The stimulating effect of tissue extracts on hypothalamo-pituitary-thyroid axis in rats

Abstract

The thyroid stimulating effect of tissue extracts was studied in rats. The serum levels of T₄, T₃ and cAMP content of thyroid increased significantly at 2–4th hour and then returned to the initial values at 6th hour after injection of spleen extract. After injection of placenta extract, the same levels increased markedly as well. Their stimulating effects on the thyroid system were probably independent of the response of the adrenal system. Administration of morphine prior to injection of tissue extracts blocked their stimulating effects on serum levels of T₄, T₃ and the cAMP content of thyroid.

The above results demonstrate that tissue extracts of spleen and placenta are capable of stimulating hypothalamo-pituitary-thyroid axis possibly via hypothalamus.

Keywords

tissue extract / hypothalamo-pituitary-thyroid axis / morphine

References

[1] JacksonIMD, et al. . Brain thyrotrophin-releasing hormone is independent of the hypothalamus. Nature, 1977, 267853-853

[2] JacksonIMD, et al. . Thyrotrophin releasing hormone (TRH) in pineal and hypothalamus of the frog: effect of season and illumination. Endocrinology, 1977, 10097-100

[3] MorleyJE, et al. . Thyrotrophin-releasing hormone in the gastrointestinal tract. Biochem Biophys Res Commun, 1977, 79314-314

[4] BaramT, et al. . Gonadotropin releasing hormone in milk. Science, 1977, 198300-300

[5] JacksonIMM, et al. . Thyrotrophin-releasing hormone: Abundance in the skin of the frog, rana piniens. Science, 1977, 198414-414

[6] SchaefferJM, et al. . Thyrotrophin-releasing hormone-like materials in the rat retina: Changes due to environmental lighting. Proc Natl Acad Sci, 1977, 743579-3579

[7] YoungbloodWW. Thyrotrophin-releasing hormone-like bioactivity in placenta: Evidence for the existence of substances other than Pyroglu-His-Pro-NH₂ (TRH) capable of stimulating pituitary thyrotrophin release. Endocrinology, 1980, 106541-541

[8] 1956; 20(4)

[9] GilmanAG. A protein binding assay for adenosine 3-5′-cyclic monophosphate. Proc Natl Acad Sci (USA), 1970, 67305-305

[10] GibbonsJM, et al. . In vitro biosynthesis of TSH-and LH-releasing factors by the human placenta. Am J Obstet Gyneco, 1975, 121127-127

[11] ShambaughG, et al. . TRH activity in the human placenta. J Clin Endocrinol Metab, 1979, 48483-483

[12] BruniJE, et al. . Effects of naloxone, morphine and methionine enkephalin on serum prolatin, luteinizing hormone, follicle stimulating hormone and growth hormone. Life Sci, 1977, 21461-461

[13] Van VugtDA, et al. . Influence of endogenous opiates on anteriorpituitary function. Federation Proc, 1980, 392533-2533

[14] BuckinghamJC. Secretion of corticotrophin and its hypothalamic releasing factor in response to morphine and opioid peptides. Neuroendocrinology, 1982, 35111-111