bluuebunny/crossref_metadata_2025_split huggingface dataset:
ELECTROLYTE AND FLUID APPETITE AND BALANCE IN MALE GUINEA-PIGS: EFFECTS OF STILBOESTROL TREATMENT AND RENAL FUNCTION TESTS
Authors: MIDDLETON E. , WILLIAMS P. C. 
Published: December 2008

SUMMARY
Male guinea-pigs were studied in individual metabolism cages for 6–12 weeks before, and for 13 weeks after, subcutaneous implantation of stilboestrol (15 mg). They were fed on cabbage and either normal pelleted diet (SG1) or sodium-enriched SG1, and had access to either water or to water and 0·86% saline. In all, 42 control and experimental animals were studied and renal function tests were made at 3-week intervals in 18 of them.
The treated animals lost appetite and weight but increased their fluid intake; they showed a preference for saline when this was available and, in doing so, reduced their polydipsia. Fluid and sodium balances were unaffected. The increased sodium appetite, whether satisfied or not, was accompanied by a fall in faecal sodium excretion and a rise in faecal potassium excretion. Renal function tests in themselves also produced some increase in sodium appetite, but no changes in faecal electrolyte excretion. These results suggest strongly that the mechanisms involved in the stimulation of sodium appetite by stilboestrol and renal function tests are different, partly because of the differences mentioned above, but also because the effects of the two procedures when combined were almost exactly additive.
The increased sodium appetite of the treated animals was not explicable by changes in renal function: inulin and creatinine clearances were only slightly reduced and concentrating ability unimpaired. This increased appetite may well be the result of adrenocortical stimulation by stilboestrol acting via extrarenal means.
No change in potassium appetite was observed, possibly because the potassium content of the diet was in excess of requirement. There was a seasonal variation in potassium balance which was lowest in summer in control and treated animals.
AN ASSESSMENT OF THE POSSIBLE ROLE OF 17α,20α-DIHYDROXY-4-PREGNEN-3-ONE IN THE REGULATION OF TESTOSTERONE SYNTHESIS BY RAT AND RABBIT TESTIS
Authors: de BRUIJN H. W. A. , van der MOLEN H. J. 
Published: December 2008

SUMMARY
17α,20α-Dihydroxy-4-pregnen-3-one is a competitive inhibitor of C17,20-lyase activity in rat testicular tissue in vitro and the significance of this inhibition in vitro was evaluated for testosterone biosynthesis in rat and rabbit testis in vivo. It is concluded that 17α,20α-dihydroxy-4-pregnen-3-one is not involved in the regulation of C17,20-activity in vivo, because it was not possible to detect any 17α,20α-dihydroxy-4-pregnen-3-one in rat and rabbit testicular tissue or in testicular venous blood. If present, the levels are lower than 10 pmol/g testis. Levels of 17α-hydroxyprogester-one are in the order of 50 pmol/g testis. The C17,20-lyase has a higher affinity for 17α-hydroxyprogesterone than for 17α,20α-dihydroxy-4-pregnen-3-one and hence inhibition under in-vivo conditions is not favoured. In rat testes the 20α-hydroxysteroid dehydrogenase activity, which can convert 17α-hydroxyprogesterone to 17α,20α-dihydroxy-4-pregnen-3-one, was found to be mainly (97%) localized in the seminiferous tubules and not at the site of testosterone formation in the interstitial tissue.
THE THYROTROPHIN RECEPTOR IN GUINEA-PIG THYROID HOMOGENATE: GENERAL PROPERTIES
Authors: MANLEY S. W. , BOURKE J. R. , HAWKER R. W. 
Published: December 2008

SUMMARY
Particulate fractions of guinea-pig thyroid homogenate contained a single class of receptors which bound 125I-labelled bovine thyrotrophin (TSH) by a saturable, reversible process with an affinity constant of 2 × 109 1/mol. The binding process was specific for TSH, and corresponded with the activation of adenylate cyclase. Cleavage of hormone—receptor bonds by treatment with lyotropic agents resulted in the release of unchanged labelled TSH. The radioligand receptor assay system was sensitive to 0·015 mu. TSH. Bovine or mouse thyroid showed reduced binding affinity with correspondingly reduced sensitivity.
EFFECTS OF VASOPRESSIN ON TOAD BLADDER MEMBRANE PROTEINS: RELATIONSHIP TO TRANSPORT OF SODIUM AND WATER
Authors: FERGUSON D. R. , TWITE B. R. 
Published: December 2008

SUMMARY
The results support previous findings that vasopressin produces dephosphorylation of a toad bladder membrane protein of 50000 mol. wt. At vasopressin concentrations of 50 mu./ml phosphorylation of this protein was 60 ± 7% of the control level, and maximal natriferic and hydro-osmotic responses were observed in intact bladders. However, at concentrations of vasopressin of 10 mu./ml when a maximal natriferic response but no significant hydro-osmotic response were observed, there was no significant difference in phosphorylation of the proteins from control or vasopressin-treated bladders.
We conclude that the 50000 mol. wt membrane protein is likely to be associated with the hydro-osmotic response of the toad bladder to vasopressin.
INACTIVATION OF ARGININE-VASOPRESSIN BY THE ISOLATED PERFUSED RABBIT KIDNEY
Authors: LEVI J. , ROSENFELD S. , KLEEMAN C. R. 
Published: December 2008

SUMMARY
The ability of the kidney to extract (inactivate and excrete) argininevasopressin (AVP) from the blood was studied in the isolated perfused rabbit kidney. AVP was added to the blood reservoir to give an initial approximate concentration of 100 μu./ml plasma and samples were taken simultaneously from the arterial and venous side at 5, 15, 30 and 45 min. The AVP concentration in the plasma samples was determined by bioassay in the water-loaded, ethanol-anaesthetized rat. The clearance (extraction ratio x renal plasma flow) of AVP from the blood was concentration-dependent. The average extraction ratio ranged from 0·25 at levels of 100 to 44 μu./ml plasma and 0·42 at levels of 44 to 19 μu./ml plasma. The excretion of AVP in the urine was 23% and 29% respectively of the calculated filtered load, in two isolated perfused kidneys, indicating tubular reabsorption and/or tissue inactivation of the filtered hormone.
LACK OF EFFECT OF PINEAL DENERVATION ON THE RESPONSES OF THE FEMALE ALBINO RAT TO EXPOSURE TO CONSTANT LIGHT
Authors: BROWN-GRANT K. , ÖSTBERG A. J. C. 
Published: December 2008

SUMMARY
Adult female albino rats were exposed to constant light after either a sham operation or bilateral removal of the cervical sympathetic chain. The second operation was later shown to have resulted in the disappearance of all fluorescent fibres from the pineal gland. Despite denervation of the pineal, there was no delay in the onset of persistent vaginal cornification and no significant differences in ovarian weight, sexual receptivity, incidence of ovulation after mating or number of eggs ovulated between the two groups.
INSULIN SECRETORY RESPONSE OF ISOLATED ISLETS OF LANGERHANS IN PREGNANT RATS: EFFECTS OF DIETARY RESTRICTION
Authors: GREEN I. C. , TAYLOR K. W. 
Published: December 2008

SUMMARY
The effects of diet on the altered insulin secretory responses of islets of Langerhans of pregnant rats have been investigated. The daily food intake of pregnant rats was found to exceed that of control non-pregnant rats by 20% on average. Depriving pregnant rats of this additional food resulted in an alteration in the pattern of insulin secretion seen in pregnancy, such that the sensitivity to stimulation by low glucose concentrations was abolished. The contribution made by different components of the diet to the secretory response in pregnancy was investigated. When additional carbohydrate, though not protein, was fed to pregnant rats on a restricted food intake, the sensitivity of the islets to glucose stimulation was restored. It was concluded that the quantity and in particular the carbohydrate content of food eaten by pregnant rats exerts an important influence on the changes in insulin secretion in pregnancy.
INTERRELATIONSHIP BETWEEN VITAMINS OF THE B-COMPLEX GROUP AND OESTRADIOL
Authors: SHARAF A. , GOMAA N. 
Published: December 2008

SUMMARY
Vitamins B2 and B6 are shown to have oestrogen-like effects and to act synergistically with oestradiol, increasing its action on the uterine weight of ovariectomized rats. Vitamins B1 and pantothenic acid enhanced the action of oestradiol but had no oestrogenic action themselves. Vitamin B12 had neither an oestrogen-like effect nor an influence on the action of oestradiol.
ALTERATIONS IN INCIDENCE OF MATING AND COPULATION-INDUCED OVULATION AFTER OLFACTORY BULB ABLATION IN FEMALE RATS
Authors: CURRY J. J. 
Published: December 2008

SUMMARY
Intact control and sham-operated rats, when given sodium pentobarbitone at 13.30 h on the day of pro-oestrus, mated (controls, 10/12; shamoperated, 13/15) that night and underwent copulation-induced ovulation. However, after removal of the olfactory bulbs only 13 out of 23 pentobarbitone-blocked rats mated. Of the mated animals only six ovulated as compared with ten in the unoperated group and ten in the sham-operated group. The incidence of ovulation in all non-mated animals was low. In addition, the bulbectomized, mated animals which ovulated shed significantly fewer ova than did intact controls and sham-operated rats (6·8 as compared with 11·3 and 13·4, respectively). The incidence of mating in bulbectomized animals was also lower than in sham-operated animals when pentobarbitone was not given (8/16 and 8/11, respectively). Ovulation was essentially complete in all groups except in bulbectomized, mated rats which shed significantly fewer ova. It is suggested that olfactory inputs are important in mediating copulation-induced ovulation in the pentobarbitone-blocked rat and that copulation in the absence of olfactory inputs interferes in some way with the normal sequence of secretion of ovulatory hormone(s) in the non-blocked rat.
THE ULTRASTRUCTURE OF THE ACCESSORY SEX ORGANS OF THE MALE RAT: THE EFFECT OF CYPROTERONE ACETATE
Authors: DAHL ERIK , TVETER K. J. 
Published: December 2008

SUMMARY
The present paper describes the fine structure of the ventral and lateral prostate and the seminal vesicles of the male rat after administration of an anti-androgen, cyproterone acetate, given as subcutaneous injections for varying periods (5–18 days). The treatment caused a general involution with macroscopic atrophy of the organs and reduced the amount of secretory material. There was a marked reduction of both the cell height and width and loss of cytoplasm. The main cytoplasmic changes consisted of a quantitative reduction of the rough endoplasmic reticulum and free ribosomes; the Golgi apparatus was diminished and the number of secretion granules markedly decreased. All the alterations observed are apparently similar to the changes induced by castration.
SEXUAL DIFFERENTIATION IN THE PHASE OF THE CIRCADIAN RHYTHM OF [35S]METHIONINE INCORPORATION INTO CEREBRAL PROTEINS, AND OF SERUM GONADOTROPHIN LEVELS
Authors: ter HAAR M. B. , MacKINNON P. C. B. , BULMER M. G. 
Published: December 2008

SUMMARY
The incorporation of [35S]methionine into protein in various regions of the brain and in the anterior pituitary, and serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were measured at 6 h intervals throughout a 24 h period in the following groups of Wistar rats: (1) normal adult males and females; (2) adult genetic males or females which had been respectively 'feminized' or 'masculinized' by androgen deprivation or administration in neonatal life. Similar measurements were made at 12 h intervals in adult male rats which had been castrated at 7 or 15 days of age.
Serum LH levels showed a circadian rhythmicity in normal adult animals of both sexes, with peak levels in the male occurring 6 h earlier than those in the female. There was no statistically significant circadian rhythm in FSH levels in any group of animals. In all groups of castrated animals LH and FSH levels were raised but no circadian rhythms were observed.
Incorporation of [35S]methionine into protein in all cerebral areas showed circadian rhythms, the peak values of which, in the adult males, were almost 8 h (120°) out of phase with those of the adult females. In the 'feminized' genetic males or 'masculinized' genetic females the rhythmic phase was reversed to that of the opposite genetic sex. Animals castrated at 7 days or 15 days of age did not appear to show a rhythm.
A 12 h rhythm of incorporation was apparent in the anterior pituitary of the normal adult male and the adult 'masculinized' female; no significant rhythm was seen in the normal adult female and the 'feminized' male.
It is suggested that a 'female type' rhythm of incorporation in the brain may be associated with the maintenance of oestrous cycles.
SPLANCHNIC, UTERINE, OVARIAN AND ADRENAL UPTAKE OF PROGESTERONE AND 20α-DIHYDROPROGESTERONE IN THE PREGNANT AND NON-PREGNANT SHEEP
Authors: BEDFORD CECELIA A. , HARRISON F. A. , HEAP R. B. 
Published: December 2008

SUMMARY
The uptake and extraction of progesterone and 20α-dihydroprogesterone (20α-diHP) by the splanchnic region and by some extra-splanchnic organs was measured by the determination of the concentration of labelled progesterone and 20α-diHP in a carotid artery and in the portal, hepatic, uterine, ovarian and adrenal veins during continuous intravenous infusion of [3H]progesterone.
The efficiency of splanchnic extraction of progesterone and 20α-diHP was 92 and 91%. The splanchnic clearance rates of progesterone and 20α-diHP were 1·210 and 1·223 l/min, respectively. Splanchnic clearance accounted for 27·1% of the metabolic clearance rate of progesterone. The efficiency of extraction of progesterone by some extra-splanchnic organs ranged from 7·9–45·9% across one uterine horn, 5·8–29·9% across one ovary and 30·9–33·3% across one adrenal. For the extraction of 20α-diHP the values were 6·1–9·4% (uterine horn), 15·5% (ovary) and 18·3% (adrenal). In some experiments there was a small production of 20α-diHP across the uterus and ovary. As the blood flow was a relatively small proportion of cardiac output, the clearance rate of progesterone by any one of these sites was less than 0·2% of the metabolic clearance rate.
Labelled progesterone and labelled 5α-pregnanedione were retained in the endometrium (but not in the myometrium) at much higher concentrations than those found in arterial or uterine venous blood. The reduced form, 20α-dihydroprogesterone, was retained in neither the endometrium nor the myometrium. There was a high concentration of polar, conjugated metabolites of progesterone in both uterine tissues compared with that in blood.
The results show that the high metabolic clearance rate of progesterone in the sheep is only partially due to splanchnic (mainly hepatic) uptake, and that over 70% of the progesterone produced is catabolized by extra-splanchnic organs.
STEROID HORMONE ADMINISTRATION AND GONADOTROPHIN SECRETION IN THE GONADECTOMIZED RAT
Authors: BROWN-GRANT K. 
Published: December 2008

SUMMARY
Facilitation of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion by progesterone was demonstrated in female rats ovariectomized 1–2 months previously and primed with oestradiol benzoate or testosterone propionate 72 h before the second injection of steroid. The priming action of testosterone propionate may be due to conversion to oestrogen as the non-aromatizable androgen, 5α-dihydrotestosterone propionate, did not have this effect. None of the steroid hormone treatments tested facilitated LH or FSH release in male rats castrated as adults or in female rats rendered anovulatory by the injection of androgen or oestrogen on day 4 of postnatal life. This abnormality may be the functional basis of the anovulatory state in these animals.
Of the progesterone derivatives tested in the oestrogen-primed ovariectomized rat only pregn-4-en-20α-ol-3-one and 5α-pregnane-3,20-dione significantly stimulated gonadotrophin secretion. These compounds, which are secreted by the rat ovary, may be involved, together with progesterone, in the initiation of the ovulatory surge of gonadotrophin during the oestrous cycle.
The time-course of the changes in gonadotrophin release in the oestrogen-primed ovariectomized rat in response to progesterone was determined. An initial depression was followed by an increase which was more marked for LH than for FSH. Although sodium pentobarbitone administration will prevent or reverse progesterone-induced gonadotrophin secretion, no clear correlation could be established between the sequence of changes in gonadotrophin secretion observed in the present study and the changes in hypothalamic neuronal activity reported by others to follow similar treatment with steroid hormones.
CALCIUM AND THE CONTROL OF CIRCADIAN MITOTIC ACTIVITY IN RAT BONE MARROW AND THYMUS
Authors: HUNT N. H. , PERRIS A. D. 
Published: December 2008

SUMMARY
Circadian changes in mitotic activity in rat bone marrow and thymus have been demonstrated to closely parallel variations in total and ionized calcium concentrations in plasma. These fluctuations in plasma calcium concentration and tissue mitosis were abolished by parathyroidectomy. Significant changes in plasma phosphate and magnesium concentrations were also observed over the 24 h period. The evidence suggests that hour-to-hour variations in the systems controlling calcium homeostasis determine the levels of mitosis in rat bone marrow and thymus.
GROWTH HORMONE INCREASE DURING SLEEP AFTER DAYTIME EXERCISE
Authors: ADAMSON LIISI , HUNTER W. M. , OGUNREMI O. O. , OSWALD I. , PERCY-ROBB I. W. 
Published: December 2008

SUMMARY
The effects of strenuous daytime physical exercise were examined in 12 healthy male volunteers. All-night electrophysiological recordings were made and blood was sampled during sleep by indwelling venous catheter.
Plasma growth hormone levels were significantly increased after exercise but the sleep electroencephalographic patterns of nights after exercise did not differ significantly from those of control nights. Plasma corticosteroids were decreased after exercise. It is suggested that higher levels of growth hormone are consistent with reparative processes during sleep.
TESTOSTERONE IN RETE TESTIS FLUID AND BLOOD OF RAMS AND RATS
Authors: COOPER T. G. , WAITES G. M. H. 
Published: December 2008

SUMMARY
Rete testis fluid (RTF) was collected from six conscious Clun Forest rams by cannulation of the efferent ducts, and from anaesthetized rats by cannulation of the rete testis 16–24 h after efferent duct ligation. Testosterone concentration in this fluid was measured by radioimmunoassay and compared with levels in blood collected from the subcapsular testicular artery and veins and spermatic and jugular veins.
The testosterone concentration in ram RTF fluctuated from nondetectable (< 100 pg/ml) levels to approximately 20 ng/ml over 1–25 h collection periods. The mean concentration was 8·5 ± 1·2 (s.e.m.). This value was approximately one fifth the mean concentration of testosterone in samples from the testicular veins at the dorsal pole of the testis.
Testosterone concentration (ng/ml) in rat RTF collected under sodium pentobarbitone anaesthesia was 26·4 ± 2·7 (18 measurements, 18 rats). A lower value was obtained when ether was the anaesthetic used during efferent duct ligation (ether, 20·3; halothane, 29·9; sodium pentobarbitone, 29·1). The mean concentration of testosterone in the RTF was similar to that in testicular venous blood (29·8 ± 3·9; 27 measurements, 27 rats), although the highest values were obtained after ether anaesthesia (ether, 38·3; halothane, 29·0; sodium pentobarbitone, 21·7).
Testosterone concentration in the testicular arterial inflow was similar to that in jugular venous blood in the ram but exceeded carotid arterial levels in the rat.
The values reported are used to discuss: the origin and significance of androgens in rete testis fluid, species differences, the effect of anaesthetics and season, and vascular exchange of testosterone in the spermatic cord.
PROTEIN AND RNA SYNTHESIS IN HUMAN PROLIFERATIVE ENDOMETRIUM IN ORGAN CULTURE AND THE EFFECT OF PROGESTERONE
Authors: SHAPIRO S. S. , HAGERMAN D. D. 
Published: December 2008

SUMMARY
Tissue concentrations of glycogen and incorporation of leucine and uridine were measured after short-term organ culture of human endometrium. Higher concentrations of glycogen and an increased rate of incorporation of leucine were found in tissue from cultures treated with oestrogen and progesterone when compared with tissue from cultures treated with oestrogen alone. No detectable difference in uridine incorporation was observed in these experiments.
PROLACTIN RELEASE AND LACTOGENESIS AFTER OVARIECTOMY IN PREGNANT RATS: EFFECT OF OVARIAN HORMONES
Authors: VERMOUTH NELIA T. , DEIS R. P. 
Published: December 2008

SUMMARY
Ovariectomy of rats on day 19 of pregnancy induced a rapid rise in serum prolactin. Levels were significantly increased 4 h after removal of the ovaries and continued to rise up to 24 h. A transient fall occurred at 32 h, but serum prolactin concentration was still raised after 36, 48 and 58 h. Similar increases of serum prolactin occurred after ovariectomy on days 17 and 18 of pregnancy. Lactogenesis occurred 24·8 or 28·2 h after ovariectomy on days 19 or 17–18 of pregnancy respectively. Rats ovariectomized on day 17 or 18 delivered on day 21 and rats ovariectomized on day 19 delivered on day 22 of pregnancy. Ovariectomy impaired parturition in all groups. Treatment with oestrogen immediately after the operation did not prevent the rise in serum prolactin levels 4, 8 and 12 h after ovariectomy, but 24 h after ovariectomy, prolactin values were not significantly different from those in sham-operated control rats. When oestrogen was injected 12 h after ovariectomy, serum prolactin was markedly increased 12 h later. Lactogenesis occurred about 22·9 h after oestrogen treatment and all animals delivered on day 21 of pregnancy. Progesterone treatment prevented the rise in prolactin levels observed 4 and 8 h after ovariectomy, but at 12 h levels had risen and were similar to those observed in untreated ovariectomized rats. Progesterone prevented lactogenesis for 14 h (around 37.5 h after ovariectomy) and induced a delay in the onset of parturition. The results indicate that the decrease of progesterone in the blood after ovariectomy in pregnant rats may induce a release of prolactin and lactogenesis. Oestrogen seems to be effective in raising prolactin levels at low blood concentrations of progesterone.
ARTIFICIAL INDUCTION OF LACTATION IN EWES
Authors: FULKERSON W. J. , McDOWELL G. H. 
Published: December 2008

SUMMARY
Lactation was induced in non-pregnant, intact ewes. The injection of 60 mg progesterone plus 240 μg oestradiol benzoate every third day for 60 days increased udder size. Subsequent daily injection of 10 mg dexamethasone trimethylacetate or 5 mg oestradiol benzoate plus 12·5 mg progesterone for 6 days led to further udder development and initiated secretion of fluid similar in appearance and composition to normal ovine milk.
Both treatments were equally effective in initiating milk secretion and subsequent production (approximately 0·50 kg/day) was similar to that of ewes lactating after normal pregnancy [0·59 ± 0·06 (s.e.m.) kg/day]. Glands of ewes receiving no treatment other than milking after oestrogen and progesterone priming remained small in size and produced only trivial volumes of secretion when milked out daily for 14 days.