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Rat liver adenyl cyclase activity in various thyroid states
The Journal of Clinical Investigation
|September 1, 1972
Summary
Thyroid hormone impacts rat liver adenyl cyclase activity differently depending on thyroid status. Triiodothyronine (T(3)) increased enzyme activity in hypothyroid rats, but not in euthyroid or hyperthyroid states.
Area of Science:
- Endocrinology
- Molecular Biology
- Biochemistry
Background:
- Thyroid hormones regulate metabolic rate and cellular processes.
- Adenyl cyclase activity is a key mediator of cellular responses to hormones and neurotransmitters.
Purpose of the Study:
- To investigate the effect of thyroid hormone on rat liver adenyl cyclase activity.
- To determine if adenyl cyclase mediates the thermogenic effects of thyroid hormone.
Main Methods:
- Thyroidectomized and euthyroid rats were injected with triiodothyronine (T(3)) or diluent.
- Liver homogenates were assayed for basal, epinephrine-stimulated, and NaF-stimulated adenyl cyclase activity.
Main Results:
- Thyroidectomy increased total adenyl cyclase activity.
- T(3) administration increased basal and epinephrine-stimulated adenyl cyclase in hypothyroid rats, but not in euthyroid or hyperthyroid rats.
- No correlation was found between thyroid hormone effects on respiration and adenyl cyclase activity.
Conclusions:
- Hepatic thermogenic response to thyroid hormone is likely not mediated by adenyl cyclase stimulation.
- An exception may be the early effects of T(3) in athyroid rats.
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