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.
View Article and Find Full Text PDFThe 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.
View Article and Find Full Text PDFIn 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.
View Article and Find Full Text PDFFollowing 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.
View Article and Find Full Text PDFHypophysectomy 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.
View Article and Find Full Text PDFInhibition of glucose-induced insulin secretion by interleukin-1 beta (IL-1 beta), or IL-1 beta plus tumour necrosis factor-alpha (TNF-alpha), was less marked when rat islets of Langerhans were cultured for 12 h with these cytokines in L-arginine-free medium as opposed to medium containing L-arginine (1 mM). Inhibition of secretion by IL-1 beta was further alleviated when islets were maintained in L-arginine-free medium supplemented with N-omega-nitro-L-arginine methyl ester (NAME), while synergism between IL-1 beta plus TNF-alpha was completely abolished. Tissue culture medium nitrite levels were raised in islets treated with IL-1 beta or TNF-alpha (48 h).
View Article and Find Full Text PDFGlucose-induced insulin secretion from islets cultured in the presence of interleukin-6 (IL-6) for 12-24 h was inhibited to a similar extent as when islets were treated with interleukin-1 beta (IL-1 beta). However, unlike IL-1 beta, IL-6 did not potentiate insulin secretion during an acute (30 min) exposure of islets to the cytokine, nor did it inhibit DNA synthesis during a 24 h culture period. A 12 h pretreatment of islets with tumour necrosis factor-alpha (TNF-alpha) combined with IL-1 beta potentiated the inhibitory effect of IL-1 beta on secretion, such that 20 mM-glucose-induced insulin secretion was abolished.
View Article and Find Full Text PDFChanges in the soluble inositol-containing metabolites of phosphoinositides have been measured in rat adrenal fasciculata reticularis cells stimulated by ACTH1-39 and ACTH5-24 (an analogue which is able to elicit maximal steroidogenesis in the absence of any discernible increase in cyclic AMP output). Small but significant increases in the total inositol-containing metabolites were found in response to stimulation with both ACTH analogues. For ACTH5-24 this effect on phosphoinositide (PI) metabolism occurred over the same dose range as that for the stimulation of steroidogenesis (with an ED50 of 10(-8) M ACTH5-24 for both effects).
View Article and Find Full Text PDFThe studies describe alterations after hypophysectomy in the proportion of the type-1 and type-2 fibres in rat skeletal muscles, and the effects of replacement treatment with pituitary human (h) GH. Cytochemical analysis of myosin ATPase, succinate dehydrogenase and lactate dehydrogenase activities in sections of rat hind limb muscles were used as markers of fibre type and revealed that hypophysectomy reduced the proportion of type-1 fibres by 50% in soleus and in extensor digitorum longus muscles. This reduction in the proportion of type-1 fibres was accompanied by the appearance of transitional fibres (type 2C/1B).
View Article and Find Full Text PDFThree ampouled preparations of purified human prolactin were assessed by 20 laboratories in eight countries for their suitability to serve as International Standards for the estimation of human prolactin in serum. Bioassays (pigeon crop sac assays and NB2 cell assays) were carried out in two laboratories, radioreceptor assays by one laboratory and radioimmunoassays by 17 laboratories. By physicochemical analysis the preparations appeared similar.
View Article and Find Full Text PDFJ Reprod Fertil Suppl
December 1989
Isolated rat adrenal glomerulosa cells were prelabelled with [3H]inositol and stimulated with 25 nM-angiotensin II in the presence of Li+. The resulting inositol monophosphates were separated using h.p.
View Article and Find Full Text PDFLuteinizing-hormone (LH)-stimulated cyclic AMP production in rat testis Leydig cells was desensitized by both LH and 12-O-tetradecanoylphorbol 13-acetate (TPA). However, TPA, but not LH, enhanced the subsequent response to cholera toxin. Treatment of the cells with pertussis toxin potentiated cyclic AMP production in both control and LH-desensitized cells, but did not potentiate further the responses obtained by TPA pretreatment.
View Article and Find Full Text PDF[3H]Inositol-prelabelled isolated rat adrenal glomerulosa cells were stimulated with 25 nM-AII ([Asp1, Ile5]-angiotensin II) in the presence of 10 mM-Li+, and the resulting inositol monophosphate isomers were separated successfully by using a recently developed h.p.l.
View Article and Find Full Text PDFWe have studied the clearance from plasma of immunoreactive growth hormone releasing hormone 1-40 (IR-GHRH) following intravenous (i.v.) and subcutaneous (s.
View Article and Find Full Text PDFA homologous radioimmunoassay (RIA) system for human growth hormone-releasing factor 1-29NH2 (hGRF 1-29-NH2) was developed and applied to the measurement of immunoreactive (IR) concentrations of the peptide in anaesthetized rats to determine some of its pharmaco-kinetics after i.v. and s.
View Article and Find Full Text PDFTwo preparations of human growth hormone (hGH) were prepared as candidates for the International Standard for Human Growth Hormone for Bioassay and were studied by 22 laboratories in 10 countries in an international collaborative study. The 2 candidate preparations, freeze-dried in ampoules coded 80/505 and 80/521, were assayed against the International Standard for Growth Hormone, bovine, for Bioassay (ISbGH), by in vivo assays; against the International Reference Preparation of Growth Hormone, human, for Immunoassay (IRP hGH), by receptor-, immunoassays and other in vitro methods; and against each other by various methods. Both preparations contained the 2 recognized main growth hormone components (22 kDa and 20 kDa forms) and other components, but that in ampoules coded 80/505 had less deamidated hGH and contaminant hormones and pyrogen than that in ampoules coded 80/521.
View Article and Find Full Text PDFA homologous radioimmunoassay (RIA) system was developed for human GRF 1-40 and used to measure immunoreactive (IR) concentrations of the peptide in rats to determine some of its pharmacokinetic characteristics after intravenous (i.v.) and subcutaneous (s.
View Article and Find Full Text PDFThe characteristics of the sensitization and desensitization of superfused, rat dissociated adrenal fasciculata cells were examined. The dynamic output of steroids and cyclic AMP was determined following pulsed treatment with various agonists. Repeated doses of identical small amounts of ACTH or ACTH gave gradually increasing responses which were maximal after 3-4 injections, but then desensitized the adrenal cells.
View Article and Find Full Text PDFJ Recept Res
April 1985
Isolated adrenal fasciculata cells were purified by centrifugation through a 0-50% hyperbolic gradient of PercollR. The dose-dependence and kinetics of both intracellular cyclic AMP accumulation and steroidogenesis in response to ACTH1-39 and ACTH5-24 (corticotropin-(1-39) and corticotropin-(5-24)-peptides) were determined using purified cells. The rate of intracellular cyclic AMP formation was maximal during the first five minutes after hormone addition and remained constant or fell thereafter.
View Article and Find Full Text PDFSeveral studies have revealed a variety of interactions between PTH and ACTH. The existence of a significant area of homology in the bioactive regions of the two molecules has been proposed as a possible reason for such interactions. To clarify the relationship, corticosteroidogenic and cAMP accumulative effects of bovine PTH (bPTH 1-84), its amino-terminal fragment (bPTH 1-34), and the amino terminal fragment of human PTH (hPTH 1-34) were compared with ACTH 1-39 by determining their dose-response characteristics in collagenase-dissociated adrenocortical cells from rats.
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