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Tricyclic antidepressants, thyroid function, and their relationship with the behavioral responses in rats
J Massol1, P Martin, F Chatelain
1Département de Pharmacologie, Faculté de Médicine, Pitié-Salpêtrière, Paris, France.
Biological Psychiatry
|December 1, 1990
Summary
Tricyclic antidepressants (TCAs) were found to decrease triiodothyronine (T3) levels in rats, regardless of learned helplessness. This thyroid function change was observed in both healthy and stressed animals, suggesting T3 levels are not linked to TCA antidepressant effects.
Area of Science:
- Neuropharmacology
- Endocrinology
Background:
- Learned helplessness is a behavioral paradigm used to study depression.
- Tricyclic antidepressants (TCAs) are a class of drugs used to treat depression.
- Thyroid hormones, including triiodothyronine (T3) and thyroid-stimulating hormone (TSH), play a role in mood regulation.
Purpose of the Study:
- To investigate the effects of TCAs on thyroid function in rats.
- To determine if TCA-induced changes in thyroid function are related to their antidepressant effects.
Main Methods:
- Rats were subjected to the learned helplessness paradigm.
- TCAs (clomipramine, desipramine, imipramine) were administered intraperitoneally for 5 consecutive days.
- Blood samples were analyzed for T3 and TSH levels using radioimmunoassay.
- Additional experiments involved diabetes induction and food deprivation models.
Main Results:
- TCA administration dose-dependently decreased T3 levels in both helpless and control rats, without affecting TSH levels.
- In diabetic and food-deprived rats, which already had decreased T3 levels, TCAs further reduced T3.
- TCAs did not alter behavior in the experimental models.
Conclusions:
- TCAs decrease thyroid function by reducing T3 levels.
- The antidepressant effects of TCAs are likely not mediated by their impact on thyroid function.