Specific uptake of human growth hormone by the liver of severely hypothyroid rats
- 4 Downloads
Severe thyroid hormone deficiency results in marked impairment of body growth. This is due, at least in part, to impaired growth hormone (GH) synthesis. We have studied the possible effects of severe thyroid hormone deficiency on liver receptors for GH and for prolactin (PRL) by an in vivo technique. Female thyroidectomized (T̅) rats and age-paired controls (C) were injected iv with tracer amounts of biologically active monoiodinated hGH, alone or together with 200 μg/100 g bw of native hGH, bGH or oPRL. The liver uptake of labelled compounds, and the liver to serum radioactivity ratio was measured 20 min later. The liver to serum radioactivity ratio of C rats was decreased both by native bGH (purely somatogenic) and native oPRL (purely lactogenic). That of the T̅ rats could only decrease with bGH, Such results confirm data obtained in vitro indicating that in the severely hypothyroid rat liver there is a marked decrease in lactogenic binding and strongly suggest that specific binding of growth hormone by the liver is not similarly affected.
Key wordsHypothyroidism lactogenic binding somatogenic binding liver rat
Unable to display preview. Download preview PDF.
- 2.Greenberg H.A., Najjar S., Blizzard R.M. Effects of thyroid hormones on growth, development and differentiation. In: Greep R.O., Geiger S.R. (Eds.), Handbook of physiology, Section 7, vol. III. American Physiological Society, Washington D.C., 1974, p. 377.Google Scholar
- 3.Daughaday W.H. Hormonal regulation of growth by somatomedin and other tissue growth factors. In: Besser G.M. (Ed.), Clinics in endocrinology and metabolism. W.B. Saunders, London, 1977, p. 177.Google Scholar
- 8.Durán-Garciá S., Padrón F., Gómez Nieto J., Obregón M., Morreale de Escobar G., Escobar del Rey F. Effects of hypothyroidism and thyroid hormone replacement on the rat liver prolactin binding sites. Endocrinologia 27: 143, 1980.Google Scholar
- 13.Snedecor G.W. Statistical methods. Iowa State University Press, Iowa, 1956.Google Scholar
- 14.Forsyth I.A. The lactogenic activity of human growth hormone in vivo. In: Pecile A., Müller E.E. (Eds.), Growth hormone. Excerpta Medica Foundation, Amsterdam, 1968, p. 364.Google Scholar
- 16.Li C.H. Recent knowledge of the chemistry of lactogenic hormones. In: Wolstenholme G.E.W., Knight J. (Eds.), Lactogenic hormones. Churchill Livingstone, London, 1972, p. 7.Google Scholar
- 19.Phillips L.S., Herrington A.G., Tweller M.C., Daughaday W.H. Growth hormone and insulin stimulation of release of somatomedin by perfused rat liver. 57th Annual Meeting of the Endocrine Society, 1975, Abstract n.132.Google Scholar