|Year : 2014 | Volume
| Issue : 4 | Page : 447-449
Effect of benzodiazepines on thyroglobulin, anti-thyroglobulin, anti-thyroid peroxidase, and thyroid stimulating hormone in rat
Mohammad-Hasan Khadem-Ansari1, Ali Ahani2, Peyman Mikaeili3, Yousef Rasmi1
1 Department of Biochemistry, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
2 Department of Veterinary, Islamic Azad University-Urmia Branch, Urmia, Iran
3 Department of Pharmacology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
|Date of Web Publication||25-Jun-2014|
Department of Biochemistry, Faculty of Medicine, Urmia University of Medical Sciences, Urmia
Source of Support: This work was supported by Research Administration in UMSU, Conflict of Interest: None
Background: Benzodiazepines are widely used as psychoactive agents and the side effects of benzodiazepines to the endocrine system are reported. Objective: This study was designed to explore the effects of the benzodiazepines - lorazepam and clonazepam - on thyroglobulin (Tg), anti-thyroglobulin (aTg), anti-thyroid peroxidase (aTPO), and thyroid stimulating hormone (TSH). Materials and Methods: Eighteen male Wistar rats were randomly divided into three groups: control (C), lorazepam-treated, and clonazepam-treated groups. The changes in Tg, aTg, aTPO, and TSH in these three groups were compared after 4 weeks. Results: The levels of Tg and aTg in the lorazepam-treated and clonazepam-treated rats significantly increased compared to the control group. But there was no significant difference in the levels of TSH and aTPO between lorazepam-treated and clonazepam-treated rats in comparison with the control group rats. Conclusion: The thyroid gland is affected by lorazepam and clonazepam, which are used in epilepsy, bruxism, anxiety, insomnia, and other psychic disorders.
Keywords: Benzodiazepines, clonazepam, lorazepam, thyroid
|How to cite this article:|
Khadem-Ansari MH, Ahani A, Mikaeili P, Rasmi Y. Effect of benzodiazepines on thyroglobulin, anti-thyroglobulin, anti-thyroid peroxidase, and thyroid stimulating hormone in rat. Med J DY Patil Univ 2014;7:447-9
|How to cite this URL:|
Khadem-Ansari MH, Ahani A, Mikaeili P, Rasmi Y. Effect of benzodiazepines on thyroglobulin, anti-thyroglobulin, anti-thyroid peroxidase, and thyroid stimulating hormone in rat. Med J DY Patil Univ [serial online] 2014 [cited 2020 Feb 26];7:447-9. Available from: http://www.mjdrdypu.org/text.asp?2014/7/4/447/135259
| Introduction|| |
Benzodiazepines are psychoactive drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. The first benzodiazepine, chlordiazepoxide (Librium), was discovered in 1955 and made available in 1960, which has also marketed diazepam (Valium) by Hoffmann-La Roche company since 1963.  Benzodiazepines enhance the effect of the neurotransmitter gamma-aminobutyric acid, which results in sedative, hypnotic (sleep-inducing), anxiolytic (anti-anxiety), anticonvulsant, muscle relaxant, and amnesic activities.  Benzodiazepines are categorized as either short-, intermediate-, or long-acting drugs. Lorazepam is a high-potency short-to-intermediate acting 3-hydroxy benzodiazepine drug that has all intrinsic benzodiazepine effects. Lorazepam is used for the short-term treatment of anxiety, insomnia, acute seizures including status epilepticus, and sedation of hospitalized patients, as well as sedation of aggressive patients.  Clonazepam is another benzodiazepine derivative having anticonvulsant, muscle relaxant, and very potent anxiolytic properties.  Clonazepam has a fast onset of action, high effectiveness rate, and low toxicity in overdose, but has drawbacks due to adverse reactions including paradoxical effects, drowsiness, and cognitive impairment. Clonazepam is classified as a high-potency benzodiazepine and is sometimes used as a second-line treatment of epilepsy.  As mentioned above, benzodiazepines are widely used as psychoactive drugs and in other conditions and the side effects of benzodiazepines to the endocrine system are being reported. , Effects on the thyroid-related hormone balances are most important in this regard.
Thyroglobulin (Tg) protein is necessary for the synthesis of thyroid hormones. These proteins are inclusively produced by follicular cells of the thyroid and also by malignant thyroid cells.  The high concentrations of Tg in serum may be secondary to the abnormal increase in thyroid mass and increase in thyroid stimulating hormone (TSH). TSH is the most important controlling hormone of the thyroid gland. The effects of TSH on thyroid gland occur after conjunction of this hormone as a ligand to its specific receptor sites.  Several types of antigens have been identified against the thyroid gland, e.g. antibodies against Tg and thyroid peroxidase.  To our knowledge, there are not sufficient reports about the effects of benzodiazepines on thyroid status in the literature. We aimed to understand the effects of clonazepam and lorazepam on Tg, anti-thyroglobulin (aTg), anti-thyroid peroxidase (aTPO), and TSH.
| Materials and Methods|| |
Eighteen male Wistar rats (weighing 360 ± 20 g) were acclimatized for 14 days before starting the studies as the accommodation period and for removal of negative effects of environmental stress and also throughout the tests in an air-conditioned room with 12-h light:dark cycle at 21-24°C and 45-55% humidity. They were fed on standard laboratory chow and tap water ad libitum. The drugs were water insoluble, and we were obliged to dissolve a dosage of 0.5 mg in 0.25 ml of 99.98% ethanol. Then, we diluted the solution tenfold with deionized water for minimizing the toxic effects of the solvent. The animals were divided into three groups (n = 6 rats in each group). The rats of the control group received daily 2.5 ml of deionized water with 0.25 ml of 99.98% ethanol. The drugs were administered through gastric gavages via oral cavity every morning for 28 days. Throughout the study, the animals were in healthy condition. Twenty-four hours after the end of this period, the animals were anesthetized with chlorate hydrate 5 ml/kg body weight and the blood samples were collected directly from the heart by heparinized syringes. All the samples were centrifuged and the plasma samples were separated and stored at −20°C until analysis. During analysis, all samples were defreezed, and in order to prevent fibrin clotting, they were again centrifuged and the supernatants decanted. The samples were then prepared for performing the Tg, aTg, aTPO, and TSH assays by using appropriate kits (DiaSorin S.P.A., Saluggia, Italy) with Liaison automated chemiluminescence (Liaison, Spain). Data were analyzed in SPSS package, version 17 by using analysis of variance (ANOVA) test for comparison of the means among the groups. P values less than 0.05 were considered as statistically significant. All procedures on animals were followed according to the Principles of Laboratory Animal Care (NIH publication no. 85-23, revised 1985), as well as specific rules of Medical Ethics Committee of the Urmia University of Medical Sciences.
| Results|| |
The measured values for the rats of groups treated with lorazepam and clonazepam and also of the control group are shown as mean ± standard deviation in [Table 1].
|Table 1: Values of the thyroid related variables in lorazepam-treated, clonazepam-treated, and control group rats (n = 6)|
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The mean of Tg values in lorazepam-treated (0.41 ± 0.04 ng/ml) and clonazepam-treated (0.41 ± 0.08 ng/ml) groups showed significant differences in comparison with the control group (0.28 ± 0.07 ng/ml) (P = 0.006 and P = 0.010, respectively). Also, the mean of aTg values in lorazepam-treated (4.64 ± 0.77 IU/ml) and clonazepam-treated (8.23 ± 2.78 IU/ml) groups showed significant differences in comparison with the control group (0.65 ± 0.21 IU/ml) (P = 0.001 and P = 0.0001, respectively). But the mean levels of aTPO and TSH in rats treated with lorazepam and clonazepam showed no significant differences in comparison with the control group (P > 0.05).
| Discussion|| |
The thyroid gland is affected by pharmacological agents such as benzodiazepines. In previous studies, the effects of diazepam on thyroid parameters have been studied. ,
Our results on Tg protein showed significant increase in the drug-treated groups in comparison to the control group. The main cause of this is not clear. Probably, these drugs cause this increase by inducing overexpression of protein. Tg is stored in the luminal side of the thyroid follicles and provides a matrix for producing and storing the thyroid hormones. 
On the other hand, studies on the serum of patients with thyroid diseases led to the discovery of seral factors, which were indeed the antibodies attached to the Tg, released from the thyroid gland.  Autoantibodies against Tg protein have been continually found in autoimmune diseases of thyroid such as Hashimoto's and Graves' diseases.  Thyroid peroxidase plays an important role in the production of thyroid hormones. Changes in the structure of this enzyme cause dysfunction of the thyroid gland.  On the other hand, the role of aTPO is not clear in the pathogenesis of thyroid diseases, although evidently its intervention elicits the cell-mediated immune reactions against follicular cells of the thyroid. 
Measuring the seral values of aTg and aTPO has been used as a method for diagnosing autoimmune diseases of the thyroid gland.  Generally, 1.4% of the healthy population, 40-60% of patients with Hashimoto's disease, and 35-49% of patients with Graves' disease have Tg and TPO antibodies.  The produced antibodies against Tg and TPO act as determinants of autoimmune diseases of the thyroid. Measuring these antibodies contributes to diagnosing dysfunctions of the thyroid. According to our results, the differences of aTPO concentrations between control and treatment groups were insignificant. But the differences of aTg factor concentrations between control and treatment groups (of lorazepam and clonazepam) were significant. The main cause of this is unclear, but it may be due to the increase in Tg concentration on administration of benzodiazepines, which acts as an activating agent of immune system, or the stimulation of immune system against the thyroid gland.
Subclinical hypothyroidism has been defined biochemically as elevation of TSH levels and normal thyroid hormone concentrations.  Patients with subclinical hypothyroidism present higher scores on scales of anxiety or depression.  In addition, long-term antiepileptic treatment with carbamazepine, valproate, and phenobarbital in children with epilepsy may cause subclinical hypothyroidism. , Benzodiazepines inhibit TSH;  however, in our study, the differences of TSH concentrations between the control and treatment groups were insignificant. The main cause of this is not clear.
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