Glycerol release in vitro from adipose tissue of obese (ob/ob) mice treated with thyroid hormones.

Glycerol release from adipose tissue of adult genetically obese (ob/ob) mice was greater than that from adipose tissue of lean litter-mates. However, a higher concentration of adrenaline was required to stimulate lipolysis in ob/ob adipose tissue. Since oxygen consumption and the uptake of radioactive iodine by the thyroid were reduced and the biological half-life of thyroidal radio-iodine was lengthened, it is suggested that ob/ob mice are hypothyroid. The poor sensitivity of ob/ob adipose tissue to low doses of adrenaline was improved by treatment with either tri-iodothyronine or thyroxine. The lipolytic responses to both dibutyryl 3':5'-cyclic adenosine monophosphate and aminophylline were enhanced in thyroid hormone-treated lean and ob/ob mice. A higher dose of tri-iodothyronine was required to enhance lipolysis in ob/ob mice than in lean controls. The possibility that hypothyroidism is responsible for the change in response of ob/ob adipose tissue to lipolytic hormones is discussed.