Experimental Study of the Effects of the Hypothalamic-Pituitary-Thyroid Axis on Platelet Functional Activity

Abstract

The hormones of the hypothalamic-pituitary-thyroid axis exert various effects in organism, but their influence on the functional activity of platelets is relatively unknown. To establish the effect of the hormones of the hypothalamic-pituitary-thyroid axis on the functional activity of platelets by means of determining the plasma level of beta-thromboglobulin (β-TG) and platelet factor 4 (PF4) a study was conducted on 40 white male rats of the “Wistar” breed. The necessary blood volume was obtained under ether narcosis by cardiac puncture in CTAD-test-tubes. Using Diagnostica Stago (France) tests, by means of enzyme-immune test, the level of two of the most informative platelet secretion markers was determined. The hormones: Thyreotropin releasing hormone (0.06 mg/kg bw), Thyroid stimulating hormone (1 MU/kg bw), Trijodthyroninum (0.08 mg/kg bw), Thyroxin (0.08 mg/kg bw), applied s.c. on three consecutive days strongly reduce the plasma level of β-TG (p<0.001) and PF 4 (p < 0.001). The reduced level of β-TG and PF 4 in the plasma is an indicator of their reduced functional activity, which is one of the determinants for the development of hemocoagulation. The functional activity of platelets in rats, determined by the level of β-TG and PF 4, is significantly suppressed by all hormones of the hypothalamic-pituitary-thyroid axis.

Thyroid hormonal axis regulates protein C anticoagulation pathway in rats

“…Overall this may suggest a general tendency of hypocoagulability which is supported by similar findings in our previous studies on the same hormones and other hemocoagulation parameters in rats [16,24].…”

“…The first group of rats were injected by thyrotropin releasing hormone (TRH), acetate salt (Sigma, minimum activity 97%), in a dose of 0.06 mg/kg body mass; the second group -by bovine thyroidstimulating hormone (TSH, activity of 2 IU/mg, Sigma), in a dose of 1 IU/kg, the third and the forth groupsrespectively by Liothyroninum (T3) and Levothyroxinum (T4) provided by VEB Berlin -Chemie, Germany -0.08 mg/kg. The doses used were determined on the basis of published literature and through preliminary analysis of logarithmic dose-effect dependence, as previously described [16]. The fifth (control) group were injected with the same schema and volume per kg.…”

Impact of Porcine Orexin a on Glucagon Plasma Concentrations in Pigs

“…in rats and compared with a strong stimulant of food, neuropeptide Y (NPY) and two weaker stimulants: a) (MCH) melanin-concentrating hormone and b) galanin (24). In addition, other studies examined the intravenous (IV) injection of Orexin A and its effect on blood glucagon in rats (25)(26)(27)(28). Besides, other authors examined the effect of Orexin A on isolated pancreatic islets of rats (29).…”

Autoimmunity and Parasites

“…Helminth infections through induction of regulatory mechanisms, such as IL-lO production, are able to modulate the inflammatory immune response involved in the pathology of autoimmune and allergic disease (28)(29). Schistosoma mansoni antigens can induce the secretion of regulatory cytokines from DC, M<I>, and NKT cells as well as BIB cells, resulting in the expansion of Th2 and Treg populations that might be responsible for maintammg self-tolerance.…”