fat cells of T-KK mice is elevated but epinephrine-stimulated activity is low compared to controls. Total cyclase activity, elicited by NaF, is higher in T-KK mice. Adenyl cyclase activity in particulate fractions prepared from fat pad homogenates ofdb mice is low compared to control mice when expressed as total activity per fat pad. Unstimulated and cyclic AMP-stimulated protein kinase activities in fat pad homogenates are normal in T-KK mice, but indb mice unstimulated activity is depressed while stimulated activity is elevated.

Lipolytic activity of cis-β-carboxyacrylamidine: Studies in vivo and in vitro

Abstract cis -β-Carboxyacrylamidine, a product isolated from the fermentation broth of the actinomycete, Streptomyces fur longus var. fur longus nov. sp., stimulated lipolysis in rat adipose tissue and isolated fat cells. Lipid-mobilizing activity in vivo was indicated by the increase in plasma FFA concentrations that occurred after the compound was administered orally. Daily doses reduced body weight gain but after approximately 5 days the rats became resistant to this effect of the compound. Resistant animals still responded to the lipid-mobilizing activity of the agent with an increase in plasma FFA levels. cis -β-Carboxyacrylamidine did not increase cyclic AMP concentrations in incubated adipose tissue. Also it neither stimulated adenylate cyclase or cyclic AMP-dependent protein kinase nor inhibited cyclic AMP phosphodiesterase or phosphoprotein phosphatase. The lipolytic mechanism was found to differ from the mechanism of N -ethylmaleimide. Also cis -β-carboxyacrylamidine inhibited soluble hormone-sensitive lipase, suggesting that soluble hormone sensitive lipase may not be the lipase mainly responsible for the response of adipose tissue and isolated fat cells to lipolytic hormones.