Effects of hypophysectomy and growth hormone administration on the mRNA levels of collagen I, III and insulin-like growth factor-I in rat skeletal muscle.

The effect of short-term treatment of normal or hypophysectomized rats with biosynthetic growth hormone (GH) was studied in extensor digitorum longus and soleus muscles. In situ hybridization revealed that in normal rats, mRNA for collagen I, collagen III and insulin-like growth factor-I (IGF-I) are expressed by fibroblasts between the muscle fibre areas and that the specificity of this location was not altered by GH administration. Hypophysectomy appeared to cause a decrease in IGF-I and decreased collagen I and III gene expression (P < 0.

Growth hormone increases IGF-I, collagen I and collagen III gene expression in dwarf rat skeletal muscle.

The effect of short-term treatment with biosynthetic growth hormone (GH) of male dwarf rats was studied in EDL and soleus muscles. In situ hybridisation revealed that in the untreated dwarf rat collagen I, collagen III and insulin-like growth factor-I (IGF-I) mRNA is mainly expressed by fibroblasts between the muscle fibre areas. Quantitative image analysis showed that, 8 h after a single GH injection, the level of mRNA for all three genes increased compared to the untreated dwarf animal.

Characterization of site-directed antibodies to the LH receptor in functionally active gonadal cells and their differential effects on LH-stimulated signal transduction in Leydig tumour (MA10) cells.

In this study site-directed antibodies have been used to investigate the structure/activity relationships of the LH receptor in functionally active gonadal cells. Polyclonal antibodies were raised in rabbits against synthetic peptides corresponding to regions within both the extracellular N-terminal domain (antibodies 1 and 2 against residues 48-65 and 187-206, respectively) and the cytoplasmic C-terminal domain (antibody 3 against residues 622-636) of the LH receptor. Following affinity purification by chromatography on columns of immobilised peptides the antibodies were demonstrated to be peptide specific both by ELISA and by dot-blotting assays.

The First International Standard for Somatropin: report of an international collaborative study.

Following an earlier decision to move away from the in vivo bioassay for determination of the potency of therapeutic somatropin (recombinant DNA human growth hormone), 18 laboratories in 12 countries participated in an international collaborative study designed to establish an international standard for somatropin, calibrated both by bioassay and by physicochemical assays of somatropin content. The mean in vivo biological potency of preparation studied, coded 88/624, was 6.75 IU/ampoule (fiducial limits 6.

Interactions between growth hormone and nutrition in hypophysectomized rats: body composition and production of insulin-like growth factor-I.

Hypophysectomy of adult rats results in a loss of body growth which can be reversed by treatment with GH. The increased growth caused by administration of GH is accompanied by an increase in food consumption. The effects of GH and interactions with nutrition were investigated by treating hypophysectomized rats with GH and either providing unrestricted food or preventing the increased food consumption by pair-feeding with the same intake as that of the hypophysectomized animals.