bluuebunny/crossref_metadata_2025_split huggingface dataset:
UPTAKE IN VITRO OF [3H]OXYTOCIN BY THE MAMMARY GLAND AND OTHER TISSUES OF THE RAT
Authors: EGAN SANDRA M. , LIVINGSTON A. 
Published: December 2008

SUMMARY
In the presence of 62 μu. or more of [3H]oxytocin/ml there was specific uptake of oxytocin by lactating rat mammary glands in vitro within 400 s under conditions similar to those used in the biossay of oxytocin with rat mammary strips in vitro. This uptake was blocked by pre-incubation with non-radioactive oxytocin. A similar, rapid, specific uptake of oxytocin by uterine tissue in vitro was observed. There was no specific uptake of oxytocin by non-target tissues such as heart and skeletal muscle. Measurements of inulin and water spaces of the tissues showed that, over these short periods of time, diffusion into mammary tissue was much less than into the other tissues. The ratios of uptake of [3H]oxytocin: [3H]inulin and [3H]oxytocin: [3H]water were much higher for mammary tissue than those for other tissues used, indicating a preferential (tissue-specific) uptake. Uterine tissue from stilboestrol-primed rats also showed a preferential uptake of oxytocin, though not as great as that for mammary tissue. It is suggested that the specific uptake of oxytocin by mammary and uterine tissue is due to binding to specific receptors.
There was a variation in the specific uptake of oxytocin with the day of lactation of the mammary tissue, and specific uptake was only observed after the 8th day. This could indicate synthesis of receptors during lactation. In a similar way, synthesis of receptors may occur in the non-pregnant uterus due to the influence of exogenous oestrogens, leading to the increase in specific uptake by non-pregnant uterine tissue for oestrogen-primed rats. There is some evidence of more than one type of binding site for oxytocin. Biological action may only be associated with one of these sites.
CHANGES IN THE LUTEINIZING HORMONE RELEASING ACTIVITY OF THE HYPOTHALAMUS, AND IN PITUITARY GLAND AND PLASMA LUTEINIZING HORMONE DURING THE OESTROUS CYCLE OF THE SHEEP
Authors: CRIGHTON D. B. , HARTLEY BARBARA M. , LAMMING G. E. 
Published: December 2008

SUMMARY
Thirty ewes with regular oestrous cycles were divided into six groups for slaughter relative to the time of first acceptance of the ram. The slaughter times were: 0 h (in practice within 40 min of onset of oestrus), 6, 12 and 36 h after onset and days 10 and 16 of the cycle. The hypothalamus was removed and the luteinizing hormone (LH) releasing factor activity extracted with 0·1 m-HCl. The extracts were tested for LH releasing activity by adding them to the medium in which anterior pituitary tissue from castrated male sheep was incubated. The LH content of the medium was measured by the ovarian ascorbic acid depletion method (Parlow, 1958).
The activity of the extract from the group slaughtered on day 16 of the cycle was high (minimal effective dose (MED) = 0·00625 hypothalamic equivalents (HE)). The potency declined with the onset of oestrus and remained low at 6 and 36 h after onset (MED in each case 0·025 HE) with intermediate potencies at 12 h and 10 days after onset (MED in each case 0·0125 HE). These changes are compared with changes in the LH content of the pituitary gland (bioassay) and of the plasma (radioimmunoassay) and with parameters of the ovarian activity of the animals.
UPTAKE AND METABOLISM OF [1,2-3H]PROGESTERONE INJECTED INTRALUMINALLY INTO THE UTERI OF SPAYED MICE
Authors: CLARK B. F. 
Published: December 2008

SUMMARY
[1,2-3H]Progesterone (5–50 pg) injected intraluminally into the uterus of spayed mice was retained only to a small extent; producing a 'half-life' of about 30 min compared with > 240 min for [6,7-3H]oestradiol-17β (50 pg). Retention of progesterone by the uterus was not significantly different from that by the plantaris muscle, a non-target tissue. Paper chromatography of extracts indicated that metabolism of [1,2-3H]progesterone occurred in both the uterus and the vagina within 5 min of local injection. There was more metabolism in the vagina and it was qualitatively different. No selective retention of progesterone or its metabolites occurred in either organ. The proportion of the radioactivity present as progesterone over 120 min after injection remained constant.
CORTICOSTERONE METABOLISM BY RAT ADRENOCORTICAL CELL SUSPENSIONS AND MONOLAYER CULTURES: THE EFFECT OF DAMAGE ON 11-DEHYDROGENASE ACTIVITY
Authors: O'HARE M. J. 
Published: December 2008

SUMMARY
The metabolism of [3H]corticosterone by freshly disaggregated suspensions and deliberately damaged monolayer cultures of rat adrenocortical cells has been examined. In both cases, increased yields of 11-dehydrocorticosterone were obtained compared with intact, undamaged monolayer cultures, in which effective 11-dehydrogenase activity was extremely low. It was concluded that the greater part of the effective 11-dehydrogenase activity of the freshly prepared adrenal cell suspension was due to cells damaged by the disaggregation procedure. The maximum rate at which corticosterone was converted to 11-dehydrocorticosterone by the suspensions was equivalent to at least 50 ng/million cells/h. Undamaged monolayer cultures did not metabolize more than 0·2 ng of corticosterone/million cells/h to 11-dehydrocorticosterone.
SERUM AND PITUITARY LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE AND PROLACTIN LEVELS IN GONADECTOMIZED MALE, FEMALE AND ANDROGENIZED FEMALE RATS TREATED WITH OESTRADIOL BENZOATE
Authors: MALLAMPATI R. S. , JOHNSON D. C. 
Published: December 2008

SUMMARY
Changes in serum concentrations and pituitary content of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin, determined by radioimmunoassay, were studied after oestradiol benzoate (OEB) administration to gonadectomized male and female rats and to gonadectomized females androgenized with 50 μg testosterone propionate on the 5th day post-partum. Oestradiol benzoate (0·05–50 μg) was given once a day for 7 days beginning 3 weeks after removal of the gonads. A rise in serum LH concentration was produced by 0·05 μg OEB in all animals, but a reduction was found with the larger doses. Serum FSH increased in females injected with 0·05 μg OEB, but males and androgenized females had decreased FSH levels with all doses. The prolactin concentrations increased in the sera of all animals treated with 0·05 μg or 0·5 μg oestrogen. Males showed no further increases with larger doses. A very large increase was found in females given 5 μg but 50 μg did not have this stimulatory effect. Dose-dependent increases in serum prolactin were noted in androgenized females. Pituitary prolactin content increased in females and androgenized females treated with oestrogen; a slight, but significant, increase was found only in the males given 50 μg. Pituitary LH was increased only in the animals receiving a large amount of oestrogen (5 or 50 μg). Glandular FSH increased in the males and androgenized females given 0·5 μg OEB, but in all animals a reduction in this gonadotrophin was found after giving 50 μg of the oestrogen. The results indicate that androgenization alters the normal female hypothalamo-hypophysial response to oestrogen but it does not induce the response pattern of the male.
PROGESTERONE AND OESTROGEN AND THE INITIATION OF LACTATION IN EWES
Authors: HARTMANN P. E. , TREVETHAN P. , SHELTON J. N. 
Published: December 2008

SUMMARY
The concentrations of lactose and progesterone were determined in mammary secretion and blood plasma, respectively, collected from ten ewes at daily intervals from 30 days before to 10 days after parturition. An initial increase in the concentration of lactose in the mammary secretion occurred as early as 30 days before parturition and was not related to changes in the concentration of progesterone in the peripheral plasma. On the other hand, there was a rapid fall in the concentration of progesterone in the peripheral plasma from 1 to 4 days before parturition and this fall was closely related to a second rapid increase in the concentration of lactose in the mammary secretion. The foetuses were removed from an additional 12 ewes by Caesarean section at 144 days of gestation; three ewes received no hormone therapy; three ewes received 62·5 mg progesterone/12 h for 5 days; three ewes received 2·0 mg oestradiol at 12, 24 and 36 h respectively after surgery; three ewes received both progesterone and oestrogen therapy. Whereas progesterone inhibited the increase in milk yield and lactose concentration after Caesarean section, progesterone and oestrogen in combination inhibited only the increase in milk yield. These results suggest that progesterone withdrawal initiates lactogenesis in the ewe.
ISOLATION AND CHARACTERIZATION OF A PITUITARY PEPTIDASE SPECIFICALLY RELEASING, FROM GROWTH HORMONE, A PEPTIDE (SOMANTIN) WITH ANTAGONISTIC ACTIVITY TO INSULIN IN VITRO
Authors: DRIVER C. J. , ARMSTRONG J. McD. , BORNSTEIN J. , NG F. M. 
Published: December 2008

SUMMARY
A peptidase has been isolated from ovine pituitary glands and has been purified. It specifically hydrolyses ovine growth hormone, releasing a peptide with somantin activity. It is proposed to call this peptidase somantin-releasing enzyme (SRE). It is a di-isopropylphosphorofluoridate-sensitive peptidase with a molecular weight of 23000 Daltons. It is optimally active near pH 8·0. It is of quite limited specificity, as it hydrolysed growth hormone to a limited extent only and did not hydrolyse most of the other proteins tested as substrates.
EFFECTS OF INTERMITTENT GLUCOSE INFUSIONS IN PREGNANT RATS ON THE FUNCTIONAL DEVELOPMENT OF THE FOETAL PANCREATIC B-CELLS
Authors: ASPLUND KJELL 
Published: December 2008

SUMMARY
During the last 5 days of gestation, pregnant rats were infused intravenously with a glucose solution daily for 2 h. The total amount of glucose administered per day was 3–4 g/kg body weight. This dose significantly raised the maternal serum glucose levels by 56 ± 17 mg/100 ml on day 17 of gestation and by 39 ± 15 mg/100 ml on day 21. Saline infusions into pregnant rats caused no significant alterations of the blood glucose concentrations. On day 21 of gestation, foetuses were delivered by Caesarean section and the insulin release was determined in vitro by incubating pieces of foetal pancreas first at a low glucose concentration (0·4 mg/ml) for 30 min and then at a high glucose concentration (3·0 mg/ml) for a subsequent 30-min period.
It was found that the foetal body weights were significantly lower in the glucose-infused group when compared with the foetal body weights from an untreated control group. The pancreatic insulin content and serum glucose levels of the foetuses when killed did not show any significant difference between the glucose-infused and control groups. In agreement with previous observations a high concentration of glucose failed to affect the insulin secretion in vitro from the pancreases of foetuses of untreated or saline-infused mothers in the control groups. By contrast, in the offspring of glucose-infused mothers, the pancreatic glands responded to the high glucose concentration in vitro with a significantly enhanced rate of insulin release.
These findings suggest that the development of the B-cell function before birth may be influenced even by minor, short-term increases in the maternal blood glucose levels. The pregnant rat, intermittently infused with glucose, may serve as a useful model for further studies on the effects of maternal carbohydrate disturbances on B-cell development in the offspring.
PLASMA OESTRADIOL-17β AND ITS RELATIONSHIP TO SERUM FOLLICLE-STIMULATING HORMONE IN IMMATURE FEMALE RATS
Authors: MEIJS-ROELOFS H. M. A. , UILENBROEK J. Th. J. , JONG F. H. de , WELSCHEN R. 
Published: December 2008

SUMMARY
Oestradiol-17β (E2) was measured by radioimmunoassay in the plasma of immature female rats. Maximal E2 levels of 55–60 pg/ml were found at 10–15 days of age; from day 25 to day 35 E2 levels were low to undetectable. The E2 measured appeared to be of ovarian origin: ovariectomy performed on day 13 resulted in a decreased E2 level 2 days later (13 pg/ml) as compared with the value from the control litter mates (46 pg/ml); after adrenalectomy the level of circulating E2 remained normal (54 pg/ml). The effects of ovariectomy and adrenalectomy on uterine weights followed a similar pattern: ovariectomy resulted in a decrease and adrenalectomy in no change in uterine weight.
In the strain of rat used, levels of follicle-stimulating hormone (FSH) in the serum (measured by radioimmunoassay) were high from day 10 to day 20 and showed a steep decrease on day 21. After ovariectomy on day 15 this decrease in serum FSH was not observed.
The influence of circulating E2 on serum levels of FSH was studied after ovariectomy followed by treatment with varying doses of oestradiol benzoate. Ovariectomy on day 13 resulted in a significantly increased FSH level 2 days later (1770 ng NIAMD-rat-FSH RP-1/ml) as compared with the value obtained from control animals (1033 ng/ml). This increase was not observed after daily injections of 0·1 μg oestradiol benzoate/100 g body weight.
The results indicate that E2 and FSH concentrations show a similar pattern between 5 and 35 days of age. Furthermore, an inhibitory feedback mechanism between oestrogens and FSH concentrations was found to be operative. The implications of these findings are discussed.
BREAKDOWN OF [3H]OXYTOCIN BY RAT TISSUES IN VITRO
Authors: EGAN SANDRA M. , LIVINGSTON A. 
Published: December 2008

SUMMARY
Tissue uptake of oxytocin by rat mammary gland, uterus, heart and skeletal muscle was demonstrated by incubation of these tissues with 3H-labelled oxytocin. Chromatography of tissue extracts showed that some breakdown of oxytocin had occurred after only 30 s. However, in all cases there was no breakdown of oxytocin in the corresponding incubation medium. This indicated that the breakdown of oxytocin occurred within the tissues.
AN ATTEMPT TO DEMONSTRATE CELL MIGRATION FROM THE ZONA GLOMERULOSA IN THE PREPUBERTAL MALE RAT ADRENAL CORTEX
Authors: WRIGHT N. A. , VONCINA D. , MORLEY A. R. 
Published: December 2008

SUMMARY
Recently, cell loss by necrosis has been demonstrated in the zona reticularis of the adrenal cortex; such loss is a prerequisite of the centripetal migration theory of adrenocortical cell renewal. Consequently a method has been evolved for the estimation of the rate of cell loss from the z. glomerulosa in prepubertal male rats aged 14 days.
The method depends upon measurement of the doubling time for the z. glomerulosa by weighing and serially sectioning adrenal glands at ages from 3 to 120 days, combined with point-counting. The doubling time for the z. glomerulosa at 14 days of age was 120 h.
A continuous labelling technique was used to estimate the growth fraction and the cell cycle time. In the z. glomerulosa these were 0·80 and 87 h respectively. These values gave an estimate of the cell production or birth rate of 0·00676 cells/cell/h, or 0·676 cells/100 cells/h, and consequently the potential doubling time (assuming no cell loss) was 102 h. Since the actual doubling time exceeds the potential doubling time, cells must be lost from the z. glomerulosa. This cell loss was found to be taking place at a rate of 0·0010 cells/cell/h, or 0·10 cells/100 cells/h, and the cell loss factor (ϕ) was 0·15.
Since necrosis has only been demonstrated in the z. reticularis, and evidently does not occur in the z. glomerulosa, this cell loss rate can be considered to represent the rate at which cells migrate from the z. glomerulosa. It is proposed, therefore, that in the prepubertal animal at least, centripetal cell migration does occur.
METABOLISM OF ANDROGENS IN VITRO BY HUMAN FACIAL AND AXILLARY SKIN
Authors: HAY J. B. , HODGINS M. B. 
Published: December 2008

SUMMARY
Human skin from forehead, cheek and axilla was incubated in vitro with [7α-3H]dehydroepiandrosterone (DHA), [7α-3H]DHA sulphate, [7α-3H]-androstenedione and [7α-3H]testosterone. The following enzyme activities were detected: 3β-hydroxysteroid dehydrogenase Δ4-5 isomerase, 17β-hydroxysteroid dehydrogenase, 3β-hydroxysteroid dehydrogenase, 3α-hydroxysteroid dehydrogenase, 5α-reductase, 5β-reductase, sulphotransferase, sulphatase, steroid hydroxylase. 5α-Reduced steroids were the major metabolites. All four substrates were converted to 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol. In axillary skin, conversion of 17-oxosteroids to 17β-hydroxysteroids was favoured, 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol being major metabolites. In facial skin, formation of 17-oxosteroids predominated with little accumulation of 5α-dihydrotestosterone or 5α-androstane-3α,17β-diol. 5α-Androstane-3β,17β-diol was a metabolite of DHA, androstenedione and testosterone but was found in lower amounts than 5α-androstane-3α,17β-diol. Similarly conversions to epiandrosterone were much lower than to androsterone in all the skin specimens.
It was concluded that the differences in accumulation of 5α-dihydrotestosterone were determined by the differences in 17β-oxidoreduction rather than differences in 5α-reductase, the activity of which was high in all skin specimens.
INFLUENCE OF TESTOSTERONE AND CYPROTERONE ACETATE ON THE RATE OF MITOSIS IN SEMINAL VESICLES OF RATS
Authors: DAHNKE H.-G. , SCHEUER A. , MOSEBACH K.-O. 
Published: December 2008

SUMMARY
From day 25 of life juvenile Wistar rats were injected with either testosterone (100 μg), cyproterone acetate (3 mg) or a combination of both substances. The rate of mitosis in the epithelium of seminal vesicles was determined 9, 24, 72 and 120 h after the initial injection. The rate of mitosis after testosterone application was found to have already increased by 120% within 24 h; after this no further increase could be detected.
Cyproterone acetate decreased the rate of mitosis by 50%, with the maximal effect after 72 h. Combined application of testosterone and cyproterone acetate augmented the rate of mitosis by 80% after 24 h; the rate decreased to control values after 72 h and remained constant for the rest of the observation time. The results are discussed on the basis of a receptor model.
LOCALIZATION OF NORETHISTERONE IN THE REPRODUCTIVE TRACT OF WOMEN
Authors: REED M. J. , FOTHERBY K. , PECK J. E. , GORDON Y. 
Published: December 2008

SUMMARY
[3H]Norethisterone was administered to women 1, 3 and 24 h before hysterectomy, when samples of blood, adipose tissue and tissues from the reproductive tract were obtained. At 1 h the highest concentrations of radioactivity were found in endometrium and stroma (0·77 and 0·78% respectively of the dose per 100 g tissue), the values in other tissues varying from 0·13 to 0·39%. By 3 h there was a decrease in the concentration in all tissues except adipose tissue and plasma and at this time the range of concentrations in all tissues, apart from plasma (0·40%), were similar (0·08 to 0·19%). There was a further decrease by 24 h. Mean values for the amount of radioactivity present in the tissues at 1 h were: uterus, 0·55%; adipose tissue, 21·6%; blood, 10·1%. By 24 h these values had decreased to 0·1, 7·0 and 6·6% respectively. In adipose tissue most of the radioactivity was present in the freely extractable state at all times studied, whereas in myometrium and cervix the amount of radioactivity freely extractable at 1 h (77%) had decreased by 24 h (39·0%). In plasma the amount of conjugated radioactivity increased from 54% at 1 h to 88% by 24 h. Whereas at 1 h most metabolites in plasma were conjugated as sulphates, by 24 h glucuronide conjugates were also important. In myometrial tissue 17·5 to 47·8% of the radioactivity was associated with the nuclear fraction.
COMPARATIVE STUDIES ON THE REDUCTION OF THE RESPONSE TO THE LONG-ACTING THYROID STIMULATOR BY SOLUBLE FRACTIONS FROM HUMAN, OVINE, BOVINE AND PORCINE THYROIDS
Authors: DIRMIKIS SUSAN , MUNRO D. S. 
Published: December 2008

SUMMARY
The response to the long-acting thyroid stimulator (LATS) but not to bovine thyroid-stimulating hormone (TSH) was reduced by soluble fractions from human, ovine, bovine and porcine thyroids. A significant increase in the capacities of human, ovine and bovine thyroidal soluble fractions to reduce the response to LATS occurred upon freezing and thawing of thyroidal homogenates. In human thyroids this change took place predominantly in the 4 S peak, which was the most active of the soluble fractions from frozen human thyroid tissue. However, in ovine and bovine thyroids, the change could be accounted for mainly by components of the 19 S peak, this being also the most active of the soluble fractions of frozen animal thyroids in reducing the response to LATS.
Whereas human LATS-binding activity (LAA) was destroyed by heating at 56 °C for 1 h the capacities of ovine, bovine and porcine thyroidal soluble fractions (or their 19 S components) to reduce the response to LATS were not affected by this treatment.
The interaction between human LAA and LATS can be reversed by 2 m-NaSCN, which also destroys LAA. However, NaSCN had no detectable effect on the capacities of soluble fractions (or their 19 S components) from ovine, bovine and porcine thyroids to reduce the response to LATS. The reduction of the response to LATS by very high concentrations of 4 S components, from frozen ovine thyroidal homogenate, was partially reversed by 2 m-NaSCN. Thus ovine thyroids may be a source of a substance with the properties of human LAA, but with a yield of approximately 10% of that obtained from human thyroid tissue.
It was concluded that ovine, bovine and porcine thyroidal soluble fractions reduced the response to LATS mainly by mechanisms other than binding to LAA.
PLASMA GROWTH HORMONE AND SERUM PHOSPHORUS CONCENTRATIONS IN RELATION TO THE MENOPAUSE AND TO OESTROGEN THERAPY
Authors: AITKEN J. M. , GALLAGHER M. J. D. , HART D. M. , NEWTON D. A. G. , CRAIG A. 
Published: December 2008

SUMMARY
Plasma human growth hormone (HGH) and serum phosphorus concentrations were measured during the fasting ambulatory state in middleaged men, pre- and postmenopausal women and postmenopausal women who had been taking 20–40 μg mestranol daily for 1–3 years.
The mean plasma HGH concentrations were consistently higher in the women than they were in the men, there was little difference between the mean values for pre- and postmenopausal women, and the mestranoltreated women had significantly higher mean values than the untreated postmenopausal women.
The mean serum phosphorus concentration was significantly higher after menopause and was significantly lower in those women on long-term lowdose mestranol therapy. A significant direct correlation was found between serum phosphorus and plasma HGH concentrations in untreated postmenopausal women.
It is suggested that the postmenopausal relative hyperphosphataemia is consistent with increased HGH activity.
EFFECTS OF ADENOHYPOPHYSECTOMY AND AMINOGLUTETHIMIDE ON WATER AND ELECTROLYTE COMPOSITION OF XENOPUS LAEVIS DAUDIN
Authors: EDWARDS B. R. , CHAN S. T. H. 
Published: December 2008

SUMMARY
Keeping Xenopus laevis Daudin in sodium-rich or sodium-free media leads to hypernatraemia or hyponatraemia respectively. Approximately 3 weeks after adenohypophysectomy, sodium and chloride concentrations in plasma and tissue water were reduced; there was also a net loss of the ions from the muscle. Potassium was not significantly affected. Aminoglutethimide, a proven inhibitor of corticosteroidogenesis in mammals, produced similar though more pronounced changes. In the adenohypophysectomized animal, this drug also produced a net increase in muscle potassium. The role of the urinary bladder in reabsorbing sodium has been demonstrated in Xenopus by an in-vivo technique. While the rate of urine flow was reduced in adenohypophysectomized toads, the rate of sodium excretion was essentially unchanged.