bluuebunny/crossref_metadata_2025_split huggingface dataset:
Superovulation in the cow: comparison of oestradiol-17β and progesterone patterns in plasma and milk of cows induced to superovulate; relationships with ovarian responses
Authors: Saumande J. , Batra S. K. 
Published: December 2008

ABSTRACT
Free oestradiol-17β, free+conjugated oestradiol-17β (total oestradiol-17β) and progesterone in milk, and free oestradiol-17β and progesterone in plasma were measured in 16 cyclic cows injected with FSH to induce superovulation during the treatment and periovulatory periods. The patterns of steroid secretion were the same in milk as in plasma but at different concentrations. Among oestrogens, the highest concentrations were measured for total oestradiol-17β in milk, followed by free oestradiol in plasma and free oestradiol in milk. Progesterone concentrations in milk were higher than in plasma. The peak concentrations of oestrogens were related to ovulation rate: Spearman Rank Correlation coefficient (r.s.) = 0·87 (P < 0·001), 0·78 (P < 0·001) and 0·69 (P < 0·001) for total oestradiol, free oestradiol in milk and free oestradiol in plasma respectively. The increase in progesterone concentrations in milk between the beginning of treatment and prostaglandin injection was negatively correlated with the percentage of viable embryos among those recovered (r.s. = −0·68; P < 0·001). This was not observed for progesterone in plasma. These results therefore show that the steroid pattern in milk gives a better indication as to the ovarian response to a superovulatory treatment than does the steroid pattern in plasma. In addition the fact that milk samples are easier to obtain and handle than blood plasma have led us to conclude that, to follow the effect of gonadotrophin stimulation, it would be more informative to assay oestradiol-17β and progesterone in milk rather than in plasma.
J. Endocr. (1985) 107, 259–264
The functional significance of glycosylation of proopiomelanocortin in melanotrophs of the mouse pituitary gland
Authors: Jenks B. G. , Ederveen A. G. H. , Feyen J. H. M. , van Overbeeke A. P. 
Published: December 2008

ABSTRACT
Pro-opiomelanocortin (POMC) is a glycoprotein precursor for a number of neuropeptides and peptide hormones. The functional significance of the glycosylation of POMC has never been established. Using the antibiotic tunicamycin to block glycosylation of the prohormone in the mouse pars intermedia, we have compared processing of non-glycosylated prohormone with that of glycosylated prohormone in pulse-chase experiments. The peptides produced from non-glycosylated prohormone were shown to be correct cleavage products. Therefore it was concluded that, with the possible exception of peptides from the N-terminal region of the prohormone, the carbohydrate on POMC plays no role in directing cleavage or in protecting the prohormone from random proteolysis. Tunicamycin treatment retarded N-terminal acetylation of melanotrophin but had no apparent effect on acetylation of β-endorphin. The mouse pars intermedia synthesizes two forms of POMC which differ in their degree of glycosylation. Our results indicated that, during secretion, the melanotrophs make no distinction between peptides derived from the two prohormones.
J. Endocr. (1985) 107, 365–374
Identification and measurement of 4-oestren-3,17-dione (19-norandrostenedione) in porcine ovarian follicular fluid using high performance liquid chromatography and capillary gas chromatography–mass spectrometry
Authors: Khalil M. W. , Walton J. S. 
Published: December 2008

ABSTRACT
4-Oestren-3,17-dione (19-norandrostenedione) has been identified as a major steroid in porcine ovarian follicular fluid for the first time. This steroid was isolated by C18 reverse-phase high performance liquid chromatography (HPLC) and its structure was established unambiguously by capillary gas chromatography–mass spectrometry. The mean concentration in pooled fluid obtained from prepubertal gilts determined by HPLC and capillary gas chromatography was 1·71 μmol/l. The level of this steroid in fluid obtained from large preovulatory follicles of sows exceeded 21·0 μmol/l on days 19 and 20 of the oestrous cycle. The high levels of this steroid within the follicle during the follicular phase might imply a possible biological role in follicular development and oocyte maturation.
J. Endocr. (1985) 107, 375–381
Identification of 3β-hydroxy-5,7-androstadien-17-one as a secretory product of the fetal horse gonad in vivo and in vitro
Authors: Raeside J. I. , Renaud R. L. 
Published: December 2008

ABSTRACT
Isolation of 3β-hydroxy-5,7-androstadien-17-one, as a major component of steroids extracted from vein blood of the fetal gonads of the horse, supports the proposed role for the compound as a precursor for equilin formation in the placenta of the mare. The 5,7-diene was extracted from blood collected from gonadal veins of fetal ovaries and testes in situ, and from a fetal testis connected to an artery in the neck region of the mare. Perfusion of fetal gonads in the laboratory was carried out to allow longer periods of collection. In addition, isolated cell preparations from a fetal testis were incubated for 4–8 h in tissue culture to investigate steroid secretion in vitro. Final purification of neutral steroids in the extracts was carried out by high performance liquid chromatography, and identification was made by u.v. and mass spectrometry. The presence of 3β-hydroxy-5,7-androstadien-17-one in extracts from all sources provided evidence for its secretion in vivo and in vitro. Other 5,7-dienes, which were less polar than the C19 compound, were noted in extracts of media but not identified. These data support the view that a 5,7-diene pathway is involved in the biosynthesis of 3β-hydroxy-5,7-androstadien-17-one in the fetal horse gonad.
J. Endocr. (1985) 107, 415–419
Effects of β-aminobutyric acid receptor agonists on the secretion of growth hormone, luteinizing hormone, adrenocorticotrophic hormone and thyroid-stimulating hormone from the rat pituitary gland in vitro
Authors: Anderson R. A. , Mitchell R. 
Published: December 2008

ABSTRACT
The effects of the γ-aminobutyric acid receptor agonists muscimol and baclofen were investigated on the secretion of GH, LH, ACTH and TSH from the anterior pituitary in vitro using a rapid superfusion system. A bicuculline-sensitive stimulatory effect of muscimol was demonstrated on the secretion of GH, LH and ACTH but not TSH. Baclofen had no effect on the basal secretion of any of the hormones, but inhibited LH-releasing hormone-stimulated release of LH and K+- and Ba2+-stimulated release of ACTH. The benzodiazepine Roll-6896 and the barbiturate secobarbital were found to potentiate the effect of muscimol on GH secretion. These results demonstrate the presence of GABAA receptors on somatotrophs, gonadotrophs and corticotrophs, and the presence of GABAB receptors on gonadotrophs and corticotrophs. Thyrotrophs appear devoid of GABA receptors.
J. Endocr. (1986) 108, 1–8
Failure of glucocorticoid feedback in males of a population of small marsupials (Antechinus swainsonii) during the period of mating
Authors: McDonald I. R. , Lee A. K. , Than K. A. , Martin R. W. 
Published: December 2008

ABSTRACT
In an investigation of the factors leading to the increase in the concentration of plasma free glucocorticoid, which results in immunosuppression and death after mating of all males in natural populations of a small shrew-like marsupial, the dusky antechinus (Antechinus swainsonii), the integrity of the glucocorticoid feedback control of the concentration of plasma cortisol was examined by use of dexamethasone-suppression tests.
Injection of 0·2 mg dexamethasone/kg i.m. caused a marked fall in the concentration of plasma cortisol 17 h later, approximately 2 months and 2 weeks before the annual mating period in mid-July. However, the same dose had no significant effect on the increased concentration of plasma cortisol characteristic of the mid- to late July mating period.
Injection of 100 i.u. ACTH/kg i.m. caused a significant increase in the concentration of plasma cortisol 6–7 h later on all occasions, indicating that the responsiveness of the adrenal cortex to ACTH did not change. Pretreatment with dexamethasone had no effect on the ACTH-stimulated cortisol concentration, ruling out a possible direct effect of dexamethasone on adrenocortical secretion in this species. Dexamethasone also reduced the concentration of plasma testosterone when the level was low, before the mating period, but not when the level was high, at the beginning of the mating period.
It is concluded that, in association with a rapid increase in the concentration of plasma testosterone, an increase in aggression and intense mating activity, glucocorticoid feedback control of ACTH secretion is impaired. This contributes to the rapid and sustained rise in the concentration of plasma free cortisol to immunosuppressive levels.
J. Endocr. (1986) 108, 63–68
Pancreatic α cell function in the fetal and newborn pig
Authors: Silver M. , Fowden A. L. , Comline R. S. , Bloom S. R. 
Published: December 2008

ABSTRACT
Plasma glucagon concentrations were measured in chronically catheterized fetal pigs during the last third of gestation and compared with the values observed in anaesthetized fetuses of similar gestational age. The mean plasma concentration of glucagon in the chronically catheterized fetuses was 10·0 ± 1·4 (s.e.m.) pmol/l (n = 11; term = 114 ± 2 days). Concentrations were increased after catheterization and fell to baseline values within 48 h of surgery. Arginine infusion evoked a rapid release of glucagon in chronically catheterized fetuses between 105 and 108 days of gestation; the mean maximum increment in plasma glucagon was 15·4 ± 4·5 pmol/l (n = 5). Plasma glucagon concentrations increased with increasing gestational age in both anaesthetized and chronically catheterized fetuses. Between 95 and 110 days of gestation, glucagon levels were significantly higher in anaesthetized fetuses than in chronically catheterized animals with similar normal pH values. Catheterization and prematurity had no apparent effect on plasma glucagon levels at birth. The plasma concentrations at birth were similar to those observed in the chronically catheterized fetuses in utero provided the piglets did not become acidotic during delivery. Significantly higher plasma levels of glucagon were found in newborn piglets with acidaemia (pH < 7·3) than in piglets with normal pH values at birth (pH > 7·3). When all the data from the newborn piglets were combined, there was a significant negative correlation (r= − 0·79, n = 39, P < 0·01) between blood pH and the plasma concentration of glucagon at birth. These observations demonstrate that the fetal α cells are functional and responsive in utero and at birth.
J. Endocr. (1986) 108, 137–142
Paradoxical LH and prolactin responses to naloxone after chronic treatment with morphine
Authors: Almeida O. F. X. , Schulz R. , Herz A. 
Published: December 2008

ABSTRACT
A series of experiments was conducted in adult male rats to study the development of tolerance to and dependence on morphine in the neural processes controlling LH and prolactin secretion. The central mechanisms controlling both these hormones became tolerant following chronic application of the opiate agonist; this was seen in the form of diminished responsiveness to the agonist with time. There was an apparently greater degree of tolerance in the mechanisms regulating LH secretion than in those regulating prolactin secretion.
In parallel experiments, the opiate antagonist naloxone was used to test for the development of dependence in rats chronically treated with morphine. While behavioural signs of physical dependence (withdrawal) were evident, the LH and prolactin responses proved to be the same as those observed in response to acute administration of opiate agonists (i.e. naloxone respectively decreased and increased serum LH and prolactin concentrations in animals chronically treated with morphine). This paper may represent the first report of such paradoxical responses to naloxone. It also demonstrates that opioid tolerance and dependence may exist as two separate phenomena in vivo.
J. Endocr. (1986) 108, 181–189
Effects of oestradiol, the oestrous cycle and pregnancy on weight, metabolism and cytosol receptors in the uterus of the brush-tail possum (Trichosurus vulpecula)
Authors: Curlewis J. D. , Stone G. M. 
Published: December 2008

ABSTRACT
Uterine weight, RNA, DNA, protein content, in-vitro rate of protein synthesis, cytosol oestrogen and progesterone receptors were examined after administration of oestradiol to ovariectomized animals and on days 0, 5, 9 and 13 of the non-pregnant cycle and day 13 of pregnancy. In ovariectomized animals, oestradiol increased uterine weight, RNA: DNA and protein: DNA ratios and the concentration of cytosol receptors for oestradiol and progesterone. During the oestrous cycle there was a linear increase in uterine weight and a significant effect of the corpus luteum on the weight of the ipsilateral uterus. Changes in RNA, DNA and protein content between days 0 and 5 were not observed, but between days 5 and 13 RNA: DNA and protein: DNA ratios increased and the DNA: tissue weight ratio decreased. Thus, cellular hypertrophy and/or increased metabolic activity rather than hyperplasia occur over this period, which is coincident with the known rise in plasma progesterone levels. The rate of in-vitro protein synthesis (per unit tissue protein) during the non-pregnant cycle was greatest at day 0. These changes in uterine metabolic activity were associated with alterations in cytosol receptor concentrations for both steroids. Cytosol progesterone receptor concentrations were highest at day 0 after which they declined to a minimum at day 13. Cytosol oestradiol receptor concentrations, however, rose between days 0 and 5 and then declined. Although lutectomy on day 8 of the cycle does not interfere with the development of a histologically normal luteal phase, high peripheral progesterone levels which occur after day 8 in intact animals are associated with major increases in uterine metabolic activity.
The unilateral effect of the corpus luteum on uterine weight was associated with a decrease in DNA: g tissue ratio and an increase in rate of in-vitro protein synthesis indicating hypertrophy and/or extracellular accumulation of secreted material as well as enhanced metabolic activity. There was a significant effect of pregnancy on uterine weight at day 13 and this was associated with an increase in DNA content of both uteri. There was a unilateral effect of pregnancy on RNA: DNA ratio and in-vitro rate of protein synthesis, but not on uterine weight.
J. Endocr. (1986) 108, 201–210
Sodium dependence of the thyrotrophin-induced depolarization in cultured porcine thyroid cells
Authors: Hambleton T. A. , Bourke J. R. , Huxham G. J. , Manley S. W. 
Published: December 2008

ABSTRACT
Cultured porcine thyroid cells exhibit a resting membrane potential of about − 73 mV and depolarize to about − 54 mV on exposure to TSH. The depolarizing response to TSH was preserved in a medium consisting only of inorganic salts and buffers, but was abolished in sodium-free medium, demonstrating dependence on an inward sodium current. Increasing the potassium concentration of the medium resulted in a reduction in the resting membrane potential of 60 mV per tenfold change in potassium concentration, and a diminished TSH response. A hyperpolarizing TSH response was observed in a sodium- and bicarbonate-free medium, indicating that a hyperpolarizing ion current (probably carried by potassium) was also enhanced in the presence of TSH. Tetrodotoxin blocked the TSH response. We conclude that the response of the thyroid cell membrane to TSH involves increases in permeability to sodium and potassium, and that the thyroid membrane ion channels bear some similarity to the voltage-dependent sodium channels of excitable tissues, despite the absence of action potentials in the thyroid.
J. Endocr. (1986) 108, 225–230
Different mechanisms controlling FSH and LH release in Japanese quail (Coturnix coturnix japonica): evidence for an inherently spontaneous release and production of FSH
Authors: Hattori A. , Ishii S. , Wada M. 
Published: December 2008

ABSTRACT
Plasma concentration of FSH and LH and their content in the adenohypophyses of Japanese quail were estimated by homologous radioimmunoassays based on chicken hormones. The results consistently showed that the plasma concentration of FSH was slightly higher than that of LH, although the FSH content in the adenohypophysis was much lower than that of LH in immature, mature and acutely photostimulated quail. These results prompted experiments in vitro to determine whether the difference was intrinsic. Adenohypophyses were collected and each cut mid-sagittally into two halves; one half was incubated for 20 h with or without chicken hypothalamic extract, and the medium was changed every 1 or 2 h to estimate the FSH and LH released. The other half served to estimate the initial content of FSH and LH in the adenohypophysis. The amount of FSH released was three times more than the original content even when adenohypophyses were incubated without hypothalamic extract, and the residual FSH content in the pituitary after 20 h of incubation was equal to the initial FSH content. In contrast, under the same incubation conditions, little LH was released and the residual LH content was decreased. When hypothalamic extract was added to the medium, LH release was enhanced sixfold compared with the control, whereas the increase in FSH was less than twofold. Spontaneous FSH release was markedly decreased in a Ca2+-deficient incubation medium, suggesting that the release was not due to leakage but to an active secretion mechanism. We therefore suggest, for the first time, that the release and production of FSH are largely autonomous, whereas release and production of LH are rigidly controlled and regulated by the releasing hormone in avian species.
J. Endocr. (1986) 108, 239–245
Influence of acute intracerebroventricular (i.c.v.) administration of adrenocorticotrophin (ACTH) on LH secretion in male rats: effect of pretreatment (i.c.v.) with ACTH antiserum on the serum LH response to an acute ether stress
Authors: Mann D. R. , Evans D. C. , Jacobs V. L. , Collins D. C. 
Published: December 2008

ABSTRACT
Adult male rats with chronic indwelling intracerebroventricular (i.c.v.) and jugular catheters were given an i.c.v. injection (over 1 min) of 1, 10, 100 ng or 1 μg ACTH(1–24), or 300 ng ACTH(4–10) or saline, and blood samples were taken 0, 5, 15, 30 and 60 min later. Increasing dosages of ACTH(1–24) caused a dose-related rise in serum LH levels. Peak levels of serum LH (ranging from 157 to 473% of pretreatment levels) were reached 5–15 min after treatment, and then serum LH values returned to pretreatment levels by 60 min. The serum LH response to 1 μg ACTH(1–24) did not differ from the response to 100 ng ACTH(1–24). Administration (i.c.v.) of 300 ng ACTH(4–10) was also effective in increasing serum LH values. Repeated withdrawal of blood during the experiment increased serum corticosterone values in all groups including saline-treated), but i.c.v. administration of ACTH(1–24) or ACTH(4–10) did not further increase serum corticosterone levels. Two additional groups of rats were injected i.p. with either saline or pentobarbital (30 mg/kg body weight) 1 h before i.c.v. administration of 10 ng ACTH(1–24) and blood samples were taken as in the other groups. The animals in these groups did not show a rise in serum LH concentrations in response to ACTH(1–24). In a third experiment, rats were pretreated (i.c.v.) with either ACTH antiserum (ACTH-Ab) or normal rabbit serum 15 min before a 2-min ether stress. The ether stress evoked a significant rise in serum LH concentrations within 15 min. Serum LH levels then fell below the 0-min value by 60 min. Pretreatment with ACTH-Ab failed to alter the serum LH response to this acute stress. The failure of ACTH-Ab to alter the response to stress suggests that the central nervous system ACTH does not play a physiological role in this process. Alternatively, we cannot be certain that the potency of the ACTH-Ab was sufficient to neutralize central nervous system ACTH effectively.
J. Endocr. (1986) 108, 275–280
Effects of various melatonin treatments on plasma prolactin concentrations in the ewe
Authors: Poulton A. L. , English J. , Symons A. M. , Arendt J. 
Published: December 2008

ABSTRACT
Ewes were treated with s.c. implants of melatonin in mid-April, mid-May and mid-June. From mid-June, other animals were given oral doses of melatonin daily at 16.30 h and another group was maintained under a short (8 h light: 16 h darkness) artificial photoperiod (lights out 16.30 h). Serial blood samples were taken from all animals in June and July. Plasma prolactin concentrations were significantly reduced in ewes treated in May and June (implant, oral and photoperiod treatments) but not in those treated in April. After treatment in June, prolactin levels were significantly suppressed after 7 days of oral and implant melatonin therapy, and after 28 days of a short artificial photoperiod. Melatonin treatment appeared more efficient than an artificial photoperiod in reducing plasma prolactin concentrations.
J. Endocr. (1986) 108, 287–292
Endocrine control of smoltification in anadromous salmonids
Authors: Barron M. G. 
Published: December 2008

ABSTRACT
The parr–smolt transformation (smoltification) of juvenile anadromous salmonids involves a morphological, physiological and behavioural metamorphosis of the fish from a freshwater-adapted form to a saltwater-adapted form. Several endocrine glands are activated during the period of smoltification, including pituitary, thyroid, and interrenal tissues. The pituitary-thyroid axis appears to be the endocrine system most directly involved in controlling smoltification. A plasma thyroid hormone surge occurs during smoltification which appears to influence various tissues and other endocrine systems, and to induce the well-documented developmental changes associated with smoltification.
The pituitary-interrenal axis has been implicated in several smoltification-related events, including development of hypo-osmotic regulatory ability. A plasma cortisol surge closely follows the thyroid hormone surge during smoltification, but in contrast to anuran metamorphosis, the peaks do not coincide. Despite recent attention, the role of the corticosteroids in development of hypo-osmotic regulatory ability remains unclear. The other endocrine tissues of the salmonids appear to be acting trophically with the thyroid hormones, or to have little involvement in the control of smoltification.
J. Endocr. (1986) 108, 313–319