Search Results

You are looking at 1 - 5 of 5 items for

  • Author: B M Chapman x
  • Refine by access: All content x
Clear All Modify Search
G. P. B. Kraan
Search for other papers by G. P. B. Kraan in
Google Scholar
PubMed
Close
,
T. E. Chapman
Search for other papers by T. E. Chapman in
Google Scholar
PubMed
Close
,
N. M. Drayer
Search for other papers by N. M. Drayer in
Google Scholar
PubMed
Close
,
B. Colenbrander
Search for other papers by B. Colenbrander in
Google Scholar
PubMed
Close
, and
G. Buwalda
Search for other papers by G. Buwalda in
Google Scholar
PubMed
Close

ABSTRACT

Urinary cortisol production rate (CPR) was calculated by two different methods in five male piglets (about 3 kg bodyweight) injected i.v. with 40–120 kBq tritiated cortisol ([3H]F). After administration of [3H]F, urine was obtained from four consecutive collections for the following 2 days, during which 80–100% of the label was recovered. Total radioactivity in the urine was measured and used to calculate the total rate constant of 0·115 ± 0·011 h−1 and, from this, the mean biological half-life (t½) of 6·0±0·6 h (s.d.; n = 4). It was found that the mass ratio of the two principal urinary cortisol metabolites tetrahydrocortisone (THE) and tetrahydrocortisol (THF) was strikingly less than 1·0 (0·4±0·1; n= 14), which is the reverse of that observed in older pigs, neonatal infants and man. To calculate CPR conventionally, the cumulative specific activities of THE and THF were calculated for the 2-day period of urine collection. The apparent mean CPR values on the basis of THE and THF were calculated as 11·5±1·6 (n = 5) and 12·8 ± 3·3 (n = 5) μmol/day respectively, and 12·1 ± 1·4 (n = 5) μmol/day for the average of THE and THF.

The second method for calculating CPR consisted of determining the masses of THE and THF (μmol) per fraction of dose (m/fd) (fd refers to the ratio of radioactivity in the metabolite and dose) at different times after administration of [3H]F. The calculated m/fd values, which are synonymous with the dose divided by the specific activities of the metabolites, and the different times of urine collection were analysed by linear regression. The resulting slope is equal to the CPR. The CPR derived by this method for the average of THE and THF, 10·1±0·91 μmol/ day was significantly (P<0·014) lower than that derived conventionally, 12·1 ± 1·40 μmol/day.

This second method may be used when CPR is determined in neonatal infants by means of non-radioactive, deuterated or 13C-enriched cortisol, where the extent of negative feedback by the relatively high dose of exogenous steroid on cortisol secretion must be kept as low as possible. This method also allows urine collections to be used at times when the tracer is still being excreted.

J. Endocr. (1986) 111, 439–448

Restricted access
T Yamamoto
Search for other papers by T Yamamoto in
Google Scholar
PubMed
Close
,
B M Chapman
Search for other papers by B M Chapman in
Google Scholar
PubMed
Close
,
D C Johnson
Search for other papers by D C Johnson in
Google Scholar
PubMed
Close
,
C R Givens
Search for other papers by C R Givens in
Google Scholar
PubMed
Close
,
S H Mellon
Search for other papers by S H Mellon in
Google Scholar
PubMed
Close
, and
M J Soares
Search for other papers by M J Soares in
Google Scholar
PubMed
Close

Abstract

Trophoblast giant cells of the rat placenta express cytochrome P450 17α-hydroxylase (P450c17) and synthesize androgens. The purpose of this study was to investigate androgen production and expression of P450c17 in the Rcho-1 trophoblast cell line. These cells are capable of differentiating along the trophoblast giant cell lineage. Androstenedione production increased approximately 70-fold as Rcho-1 trophoblast cells progressed from the proliferation to the differentiation state. P450c17 enzyme activity and mRNA also showed significant increases associated with trophoblast giant cell differentiation. To study the transcriptional regulation of the P450c17 gene, the activities of a series of P450c17 promoter–luciferase reporter constructs were evaluated following transient transfection into Rcho-1 trophoblast cells. A DNA region located – 98 bp upstream of the P450c17 gene transcriptional start site was the shortest promoter DNA construct consistently possessing activity in Rcho-1 trophoblast cells. Activities of longer constructs (−156 to −1560 bp) in this population of cells were significantly greater than the −98 bp promoter–reporter construct. The − 476 bp P450c17 construct showed maximal promoter activity in transiently transfected Rcho-1 trophoblast cells and was developmentally activated in stably transfected Rcho-1 trophoblast cells. Activation of the cyclic AMP/protein kinase A pathway did not significantly affect P450c17 promoter activity in Rcho-1 trophoblast cells, in contrast to its effects in mouse MA-10 Leydig cells. In summary, Rcho-1 trophoblast cells are capable of endocrine differentiation and are a useful in vitro system for studying the regulation of trophoblast androgen production and P450c17 gene expression.

Journal of Endocrinology (1996) 150, 161–168

Restricted access
P. C. Wynn
Search for other papers by P. C. Wynn in
Google Scholar
PubMed
Close
,
I. G. Maddocks
Search for other papers by I. G. Maddocks in
Google Scholar
PubMed
Close
,
G. P. M. Moore
Search for other papers by G. P. M. Moore in
Google Scholar
PubMed
Close
,
B. A. Panaretto
Search for other papers by B. A. Panaretto in
Google Scholar
PubMed
Close
,
P. Djura
Search for other papers by P. Djura in
Google Scholar
PubMed
Close
,
W. G. Ward
Search for other papers by W. G. Ward in
Google Scholar
PubMed
Close
,
E. Fleck
Search for other papers by E. Fleck in
Google Scholar
PubMed
Close
, and
R. E. Chapman
Search for other papers by R. E. Chapman in
Google Scholar
PubMed
Close

ABSTRACT

Specific receptor sites for murine epidermal growth factor (EGF) have been characterized and their distribution determined in ovine skin. Binding of 125I-labelled EGF to skin membrane particles was temperature- and time-dependent, with equilibrium being reached within 1 h at 23 °C. Analysis of skin biopsies collected from ten castrated Merino sheep demonstrated the presence of a single class of saturable, high-affinity binding sites with a dissociation constant of 64 ± 4 (s.e.m.) pmol/l and a binding capacity of 33·8 ± 4·5 fmol/mg protein. Skin particle binding of 125I-labelled EGF was inhibited equipotently by mouse salivary gland EGF, EGF produced by recombinant DNA procedures and urogastrone. The EGF peptides 1–48, 6–53 and 7–53, derived from the native molecule by enzymatic cleavage, were much less potent. The relative binding potency of these molecules was correlated with their ability to induce precocious eyelid opening in mice and to inhibit wool follicle activity. Synthetic fragments representing the major structural domains of the EGF molecule (EGF(29–44), EGF(33–42) and EGF(3–31)) were inactive in both the receptor and bioassays. Auto-radiography of skin sections incubated with 125I-labelled EGF in vitro or of sections from skin which was perfused with 125I-labelled EGF in vivo demonstrated that EGF receptors were localized in undifferentiated cells of the epidermis and sebaceous glands, the inner and outer root sheath and bulb of wool follicles and in dermal arterioles. Differences in receptor concentration were observed between follicles following in-vivo perfusion of 125I-labelled EGF but not when the in-vitro labelling technique was used. The presence of receptors in these regions is consistent with the morphological changes in sheep skin in reponse to EGF administration which have been reported previously.

Journal of Endocrinology (1989) 121, 81–90

Restricted access
Andrea Lovdel University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Andrea Lovdel in
Google Scholar
PubMed
Close
,
Karla J Suchacki University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Karla J Suchacki in
Google Scholar
PubMed
Close
,
Fiona Roberts University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Fiona Roberts in
Google Scholar
PubMed
Close
,
Richard J Sulston University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Richard J Sulston in
Google Scholar
PubMed
Close
,
Robert J Wallace Department of Orthopaedics, The University of Edinburgh, Edinburgh, UK

Search for other papers by Robert J Wallace in
Google Scholar
PubMed
Close
,
Benjamin J Thomas University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Benjamin J Thomas in
Google Scholar
PubMed
Close
,
Rachel M B Bell University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Rachel M B Bell in
Google Scholar
PubMed
Close
,
Iris Pruñonosa Cervera University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Iris Pruñonosa Cervera in
Google Scholar
PubMed
Close
,
Gavin J Macpherson Department of Orthopaedic Surgery, Royal Infirmary of Edinburgh, Edinburgh, UK

Search for other papers by Gavin J Macpherson in
Google Scholar
PubMed
Close
,
Nicholas M Morton University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK
Centre for Systems Health and Integrated Metabolic Research, Department of Biosciences, School of Science and Technology, Nottingham Trent University, Nottingham, UK

Search for other papers by Nicholas M Morton in
Google Scholar
PubMed
Close
,
Natalie Z M Homer University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Natalie Z M Homer in
Google Scholar
PubMed
Close
,
Karen E Chapman University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by Karen E Chapman in
Google Scholar
PubMed
Close
, and
William P Cawthorn University/BHF Centre for Cardiovascular Science, The University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh BioQuarter, Edinburgh, UK

Search for other papers by William P Cawthorn in
Google Scholar
PubMed
Close

Bone marrow adipose tissue (BMAT) comprises >10% of total adipose mass in healthy humans. It increases in diverse conditions, including ageing, obesity, osteoporosis, glucocorticoid therapy, and notably, during caloric restriction (CR). BMAT potentially influences skeletal, metabolic, and immune functions, but the mechanisms of BMAT expansion remain poorly understood. Our hypothesis is that, during CR, excessive glucocorticoid activity drives BMAT expansion. The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) amplifies glucocorticoid activity by catalysing intracellular regeneration of active glucocorticoids from inert 11-keto forms. Mice lacking 11β-HSD1 resist metabolic dysregulation and bone loss during exogenous glucocorticoid excess; thus, we hypothesised that 11β-HSD1 knockout mice would also resist excessive glucocorticoid action during CR, thereby restrining BMAT expansion and bone loss. To test this, we first confirmed that 11β-HSD1 is expressed in mouse and human bone marrow. We then investigated the effects of CR in male and female control and 11β-HSD1 knockout mice from 9 to 15 weeks of age. CR increased Hsd11b1 mRNA in adipose tissue and bone marrow. Deletion of Hsd11b1 did not alter bone or BMAT characteristics in mice fed a control diet and had little effect on tibial bone microarchitecture during CR. Notably, Hsd11b1 deletion attenuated the CR-induced increases in BMAT and prevented increases in bone marrow corticosterone in males but not females. This was not associated with suppression of glucocorticoid target genes in bone marrow. Instead, knockout males had increased progesterone in plasma and bone marrow. Together, our findings show that knockout of 11β-HSD1 prevents CR-induced BMAT expansion in a sex-specific manner and highlights progesterone as a potential new regulator of bone marrow adiposity.

Open access
S Khan Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by S Khan in
Google Scholar
PubMed
Close
,
D E W Livingstone Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK
Centre for Discovery Brain Science, University of Edinburgh, Hugh Robson Building, Edinburgh, UK

Search for other papers by D E W Livingstone in
Google Scholar
PubMed
Close
,
A Zielinska College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK

Search for other papers by A Zielinska in
Google Scholar
PubMed
Close
,
C L Doig Department of Biosciences, School of Science & Technology, Nottingham Trent University, Nottingham, UK

Search for other papers by C L Doig in
Google Scholar
PubMed
Close
,
D F Cobice Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by D F Cobice in
Google Scholar
PubMed
Close
,
C L Esteves Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by C L Esteves in
Google Scholar
PubMed
Close
,
J T Y Man Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by J T Y Man in
Google Scholar
PubMed
Close
,
N Z M Homer Mass Spectrometry Core Laboratory, Edinburgh Clinical Research Facility, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by N Z M Homer in
Google Scholar
PubMed
Close
,
J R Seckl Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by J R Seckl in
Google Scholar
PubMed
Close
,
C L MacKay SIRCAMS, School of Chemistry, University of Edinburgh, Joseph Black Building, King's Buildings, Edinburgh, UK

Search for other papers by C L MacKay in
Google Scholar
PubMed
Close
,
S P Webster Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by S P Webster in
Google Scholar
PubMed
Close
,
G G Lavery Department of Biosciences, School of Science & Technology, Nottingham Trent University, Nottingham, UK

Search for other papers by G G Lavery in
Google Scholar
PubMed
Close
,
K E Chapman Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by K E Chapman in
Google Scholar
PubMed
Close
,
B R Walker Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK
Clinical & Translational Research Institute, Newcastle University, International Centre for Life, Central Parkway, Newcastle upon Tyne, UK

Search for other papers by B R Walker in
Google Scholar
PubMed
Close
, and
R Andrew Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK
Mass Spectrometry Core Laboratory, Edinburgh Clinical Research Facility, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK

Search for other papers by R Andrew in
Google Scholar
PubMed
Close

11β-Hydroxysteroid dehydrogenase 1 (11βHSD1) is a drug target to attenuate adverse effects of chronic glucocorticoid excess. It catalyses intracellular regeneration of active glucocorticoids in tissues including brain, liver and adipose tissue (coupled to hexose-6-phosphate dehydrogenase, H6PDH). 11βHSD1 activity in individual tissues is thought to contribute significantly to glucocorticoid levels at those sites, but its local contribution vs glucocorticoid delivery via the circulation is unknown. Here, we hypothesised that hepatic 11βHSD1 would contribute significantly to the circulating pool. This was studied in mice with Cre-mediated disruption of Hsd11b1 in liver (Alac-Cre) vs adipose tissue (aP2-Cre) or whole-body disruption of H6pdh. Regeneration of [9,12,12-2H3]-cortisol (d3F) from [9,12,12-2H3]-cortisone (d3E), measuring 11βHSD1 reductase activity was assessed at steady state following infusion of [9,11,12,12-2H4]-cortisol (d4F) in male mice. Concentrations of steroids in plasma and amounts in liver, adipose tissue and brain were measured using mass spectrometry interfaced with matrix-assisted laser desorption ionisation or liquid chromatography. Amounts of d3F were higher in liver, compared with brain and adipose tissue. Rates of appearance of d3F were ~6-fold slower in H6pdh−/− mice, showing the importance for whole-body 11βHSD1 reductase activity. Disruption of liver 11βHSD1 reduced the amounts of d3F in liver (by ~36%), without changes elsewhere. In contrast disruption of 11βHSD1 in adipose tissue reduced rates of appearance of circulating d3F (by ~67%) and also reduced regenerated of d3F in liver and brain (both by ~30%). Thus, the contribution of hepatic 11βHSD1 to circulating glucocorticoid levels and amounts in other tissues is less than that of adipose tissue.

Open access