بررسی اثر اختلالات غده تیروئید بر روی عملکرد سیستم عصبی: اندازه گیری برخی ازهورمون¬ها و پروتئین¬های سیستم عصبی، پروفایل لیپیدی و عناصر خونی

چکیده:

Abstract ‌ ‌

Thyroid hormones play an essential role in metabolism regulation and circadian rhythm control. Recent studies approved their role in normal development and healthy central nervous system (CNS) function. The thyroid gland is a component of the hypothalamic-pituitary-thyroid axis disrupted during thyrotoxicosis and hypothyroidism, two main clinical conditions that induce more liability against dementia-related disease. Therefore, the aim of this research was to investigate the effect of thyroid gland deficits on some neurohormones and neuroproteins, lipid profile and blood elements. Studies were conducted in 3 experimental groups (healthy, hyperthyroid, hypothyroid) and results compared by using Tukey's statistical method. Cholesterol and LDL have a positive correlation with thyroid disorders, because there is a significant difference in the average distribution of these two factors between the control group and the thyroid-deficit patients (P<0.05). While the amount of HDL decreased in two groups with thyroid disorders compared to the control group (P<0.05). The mean difference of TG distribution in all three groups was significantly different from each other (P<0.05). In the first step, this study evaluated the circular level of neuropeptide Y (NPY), leptin, oxytocin, and vasopressin in hyperthyroidism and hypothyroidism patients. In the second step, we investigated neurological and cognitive abnormalities by assessment of the hallmark proteins and peptides such as amyloid β (Aβ) variants, glycogen synthase kinase 3β (GSK-3β), and tau protein in thyroid-deficient samples. The results show increased content of leptin hormone in patients with hypothyroidism who also manifested high levels of vasopressin. Underactivation and overactivation of the thyroid gland are accompanied by reduced circular oxytocin. We may conclude that hypothyroidism is associated with neurohormone dysregulation. Interestingly, both patient groups exhibited significant increases in Aβ₄₀ and Aβ₄₂ levels relative to the control group, which was also accompanied by the rise in GSK-3; this might be interpreted as cholinergic system dysfunction and cognitive impairment. The results revealed Tau content increased considerably in thyrotoxicosis but did not change significantly in hypothyroidism compared to the control group. Therefore, our results have shown that thyroid gland dysfunction is a risk factor for cognitive impairment, mainly through neuroendocrine dysregulation. This study provides a relationship between hyperthyroidism/hypothyroidism and biomarkers of neurological abnormalities in blood serum.