Regulation of a thyroid hormone-dependent protein by growth hormone: the induction of hepatic alpha 2U globulin and its messenger ribonucleic acid in adult male hypothyroid rats

Developmental and hormonal regulation of alpha 2u-globulin gene transcription

Hepatic alpha 2u-globulin protein and RNA levels are under developmental and complex multihormonal control. The present studies directly evaluate the degree to which this regulation is transcriptional. alpha 2u-Globulin transcription was determined by measuring nuclear runoff RNA in vitro, and tissue alpha 2u-globulin mRNA levels were measured by dot blot hybridization. These studies reveal that (i) in male rats the transcriptional rate of the alpha 2u-globulin genes increases during postnatal development; (ii) no alpha 2u-globulin transcription is detectable in hepatic nuclei derived from hypophysectomized rats; (iii) growth hormone and glucocorticoid are both absolutely required, and glucocorticoid can replace androgen for alpha 2u-globulin gene transcription in the livers of hypophysectomized male rats; and (iv) chronic treatment of mature male rats with estrogen results in a progressive decrease in the hepatic transcription of alpha 2u-globulin genes. In all instances changes in the transcriptional rate of alpha 2u-globulin genes paralleled the tissue level of alpha 2u-globulin RNA. Thus transcriptional control predominates in regulating hepatic alpha 2u-globulin RNA levels.

The mode of growth hormone administration is of major importance for the excretion of the major male rat urinary proteins

Male and female urinary proteins were analysed using chromatofocusing. Male rat urine had a higher protein content (measured as UV absorbance), particularly in the pI range 5.0-5.5, where female rat urine seemed to lack UV-absorbing material. The molecular weight of the major male rat urinary protein(s) is approximately 16 000 according to sodium dodecylsulphate (SDS)-polyacrylamide gel electrophoresis. The regulation of the major male rat urinary protein(s) (pI 5.3; MRUP) was studied in normal male rats and hypophysectomized rats treated for 1 week with various hormones. Urine was collected during the last day of hormone treatment and analysed by chromatofocusing and SDS-polyacrylamide gel electrophoresis. It was found that estrogen treatment of male rats suppressed the appearance of MRUP. This 'feminizing' effect was also observed following continuous infusion for 1 week of human growth hormone (hGH) or rat growth hormone (rGH) in male rats. Single injections of hGH, however, given once daily for 1 week and supplemented with glucocorticoid, thyroid hormone and androgen had an opposite effect and induced MRUP in hypophysectomized male rats. It is concluded that the mode of administration of GH is of great importance for the effects of the hormone and that continuous, as compared to intermittent, administration of GH may result in suppression or induction, respectively, of major male rat urinary protein(s).