bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of hypophysectomy and metyrapone on the catecholamine content and volumes of adrenaline- and noradrenaline-storing cells in the rat adrenal medulla
Authors: Coupland R. E. , Tomlinson A. , Crowe J. , Brindley D. N. 
Published: December 2008

ABSTRACT
Using morphometric analysis and high-pressure liquid chromatography with electrochemical detection of catecholamines the volumes of adrenaline-storing (A) and noradrenaline-storing (NA) cells and the adrenaline and noradrenaline contents of adrenal glands of normal and age-matched hypophysectomized rats were determined and compared. Some hypophysectomized rats were also administered 150 mg metyrapone/kg daily for a 4-week period.
Hypophysectomy resulted in an increase in noradrenaline storage in adrenal glands. This was more marked in hypophysectomized animals not treated with metyrapone even though the combination of metyrapone and hypophysectomy resulted in a reduction of blood corticosterone concentration to only ∼ 6% normal.
There was no evidence of a change in proportion of A and NA cells in the adrenal medulla of hypophysectomized rats or hypophysectomized animals treated with metyrapone and it is concluded that the changes in amine concentrations and proportions observed reflect an increase in the storage of noradenaline in A cells as a consequence of less efficient methylation of noradrenaline after hypophysectomy.
The findings also showed that the left adrenal gland and medulla was usually slightly larger and had a greater catecholamine content and slightly higher proportion of NA cells than the right adrenal gland. During the period of the experiment (animals aged 6–15 weeks) there was an increase in the concentration of both adrenaline and noradrenaline in the normal adrenal glands. In normal Sprague—Dawley rats weighing 140 and 400 g the adrenal medulla accounted for some 5% of adrenal volume; this increased to 13% after hypophysectomy; A and NA cells together accounted for 50–60% of the volume of adrenal medulla.
J. Endocr. (1984) 101, 345–352
Characteristics of corticosteroid inhibition of adrenocorticotrophin release from the anterior pituitary gland of the rat
Authors: Mahmoud S. N. , Scaccianoce S. , Scraggs P. R. , Nicholson S. A. , Gillham B. , Jones M. T. 
Published: December 2008

ABSTRACT
The occurrence and nature of corticosteroid inhibition of ACTH secretion at the rat anterior pituitary gland was investigated using three experimental models: animals bearing lesions of the basal hypothalamus, and two preparations of the gland incubated in vitro; these were tissue segments and collagenase-dispersed cells. Release of ACTH in the experiments was provoked using one of three distinct stimuli: acid extracts of whole hypothalami, corticotrophin releasing activity released by serotonin from hypothalami incubated in vitro and synthetic ovine corticotrophin releasing factor. Irrespective of whether ACTH was measured directly by radioimmunoassay (in the experiments in vitro) or indirectly in terms of corticosterone production (in the lesioned animals), its stimulated release from the anterior pituitary gland was inhibited by corticosterone. Two phases of inhibition were observed; these had some of the characteristics inferred previously from experiments with intact animals and designated fast feedback and delayed feedback.
However, the fast feedback demonstrable in lesioned animals did not show the rate-sensitivity shown previously in intact animals. 11-Deoxycortisol (or 11-deoxycorticosterone) and prednisolone proved to be agonists of corticosterone in provoking fast feed-back in lesioned animals, whereas they had been shown respectively to act as an antagonist or to have no effect in intact rats. Several steroids were able to cause delayed feedback in lesioned rats, but beclomethasone dipropionate (shown to be an agonist of corticosterone in intact rats) proved to have no inhibitory effect at the anterior pituitary gland of lesioned animals.
It is concluded that the dynamics of corticosteroid feedback mechanisms at the anterior pituitary gland, as indicated by experiments in lesioned animals, differ from those operative in the intact animals. Other work suggests that a more important site for such inhibitory mechanisms in vivo is the hypothalamus.
J. Endocr. (1984) 102, 33–42
Use of the perifusion technique on rat thyroid fragments in the study of thyroid hormone secretion: short-term effects of thyrotrophin, theophylline and glucagon
Authors: Attali J. R. , Darnis D. , Valensi P. , Weisselberg C. , Sebaoun J. 
Published: December 2008

ABSTRACT
Perifusion of rat thyroid fragments was performed to study short-term effects of TSH, theophylline and glucagon on thyroid hormone secretion. This technique proved to be relatively convenient and sensitive, and gave reproducible results for at least 3 h, permitting precise kinetic studies of response to hormonal and pharmacological agents without any interference. There was a significant (P < 0·001) linear correlation between the log TSH concentrations over the range 20–150 mu./ml and thyroid response. A second stimulation, using the same concentration of TSH, did not differ from the first stimulation if they were separated by an active 'washing' period of only 15 min. Theophylline also had a stimulating effect and like TSH induced an early release of the hormone fraction with a peak between 2 and 4 min, but it did not potentiate the TSH effect.
Perifusion of rat thyroid fragments was found to be a useful tool for analysing dynamic effects of various substances. These effects were significant for periods of time as short as 20 min. Each thyroid preparation could be used a second time for another pharmacological or hormonal test. Our preliminary results also suggested that there was a direct glucagon effect on thyroid hormone secretion with a dose–response correlation.
J. Endocr. (1984) 102, 43–48
The role of steroid hormones, prolactin and placental lactogen on mammary gland development in ewes and heifers
Authors: Schams D. , Rüsse I. , Schallenberger E. , Prokopp S. , Chant J. S. D. 
Published: December 2008

ABSTRACT
In the first part of the investigations the interaction between oestradiol-17β, progesterone and prolactin on the formation of the lobuloalveolar structure of the mammary gland was studied in 21 nulliparous intact postpubertal ewes. Tissue specimens of the mammary gland were evaluated by light microscopical examination and prolactin was measured in blood samples. Combined treatment with oestradiol and progesterone induced physiological development of the lobuloalveolar structure of the mammary gland in the presence of prolactin. Suppression of prolactin by bromocriptine prevented this effect. Treatment with progesterone alone was not effective and revealed histological structures comparable to the controls. The interaction of oestradiol-17β with prolactin appears to be a main trigger for mammary gland development.
In the second part of the investigations the effect of bromocriptine treatment during pregnancy on mammary gland development was studied in primigravid ewes and heifers. Mammary gland specimens were obtained for light and electron microscopical evaluation in ewes and heifers 5 and 10 days respectively before the expected date of parturition. Concentrations of prolactin and ovine placental lactogen were determined by radioimmunoassay. Bromocriptine treatment suppressed prolactin concentrations in ewes to minimal values but did not affect ovine placental lactogen concentrations. The histological evaluation revealed almost comparable stages of mammogenesis in both ewes and heifers. This effect can be attributed, at least in ewes, to the action of placental lactogen on mammogenesis. Placental lactogen might therefore be of physiological relevance during mammogenesis.
J. Endocr. (1984) 102, 121–130
Sexual inhibition in a prosimian primate: a pheromone-like effect
Authors: Schilling A. , Perret M. , Predine J. 
Published: December 2008

ABSTRACT
The effect of dominant urine odour on plasma levels of testosterone and cortisol was studied in the prosimian primate Microcebus murinus. This species shows a photoperiod-dependent cycle of sexual activity. In particular, mean testosterone levels vary from 15 nmol/l during the annual rest period to 245 nmol/l during the breeding season. When males of this solitary and territorial species are artificially grouped in captivity, they develop a social hierarchy which in turn results in physiological disorders, especially of reproductive function, in non-dominant individuals. Since olfactory behaviours appear to be important in the establishment and maintenance of the social structure, we have tested the effects of dominant odorant signals upon the sexual inhibition observed in male conspecifics. A preliminary experiment showed that a decrease in plasma testosterone concentrations could be induced by dominant scent marks. Furthermore, dominant urine odour alone was found to be sufficient to induce this modification. Plasma cortisol levels also increased in these animals. Conversely, when sexually inhibited males were olfactorily isolated from dominant urine odour, testosterone and cortisol concentrations returned to a normal seasonal level. These effects were observed even in males which had had no previous contact with the dominant urine donor. It is inferred from these results that a pheromone-like process could lead to sexual inhibition in male Microcebus murinus exposed to an odorant urinary signal produced by a dominant individual. Nevertheless, the endocrine response seems to vary according to the seasonal period of the sexual activity cycle which suggests that the social effect described is modulated by other external (e.g. photoperiodic) or internal (e.g. reproductive physiology) factors.
J. Endocr. (1984) 102, 143–151
Inhibition by testosterone of prolactin and growth hormone release from chicken anterior pituitary glands in vitro
Authors: Hall T. R. , Harvey S. , Chadwick A. 
Published: December 2008

ABSTRACT
Pituitary glands and hypothalami from broiler fowl were incubated in medium containing testosterone, and prolactin and GH release were determined. Pituitary glands were also preincubated for 20 h in medium containing testosterone, and then in medium containing various secretagogues.
Testosterone inhibited the release of prolactin directly from the pituitary gland in a concentration-related manner. The hypothalamus stimulated the release of prolactin, but by a lesser amount in the presence of testosterone. When pituitary glands were preincubated with testosterone, subsequent release of prolactin was inhibited, except with the highest concentration which stimulated prolactin release. Hypothalamic extract (HE) markedly stimulated prolactin release from control pituitary glands although testosterone-primed glands were less responsive. The stimulation of prolactin release by thyrotrophin releasing hormone (TRH) and prostaglandin E2 (PGE2) was also reduced by preincubation of the pituitary glands with testosterone.
Priming with testosterone did not affect the release of GH from pituitary glands alone, but reduced the TRH-, HE- and PGE2-stimulated release of GH. These results demonstrate that testosterone directly inhibits prolactin secretion and reduces the sensitivity of pituitary lactotrophs and somatotrophs to provocative stimuli.
J. Endocr. (1984) 102, 153–159
Effect of adrenalectomy and steroid treatment on rat skin cytosol glucocorticoid receptor
Authors: Smith K. , Shuster S. 
Published: December 2008

ABSTRACT
Using an exchange assay to measure occupied and unoccupied binding sites, the glucocorticoid receptor in rat skin cytosol has been measured after adrenalectomy and parenteral steroid administration. Adrenalectomy increased the number of receptor sites with maximal effect after 5 days, after which numbers decreased to those of intact animals. Injection of adrenalectomized animals with the unlabelled agonist corticosterone resulted in a rapid dose-related decrease in the number of cytosolic receptor sites at 30 min whereas the antagonist progesterone had no effect. It is concluded that changes in glucocorticoid concentration lead to rapid inverse changes in cytosolic receptor.
J. Endocr. (1984) 102, 161–165
Seasonal differences in ovarian activity in cows
Authors: McNatty K. P. , Hudson N. , Gibb M. , Henderson K. M. , Lun S. , Heath D. , Montgomery G. W. 
Published: December 2008

ABSTRACT
The plasma concentrations of LH and prolactin and various parameters of ovarian function were examined in cows on known days of the oestrous cycle during May and June (autumn and winter) and during October (spring).
Luteinizing hormone peak frequency and plasma prolactin concentrations were significantly higher in October than during the May–June period (LH, P<0·05; prolactin, P<0·01). The mean diameters of large healthy follicles (≥8 mm diameter) and the dominant oestrogen-secreting follicles were significantly larger (P<0·01 for both follicle types) and each follicle contained more granulosa cells (both P<0·01) in May–June than in October. The LH responsiveness of theca interna with respect to androstenedione production and the levels of aromatase activity in granulosa cells did not differ with time of year. The corpora lutea were heavier (P<0·05) and secreted more progesterone (P<0·01) in May–June than in October.
It is concluded that seasonal differences in ovarian activity exist in cows and that these differences are probably the consequence of seasonal differences in gonadotrophin secretion.
J. Endocr. (1984) 102, 189–198
Effects of pinealectomy, oestradiol and melatonin on plasma prolactin and LH secretion in ovariectomized sheep
Authors: Kennaway D. J. , Dunstan E. A. , Gilmore T. A. , Seamark R. F. 
Published: December 2008

ABSTRACT
The study examines whether the pineal gland mediates in the seasonal rhythm in the response of the hypothalamo-pituitary axis to oestrogen in the sheep. Five groups of ewes, each comprised of five sham-pinealectomized ewes and five pinealectomized ewes, were maintained under field conditions over a 2-year period. Group 1 ewes were ovariectomized and treated with two oestradiol capsules in the first year and one oestradiol capsule in the second year; group 2 ewes were ovariectomized and treated with two oestradiol capsules and three melatonin sachets in the first year and one oestradiol capsule and three melatonin sachets in the second year; group 3 ewes were ovariectomized and treated with three melatonin sachets in the first year and one oestradiol capsule in the second year; group 4 ewes were ovariectomized and treated with empty implants; group 5 had intact ovaries. Blood samples were taken at weekly intervals for determination of plasma prolactin, LH and FSH levels. Cyclic ovarian activity, determined by rams fitted with a marking harness, occurred in both sham-pinealectomized and pinealectomized ewes in group 5 during December to May in both years. A circannual rhythm in plasma prolactin levels was apparent in all ten groups of animals. The levels were highest in spring (September to November) and decreased before the onset of breeding activity in midsummer (December). Ovariectomized ewes with intact pineal glands and treated with oestradiol capsules (group 1) exhibited marked changes in LH and FSH concentrations during the study. The highest plasma gonadotrophin levels were observed coincident with the breeding season in control ewes (group 5). Continuous melatonin administration together with oestradiol (group 2, sham-pinealectomized) resulted in higher levels of gonadotrophins but the loss of the seasonal rhythm. However, melatonin alone was not able to alter gonadotrophin levels in either sham-pinealectomized or pinealectomized ovariectomized ewes. Pinealectomized ovariectomized ewes treated with oestradiol alone did not show a seasonal change in LH or FSH; in fact these animals appeared to be more sensitive to the negative feedback actions of oestradiol. Combined melatonin/oestradiol administration resulted in an increase in gonadotrophin levels but did not restore seasonality. These results suggest that the pineal gland is the mediator of the seasonal rhythm in oestradiol feedback sensitivity. It is apparent that a seasonal change in breeding activity can occur in the absence of any change in oestradiol feedback sensitivity. The results of this study highlight the complex nature of photoperiod/environment interactions involved in seasonal breeding.
J. Endocr. (1984) 102, 199–207
Insulin binding and action in adipocytes of pregnant rats: evidence that insulin resistance is caused by post-receptor binding defects
Authors: Sutter-Dub M. Th. , Sfaxi A. , Latrille F. , Sodoyez-Goffaux F. , Sodoyez J. C. 
Published: December 2008

ABSTRACT
Insulin resistance was investigated in the adipose cell of rats which were at days 16 and 20 of pregnancy. Data are presented to relate insulin binding and biological effect, which was evaluated by the ability of insulin to stimulate [1-14C]glucose oxidation. Adipocytes from pregnant rats bound more insulin than fat cells from control (non-pregnant) animals and the number of insulin receptors per adipocyte increased during pregnancy. Basal glucose oxidation rate was decreased at 16 and 20 days of pregnancy: however, the dose–response curve for insulin-stimulated glucose oxidation was significantly depressed only after 20 days of pregnancy. The concentration at which insulin increased glucose oxidation by 50% increased with the duration of pregnancy. We conclude that during pregnancy in the rat the adipocyte response to insulin was decreased, despite an increase in insulin binding. This result suggests that a major determinant of insulin resistance in rat adipocytes during pregnancy is present after the initial insulin–receptor interaction. Consequently, a post-receptor defect may be largely responsible for the insulin resistance.
J. Endocr. (1984) 102, 209–214
Effect of calcitonin on salivary phosphorus and calcium excretion in sheep
Authors: Matsui T. , Kanagawa Y. , Yano H. , Kawashima R. 
Published: December 2008

ABSTRACT
Three thyroidectomized sheep were infused intravenously with porcine calcitonin at a rate of 30 mi.u./h per kg and three sham-operated sheep were infused with vehicle for 5 h. Saliva was collected from the left parotid duct by cannulation for 10 min in every hour. Salivary secretion rates were not changed in either thyroidectomized or sham-operated sheep throughout the experiment. Before the infusion, salivary phosphorus excretion was less in thyroidectomized sheep than in sham-operated animals. Calcitonin infusion increased salivary phosphorus excretion and decreased serum phosphorus concentrations in thyroidectomized sheep. Vehicle infusion did not affect salivary phosphorus excretion in sham-operated sheep. Serum concentrations and salivary excretion of calcium were decreased by calcitonin infusion into thyroidectomized sheep but were not changed in sham-operated sheep infused with vehicle. Calcitonin infusion increased serum parathyroid hormone concentrations in thyroidectomized sheep after the decrease of serum calcium concentrations. However, vehicle infusion did not affect serum parathyroid hormone concentrations in sham-operated sheep. There was little change of cyclic AMP excretion during the experiment in either thyroidectomized or sham-operated sheep. It is concluded that calcitonin increases salivary phosphorus excretion in sheep.
J. Endocr. (1984) 102, 365–368
Receptors for thyroid-stimulating hormone in normal and pathological human thyroid tissues
Authors: Kermode J. C. , Edmonds C. J. , Morgans M. E. 
Published: December 2008

ABSTRACT
The receptors for TSH have been studied in human thyroid tissue to assess their density and binding characteristics in various disease states. A single set of similar independent receptors appeared to be present in both healthy and pathological thyroid tissue. Their binding affinity for bovine TSH averaged 1·1 × 1010l/mol in healthy tissue and, with the exception of papillary carcinoma which showed some reduction, was not significantly altered in the various disease states studied. No receptors with low binding affinity were found. The number of receptors was significantly greater in toxic diffuse goitre and in hyperfunctioning follicular adenoma (but these tissues came from patients given antithyroid drugs and often iodine preoperatively), and was reduced in Hashimoto's thyroiditis. In well-differentiated thyroid carcinoma, the number of receptors was similar to or greater than in normal tissue, but in undifferentiated and medullary carcinoma, and in lymphoma of the thyroid, receptors were completely absent. Tracer-binding data obtained with human TSH were uniformly lower than the corresponding data obtained with bovine TSH, but showed an analogous pattern of differences amongst the various normal and pathological tissues.
J. Endocr. (1984) 102, 369–374
CORTICOTROPHIN-RELEASING FACTOR - MEDIATED ADRENOCORTICOTROPHIN RELEASE FROM RAT ANTERIOR PITUITARY CELLS IS POTENTIATED BY C-TERMINAL GASTRIN-RELEASING PEPTIDE
Authors: Hale A.C. , Price J. , Ackland J.F. , Doniach I. , Ratter S. , Besser G.M. , Rees L.H. 
Published: December 2008

ABSTRACT
The remission of Cushing's syndrome following surgical removal of a tumour containing bombesin-like immunoreactivity (BLI), but insignificant levels of ACTH, is described. However, an acid extract of the tumour tissue caused the release of ACTH from isolated rat anterior pituitary cells in vitro. These observations led to an investigation of the effects of synthetic C-terminal gastrin-releasing peptide (GRP(14-27)) on ACTH release from isolated rat anterior pituitary cells. GRP(14-27) (10-1000 ng/ml) directly stimulated the release of ACTH in vitro, whereas lower doses (10-1000 pg/ml), ineffective themselves in eliciting ACTH release, potentiated the CRF-mediated in-vitro release of ACTH.
ABSENCE OF NUCLEAR PROGESTERONE RECEPTOR IN LH RELEASING HORMONE NEURONES IN LAYING HENS
Authors: Sterling R.J. , Gasc J.M. , Sharp P.J. , Tuohimaa P. , Baulieu E.E. 
Published: December 2008

ABSTRACT
Using a double immunohistochemical technique, LH releasing hormone (LHRH) neurones and 110kDa nuclear progesterone receptor were localized in the hypothalamus of the laying hen. Nuclear progesterone receptor was widely distributed throughout the hypothalamus, occurring in the preoptic, septal, anterior and basal areas. The region where progesterone receptor was revealed in nuclei of neurones overlapped that containing LHRH neurones. However, LHRH cell bodies did not contain progesterone nuclear receptor. It is concluded that the positive feedback action of progesterone on LH release is not mediated by a genomic mechanism within the LHRH neurone.
Involvement of rat corticotrophin-releasing factor-41-related peptide and vasopressin in adrenocorticotrophin-releasing activity from superfused rat hypothalami in vitro
Authors: Gillies G. , Puri A. , Hodgkinson S. , Lowry P. J. 
Published: December 2008

ABSTRACT
Superfused rat hypothalamic pieces stimulated with a high K+ medium released corticotrophin-releasing factor (CRF) as detected in the rat isolated anterior pituitary cell column bioassay. This activity has components related to ovine CRF-41 (oCRF-41) and vasopressin as assessed by the effects of specific antisera on the ACTH-releasing activity of the hypothalamic column effluent. Release of immunoactive vasopressin paralleled that of CRF bioactivity. Immunoactive oCRF-41 could not be detected, as it is likely to be below the sensitivity of present radioimmunoassays.
J. Endocr. (1984) 103, 25–29