الفهرس | Only 14 pages are availabe for public view |
Abstract Hashimoto thyroiditis is the most common endocrine disorder after diabetes mellitus. It is characterized by the accumulation of antibodies against thyroid tissues. It affects females more than males at a mild age. The pathogenesis of the disease is not completely understood. Two types of antibodies are produced, TPO-Ab and Tg-Ab. Synthesis and secretion of thyroid hormones (T3 & T4) decreased, while serum levels of TSH increased to stimulate the secretion of thyroid hormones. The circadian system is composed of many genes and proteins which control several physiological and metabolic processes. It acts like an orchestra, regulated by two limbs, a stimulatory and an inhibitory. The two limbs form a feedback loop. Clock systems are regulated by the transcription and translation of circadian genes. Bmal-1 gene is an element of the stimulatory limb, upregulates transcription of genes of the inhibitory limb and other circadian controlled-genes. The proteins of the inhibitory limb, in turn, downregulates the Bmal-1 gene. Melatonin is a circadian hormone secreted by the pineal gland mainly at night. Melatonin rhythm is regulated by BMAL-1 protein and can affect thyroid cells. The present study aimed at the evaluation of circadian clock gene Bmal-1 expression in peripheral blood leukocytes and blood melatonin level of Egyptian patients with Hashimoto’s thyroiditis. The study was conducted on 60 Egyptian female volunteers and they were divided into two groups: Hashimoto thyroiditis patients and normal control individuals. group I (control group) consists of 30 normal Egyptian healthy females not receiving any type of treatment. group II (Hashimoto thyroiditis patients) consists of 30 Egyptian females with Hashimoto thyroiditis not receiving any type of treatment. Blood samples were collected from all volunteers for the determination of different parameters including TSH, FT3, FT4, TPO-Ab, Tg-Ab, ionized calcium, and Hemoglobin. Gene expression of Bmal-1, NF-κB, and TLR-4 genes was determined using the RT-PCR method. Melatonin concentration in serum was also determined using ELISA kits. The current study results revealed increased serum TSH, TPO-Ab, and Tg-Ab in the Hashimoto thyroiditis group in comparison to the control group. On the other hand, the current study also showed decreased serum concentration of FT3, FT4, ionized calcium, blood hemoglobin in the diseased group when compared to the control group. The current study results revealed that the gene expression of the Bmal-1 gene in peripheral blood leucocytes was downregulated in the Hashimoto thyroiditis group in comparison to the control group. On the contrary, the levels of gene expression of NF-κB and TLR-4 genes in peripheral blood leucocytes were upregulated in Hashimoto thyroiditis in comparison to the control group. Finally, serum melatonin concentration decreased in the diseased group when compared to the control one. |