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In vivo Characterization of Endocrine Disrupting Chemical Effects via Thyroid Hormone Action Indicator Mouse
Published on: October 6, 2023
Acetylcholine and norepinephrine: compared actions thyroid metabolism
Endocrinology
|April 1, 1983
Summary
Acetylcholine (ACh) stimulates thyroid iodide organification and inhibits thyroxine (T4) release, acting via muscarinic receptors. This suggests a cholinergic pathway influences thyroid hormone regulation.
Area of Science:
- Endocrinology
- Neuroscience
- Cell Biology
Background:
- Norepinephrine (NE) and acetylcholine (ACh) are neurotransmitters with known roles in thyroid function.
- Previous studies indicated NE stimulates iodide organification and inhibits thyroxine (T4) release.
- The precise mechanisms of ACh action on thyroid hormone regulation were not fully elucidated.
Purpose of the Study:
- To investigate the effects of acetylcholine (ACh) on thyroid hormone synthesis and release in mouse thyroids in vitro.
- To determine the involvement of cyclic nucleotides (cAMP and cGMP) and specific receptor subtypes in ACh-mediated thyroid responses.
- To explore the potential role of a presynaptic cholinergic pathway in modulating thyroid neurotransmission.
Main Methods:
- In vitro incubation of mouse thyroid tissue with ACh and other agents.
- Measurement of iodide organification and T4 release.
- Assessment of intracellular cAMP and cGMP concentrations.
- Pharmacological blockade using atropine (ATR) and d-tubocurarine.
Main Results:
- ACh (5 X 10(-4) M) stimulated iodide organification and inhibited TSH- or (Bu)2cAMP-induced T4 release.
- ACh did not alter thyroid cAMP levels but increased cGMP concentrations.
- (Bu)2cGMP and 8-bromo-cGMP did not affect thyroid function.
- ACh-induced effects were reversed by atropine (ATR; 10(-5) M) but not d-tubocurarine, indicating muscarinic receptor involvement.
- ATR also reversed NE-induced inhibition of T4 release.
Conclusions:
- ACh modulates thyroid function through a mechanism downstream of cAMP production, likely involving muscarinic receptors.
- Cholinergic neurotransmission, potentially via a presynaptic pathway, plays a role in regulating thyroid hormone release and organification.
- These findings suggest a complex interplay between cholinergic and adrenergic signaling in the thyroid gland.
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