bluuebunny/crossref_metadata_2025_split huggingface dataset:
BINDING OF THYROID HORMONES TO A SOLUBLE FRACTION FROM PORCINE ANTERIOR PITUITARY
Authors: SUFI S. B. , TOCCAFONDI R. S. , MALAN P. G. , EKINS R. P. 
Published: December 2008

SUMMARY
The binding of 125I-labelled thyroxine and tri-iodothyronine to a 100000 g supernatant fraction (cytosol) from homogenates of porcine anterior pituitary lobes was examined. The kinetics of thyroxine binding were studied and the dissociation rate-constant observed at 4 °C was 2·4 × 10−4 s−1. Equilibrium constants of relatively high affinity for both iodothyronine hormones were obtained from Scatchard plots of dose-response data, and were found to be 0·4 × 109 m−1 for tri-iodothyronine and 1·4 × 109 m−1 for thyroxine. Bound [125I]thyroxine could be virtually completely displaced by unlabelled thyroxine, but only partially by unlabelled tri-iodothyronine. From these relative potency experiments it is tentatively suggested that a thyroxine-specific site of low affinity is present in the cytosol. A protein component is probably involved in thyroxine binding, since a decrease in bound hormone was seen only after treatment with proteolytic enzymes.
The thyroxine-binding capacities of anterior pituitary cytosol and porcine serum were similar, and were two or three times greater than the binding capacities of cytosol fractions from either posterior pituitary or brain frontal lobe. These results suggest that thyroxine binding in the anterior pituitary cytosol is unlikely to have resulted solely from contamination by serum thyroxine-binding proteins. Further evidence for this belief was provided by thin-layer chromatographic separation of labelled thyroxine bound to either cytosol or to serum proteins. The possible relevance of these studies to the feedback regulation of thyrotrophin secretion is discussed.
METABOLISM OF 3β-HYDROXY-5-ENE STEROIDS BY TESTES OF RATS ACCLIMATIZED TO A HOT ENVIRONMENT
Authors: BEDRAK E. , SAMOILOFF V. , SOD-MORIAH U. A. 
Published: December 2008

SUMMARY
The metabolism of 3β-hydroxysteroids, in the presence of NADPH, by testicular homogenates of adult rats acclimatized to a hot environment (33–35 °C, 25–40% relative humidity), was compared with that of control and surgically produced cryptorchid testes. Prolonged exposure to a hot environment stimulated the transformation of 3β-hydroxysteroids to 3-oxo-4-ene metabolites, so that relatively large amounts of the latter accumulated. Pregnenolone was metabolized rapidly to progesterone, 17α-hydroxyprogesterone, androstenedione and testosterone. A similar trend was observed in the metabolism of 17α-hydroxypregnenolone. In-vitro synthesis of testosterone in the rat apparently takes place primarily by the 4-ene pathway. The 5-ene-17,20-lyase reaction appears to be rate-limiting. Heat acclimatization does not seem to affect this step. It does, however, seem to enhance the conversion of dehydroepiandrosterone via 5-androstene-3β,17β-diol to testosterone. Enzymic activity was much lower in cryptorchid than in heat-acclimatized testes, where it actually increased, except for 17β-hydroxysteroid oxidoreductase.
Continuous exposure of rats to a high ambient temperature for 4–6 months tended to decrease testosterone concentration in peripheral blood, and retarded growth rate and gonadal size. Histological examination showed atrophied areas in the testes where necrobiosis of the germinal epithelium had occurred. These necrotic foci, unlike those found in cryptorchid testes, were randomly scattered among intact seminiferous tubules in which active spermatogenesis was taking place.
PERIPHERAL PLASMA PROGESTERONE CONCENTRATIONS IN SHEEP DURING THE OESTROUS CYCLE
Authors: McNATTY K. P. , REVFEIM K. J. A. , YOUNG A. 
Published: December 2008

SUMMARY
Progesterone concentrations in peripheral plasma were measured once daily during one oestrous cycle in each of eight sheep. In addition, on days 4–5, 8–9, 12–13 and 15–16 of the oestrous cycle, blood samples were collected at 30-min intervals throughout each 24-h period. A total of three ewes was sampled in each 24-h period and the same three animals were not bled again for at least 1 week. Plasma progesterone concentrations in all the ewes fluctuated considerably throughout each 24-h period. The within-sheep within-day variations observed in peripheral progesterone concentrations were compared with the between-sheep within-day variations and the within-sheep between-day variations previously reported. It is concluded that these previously reported variations in peripheral plasma progesterone concentration could be attributed to within-day variations in each animal.
On days 8–9 and 12–13 of the oestrous cycle there were significantly higher concentrations of progesterone in plasma during the hours of daylight than during the hours of darkness. In contrast, progesterone concentrations on days 4–5 and 15–16 were not found to be significantly different between the hours of daylight and darkness. These results suggest that diurnal changes in peripheral plasma progesterone concentration occur during the luteal phase of the ovine oestrous cycle.
INFLUENCE OF PREGNENOLONE-16α-CARBONITRILE ON SPERMATOGENESIS AND ON THE SPERMATOGENIC ACTIVITY OF PREGNENOLONE
Authors: TACHÉ Y. , SELYE H. , SZABO S. , TACHÉ J. 
Published: December 2008

SUMMARY
In hypophysectomized rats, treatment with pregnenolone (pregn-5-en-3β-ol-20-one) for 14 days prevented testicular atrophy, maintained spermatogenesis but did not counteract Leydig cell atrophy. Spermatogenic activity was abolished when a 16α-nitrile group was attached to the pregnenolone molecule, but pregnenolone-16α-carbonitrile (PCN) did not interfere with the spermatogenic effect of pregnenolone. These results are discussed in view of the fact that PCN inhibits intoxication with excess amounts of many steroids (e.g. anaesthesia due to heavy overdosage with progesterone or hydroxydione), whereas steroid hormones, administered at doses necessary to maintain physiological functions, are virtually resistant to this type of catatoxic action, which usually takes the form of enhanced metabolic degradation and/or substrate excretion.
INCORPORATION OF 32P INTO PHOSPHOLIPIDS OF THE HYPOTHALAMO-NEURO-HYPOPHYSIAL SYSTEM AND SUBCELLULAR DISTRIBUTION OF LABELLED PHOSPHOLIPIDS IN THE RAT NEURAL LOBE
Authors: BRIDGES T. E. , LEDERIS K. 
Published: December 2008

SUMMARY
The uptake of 32P into the rat neural lobe and hypothalamus was studied after intraperitoneal and intraventricular (lateral ventricle of the brain) administration of the isotope. After intraventricular injection the uptake into both tissues was greater by up to three orders of magnitude than after intraperitoneal administration. Maximum uptake of isotope after intraventricular injection occurred at 4 h in the hypothalamus and at 48 h in the neural lobe. Incorporation of isotope into phospholipids was maximal at 24 h in both the hypothalamus and neural lobe.
Isolated neurosecretory granules and small vesicles contained 46·5 ± 2·3% and 11·9 ± 1·7% respectively of the total phospholipids found in particulate fractions of neural lobe homogenates. Two-dimensional thin-layer chromatography showed that all seven phospholipids tested for occurred in both the isolated neurosecretory granules and small vesicles.
THE SUBMAXILLARY SALIVARY GLANDS AS TEST ORGANS FOR RESPONSE TO ANDROGEN IN MICE WITH TESTICULAR FEMINIZATION
Authors: LYON MARY F. , HENDRY I. , SHORT R. V. 
Published: December 2008

SUMMARY
The effect of testosterone injections on the histology of the submaxillary salivary glands, and their content of nerve growth factor (NGF), were studied in normal and gonadectomized male and female mice, and in those affected with testicular feminization (due to the X-linked gene, Tfm). In intact and spayed female and castrated male mice testosterone increased the quantity of NGF and caused the histology of the glands to become like the male type. In mice with testicular feminization both the histology and the NGF content were of the female type, and were completely unaffected by testosterone injections. Female mice heterozygous for Tfm responded to testosterone, but in some the response appeared intermediate. The submaxillary gland provides a suitable test organ for studies of the androgen insensitivity of Tfm mice, and may prove more useful than the kidneys for some experiments.
GLUCOCORTICOID SYNTHESIS FROM PREGNENOLONE BY SHEEP FOETAL ADRENALS IN VITRO
Authors: DAVIES I. J. , RYAN K. J. 
Published: December 2008

SUMMARY
[7-3H]Pregnenolone was incubated with homogenates of adrenal glands from two 100-day-old sheep foetuses. Cortisol and corticosterone were isolated and identified by reverse isotope dilution and recrystallization to constant specific activity. Together these two compounds accounted for 12% and 17% of the substrate with the two tissue preparations. Other C21 and C19 metabolites which were sought were not present in appreciable quantities. Additional incubations were done with the adrenals of lamb foetuses ranging in age from 110 days of gestation to the immediate newborn period. Glucocorticoidogenic capacity similar to that of the 100-day-old foetuses was demonstrated throughout this period and no age-related change was evident. These results demonstrate that the lamb foetal adrenal has a substantial enzymic capacity for glucocorticoid synthesis throughout at least the last third of gestation. In conjunction with the observations of others, these experiments support the hypothesis that during this period of gestation the lamb foetal adrenal is actively synthesizing glucocorticoids in a manner which is similar to the lamb at term and the adult sheep.
OESTROGEN RECEPTORS IN THE MAMMARY GLAND OF THE LACTATING RAT
Authors: HSUEH A. J. W. , PECK E. J. , CLARK J. H. 
Published: December 2008

SUMMARY
Oestrogen receptors were identified in both the cytoplasmic and the particulate fractions of the mammary glands of lactating rats. The quantities of cytoplasmic receptor and nuclear receptor—oestrogen complex in the particulate fraction were measured by the charcoal adsorption assay and the [3H]oestradiol exchange assay respectively. The quantity of cytoplasmic oestrogen receptor increased markedly between day 1 and day 10 and reached a maximum value on the 21st day of lactation. Although the quantity of cytoplasmic receptor increased markedly during lactation, the concentration of nuclear receptor—oestrogen complex that resulted from endogenous concentrations of blood oestrogen changed only slightly, indicating that the blood level of oestrogen was quite low during lactation. One hour after a subcutaneous injection of 25 μg oestradiol, the concentration of nuclear receptor—oestrogen complex increased dramatically and a translocation process similar to that for the uterine receptor—oestrogen complex was observed. The increased quantity of particulate receptor—oestrogen complex after the administration of exogenous oestradiol indicated that the low levels of endogenous nuclear receptor—oestrogen complex observed during lactation were not the result of failure of the translocation process. The concentration of cytoplasmic receptor on day 21 of lactation in rats that were ovariectomized on day 1 of lactation was not significantly different from the concentration in intact control animals. The translocation process was also similar in ovariectomized and intact rats on day 21 of lactation. These results suggest that the increased quantity of oestrogen receptors in lactating mammary tissue is not dependent on ovarian oestrogens.
THYROID FUNCTION IN THE FOETAL LAMB DURING THE LAST THIRD OF GESTATION
Authors: NATHANIELSZ P. W. , COMLINE R. S. , SILVER MARIAN , THOMAS A. L. 
Published: December 2008

SUMMARY
Foetal plasma thyroxine levels as well as thyroxine turnover and placental permeability to this hormone were investigated in the conscious pregnant ewe with foetal and maternal intravascular catheters. Foetal plasma thyroxine levels ranged from 4·6 to 6·2 μg/100 ml between 103 days of gestation and the day of birth. Maternal plasma thyroxine levels varied between 2·3 and 4·1 μg/100 ml over the same period. The maternal: foetal ratio across the placenta for thyroxine varied from 0·52 to 0·65. Distribution of radioactive thyroxine injected into the foetal or maternal circulation demonstrated the impermeability of the placenta to thyroxine. Maternal to foetal ratios for labelled thyroxine were 6·2 to 11·9 when injected into the maternal circulation and 0·013 to 0·003 when injected into the foetal circulation. The sheep placenta appears to be capable of actively transporting iodide to maintain a foetal to maternal iodide ratio of up to 8:1.
Foetal thyroxine utilization was of the same order at 111 days of gestation as immediately before parturition when expressed per unit body weight. Utilization of thyroxine per kg by the foetus was about five times that of the mother. Various factors which influence thyroid function are discussed and the activity of the foetal pituitary—thyroid system is compared with other foetal endocrine systems.
DEVELOPMENT OF THE MECHANISMS INVOLVED IN THE FACILITATORY AND INHIBITORY EFFECTS OF OVARIAN STEROIDS ON THE RELEASE OF FOLLICLE-STIMULATING HORMONE IN THE IMMATURE RAT
Authors: CALIGARIS L. , ASTRADA J. J. , TALEISNIK S. 
Published: December 2008

SUMMARY
Serum follicle-stimulating hormone (FSH) concentration was found to be higher in neonatal female rats than in adults. The values increased to a maximum on day 15 and decreased thereafter. Ovariectomy soon after birth or at 5 days of age induced a significant rise in serum FSH concentration 9 days later. Administration of 10 μg oestradiol benzoate (OB) lowered FSH concentration in both intact and spayed animals.
Progesterone (1 mg) injected 3 days after priming female rats with a single dose of 10 μg OB induced, on the same day, a significant rise in serum FSH concentration in animals older than 22 days of age. In younger animals progesterone reversed the effect of OB. The facilitatory effect of progesterone occurred when the hormone was given in the afternoon but not when it was given in the morning.
Male rats, although showing the negative feedback effect of OB injection, failed to show the positive feedback effect of progesterone.
It is concluded that the central nervous system—hypophysial mechanism responsible for FSH secretion is ready to function before puberty. In female rats initiation of puberty probably depends on the activation of that mechanism by appropriate facilitatory ovarian steroid signals.
CHANGES IN SERUM GONADOTROPHIN LEVELS, AND IN PROTEIN LEVELS AND IN-VIVO INCORPORATION OF [35S]METHIONINE INTO PROTEIN OF DISCRETE BRAIN AREAS AND THE ANTERIOR PITUITARY OF THE RAT DURING THE OESTROUS CYCLE
Authors: HAAR M. B. ter , MacKINNON P. C. B. 
Published: December 2008

SUMMARY
Serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were measured by radioimmunoassay in groups of Wistar rats at 6-hourly intervals during the course of a 4-day oestrous cycle. In addition to a surge at about 18.00 h on the day of pro-oestrus, a circadian rhythm in LH levels was observed which was accentuated during metoestrus. FSH levels showed a protracted periovulatory rise which reached peak levels at about 03.00 h on the day of oestrus. A daily rhythm was not observed.
The incorporation of [35S]methionine (injected subcutaneously 1 h before death) into the trichloroacetic acid-precipitable proteins of the anterior pituitary and of discrete brain areas implicated in the control of gonadotrophin release, was also measured. An increase in protein synthetic activity was observed in the anterior pituitary and the area of the median eminence on the evening of pro-oestrus with peak levels coinciding with the LH surge at 18.00 h on the day of pro-oestrus. An increase in protein synthetic activity relative to that in a 'control' area (the putamen) was observed in the preoptic area and in the amygdala 15–18 h before the LH surge. It is suggested that these changes in protein synthetic activity are associated with the train of neural and humoral events leading to ovulation.
After ovariectomy, protein synthetic activity in all areas investigated was at the low levels observed during the oestrous cycle. Daily injections of 20 μg oestradiol benzoate into intact females led to levels of protein synthesis as great as, or greater than, the maximal levels observed during the oestrous cycle.
Measurements of variations in total protein concentration/unit wet weight of pituitary or brain tissue showed that they were apparently unrelated to variations in protein synthetic activity. Protein concentration appeared to be high in all the brain samples taken at oestrus and low in those taken at metoestrus. Furthermore, superimposed upon a marked daily rhythm, there was a peak of protein concentration on the evening of dioestrus both in the preoptic area and in the area of the median eminence.
THE ROLE OF THE PINEAL COMPLEX AND LATERAL EYES IN THE COLOUR CHANGE RESPONSE OF THE DOGFISH, SCYLIORHINUS CANICULA L.
Authors: WILSON J. F. , DODD J. M. 
Published: December 2008

SUMMARY
The effects of black and white illuminated backgrounds, and darkness, on the colour-change responses of intact, blinded and pinealectomized Scyliorhinus canicula were investigated. Blinding caused an immediate darkening response followed by a gradual paling, the background responses being absent, while darkness produced a further slight paling in blinded fish indicating a non-visual response. Pinealectomy did not affect the background responses but the normal paling response in darkness was abolished and the fish darkened. The latter result demonstrates a paling mechanism, mediated by the pineal, the interaction of which with the known inhibitory control system for melanophore-stimulating hormone release allows an interpretation of the chromatic responses.
THE EFFECT OF FASTING AND GLUCOSE LOAD ON INSULIN SECRETION AND THE STAUB—TRAUGOTT PHENOMENON IN PIGS
Authors: ANDERSON D. M. 
Published: December 2008

SUMMARY
Pigs were fasted for 18, 39, or 72 h; they were then given two glucose infusions, the second infusion 40 min after the first. Either 0·15, 0·30 or 0·75 g glucose/kg were given at each infusion. Plasma glucose, free fatty acids, insulin and 3-hydroxybutyrate concentrations were measured. The rate of glucose removal Kt was calculated after the first infusions, (Kt1), and after the second infusion (Kt2).
When food was withheld the peak insulin concentration decreased in response to glucose but lack of food only affected the mean increase in insulin concentration when 0·75 g glucose/kg was given. The value of Kt1 decreased as the period without food increased and additions of insulin did not affect the difference in Kt1 between animals fasted for 18 h and those fasted for 72 h. Plasma insulin concentration was closely related to the rate of glucose removal; the correlation coefficient (r) for maximum rate of glucose removal versus maximum insulin concentration was 0·9; and that for mean rate of glucose removal versus mean increment in insulin concentration was 0·84. It is suggested that insulin does not itself determine the rate of glucose removal but is secreted in response to the amount of glucose removed.
In the pig, the Staub—Traugott phenomenon was found to occur only under special circumstances. The relationship between Kt1 and Kt2 depended on the amount of glucose infused and the time during which food was withheld. Kt2 ranged from smaller than—through the same as—to greater than Kt1. The concentrations of free fatty acids, ketones or insulin did not explain the differences.
THE EFFECTS OF NEONATAL ANDROGEN ADMINISTRATION ON THE AGGRESSION AND RELATED BEHAVIOUR OF MALE GOLDEN HAMSTERS DURING INTERACTIONS WITH FEMALES
Authors: PAYNE A. P. , SWANSON H. H. 
Published: December 2008

SUMMARY
Male golden hamsters received either 300 μg testosterone propionate or oil on day 1 of life. As adults they were observed (i) when intact (ii) when castrated and (iii) when receiving 1 mg testosterone propionate per day in interactions with intact dioestrous females. Male controls which had received oil neonatally resembled normal untreated males in showing less aggressive behaviour than females. Castration and subsequent androgen administration did not affect aggression in the controls. Conversely, neonatally androgenized males showed comparable levels of aggression to the females with which they interacted. Castration reduced aggressive behaviour in these males, while subsequent androgen administration resulted in them showing significantly more aggression than females. In particular, when intact or receiving androgen replacement, neonatally androgenized males attacked and bit females, a behaviour seldom seen in normal males or in those given oil neonatally. Sexual investigation and following decreased in both groups of males after castration, and increased under androgen replacement. These changes were more pronounced in the neonatally androgenized males, indicating a greater behavioural responsiveness to androgens in this group. It is suggested that the behaviour of the normal male hamster is incompletely 'masculinized' during neonatal development, and the possible adaptive significance of this is discussed.
LOCALIZATION OF ETHYNYLOESTRADIOL IN THE REPRODUCTIVE TRACT OF WOMEN
Authors: REED M. J. , FOTHERBY K. , STEELE S. J. 
Published: December 2008

SUMMARY
[4-14C]Ethynyloestradiol was administered to women at varying times before hysterectomy. At operation, samples of blood, adipose tissue and tissue from the reproductive tract were obtained. All tissues examined took up radioactivity, the concentration at 1 h varying from 0·22 to 0·4% of the dose per 100 g of tissue except for stroma and endometrium which showed high levels (0·68% and 0·60%, respectively). By 24 h the amount of radioactivity in the tissues had decreased markedly. Mean values for the amount of radioactivity present in total tissues at 1 h were: uterus, 0·9%; adipose tissue, 28·2%; blood, 8·8%. By 24 h these values had declined to 0·2%, 6·8% and 1·6%, respectively. In adipose tissue almost all the radioactivity was present in a freely extractable state whereas in myometrium and cervix about 20% of the radioactivity was in a conjugated form. In plasma, more than 80% of the metabolites were conjugated, mainly as sulphates. The major metabolite detected in the uterus was ethynyloestradiol itself and most of the radioactivity in the myometrium was associated with the nuclear fraction. In one pregnant subject studied, radioactivity crossed the placenta and small amounts of the dose were found in the foetus.
INSULIN RELEASE FROM HUMAN FOETAL PANCREAS IN TISSUE CULTURE
Authors: LEACH F. N. , ASHWORTH M. A. , BARSON A. J. , MILNER R. D. G. 
Published: December 2008

SUMMARY
Various methods of tissue culture were studied in an attempt to grow human foetal pancreas under conditions favourable for insulin release. Simple dicing of pancreas was superior to plasma clot adhesion or collagenase digestion for the preparation of tissue for culture. The culture medium described by Kahri (1966) (containing 25% heated postnatal calf serum) was the most suitable of four tested for the study of insulin release from the tissue culture. In this medium insulin could be measured quantitatively by radioimmunoassay and insulin degradation occurred at the rate of 20–25%/24 h. In other media the pancreas grew less well or insulin degradation was much greater.
Human foetal pancreas grown under optimal conditions released insulin for up to 34 days. Insulin released into the culture medium did not appear to inhibit the further release of insulin. In some experiments the total amount of insulin released into the culture medium was several-fold greater than that in the pancreas originally seeded. In acute incubation experiments barium and theophylline stimulated insulin release from pancreas cultures. It proved impossible to identify the cells from which insulin was released but they did not appear to be in the monolayer which was composed of fibroblasts.