The Importance of Adrenal Hormones in the Implementation of Stress-Protective Effect of Low L-Thyroxine Doses

IF 0.6 4区生物学 Q4 BIOCHEMISTRY & MOLECULAR BIOLOGY

Journal of Evolutionary Biochemistry and Physiology Pub Date : 2024-06-26 DOI:10.1134/s0022093024030141

E. A. Gusakova, I. V. Gorodetskaya

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Abstract

Although low L-thyroxine doses have previously been found to increase body’s stress resistance, it has remained unclear whether this effect is related to the action of L-thyroxine itself or is mediated by its activating/potentiating impact on other hormones. The aim of this work was to study the role of adrenal hormones in the implementation of the protective effect of low L-thyroxine doses under stress. The work was carried out on white mongrel male rats; stress was modeled by a time deficit situation. L-thyroxine was administered at low, close to physiological, doses according to the following schedule: week 1—1.5 µg/kg, week 2—2.0 µg/kg, week 3—2.5 µg/kg, week 4—3.0 µg/kg. It was found that stress exposure (1) increases the blood concentration of iodine-containing thyroid hormones (ITH) by 23–44%, corticosteroids by 40%, and adrenal relative mass (RM) by 31%, (2) reduces thymic and splenic RMs by 26 and 14%, respectively, and insulin level by 46%, (3) causes damage to the gastric mucosa (GM) with a damage index (DI) of 1.36, (4) increases animal physical endurance, locomotor activity and anxiety, while decreasing the intensity of exploratory responses. Bilateral adrenalectomy (BA) prevents the activation of thyroid function, abolishes the increase in physical endurance, and alters the structure of behavior, as well as determines a more severe damage to the GM (DI 2.7), an increase in anxiety, and the suppression of exploratory behavior under stress. BA limits the protective effect of L-thyroxine under stress, as manifested by lower values of rat horizontal locomotor and exploratory activity, higher anxiety, and damage to the GM (after L-thyroxine administration, DI under stress without BA is 0.12, against BA is 1.19). This corresponds to a lower blood ITH concentration (by 14–43%). Hence, low L-thyroxine doses have a stress-protective effect. BA limits but does not completely prevents its implementation, suggesting that adrenal hormones play an important, albeit not crucial, role in shaping the L-thyroxine anti-stress effect.

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肾上腺激素在实施压力-低剂量左旋甲状腺素的保护作用中的重要性

摘要虽然以前曾发现低剂量的左旋甲状腺素能增强机体的抗应激能力，但一直不清楚这种效应是与左旋甲状腺素本身的作用有关，还是由其对其他激素的激活/促进作用所介导。这项工作是在白色杂种雄性大鼠身上进行的；压力是以时间不足的情况来模拟的。按照以下时间表，以接近生理剂量的低剂量服用左旋甲状腺素：第1-1.5微克/千克，第2-2.0微克/千克，第3-2.5微克/千克，第4-3.0微克/千克。研究发现，应激暴露（1）会使血液中的含碘甲状腺激素（ITH）浓度增加 23-44%，皮质类固醇增加 40%，肾上腺相对质量（RM）增加 31%；（2）会使胸腺和脾脏的 RM 分别减少 26% 和 14%，胰岛素水平减少 46%；（3）会对胃黏膜（GM）造成损伤，损伤指数（DI）为 1。36，（4）增加动物的身体耐力、运动活动和焦虑，同时降低探索反应的强度。双侧肾上腺切除术（BA）阻止了甲状腺功能的激活，取消了体能耐力的提高，改变了行为结构，并对基因组造成了更严重的损害（DI 2.7），增加了焦虑，抑制了应激下的探索行为。乙酰胆碱限制了左旋甲状腺素在应激下的保护作用，表现为大鼠水平运动和探索活动的数值降低、焦虑增加以及基因组受损（注射左旋甲状腺素后，在不注射乙酰胆碱的情况下，应激下的DI为0.12，注射乙酰胆碱后为1.19）。因此，低剂量的左旋甲状腺素具有应激保护作用。因此，低剂量的左旋甲状腺素具有应激保护作用。BA 限制但并不完全阻止其实施，这表明肾上腺激素在形成左旋甲状腺素抗应激作用方面发挥着重要作用，尽管不是关键性作用。

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来源期刊

Journal of Evolutionary Biochemistry and Physiology 生物-进化生物学

自引率

33.30%

发文量

110

审稿时长

6-12 weeks

期刊介绍： Journal of Evolutionary Biochemistry and Physiology publishes original experimental and theoretical and review articles related to evolution of the main forms of metabolism in connection with life origin; comparative and ontogenetic physiology and biochemistry, biochemical evolution of animal world; as well as evolution of functions; morphology, pharmacology, pathophysiology and ecological physiology. The journal welcomes manuscripts from all countries in the English or Russian language.