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Chronic effect of morphine on thyroid glands in male rats
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M Khalili Najafabady   , A Bagheri , A Hadavandkhani |
| , najafabady@yahoo.com |
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Abstract: (40360 Views) |
| Introduction: Drug dependence, especially morphine addiction could markedly change the activity of the hypothalamic-hypophysial (H-H) axis. Thyroid secretion under the influence of H-H axis could play an important role in biological function. The present study was carried out to evaluate the effect of chronic consumption of morphine on thyroid function. For this purpose serum levels of T3, T4 and TSH were measured in male addicted rats. Materials and Methods: Male wistar rats were used for this investigation. We took the blood from the retroorbital plexus, and following separation of the serum from the blood, T3, T4, and TSH were measured by special kits using the Elisa method (control group, n=50). Control animals received morphine sulfate for 21 days. At the end of 21 days, T3, T4, and TSH were again measured and the levels now introduced as those of the addict group (chronic morphine consumption, n=50). Finally, the addict group were divided into physiologic and pharmacological (post naloxone treatment) withdrawal groups (n=25 for each group). We used naloxone (2 mg/kg, i.p.) for the induction of the pharmacologic withdrawal syndrome and physiologic withdrawal was induced 24 h following discontinuation of morphine consumption. After occurrence of withdrawal signs, again (the animal’s) blood was collected for the mentioned hormone assay. Another group (naloxone pre-treatment group, n=20) received naloxone before morphine consumption. Results: In addicted animals, serum levels of T3 and T4 were decreased by 17. 83 and 39. 15%, respectively and T3UP was augmented to 18. 16%. Post-treatment with naloxone (pharmacological withdrawal) could significantly enhance the decreasing effect of morphine on T3. However, the increasing effect of morphine on T3UP was reduced by naloxone post-treatment. Pre-treatment of animals with naloxone had no significant effect on morphine influence on T3, T4, and TSH. Conclusions: The present study showed that the serum levels of T3 and T4 significantly decrease in chronic morphine consumption. Since no changes in TSH level were observed in addicted rats, factors other than H-H axis could affect the levels of the thyroid hormones. Considering the higher level of T3UP during morphine consumption, the increased synthesis of thyroid binding proteins may be responsible for lower levels of T3 and T4 in addicted rats. |
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| Keywords: Addiction, Withdrawal syndrome, T3, T4, TSH, Rat |
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Full-Text [PDF 311 kb]
(3206 Downloads)
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Type of Study: Original |
Subject:
Endocrinology
Received: 2006/11/19 | Published: 2005/03/15
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