bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF STRESS AND ENVIRONMENTAL TEMPERATURE ON ADRENAL FUNCTION IN RANA ESCULENTA
Authors: JURÁNI M. , MURGAŠ K. , MIKULAJ L. , BABUŠÍKOVÁ F.
Published: December 2008

The effect of immobilization for 60 min on the adrenal activity of frogs (Rana esculenta) was studied by measuring corticosterone in plasma and corticosterone and catecholamines in adrenorenal homogenates. An increase in plasma corticosterone and in noradrenaline in the adrenorenal homogenate was observed after immobilization for 5 min and there was further increase after prolonged immobilization. However, there was no change throughout the period of immobilization in the corticosterone and adrenaline content of the adrenorenal homogenates. When frogs were exposed to various environmental temperatures the resting plasma corticosterone level did not change at temperatures below 20 °C, but rose significantly at temperatures above 20 °C. No increase in plasma corticosterone concentration occurred at 1 °C after corticotrophin (ACTH) administration. At higher temperatures (up to 30 °C) a significant correlation was found between plasma corticosterone levels after ACTH administration and environmental temperature. No further increase in plasma corticosterone took place at temperatures up to 40 °C. The results indicate a rapid activation of both the interrenal and chromaffin components of the adrenal gland in Rana esculenta when subjected to this type of stress. Changes in plasma corticosterone levels resulting from changes in environmental temperature may be either an expression of specific changes in steroidogenesis of the adrenals, or of the entire metabolic activity of the organism.
THE SEPARATION OF DIFFERENT FORMS OF MELANOCYTE-STIMULATING HORMONE FROM THE RAT NEUROINTERMEDIATE LOBE BY POLYACRYLAMIDE GEL ELECTROPHORESIS, WITH A NOTE ON RAT NEUROPHYSINS
Authors: BAKER BRIDGET I.
Published: December 2008

Extracts of rat neurointermediate lobes were subjected to electrophoresis on polyacrylamide gels at both acidic and alkaline pH. Melanocyte-stimulating hormone (MSH) was located in the gels by the Anolis skin method and was associated with bands of stainable material. Three bands with MSH activity were located after electrophoresis on acidic gels and two bands after electrophoresis on alkaline gels. The identity of these bands is discussed. Two further bands on the alkaline gels were associated with neurophysins.
THE PO2, PCO2, pH AND OXYGEN CONTENT OF OVARIAN VENOUS BLOOD OF SHEEP
Authors: BAIRD D. T. , GILES M. , COCKBURN F.
Published: December 2008

The PO2, PCO2, pH and oxygen content were measured in blood from the carotid artery, and jugular and ovarian veins of six sheep with cervical ovarian autotransplants. The PO2 in ovarian venous blood (56·0 ± 3·9 (s.e.m.) mmHg) was lower than that in carotid arterial blood (94·3 ± 8·3) but higher than that in jugular venous blood (43·4 ± 3·1). The oxygen content of ovarian venous blood was significantly higher than that of jugular venous blood. The high PO2 and oxygen content in ovarian venous relative to jugular venous blood together with the high blood flow suggests the possibility of arterio-venous shunts within the ovary or its vascular pedicle.
THYROID FUNCTION IN MOLYBDENOTIC RABBITS
Authors: WIDJAJAKUSUMA M. C. R. , BASRUR P. K. , ROBINSON G. A.
Published: December 2008

The endocrine activity of the thyroid glands of rabbits fed a diet containing 0·3% molybdate ion for 25 and 31 days was evaluated. Means (± s.e.m.) were plasma thyroxine (T4) concn (μg/100 ml): 15 molybdate-fed rabbits, 2·31 ± 0·34; 19 control rabbits, 4·40 ± 0·34. T4 distribution space (ml/100 g body wt): molybdate-fed rabbits, 21·5±2·1; controls, 21·4 ± 0·9. T4 secretion rate (μg/24 h/100 g): molybdate-fed rabbits, 0·320 ± 0·073; controls, 0·601 ± 0·046. Histometric measurements made on photographs of gland sections showed that the follicular epithelial cells formed 12·8% of the total area in molybdate-fed rabbits and 25·8% in controls. The histological appearance of the sections was one of increased colloidal storage and of epithelial inactivity in the molybdate-fed rabbits. Comparisons with glands from a food-restricted group of rabbits supported the view of thyroidal hypofunction in molybdenosis in rabbits, with reduced food intake as the major causal factor. Some additional degeneration of the thyroid gland was attributed directly to the molybdate ion.
THE INHIBITION BY PROGESTERONE OF UTERINE EPITHELIAL PROLIFERATION IN THE MOUSE
Authors: MARTIN L. , DAS R. M. , FINN C. A.
Published: December 2008

Progesterone given at the same time as oestradiol-17β prevented approximately 40% of uterine luminal epithelial cells from entering DNA synthesis, but did not prolong the G1, S or G2 phases in the remainder. However, it blocked the entry of these cells into a second round of DNA synthesis. It is suggested that uterine luminal epithelial cells are only sensitive to progesterone for a limited period in G1.
SEX DIFFERENCES IN GROWTH OF GUINEA-PIGS AND THEIR MODIFICATION BY NEONATAL GONADECTOMY AND PRENATALLY ADMINISTERED ANDROGEN
Authors: SLOB A. K. , GOY R. W. , ten BOSCH J. J. van der WERFF
Published: December 2008

One group of animals received androgen prenatally, by daily s.c. injections of 5 mg testosterone propionate (TP) to the doe on days 24 to 41 inclusive of pregnancy, while a second group remained untreated. Some animals of each group were gonadectomized on the day of birth (= day 1) or on day 2. Weight at birth served as a measure of prenatal growth. Comparisons were made between animals born in litters of identical size. Postnatal growth was studied by weighing the animals at 5-day intervals until the age of 130 days. Comparisons were made between groups of animals that were matched for their weights at birth.

At birth males from TP-treated mothers were heavier than their sisters and heavier than control males. After birth, control males grew at faster rates than control females. This difference was not affected by neonatal gonadectomy, but from pubertal age onward the difference decreased and gonadectomized males and females were similar in growth. Female pseudohermaphrodites (from TP-treated mothers), both intact and neonatally ovariectomized, had growth curves similar to those of appropriate male controls at prepubertal ages; at postpubertal ages they were not significantly different from their female counterparts. It is concluded that the sex difference in the rate of prepubertal growth is determined by the absence or presence of androgens before birth, and that the difference in postpubertal growth rate is caused by the stimulatory action of the testes and inhibitory action of the ovaries. It was further found that normal female guinea-pigs have a secondary spurt in growth rate, some time after puberty, whereas in males this was much less clear.
EVIDENCE FOR A TIME DELAY BETWEEN PROLACTIN RELEASE AND THE RESULTING RISE IN MILK SECRETION RATE IN THE RAT
Authors: GROSVENOR C. E. , MENA F.
Published: December 2008

The mammary glands of rats either maintained continuously in the animal room on day 14 post partum or isolated in a room without other rats on day 21 post partum, refilled only partially within 8 h after the pups had withdrawn the milk from the glands by suckling with the aid of oxytocin injections to the mother. The partial refilling occurred regardless of whether or not the release of prolactin at the time of suckling was blocked by an injection of an extract of stalk median eminence (SME). The mammary glands of rats not injected with SME continued to refill and reached near capacity within 16 h whereas those of the SME-injected rats failed to refill any further. The glands of the SME-injected rats could be stimulated to refill more completely within 8 h after the initial emptying provided prolactin either was injected or was released endogenously by exposing the mothers to exteroceptive signals from their pups midway during the 8-h period of non-suckling which preceded the initial emptying. More complete mammary refilling also occurred within 8 h if a 4-h rather than an 8-h period of non-suckling preceded the initial emptying of the glands. The results of these investigations indicate that the prolactin released by suckling at the time of the initial emptying of the glands influenced only that milk which reaccumulated in the emptied glands during the 8th—16th h following suckling. The milk which reaccumulated during the first 8 h appeared to be influenced by prolactin released several hours before suckling.

The results suggest, therefore, that a time delay of several hours exists from the time of release of prolactin by suckling until the full stimulatory effect of the hormone upon milk secretion is manifest. Thus the milk secreted after emptying of the glands at a given suckling would be the result of prolactin released earlier either at previous sucklings or in response to exteroceptive stimulation.
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

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

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

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

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

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

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

[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

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

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

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

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

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

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

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

[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

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.
THE MAINTENANCE OF PREGNANCY, AND PARTURITION, IN GUINEA-PIGS HYPOPHYSECTOMIZED WITHIN 4 DAYS OF MATING
Authors: ILLINGWORTH DOREEN V. , PERRY J. S. , ACKLAND NICOLA , BURTON ANGELA M.
Published: December 2008

Pregnancy was sustained to term (>63 days) in 15 out of a total of 46 guinea-pigs, hypophysectomized within 4 days after mating. The majority (22/29) of complete or partial abortions occurred between 20 and 35 days post coitum. Analysis of plasma samples showed that the pregnant hypophysectomized animals with live foetuses had high progesterone and progesterone-binding protein concentrations, equivalent to those found in intact pregnant guinea-pigs. Animals that received daily injections of cortisone acetate from day 55 (7/15) gave birth to live young at the normal time (67–68 days). Plasma samples from one animal taken during parturition showed no measurable oxytocin in maternal plasma, but oxytocin was present in foetal plasma at the moment of birth.
THE RELATIONSHIP BETWEEN FOOD, GASTRO-INTESTINAL HORMONES AND CALCITONIN SECRETION
Authors: SWAMINATHAN R. , BATES R. F. L. , BLOOM S. R. , GANGULI P. C. , CARE A. D.
Published: December 2008

The role of calcitonin (CT) in postprandial calcium homeostasis and the possibility of a gastroentero-thyroid C-cell system was studied in young pigs. When pigs were fasted for more than 36 h and then fed, the plasma calcium concentration decreased by 6·1% over a period of 60–120 min after a meal. Since in thyroidectomized pigs the plasma calcium concentration increased by 7·2% when they were fed after a fast of 36 h it is suggested that increased CT secretion assists in the control of postprandial hypercalcaemia. Direct measurement of CT in peripheral plasma supported this suggestion. Because the plasma calcium concentration in an intact pig on a normal feeding regime does not change after a meal, the possibility of the involvement of one or more humoral factors in the stimulation of thyroid C-cells was investigated. Exogenous gastrin and endogenous gastrin stimulated by meat extract were both previously shown by us to increase CT secretion rate. This observation has now been extended to include other stimuli to endogenous gastrin, e.g. glycine and gastric distension. Furthermore, partially purified enteroglucagon increased CT secretion rate from perfused thyroid glands, isolated in situ. Stimulation of endogenous entero-glucagon by the intraduodenal administration of glucose, and probable stimulation of endogenous pancreozymin by intraduodenal fat, were both associated with an increased CT secretion rate from the thyroid gland.

These results support the concept of a gastroentero-thyroid C-cell system which serves to stimulate CT secretion and thus to protect the skeleton from excessive bone resorption during periods of dietary sufficiency.
RADIOIMMUNOASSAY OF PLASMA ADRENOCORTICOTROPHIN IN CUSHING'S SYNDROME
Authors: CROUGHS R. J. M. , TOPS C. F. , de JONG F. H.
Published: December 2008

The present study describes a radioimmunoassay for plasma adrenocorticotrophin (ACTH) in man with a sensitivity of at least 15 pg/ml. In-vitro studies using various fragments of ACTH showed immunobiological dissociation. However, this phenomenon does not appear to be of major importance in vivo, since stimulation and suppression tests showed overall parallel changes of immunoreactive plasma ACTH and plasma cortisol. The results obtained from patients with various forms of Cushing's syndrome are presented. It is concluded that basal plasma ACTH determinations are useful in the differential diagnosis of Cushing's syndrome and may help in predicting the development of a pituitary tumour after adrenalectomy.

The supranormal plasma cortisol response to i.m. injection of lysinevasopressin in subjects with pituitary-dependent Cushing's syndrome is attributed both to an increased ACTH release by the pituitary and to an excessive response of the hyperplastic adrenal cortex. The i.v. infusion of dexamethasone at a rate of 1 mg/h for 5 h in subjects with pituitarydependent Cushing's syndrome was followed by significant and parallel decreases of both immunoreactive plasma ACTH and plasma cortisol. No rise of plasma ACTH levels was found with insulin-induced hypoglycaemia in subjects with untreated pituitary-dependent Cushing's syndrome.
CIRCADIAN PERIODICITY OF PITUITARY-ADRENAL FUNCTION AFTER p-CHLOROPHENYLALANINE ADMINISTRATION IN THE RAT
Authors: van DELFT A. M. L. , KAPLANSKI J. , SMELIK P. G.
Published: December 2008

Two days after a single or repeated administration of p-chlorophenylalanine (p-CPA; 316 mg/kg i.p.) in the rat, a marked diminution to 20% of control levels of brain 5-hydroxytryptamine, partial but not complete abolition of the circadian pituitary—adrenal rhythm and a profound decrease in adrenal responsiveness to ether stress or exogenous adrenocorticotrophin were found. Pituitary—adrenal activity in unstressed or stimulated animals was assessed by the level of corticosterone in plasma and the corticosteroid production by adrenal tissue in vitro. The effect of p-CPA administration on changes in pituitary—adrenal periodicity were concomitant with a reduction in food intake and body growth and a pronounced increase in adrenal weight. In the light of the marked functional alterations after p-CPA treatment, the proposed relationship between decreased brain 5-hydroxytryptamine content and pituitary—adrenal periodicity is questioned.
ANDROGEN METABOLISM IN THE VENTRAL SEBACEOUS GLAND PATCH OF THE MONGOLIAN GERBIL
Authors: HODGINS M. B. , HAY J. B.
Published: December 2008

The metabolism of [7α-3H]dehydroepiandrosterone (DHA), [7α-3H]-androstenedione and [7α-3H]testosterone was studied in the ventral sebaceous gland patch of the Mongolian gerbil in vitro. The main enzyme activities found were 17β-hydroxysteroid dehydrogenase, 5α-reductase, 17α-hydroxysteroid dehydrogenase, 3α-hydroxysteroid dehydrogenase, sulphotransferase and hydroxylase. The active androgen 5α-dihydrotestosterone was formed in appreciable amounts from both testosterone and androstenedione. The 17β-hydroxysteroid dehydrogenase actively formed both 17-oxo and 17β-hydroxysteroids in this tissue. The conversion of DHA to C4–5 unsaturated steroids and 5α-steroids was not observed presumably due to a lack of 3β-hydroxysteroid dehydrogenase Δ4–5isomerase. The metabolism was compared with that in human and rat skin and its significance discussed.
THE EFFECT OF SYNTHETIC HYPOTHALAMIC RELEASING FACTORS ON PLASMA LEVELS OF LUTEINIZING HORMONE IN THE COCKEREL
Authors: FURR B. J. A. , ONUORA G. I. , BONNEY ROSEMARY C. , CUNNINGHAM F. J.
Published: December 2008

The capacity of synthetic luteinizing hormone releasing factor (LH-RF) to stimulate the release of luteinizing hormone (LH) from the pituitary gland of the cockerel has been examined. Administration of LH-RF to 21 intact and 12 castrated cockerels aged between 14 and 20 months resulted in a rapid increase in the levels of LH in the plasma within 5–10 min of injection in both groups of birds. Plasma LH then declined rapidly and returned to basal values within 1 h. The amount of LH released in the intact birds was dependent on the dose of LH-RF. Concentrations of LH in the plasma did not increase after injection of thyroid-stimulating hormone releasing factor but the response of the pituitary gland to a subsequent injection of LH-RF 2 h later was not altered. The pattern of release of LH in the cockerel is compared with that of some mammalian species.
EFFECT OF HYPOTHALAMIC RELEASING FACTORS AND STEROIDS ON RELEASE OF GONADOTROPHINS BY ORGAN CULTURES OF HUMAN FOETAL PITUITARIES
Authors: GROOM G. V. , BOYNS A. R.
Published: December 2008

Release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from organ cultures of human foetal pituitaries was stimulated by ovine hypothalamic extract (OHE), synthetic gonadotrophic hormone releasing factor and dibutyryl cyclic AMP. In each case, LH release was greater than that of FSH. Synthetic gonadotrophic hormone releasing factor produced an increase in the total FSH and LH content of the cultures.

Oestradiol-17β stimulated release of FSH but not LH. Testosterone, progesterone and 5α-dihydrotestosterone were without effect on hormone release. Chronic exposure of cultures to progesterone prevented stimulation of hormone release by OHE. Long-term contact with oestradiol-17β did not modify tissue sensitivity to OHE.
KINETIC STUDIES ON THE ENZYMES CATALYSING THE CONVERSION OF 17α-HYDROXY-PROGESTERONE AND DEHYDROEPIANDROSTERONE TO ANDROSTENEDIONE IN THE HUMAN ADRENAL GLAND IN VITRO
Authors: YATES JEAN , DESHPANDE N.
Published: December 2008

Factors controlling the synthesis of androstenedione in the human adrenal gland were investigated in a kinetic study of the enzymes catalysing the conversion of 17α-hydroxyprogesterone and dehydroepiandrosterone to the hormone. Both reactions are associated with the microsomal fraction of the adrenal cell. 17α-Hydroxyprogesterone is converted to androstenedione by a NADPH-dependent 17-desmolase whereas there is an obligatory requirement for NAD+ for the conversion of dehydroepiandrosterone to the hormone. None of the other cofactors investigated inhibited or enhanced the enzymic conversions.

The side-chain cleavage of 17α-hydroxyprogesterone was competitively inhibited by the precursors of the substrate, pregnenolone, progesterone and 17α-hydroxypregnenolone. Other C19 or C18 compounds known to be synthesized by the human adrenal gland were found to be ineffective in modifying the enzyme action. The conversion of dehydroepiandrosterone to androstenedione was non-competitively inhibited by oestrone and oestradiol-17β. No C21 compounds were found to affect the reaction. 5α-Dihydrotestosterone (17β-hydroxy-5α-androstan-3-one) inhibited both enzymic conversions competitively but the inhibition constants observed were so high that it is unlikely that this finding has any relevance to the control of androstenedione synthesis in vitro.
CHORIONIC GONADOTROPHIN IN THE HUMAN PLACENTA IN RELATION TO THE SEX OF THE FOETUS AT TERM
Authors: HOBSON BRUCE , WIDE LEIF
Published: December 2008

Human chorionic gonadotrophin (HCG) was assayed by biological and radioimmunological methods in 40 human term placentae. It was found that the concentration of HCG per g and per placenta was lower when the sex of the foetus was male than when it was female. This difference is significant (P < 0·005) and applies to the results obtained both in the biological and the radioimmunological assays.
THE MECHANISM OF ANDROGEN UPTAKE AND CONCENTRATION BY RAT VENTRAL PROSTATE IN ORGAN CULTURE
Authors: LASNITZKI ILSE , FRANKLIN HILARY R. , WILSON JEAN D.
Published: December 2008

The uptake and metabolism of [1,2-3H]dihydrotestosterone and [1,2-3H]-testosterone by explants of rat ventral prostate maintained in organ culture have been assessed under circumstances in which constant intracellular levels of the hormones have been achieved. Dihydrotestosterone was the principal intracellular androgen whether the hormone in the incubation medium was testosterone or dihydrotestosterone, and intracellular to extracellular gradients for dihydrotestosterone were greater than those for testosterone under all conditions studied. These findings are compatible with the possibility that the conversion of testosterone to dihydrotestosterone and the subsequent binding of dihydrotestosterone to receptor sites within the tissue serve to keep the activity of intracellular testosterone low and to promote passive diffusion down an activity gradient from blood. The net effect of such a system is the development in the prostate of a higher concentration of total androgen (testosterone plus dihydrotestosterone) than in the medium.
THE CONCENTRATIONS OF ANDROGENS, OESTROGENS, PROGESTERONE AND LUTEINIZING HORMONE IN THE SERUM OF FOETAL CALVES THROUGHOUT THE COURSE OF GESTATION
Authors: CHALLIS J. R. G. , KIM C. K. , NAFTOLIN F. , JUDD H. L. , YEN S. S. C. , BENIRSCHKE K.
Published: December 2008

The concentrations of luteinizing hormone (LH), progesterone, testosterone, androstenedione, oestrone and oestradiol in mixed umbilical cord blood taken from foetal calves during months 3 to 9 of gestation have been measured by radioimmunoassay. The levels of progesterone were low (compared with those in maternal plasma) and constant during pregnancy. There were large variations in the concentrations of androstenedione, oestrone, oestradiol and LH, with lower values found during months 7 to 8 of gestation. Significant differences (P < 0·05–< 0·001) in hormone levels between male and female foetuses were found for testosterone, LH, and the oestrogens during months 3 to 7, 3 and 4, and 7 and 8, respectively. No significant differences (P > 0·05) between sexes were found at any time between the concentrations of progesterone and androstenedione.
EFFECT OF HUMAN CHORIONIC GONADOTROPHIN ON TESTOSTERONE SECRETION BY THE FOETAL HUMAN TESTIS IN ORGAN CULTURE
Authors: ABRAMOVICH D. R. , BAKER T. G. , NEAL P.
Published: December 2008

Foetal human testes (12–22 weeks gestation), maintained in organ culture, were treated with human chorionic gonadotrophin (HCG) and the amount of testosterone produced compared with control cultures. In all cases the testes produced testosterone, but from the 13th to 18th week of gestation significantly more testosterone was produced by, and the Leydig cell hyperplasia was maintained in, the HCG stimulated organ cultures. It is suggested that HCG is ultimately responsible for differentiation of the human male external genitalia.
CONVERSION OF PROGESTERONE TO ANDROGENS BY NON-FLAGELLATE GERMINAL CELLS ISOLATED FROM SEMINIFEROUS TUBULES OF RAT TESTIS
Authors: GALENA H. J. , TERNER C.
Published: December 2008

A method is described for the isolation of non-flagellate germinal cells of the testis. The interstitial cells were removed by submersion of teased seminiferous tubules in distilled water. The interstitial cells exposed to water burst while the germinal cells inside the tubules remained intact. The tubules were then homogenized in isotonic saline and the non-flagellate germinal cells (spermatocytes and young spermatids) were isolated by centrifugation and filtration through a layer of Sephadex G-25 gel. On incubation with progesterone these cells produced 17α-hydroxyprogesterone, androstenedione, and testosterone. The rate of conversion of progesterone to testosterone in vitro was 0·20 μg/h/109 germinal cells. These results suggest that the non-flagellate germinal cells of the testis may make a significant contribution to the production of androgens.
HUMAN FOETAL SYNTHESIS OF TESTOSTERONE FROM PERFUSED PROGESTERONE
Authors: TAYLOR T. , COUTTS J. R. T. , MACNAUGHTON M. C.
Published: December 2008

Two male and four female human foetuses of 16–20 weeks gestation were perfused with [4-14C]progesterone. Subsequently, testosterone and androstenedione bearing a 14C-label were isolated in significant amounts from the testes and adrenals, respectively, of the male foetuses. Both C19-steroids were also isolated from the perfusate of one of the male foetuses. Neither C19-steroid was present in the livers of the male foetuses or in the ovaries, adrenals, livers or perfusates of the female foetuses.

It is concluded that the mid-term male foetus can readily synthesize testosterone from the large amounts of progesterone of placental origin present in the foetal circulation. The results suggest that the conversion is primarily a testicular function, but a direct or indirect adrenal involvement cannot be excluded.