IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 Study the Effect of Rifampicin in the Level of Thyroid's Gland Hormones and Thyroid - Stimulating Hormone in Rabbits D. A. Sabrei Department of Biology, College of Education Ibn AL- Haitham, University of Baghdad Abstract The aim of this study was intended to study the effect of rifampicin in the level of thyroid's gland hormones (T4 ، T3) and thyroid -stimulating hormone (TSH) in rabbits. Eight male rabbits were used through out this study, their weights were measured before the starting of the experiment. Animals were divided into two groups (each group contains 4 rabbits), the first group was administrated daily with 15 mg/Kg physiological normal saline for 35 days and used as a control group, while the second group was administrated with 15 mg /Kg daily for 35 day of rifampicin capsule 300 mg. At the end of the experiment, all of animal groups were weighted and the sera was prepared to measure the hormones. The results showed that there was a significant decrease (P < 0.05) in the mean of animals weights in the second group that was treated with rifampicin in comparison with the control group. A significant increase (P < 0.05)was in T4, and T3 hormones level, and a significant decrease (P < 0.05)was in TSH hormone level in the second group that treated with rifampicin in comparison with the control group. From this study, can conclude that rifampicin has a negative effect on thyroid gland function which might disorder on the secretion activity of thyroid gland hormones. Key words: Rifampicin, Thyroid Gland, Thyroid Hormones. Introduction The thyroid is one of the largest endocrine glands in the body. This gland is found in the neck inferior to (below) the thyroid cartilage (also known as Adam's apple in men) and at approximately the same level as the cricoid cartilage(1). The thyroid controls how quickly the body burns energy, makes proteins, and how sensitive the body should be to other hormones (2). The primary function of the thyroid is production of the hormones thyroxine (T4), IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 triiodothyronine (T3), and calcitonin. Up to 80% of the T4 is converted in to T3 by peripheral organs such as the liver, kidney and spleen. T3 is about ten times more active than T4 (3). Thyroxine (T4) is synthesized by the follicular cells from free tyrosine and of the tyrosine residues of the protein is called thyroglobulin (TG). Iodine is captured with the "iodine trap" by the hydrogen peroxide generated by the enzyme thyroid peroxidase (TPO) (4) and linked to the 3' and 5' sites of the benzene ring of the tyrosine residues on TG, and on free tyrosine. Upon stimulation by the thyroid -stimulating hormone (TSH), the follicular cells reabsorb TG and proteolytically cleave the iodinated tyrosines from TG, forming T4 and T3 (in T3, one iodine is absent compared to T4), and releasing them into the blood. Diiodinase enzymes convert T4 to T3 (5). Thyroid hormones that are secreted from the gland are about 90% T4 and about 10% T3. (3) Cells of the brain are a major target for the thyroid hormones T3 and T4. Thyroid hormones play a particular crucial role in brain maturation during fetal development. (6) A transport protein (OATP1C1) has been identified that seems to be important for T4 transport across the blood brain barrier. A second transport protein (MCT8) is important for T3 transport across brain cell membranes (7). In the blood, T4 and T3 are partially bound to thyroxine-binding globulin. Only a very small fraction of the circulating hormone is free (unbound) - T4 0.03% and T3 0.3%. Only the free fraction has hormonal activity (8). The production of thyroxine and triiodothyronine is regulated by thyroid -stimulating hormone (TSH), released by the anterior pituitary (that is in turn released as a result of TRH release by the hypothalamus) (8),(9). Rifampicin, or Rifadin, or Rifampin is a semisynthetic antibiotic derivative of rifamycin SV. Rifampin is a red-brown crystalline powder very slightly soluble in water at neutral pH, freely soluble in chloroform, soluble in ethy l acetate and in methanol. Its molecular weight is 822.95 and its chemical formula is C43H58N4O12. The chemical name for rifampin is either: 3-[[(4-Methyl-1-piperazinyl)imino]methyl]rifamycin or 5,6,9,17,19,21-hexahydroxy-23-methoxy-2,4,12,16,20,22- heptamethyl-8-[N-(4-methyl-1-piperazinyl)formimidoyl]-2,7-(epoxypentadeca [1,11,13]trienimino)naphtho[2,1-b]furan-1,11(2H)-dione 21-acetate.(10) Its structural formula is: IBN AL- HAITHAM J. FO R PURE & APPL. SCI VOL.22 (3) 2009 Rifampicin drug i.e. (rifampin) Capsules, and (rifampin) for Injection IV an active antibiotic used for tuberculosis and against some gram negative, gram positive, some enteric bacteria, and mycobacterium. Rifampicin binds strongly to DNA dependent RNA polymerase thus it inhibits RNA synthesis in bacteria and Chlamydia (11), (12). Rifampicin has many sides effects for example it causes anemia (13), thrombocytopenia, and leucopenia (14), also rifampicin reduces the level of glutathione, creatinine, WBCs counts and the level of lipid (15) ….etc. Few of researches insinuate that Rifampicin may increase T3 level, and until yet to our knowledge, no study was devoted to the still poorly exploited aspect of the effect of Rifampicin on the level of thyroid gland hormones, i.e. does the Rifampicin has side effects on the thyroid gland function, which is the aim of the present study. Material and Methods Eight male rabbits were used in this study were taken from the animal house in the Biotechnology Researches Center / Al – Nahrain University, and their ages were between, (9 – 12) months. Isolated in a relatively controlled environment at a temperature of a bout 37°C, their weights were between (1500 – 1250) gm at the beginning of the experiment ,their weights about and they were given free access for tap water and food adlibitum. Animals were divided into two groups (each group contains 4 rabbits) as follows: 1. First group was administrated daily with 15 mg / kg physiological normal saline by Orogastric tube for 35 days and used as a control group. 2. Second group was administrated daily with 15 mg / kg of rifampicin 300 mg by Orogastric tube for 35 days. At the end of the experiment the weights of the animals were taken. and pull up the blood by heart puncture and prepared the sera to measure the thyroid gland hormones (T4, T3) and thyroid -stimulating hormone (TSH) by the (ELISA method) and used the specific ELISA hormones kits for (T4, T3 ), and (TSH). The experiment and the hormonal assay were done in IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 the laboratory of the Biotechnology Researches Center / Al – Nahrain University from (20 / November / 2008) to (25 / January / 2009). Results and Discussion Animals treated with rifampicin showed a significat (P < 0.05) decrease in the body weights (from 1450.00  50.00 to 467.50 ± 46.26) gm in comparison with the animals weights of the control group (from 1250.00  104.08 to 1825.00  85.39) gm (tab-1). These changes reflect the effect of rifampic in administration on the thyroid gland function i.e. increase secretion it’s hormones (T4 , T3) thus increase the body’s basal metabolic rate, stimulate carbohydrate metabolism ,break down fats, and affect protein synthesis.(2), (16),(17), (18). Also the results showed a significant increase (P < 0.05) in T4, and T3 hormone level, and a s ignificant decrease (P <0.05) in TSH hormone level in comparison with the control group (tab- 2). These results show that rifampicin had side effects on thyroid gland function i.e. increase forming and release it s hormones over the normal value especially (T4 & T3), that’s mean primary hyperthyroidism and the weights results above proved that. May be it s increase thyroxine (T4) synthesized by the follicular cells from free tyrosine or from the tyrosine residues of the protein called thyroglobulin (TG) (10), (19). A decrease that happened to TSH it’s a result to the negative feed back mechanism (18),(19), i.e. thyroxine T4 and triiodothyronine T3 is regulated by thyroid-stimulating hormone (TSH), released by the anterior pituitary (that is in turn released as a result of TRH release by the hypothalamus). The thyroid and thyrotropes form a negative feedback loop: TSH production is suppressed when T4 level is high, and vice versa. The TSH production itself is modulated by thyrotropin-releasing hormone (TRH), which is produced by the hypothalamus and secreted at an increased rate in situations such as cold (in which an accelerated metabolism would generate more heat). TSH production is blunted by somatostatin (SRIH), rising levels of glucocorticoids and sex hormones IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 (estrogen and testosterone), and excessively high blood iodide concentration (20). The results concluded that rifampicin had negative effect on thyroid gland function which might have disorder on the secretion activity of thyroid gland hormones. References 1. Anonymous, (2003). The Thyriod gland. Internet address: www.umm.edu. pp: 1-2. 2. Miller, F.R. & Netterville, J.L. (1999). Med. Clin. North. Am., 83: 247-259. 3. Nussey, Stephen & Whitehead, Saffron (2001). The thyroid gland in Endocrinology: An Integrated Approach. Published by BIOS Scientific Publishers Ltd. pp: 225. 4. Ekholm, R. and Bjorkman, U. (1997). Endocrinology, 138 (7): 2871–2878. 5. Bianco, A.C.; Salvatore, D.; Gereben, B.; Berry, M.J. & Larsen, P.R. (2002).. Endocr. Rev., 23 (1): 38–89. 6. Kester, M.H.; Martinez de Mena, R.; Obregon, M.J.; Marinkovic, D.; Howatson, A.; Visser, T.J.; Hume, R. & Morreale de Escobar, G.(2004). J. Clin. Endocrinol. Metab., 89(7):3117–3128. 7.Jansen, J.; Friesema, E.C.H.; Milic i, C. & Visser, T.J. (2005). Thyroid, 15: 757-768. 8.Yalçin, B. & Ozan, H. (2006). Journal of the American College of Surgeons, 202 (2): 291–6. 9. Taurog, A. (1996). Hormone Synthesis. In: L. Braverman & R. Utiger (eds.). Werner and Ingbar’s the thyroid gland. J.B. Lippincott-Kaven Co. Philadelphia. pp: 47-81. 10. Anonymous. (2009). Rifadin (Rifampin) Drug Information Uses, Side Effects, Drug Interactions and Warnings at RxList2. Internet address: http://www.rxlist.com/rifadin- drug.htm. pp: 1-8. 11. Joshi, R. (2007).J.A.P.I., 54: 57-74 IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 12. Mihic, P. & Gandhi, T. (2008) .Pharmacology Reviews, 2(3):1-1. 13. Mansouthi, W. (2008).Biol. med. Central., 8 (136) :1-7. 14. Mahmood , K .(2007).Park J. Med. Sci., 23(1):1-2. 15. Adhvaryu, R.; Narsimha, R.; Minoo, H. & Bapalal, V. (2007).W. J. Gastroenterol., 13 ( 23): 3199-3205. 16. Simon, H.(2003). Hypothyroidis im. Internet address: www.thyroid.com/index./ Pp: 1-3. 17. Anonymous. (2009).Thyroid and Anti-Thyroid Drugs. Internet address: http://www.thyroid-info.com/drugs/armour.htm pp:4. 18. Junqueira, L.C.; Carneiro, J. & Kelly, R.O. (2002). Basic Histology. 9th. edn., Appleton and Lang, Asimon and Schuster Company, USA. pp: 218- 230. 19. Inzucchi, S.; Burrow, G. (1999). The thyroid gland and reproduction In: S. Yen; R. Jaffe & R. Barbieri (eds.). Reproductive Endocrinology, Physiology Pathology and Clinical Management. 4th. edn., W.B. Saunders Company, Philadelphia. pp: 314-318. 20. Wikipedia, the free encyclopedia. (2009). Thyroid. Internet address: Wikipedia, the free encyclopedia.htm . pp: 1 of 1. Table (1): Explain the effect of administration rifampicin on the Rabbits Mean weights in treated and control group M  SE: Mean  Stander Error * : Significant Difference (P <0.05) Groups Mean weight(gm) (zero time) M  SE Mean weight (gm) (end of treatment) M  SE 1. Control group 1250.00  104.08 1825.00  85.39 2.Group treated with rifampicin 1450.00  50.00 467.50  46.26 * IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 Table (2): Explain the effect of administration rifampicin in the Level of T4, T3, and TSH in Rabbits in treated and control group M  SE: Mean  Stander Error * : Significant Difference (P <0.05) Groups T4 µg / dl M  SE T3 ng / ml M  SE TSH µu / l M  SE 1.Control group 6.05  0.16 0.93  0.11 0.80 ± 0.04 2.Group treated with rifampicin 8.80  0.45 * 2.53  0.13 * 0.18  0.05 * 2009) 3( 22المجلد مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة والهرمون مستوى هرمونات الغدة الدرقیةفي الریفامبیسین ردراسة تأثیر عقا في األرانب ةالمحفز للدرقی دالیا عبد اللطیف صبري ابن الهیثم،جامعة بغداد -قسم علوم الحیاة ، كلیة التربیة الخالصة والهرمون T4 (T3,(مستوى هرمونات الغدة الدرقیة في الریفامبیسین رتأثیر عقا دراسة الى هدفت الدراسة الحالیة أوزانها ومن ثم قسمت على تخذأ اذ أرانب ذكور 8الدراسة في هذه استخدم .األرانبفي (TSH)ةالمحفز للدرقی رانب 4مجموعتین كل مجموعة مكونة من ملحي الفسیولوجي )مجموعة سیطرة( األولىالمجموعة جرعت .أ بالمحلول ال ة وجرعتیومًا ، 35مدة و كغم / ملیغرام 15 یومیا بجرعة normal saline physiologicalالسوي المجموعة الثانی . یوماً 35مدة و یومیًا كغم / ملیغرام 15 مقدارهاوبجرعة ملیغرام 300 الریفامبیسین عقارب (TSH). و T4 (T3,(وزنت الحیوانات وتم سحب الدم لتهیئة األمصال لقیاس مستوى هرمون في نهایة المعاملة في معدل أوزان الحیوانات المعاملة بالریفامبیسین مقارنًة بمجموعة (p<0.05)وجود نقصان معنوي النتائج وأظهرت في مستوى هرمون (p<0.05)ونقصان معنوي T3و T4,في مستوى هرموني (p<0.05)السیطرة وحصول زیادة معنویة TSH مقارنًة بمجموعة السیطرة . فعالیة الغدة الدرقیة اإلفرازیة مما یؤدي الى حدوث خلل في الریفامبیسین تأثیرًا سلبیًا فيلعقار نستنتج من هذه الدراسة إن . اإلفراز الهرموني .ریفامبیسین، الغدة الدرقیة، هرمونات الغدة الدرقیة: كلمات المفتاح