Effects of Thyroid Hormone and Adrenalectomy on [Na⁺ + K⁺]ATPase in the ob/ob Mouse

Summary

The absence of the thyroid stimulation of hepatic [Na⁺ + K⁺]ATPase in obese (ob/ob) mice has been investigated. A wide range of tri-iodothyronine (T₃) concentrations failed to enhance the hepatic [Na⁺ + K⁺]ATPase of ob/ob mice made hypothyroid by methimazole treatment but glycero-phosphate dehydrogenase activity was maximally stimulated at low doses of T₃. Adrenalectomy increased the basal activity of [Na⁺ + K⁺]ATPase to levels found in lean control mice and restored the response of this enzyme to T₃. Body weight gain was unaffected by the induction of hypothyroidism in either lean or ob/ob mice. It is concluded that the adrenal steroids play an important role in the expression of [Na⁺ + K⁺]ATPase activity in the ob/ob mouse.

Key-Words:

Tri-Iodothyronine - Glycerophosphate Dehydrogenase - Hypothyroidism - Body Weight