bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uncoupling between proliferation and differentiation of ovine granulosa cells in vitro
Authors: Monniaux D , Pisselet C , Fontaine J 
Published: December 2008

Abstract
Granulosa cells of ovarian follicles both proliferate and undergo differentiation. In vivo, an inverse relationship between proliferation and steroidogenesis is observed. However, both processes can be enhanced by insulin-like growth factor-I (IGF-I) in vitro. Studies were undertaken in the ewe to understand the mechanisms controlling the balance between proliferation and differentiation in cultured granulosa cells from antral follicles better. For this purpose, granulosa cells from ovine small follicles (1–3 mm in diameter) and large follicles (5–7 mm in diameter) were compared for progesterone secretion, cytochrome P450 side-chain cleavage (P450scc) expression and their proportions of non-proliferating (G0) cells, in response to IGF-I and FSH stimulation in vitro.
IGF-I mainly enhanced the proliferation of granulosa cells from small follicles but it strongly increased progesterone secretion and P450scc expression in granulosa cells from large follicles, in synergy with FSH. Blocking granulosa cell proliferation by the administration of colcemid or aphidicolin had no effect or a weak stimulating effect on progesterone secretion. At the beginning of the culture period, the proportion of non-proliferating cells, estimated by continuous [3H]thymidine labelling experiments, was clearly higher in large than in small follicles (91% vs 30%, P<0·001). For both cell types, treatment with IGF-I in vitro reduced the proportion of non-proliferating cells at 72 h of culture (40% vs 70% respectively in IGF-I-stimulated and unstimulated cells from large follicles, P<0·001, and 17% vs 30% respectively in IGF-I-stimulated and unstimulated cells from small follicles, P<0·001). Treatment with FSH had no effect on the proportion of non-proliferating cells. As revealed by immunohistochemistry experiments, IGF-I, in synergy with FSH, clearly increased the percentage of cells expressing P450scc enzyme and the intensity of staining in granulosa cells from large follicles. Unexpectedly, heavily stained cells in mitosis were observed in IGF-I-stimulated cells from large follicles after 96 h of culture, suggesting that dividing cells might also produce progesterone.
Overall, these results support the hypothesis that the growth-promoting and the cytodifferentiative effects of IGF-I are clearly distinct. Moreover, they suggest that uncoupling between proliferation and steroidogenesis may occur in cultured ovine granulosa cells. The loss of proliferative activity accompanying terminal follicular growth in vivo could be reversed in vitro. During terminal follicular growth in vivo, the existence of an active mechanism inhibiting granulosa cell proliferation, and unrelated to terminal differentiation, is therefore strongly suspected.
Journal of Endocrinology (1994) 142, 497–510
Lactogenic actions of different growth hormone preparations in pregnant and lactating rats
Authors: Carón R W , Jahn G A , Deis R P 
Published: December 2008

Abstract
We studied the capacity of different GH preparations, natural human (h)GH, recombinant hGH (rhGH), rat (r)GH, ovine (o)GH, bovine (b)GH and porcine (p)GH, and ovine prolactin (oPRL), to stimulate lactogenesis in ovario-hysterectomized pregnant rats or intact lactating rats treated with bromocriptine (BC). Ovariohysterectomy (OVX-HYS) performed at 0800 h on day 19 of pregnancy induced lactogenesis, i.e. increases in mammary casein and lactose and positive response to the oxytocin test, 28 h later. Lactogenesis was prevented by treatment with BC (1·5 mg/kg) immediately after surgery (OVX-HYS-BC). The hormones were given at doses of 0·25 or 0·5 mg/rat (except rhGH given only at 0·5 mg/rat) at 1200 and 2000 h on day 19. Casein was increased by both doses of oPRL and hGH, rhGH and 0·25 mg oGH, and lactose by both doses of oPRL, rhGH and 0·25 mg rGH. The other GH preparations had no effect. The oxytocin test demonstrated the presence of milk in the mammary tissues of the OVX-HYS rats and in the OVX-HYS-BC plus oPRL (0·25 and 0·5 mg) or rhGH-treated groups.
Injection of BC to pregnant rats at 2000 h on day 20 and at 0800 h on day 21 decreased litter growth on the first 4 days postpartum. Two-thirds of the litters resumed growth after day 4, indicating the recuperation of milk production, while the rest never recuperated. Serum prolactin in BC-treated rats was reduced until day 4 postpartum. On day 6 the rats which had recuperated had normal values, while those which had still not recuperated had lower values. BC-treated rats were injected s.c. with 0·25 mg each of oPRL, hGH, rGH, oGH, bGH or pGH, or 0·25 or 0·5 mg rhGH/rat, immediately postpartum and 12, 24 and 36 h later. hGH and 0·5 mg rhGH induced levels of milk production similar to controls except on day 3. oPRL and rhGH (0·25 mg), induced a partial reversion of the effect of BC. rGH and oGH had a slight effect on days 1 and 2 and all the litters resumed growth on day 7. In contrast, pGH and bGH were inactive.
The affinity of hGH for the prolactin receptor, measured as displacement of 125I-labelled oPRL binding to crude liver membranes, was comparable with that of oPRL. While rhGH was ten times less active than oPRL, rPRL was 100 times lower and all the other GH preparations had at least 104 times lower capacity to displace 125I-labelled oPRL.
These results indicate that both natural and recombinant hGHs are potent inductors of milk synthesis in pregnant or lactating rats, most probably due to their actions at the level of the prolactin receptor. rGH and oGH have a partial action, while pGH and bGH seem to be inactive. The actions of non-human GHs may be explained by their somatogenic properties exclusively, and indicate that GH may play a role in the optimization of milk production during lactation and an accessory role in the induction of lactogenesis in pregnant rats.
Journal of Endocrinology (1994) 142, 535–545
Dexamethasone potentiates the stimulatory effect of insulin-like growth factor-I on collagen production in cultured human fibroblasts
Authors: Bird J L E , Tyler J A 
Published: December 2008

Abstract
We examined the effects of insulin-like growth factor-I (IGF-I) and dexamethasone on the production of collagen by cultures of human infant foreskin fibroblasts, and the interaction between these two factors. IGF-I at 500 ng/ml maximally increased collagen accumulation fourfold. Collagen was increased twofold relative to total protein production. Dexamethasone at a concentration of 1 μmol/l reduced collagen production by between 25% and 40% in unstimulated cells and those cultured with up to 100 ng IGF-I/ml. However, dexamethasone did potentiate collagen production in cells stimulated with 250 ng IGF-I/ml. This potentiation was independent of any effects of IGF-I or dexamethasone on prostaglandin (PG)E2 production. Transforming growth factor-β (TGF-β) is also a potent stimulator of collagen formation. However, no potentiation of TGF-β-stimulated collagen production by dexamethasone was apparent. The mechanism by which dexamethasone potentiates IGF-I-stimulated collagen production was investigated. Dexamethasone treatment increased IGF-I binding to the type 1 IGF receptor without altering the binding affinity. Dexamethasone also attenuated the secretion of IGF-binding proteins by IGF-I-maintained cells.
Journal of Endocrinology (1994) 142, 571–579
Tumour necrosis factor-α differentially alters progesterone and prostaglandin F2α production by porcine luteal cells
Authors: Richards R G , Almond G W 
Published: December 2008

Abstract
This study examined the effects of tumour necrosis factor-α (TNFα) on basal and stimulated progesterone secretion, as well as prostaglandin F2α production, by small, large and mixed porcine luteal cells and assessed the action of TNFα in the presence and absence of indomethacin. Corpora lutea were isolated from gilts on days 8–9 of the oestrous cycle and enzymatically dissociated. Luteal cells were either subjected to elutriation to isolate small and large cells or were separated from erythrocytes by a polysucrose gradient to serve as the mixed luteal cell group. Then 24-well culture plates were seeded with 150 000 small, 30 000 large and mixed (30 000 large+100 000-250 000 small) luteal cells suspended in 1 ml medium 199 media supplemented with 5 μg insulin/ml, 40 ng cortisol/ml and 50 μg low-density lipoproteins/ml. Cells were cultured for up to 24 h in a humidified incubator at 37 °C with 5% CO2 in air. TNFα time- and dose-dependently suppressed (P<0·05) LH-induced, but not basal, progesterone secretion by small luteal cells. Moreover, TNFα inhibited (P<0·05) forskolin-mediated, but not cyclic AMP-mediated, progesterone secretion by small luteal cells. The LH-stimulated progesterone secretion by small luteal cells was not affected by TNFα in the presence of indomethacin. Progesterone secretion by large and mixed luteal cells was not affected by TNFα. Prostaglandin F2α production by small and mixed, but not large, luteal cells was enhanced (P<0·05) by TNFα. These data demonstrated that TNFα acts primarily on a target cell(s) in the small cell fraction, and the cytokine-induced inhibition of LH-stimulated progesterone secretion by small cells was mediated by prostaglandin F2α and involved a site(s) proximal, but not distal, to cyclic AMP generation.
Journal of Endocrinology (1994) 143, 75–83
Consequences of thyroid hormone deficiency induced by the specific ablation of thyroid follicle cells in adult transgenic mice
Authors: Wallace H , McLaren K , Al-Shawi R , Bishop J O 
Published: December 2008

Abstract
The herpes simplex type 1 virus thymidine kinase (HSV1-TK) reporter gene was coupled to a bovine thyroglobulin promoter (TG-tk construct). Within the thyroid glands of transgenic mice expression was confined to thyroid follicle cells. Infusion of Ganciclovir (9-[(1,3-dihydroxy-2-propoxy)methyl]guanine) to 8 to 12 week transgenic females led to the complete loss of thyroid HSV1-TK activity (at 3 to 4 days) and thyroid follicles (between 7 and 14 days). During the first 5 days of treatment a single reciprocal oscillation in circulating thyroxine (T4) and TSH levels occurred. By 14 days the circulating triiodothyronine (T3) and T4 levels of all treated animals were below the detection limits of the assays, while TSH levels were elevated ten-fold and continued to increase thereafter. During 14 days of treatment the thyroids regressed, protein content fell by 80–90% and the C cells, normally dispersed within the central region of each gland, came together in aggregates. Pituitary GH levels in females rose and fell back to normal within 14 days and between 14 and 28 days fell to a level comparable with that of GH-deficient lit/lit mice. The levels of hepatic GH receptor mRNA and the predominant 6·6 kb T3 receptor mRNA were unaffected by thyrocyte ablation. Thyrocyte ablation had no effect on the level of prolactin (Prl) receptor mRNA in females, but increased Prl receptor mRNA levels in males and eliminated group 1 major urinary protein (MUP) mRNA in females. T4 replacement reversed the effects of thyrocyte ablation on MUP mRNA in females and on Prl receptor mRNA in males. Despite the many physiological changes induced by thyrocyte ablation, ablated mice have been maintained for up to 1 year without thyroid hormone supplementation. T4-deficient females were normally fertile and carried pups to term. Although transgenic males expressed HSV1-TK ectopically in spermatids and spermatozoa at levels similar to thyrocyte levels, a rate of Ganciclovir infusion which successfully ablated the thyrocytes did not affect the testis. As an alternative to infusion by minipump, thyrocyte ablation could be achieved by 6 twice-daily injections of Ganciclovir, at a level of 112 μg Ganciclovir/g body weight per day, and fetuses in utero could be thyrocyte ablated by administering 50 or 15 μg/g body weight per day to pregnant females between days 14 and 18 of gestation. These data demonstrate the potential value of transgenic thyrocyte ablation in the study of the effects of thyroid hormone deprivation.
Journal of Endocrinology (1994) 143, 107–120
Expression of inhibin α,βA and βB messenger ribonucleic acids in the normal human ovary and in polycystic ovarian syndrome
Authors: Jaatinen T-A , Penttilä T-L , Kaipia A , Ekfors T , Parvinen M , Toppari J 
Published: December 2008

Abstract
We studied the cellular distribution of inhibin α, βA and βB mRNAs in the normal human ovary and in polycystic ovarian syndrome (PCOS) by in situ hybridization. Our results show that human granulosa cells express inhibin α, βA and βB subunit mRNAs, and theca cells express inhibin α and βA subunit mRNAs. The co-localization of α and βA mRNAs in theca cells supports the hypothesis that inhibin also has an autocrine function in these cells. We did not detect any inhibin subunit mRNA in the granulosa cells of atretic follicles, while theca cells also expressed α subunit mRNA in those follicles. The present findings suggest that the expression of inhibin subunits is regulated differently in human follicular granulosa and theca cells. It has been speculated that inhibin may be involved in the development of PCOS. Our results show that the cellular localization of inhibin subunit mRNAs is not disturbed in PCOS ovaries.
Journal of Endocrinology (1994) 143, 127–137
Expression of 17β-hydroxysteroid dehydrogenase in human granulosa cells: correlation with follicular size, cytochrome P450 aromatase activity and oestradiol production
Authors: Ghersevich S A , Poutanen M H , Martikainen H K , Vihko R K 
Published: December 2008

Abstract
The aim of this study was to examine the expression and regulation of type 1 17β-hydroxysteroid dehydrogenase (type 1 17-HSD) enzyme protein and mRNA, and 17-HSD activity in human granulosa cells. The cells were obtained from patients taking part in an in vitro fertilization programme. The cells from each patient were divided into two groups: cells obtained from preovulatory follicles (LGC=granulosa cells from large follicles ≥ 18 mm in diameter), and cells from other visible follicles (SGC=granulosa cells from small follicles, less than 15 mm in diameter). The identity of 17-HSD enzyme protein expressed in human granulosa cells with placental cytosolic 17-HSD (type 1 17-HSD) was assessed by immunoblot analysis using polyclonal antibodies, and the enzyme was immunolocalized in the cytoplasm of granulosa cells. Type 1 17-HSD protein concentration, 17-HSD and cytochrome P450 aromatase (P450arom) activities and oestradiol (OE2) production in cells from LGC were significantly lower than the corresponding values obtained in SGC in the same patient (paired t-test). The type 1 17-HSD protein concentration, 17-HSD activity and P450arom activity were 140±16% (mean±s.e.m.), 121±22% and 113±26% higher in cells from SGC, which was also reflected in a 70±12% higher OE2 production in these cells. In freshly isolated cells from LGC or SGC, a high correlation between 17-HSD and P450arom activities was observed (r=0·93, P<0·001). In long-term cultured cells, type 1 17-HSD was stably expressed at least until day 9, while P450arom expression decreased. In addition, treatments with gonadotrophins did not affect type 1 17-HSD protein concentration and 17-HSD activity. In contrast to this, both P450arom activity and OE2 production were significantly increased (P<0·05). The data, therefore, suggest that type 1 17-HSD and P450arom are expressed in parallel during the latest stages of follicular maturation but, in cultured granulosa-luteal cells, the enzymes are regulated by distinct mechanisms.
Journal of Endocrinology (1994) 143, 139–150
Liposomal delivery of antioxidant enzymes protects against hydrogen peroxide- but not interleukin-1β-induced inhibition of glucose metabolism in rat pancreatic islets
Authors: Welsh N , Margulis B , Bendtzen K , Sandler S 
Published: December 2008

Abstract
The aim of the present investigation was to evaluate the putative involvement of oxygen free radicals in interleukin-1β (IL-1β)-induced suppression of islet glucose oxidation. Isolated adult rat pancreatic islets were exposed for 1 h to liposomally encapsulated superoxide dismutase (SOD; 10 mg/ml), catalase (CAT; 10 mg/ml) and glutathione peroxidase (GPX; 5 mg/ml), after which IL-1β (25 U/ml) or hydrogen peroxide (H2O2; 0·1 mm) was added, and the incubation was continued overnight. The following day, samples were taken from the incubation media for nitrite determinations, and islet glucose oxidation rates were measured. The CAT activity increased fourfold after addition of CAT-containing liposomes. It was found that IL-1β induced a marked increase in islet nitrite production, as an index of nitric oxide formation, and that this was paralleled by a decrease in islet glucose oxidation rates. H2O2-treated islets exhibited a modest decrease in glucose oxidation rates and a minor increase in the release of nitrite to the media. Treatment of islets with liposomes containing the antioxidant enzymes SOD, CAT and GPX, either alone or in combination, did not decrease the effect of IL-1β. However, the H2O2-induced decrease in glucose oxidation rates was counteracted by the combination of the antioxidants. It was concluded that, provided the intracellular delivery of the antioxidant enzymes to the islet cells was effective, oxygen free radicals probably do not play a decisive role in IL-1β suppression of islet glucose metabolism.
Journal of Endocrinology (1994) 143, 151–156
Androgen and oestrogen responsiveness of stromal cells derived from the human hyperplastic prostate: oestrogen regulation of the androgen receptor
Authors: Collins A T , Zhiming B , Gilmore K , Neal D E 
Published: December 2008

Abstract
Stromal cells derived from collagenase-digested benign hyperplastic adult prostates were isolated and grown in culture. Androgen and oestrogen receptor status were determined and growth in response to mibolerone (a synthetic androgen) and oestradiol-17β was measured. In addition, the ability of oestrogens to regulate the androgen receptor in stromal cells was investigated.
[3H] Thymidine incorporation into DNA was stimulated by mibolerone in primary and secondary cultures, but sensitivity was lost with subsequent passages. Androgen stimulation of [3H] thymidine incorporation was consistently inhibited by the anti-androgen cyproterone acetate. Oestradiol-17β also stimulated [3H]thymidine incorporation into DNA, and this effect was inhibited by the anti-oestrogen tamoxifen. Sensitivity to oestradiol was lost with subsequent passages. A combination of mibolerone and oestradiol was not synergistic in increasing [3H] thymidine incorporation into DNA, but maximal stimulation occurred at 100-fold lower concentrations of mibolerone and oestradiol when the two hormones were applied in combination. Specific high-affinity [3H] mibolerone- and [3H]oestradiol-binding sites were demonstrated by radioligand binding in intact cells. The affinity for oestradiol binding to its receptor exceeded that quantified for mibolerone binding to the androgen receptor, whilst the number of oestradiol-binding sites was approximately tenfold less than that quantified for mibolerone. Treatment with oestradiol down-regulated the number of [3H] mibolerone binding sites 1·7-fold (P<0·005) as early as day 2 after oestradiol treatment.
In conclusion, we successfully cultured stromal cells derived from hyperplastic prostates which retained sensitivity to androgen and oestrogen. These results suggest that mibolerone and oestradiol exert their biological effects independently of each other, but there is a close relationship in which one steroid increases the sensitivity of the other in the stromal cells of the hyperplastic prostate.
Journal of Endocrinology (1994) 143, 269–277
Isolation and characterization of distinct bioactive forms of LH from male buffalo pituitaries: differences localized to their α subunits
Authors: Sairam M R , Zaky A A H , Hassan A A 
Published: December 2008

Abstract
The isolation of highly purified forms of pituitary LH from Egyptian male (Nile) buffaloes is described. The total LH content (receptor binding activity) which was approximately 30 to 50 fold higher than FSH in the pituitary could be divided into three pools based upon fractionation patterns on a cation exchanger. The acidic fraction which also contained FSH was not purified to homogeneity. A basic fraction (bu-LH-2; 300 mg/kg anterior pituitary) and a very basic fraction (bu-LH-3; 80 mg/kg) were both highly purified and free of FSH activity as tested by specific FSH receptor and immunoassays. The basic buffalo LH fraction, bu-LH-2, was as active as highly purified ovine LH (oLH). The most basic form of buffalo LH, bu-LH-3, was, however, about twice as active as highly purified oLH in the in vitro bioassay using mouse Leydig tumour (MA-10) cells. In a receptor binding assay employing 125I-labelled buffalo LH (bu-LH-3) and porcine testicular membranes, the affinity of bu-LH-3 was about five times higher than purified oLH. The Mr of both forms of purified buffalo LH and subunits was similar to that of oLH. Amino acid composition of buffalo LH was also very similar to oLH except for small differences. Fractionation by fast protein liquid chromatography on Mono-Q columns revealed further evidence of microheterogeneity in each of the pools of buffalo LH with bu-LH-3 exhibiting a predominant single component. By reverse-phase high-pressure liquid chromotography analysis we have localized differences in the two purified isoforms of male buffalo LH to the α subunit. It is suggested that differences in biological potencies could be due to variations in terminal glycosylation and/or differences in branching of this subunit which is known to be important for signal transduction.
Journal of Endocrinology (1994) 143, 313–323
Vitamin D metabolism in the Damara mole-rat is altered by exposure to sunlight yet mineral metabolism is unaffected
Authors: Pitcher T , Sergeev I N , Buffenstein R 
Published: December 2008

Abstract
Vitamin D may be endogenously synthezised in the skin in the presence of sunlight or, alternatively, acquired from dietary sources. Cryptomys damarensis appear to have a naturally impoverished vitamin D status with low plasma concentrations of both 25-hydroxyvitamin D (25(OH)D; <5 ng/ml) and 1,25-dihydroxyvitamin D (1,25(OH)2D; <20 pg/ml). We attribute this to their underground habitat and herbivorous habits. We questioned whether these subterranean mammals could utilize sunlight-mediated pathways and therefore compared vitamin D metabolism and function when animals were (a) housed naturally (control), (b) given an oral vitamin D3 (D3) supplement (1 IU/g dry matter food eaten per day) and (c) exposed to 10 h of sunlight. Control animals exhibited a highly efficient apparent fractional absorption of both calcium (Ca) and inorganic phosphorus (Pi) (>90%), passive mode of intestinal mineral uptake, yet tightly regulated serum ionized calcium (Ca2+). The ratio of 25(OH)D-1α-hydroxylase (1-OHase) to 25(OH)D-24R-hydroxylase (24-OHase) activity in the kidney, corresponded with a state of vitamin D deficiency. Cryptomys damarensis responded to both oral D3 supplementation and sun exposure by an increase in plasma concentration of 1,25(OH)2D with a commensurate decline (P<0·05) in 1-OHase activity, and a resulting decrease (P<0·05) in the ratio of 1-OHase:24-OHase activity. Despite these changes, the intestinal mode of Ca uptake and plasma total Ca, Ca2+ and Pi remained unchanged with either treatment. Responses to sunlight were less pronounced than that of oral D3 supplementation. These data confirm that naturally vitamin D-deficient mole-rats can convert vitamin D to the active hormone 1,25(OH)2D, and indicate that mole-rats function optimally at the low concentrations of vitamin D metabolites found naturally. Furthermore, these animals exhibit a highly efficient vitamin D-independent mode of intestinal Ca absorption.
Journal of Endocrinology (1994) 143, 367–374