Human pituitary FSH increased the incorporation of [5-3H]uridine into RNA in vivo in the testes of intact 9-day-old mice and of hypophysectomized adults. In both groups the effect was greatest 8 h after administration of 5–7·5 i.u. FSH. Autoradiographs were prepared from the testes of hypophysectomized adult mice given subcutaneous injections of FSH or of 0·9% saline 6 h, and [5-3H]uridine 1·5 h, before death. Treatment with FSH caused statistically significant increases in the density of silver grains over the nuclei of Sertoli cells, type A and intermediate spermatogonia, and preleptotene and mid-pachytene primary spermatocytes. It was concluded that FSH has a generalized stimulatory action on RNA synthesis in the nuclei of Sertoli cells and those types of germinal cell which synthesize RNA most actively.
You are looking at 1 - 10 of 10 items for
- Author: N Davies x
- Refine by Access: All content x
A. G. DAVIES and N. R. LAWRENCE
Hypophysectomized adult mice were given injections of highly purified FSH 12 h before killing, and of tritiated lysine or arginine 2 h before killing. Autoradiographs were prepared from paraffin wax sections of testes. Treatment with FSH increased the density of silver grains over the nuclei of the Sertoli cells and of all types of germinal cell except the early spermatids. The stimulatory effect of FSH on incorporation of both lysine and arginine was most marked in the nuclei of preleptotene primary spermatocytes. The ratio of arginine to lysine incorporation was greater in spermatids undergoing nuclear elongation than in other types of cell.
N. Kyprianou, J. C. Gingell, and P. Davies
Androgen receptors in nuclei from human prostate carcinomas were characterized on the basis of their solubilization by, or resistance to, micrococcal nuclease. By this means, androgen receptors were assigned to three nuclear categories: those associated with nuclease-resistant structures, those associated with chromatin and those apparently uncommitted by association with either of these. Prostate carcinoma nuclei contained high concentrations (57–82% of total nuclear content) of nuclease-resistant androgen receptors. This was a different pattern from that observed previously for benign hypertrophic prostate epithelial nuclei which contained a variable high proportion of uncommitted androgen receptors. The differences could not be attributed to differential losses to cytosol, or to loss of functionality, as determined in vitro. The differences in distribution could reflect different responses of diseased cells to androgens, or the intervention of other factors more relevant to the disease process.
J. Endocr. (1987) 112, 161–169
N. AL-NUAIMI, P. DAVIES, and K. GRIFFITHS
The oestrogen receptor from mammary tumours induced in rats by dimethylbenz(a)-anthracene has been extensively purified by affinity chromatography and isoelectric focusing. The unpurified cytoplasmic 8 S oestrogen receptor had a molecular weight of 240 000, a Stokes radius of 5·4 nm and a frictional ratio of 1·32; the K m (dissociation constant) at 4 °C for [3H]oestradiol-17β was 0·184 nmol/l. At the end of affinity chromatography the molecular weight was still 240 000 but under the conditions of isoelectric focusing it was reduced to 110 000, with a Stokes radius of 4·0 nm, a frictional ratio of 1·26 and an isoelectric point of 6·4.
P. DAVIES, P. THOMAS, N. M. BORTHWICK, and M. G. GILES
Rat ventral prostate chromatin was separated into two main fractions by controlled digestion with micrococcal nuclease. The soluble fraction obtained after lysis of digested nuclei with EDTA (1 mmol/l), the S2 fraction, represented approximately 17% of the original nuclear DNA, and showed properties consistent with transcriptional activity, i.e. enrichment in nascent RNA, non-histone protein and endogenous RNA polymerase B activity as well as depletion in histones. The fraction sedimented after lysis of nuclei, fraction P, comprised approximately 60% of nuclear DNA, was depleted in nascent RNA, non-histone proteins and endogenous RNA polymerase B activity, but had a higher content of histones. In an attempt to relate the concentration of acceptor sites for androgen-receptor complexes with transcriptional activity, it was shown that the S2 fraction was enriched in these acceptor sites. However, if measurements were based on the intact cell the transcriptionally inactive portion contained 2·5–3 times as many 'acceptor' sites, although these sites had lower affinity for androgen-receptor complexes than had those in the transcriptionally active fraction.
N. T. DAVIES, K. A. MUNDAY, and B. J. PARSONS
A study was made of the effects of cyclic AMP, theophylline, cycloheximide, puromycin and actinomycin D on the stimulation by angiotensin of fluid transport by sacs of rat colon mucosa.
Cyclic AMP and theophylline, added together or separately, had no effect on fluid transport by colon sacs, suggesting that the stimulation of fluid transport after the application of angiotensin is not mediated through cyclic AMP. Cycloheximide and puromycin (used at concentrations which block colon protein synthesis by 50–90%) had no effect on fluid transport by control colon sacs, but completely blocked the stimulatory response of the colon to angiotensin. In contrast, actinomycin D (at a concentration which significantly inhibits RNA synthesis) did not affect fluid transport in control or angiotensin-stimulated colon sacs. The results are discussed in relation to the possibility that protein synthesis, at the stage of translation, is involved in the action of angiotensin on fluid transport by the colon.
N. T. DAVIES, K. A. MUNDAY, and B. J. PARSONS
Fluid transfer by isolated everted sacs of rat jejunum, ileum and intact colon prepared from adrenalectomized-nephrectomized rats 48 h after operation was reduced when compared with that of sacs prepared from untreated controls (P < 0·001). Angiotensin at 10−10 g/ml significantly (P < 0·01) stimulated fluid transfer by intestinal sacs prepared from the adrenalectomized-nephrectomized rats; all three regions of gut were equally sensitive.
Fluid transfer was similarly reduced in stripped colon sacs prepared from adrenalectomized-nephrectomized rats. Angiotensin had a dose-dependent biphasic action on fluid transfer by stripped colon sacs: low concentrations (10−11 and 10−12 g/ml) stimulated (P < 0·05), whilst high concentrations (10−9 and 10−8 g/ml) inhibited fluid transfer (P < 0·01). Histological examination of the colon preparations showed that the stripping procedure removed the ganglia, indicating that both angiotensin effects were due to direct action on the colon mucosa.
The significance of these results is discussed in relation to the role of angiotensin in the control of salt and fluid transport by the mammalian kidney and other epithelial tissues.
R. L. Kennedy, T. H. Jones, R. Davies, S. K. Justice, and N. R. Lemoine
Interleukin-6 (IL-6) has actions on a variety of endocrine tissues. The cytokine is secreted by cells of the anterior pituitary and endocrine pancreas and has recently been shown to be produced by cultures of thyroid epithelial cells. In this study we have examined some of the factors which regulate IL-6 release from an immortalized human thyroid line (HTori3).
IL-6 release over 24 h was stimulated by TSH (5000 μU/ml), by forskolin (0·01 mmol/l), by fetal calf serum (1–20%) and by epidermal growth factor (20 ng/ml). Stimulation was also apparent with γ-interferon and with tumour necrosis factor at concentrations known to enhance class II major histocompatibility antigen expression by thyroid epithelium. The most potent factor tested was interleukin-1 (IL-1), which controls IL-6 release from other cell types. Threefold stimulation was found with 1 U/ml rising to 350-fold with 1000 U/ml. The effect of IL-1 took 2 h to develop and was blocked by cycloheximide (100 μmol/l). Stimulation was not markedly inhibited by pertussis toxin. Many of the actions of IL-1 are mediated by prostaglandin E2 (PGE2). At concentrations as low as 30 nmol/l, PGE2 stimulated IL-6 release but the maximum stimulation obtained with PGE2 was only threefold. The effect of IL-1 was not inhibited by indomethacin.
These data provide further evidence that IL-6 is produced by human thyrocytes. The effect of IL-1 has not been demonstrated previously. Stimulation of IL-6 release by IL-1 did not appear to be mediated by prostaglandin. IL-6 may influence hormone release from the thyroid as it does in other tissues. High concentrations of IL-6 in the thyroid may increase infiltration by, and activation of, lymphocytes in patients with autoimmune thyroid disease.
Journal of Endocrinology (1992) 133, 477–482
LE Pritchard, D Armstrong, N Davies, RL Oliver, CA Schmitz, JC Brennand, GF Wilkinson, and A White
Interactions between pro-opiomelanocortin (POMC)-derived peptides, agouti-related protein (AGRP) and the melanocortin-4 receptor (MC4-R) are central to energy homeostasis. In this study we have undertaken comprehensive pharmacological analysis of these interactions using a CHOK1 cell line stably transfected with human MC4-R. Our main objectives were (1) to compare the relative affinities and potencies of POMC-derived peptides endogenously secreted within the hypothalamus, (2) to investigate the potency of AGRP(83-132) antagonism with respect to each POMC-derived peptide and (3) to determine whether AGRP(83-132) and POMC-derived peptides act allosterically or orthosterically. We have found that beta melanocyte-stimulating hormone (betaMSH), desacetyl alpha MSH (da-alphaMSH) and adrenocorticotrophic hormone all have very similar affinities and potencies at the MC4-R compared with the presumed natural ligand, alphaMSH. Moreover, even MSH precursors, such as beta lipotrophic hormone, showed significant binding and functional activity. Therefore, many POMC-derived peptides could have important roles in appetite regulation and it seems unlikely that alphaMSH is the sole physiological ligand. We have shown that AGRP(83-132) acts as a competitive antagonist. There was no significant difference in the potency of inhibition by AGRP(83-132) or agouti(87-132) at the MC4-R, regardless of which POMC peptide was used as an agonist. Furthermore, we have found that AGRP(83-132) has no effect on the dissociation kinetics of radiolabelled Nle4,D-Phe7 MSH from the MC4-R, indicating an absence of allosteric effects. This provides strong pharmacological evidence that AGRP(83-132) acts orthosterically at the MC4-R to inhibit Gs-coupled accumulation of intracellular cAMP.
A. Blacklay, A. Grossman, R. J. M. Ross, M. O. Savage, P. S. W. Davies, P. N. Plowman, D. H. Coy, and G. M. Besser
A synthetic 29-amino acid analogue of human pancreatic GH-releasing hormone (GHRH(1–29)NH2) has recently been shown to stimulate the release of GH in normal subjects. We have studied the GH response to GHRH(1–29)NH2 in nine children irradiated for brain and nasopharyngeal tumours, who were not growing and were deficient in GH as assessed by insulin-induced hypoglycaemia. Serum GH rose in response to GHRH(1–29)NH2 in all the children, and in five the peak serum GH response was > 20 mu./l. The data suggest that when hypothalamo-pituitary irradiation results in GH deficiency, this is due to a failure of the synthesis or delivery of endogenous GH RH from the hypothalamus to the pituitary cells. It also suggests that it may be possible to treat such children using synthetic GHRH in place of exogenous GH.
J. Endocr. (1986) 108, 25–29