Long-Term Voluntary Exercise and the Mouse Hypothalamic-Pituitary-Adrenocortical Axis: Impact of Concurrent Treatment with the Antidepressant Drug Tianeptine

• Published in: Journal of neuroendocrinology 2006-12, Vol.18 (12), p.915-925
• Main Authors: Droste, S. K., Schweizer, M. C., Ulbricht, S., Reul, J. M. H. M.
• Format: Article
• Language: English
• Subjects: Adrenal Cortex - anatomy & histology; Adrenal Cortex - drug effects; Adrenal Cortex - physiology; Analysis of Variance; Animals; antidepressant; Antidepressive Agents, Tricyclic - pharmacology; Biological and medical sciences; Choice Behavior; Circadian Rhythm - drug effects; Corticosterone - blood; corticotrophin-releasing factor; Corticotropin-Releasing Hormone - genetics; Corticotropin-Releasing Hormone - metabolism; Fundamental and applied biological sciences. Psychology; HPA axis; Hypothalamo-Hypophyseal System - drug effects; Hypothalamo-Hypophyseal System - metabolism; Locus Coeruleus - drug effects; Locus Coeruleus - metabolism; Male; Medical sciences; Mice; Mice, Inbred C57BL; Neuropharmacology; Organ Size; Paraventricular Hypothalamic Nucleus - drug effects; Paraventricular Hypothalamic Nucleus - metabolism; Pharmacology. Drug treatments; Physical Conditioning, Animal - physiology; Pituitary-Adrenal System - drug effects; Pituitary-Adrenal System - metabolism; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; RNA, Messenger - analysis; Thiazepines - pharmacology; tianeptine; Time Factors; Tyrosine 3-Monooxygenase - genetics; Tyrosine 3-Monooxygenase - metabolism; tyrosine hydroxylase; Vertebrates: endocrinology; voluntary exercise
• ISSN: 0953-8194; 1365-2826
• DOI: 10.1111/j.1365-2826.2006.01489.x

We investigated whether voluntary exercise and concurrent antidepressant treatment (tianeptine; 20 mg/kg/day; 4 weeks) exert synergistic effects on the mouse hypothalamic‐pituitary‐adrenocortical (HPA) axis. Animals had access to a running wheel, were treated with the antidepressant, or received both conditions combined. Control mice received no running wheel and no drug treatment. Exercise resulted in asymmetric changes in the adrenal glands. Whereas sedentary mice had larger left adrenals than right ones, this situation was abolished in exercising animals, mainly due to enlargement of the right adrenal cortex. However, antidepressant treatment alone was ineffective whereas the combination of antidepressant treatment and exercise resulted in an enlargement of both adrenal cortices. In these respective conditions, the levels of tyrosine hydroxylase (TH) mRNA expression in the left and right adrenal medullas varied greatly in parallel to the changes observed in the adrenal cortex sizes. TH mRNA expression in the locus coeruleus of exercising mice was significantly increased irrespective of concomitant tianeptine treatment. Corticotrophin‐releasing factor mRNA levels in the hypothalamic paraventricular nucleus were decreased after voluntary exercise but were unaffected by tianeptine. Exercise, particularly in combination with tianeptine treatment, resulted in decreased early morning baseline plasma levels of corticosterone. If animals were exposed to novelty (i.e. a mild psychological stressor), a decreased response in plasma corticosterone levels was observed in the exercising mice. By contrast, after restraint, a mixed physical and psychological stressor, exercising mice showed an enhanced response in plasma corticosterone compared to the controls; a response which was even further boosted in exercising mice concomitantly treated with tianeptine. Under either condition, plasma adrenocorticotrophic hormone levels were not different between groups. Thus, voluntary exercise impacts substantially on HPA axis regulation. Concurrent tianeptine treatment results in synergistic actions, mainly at the adrenal level, affecting both its structure and function.