bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perineal muscles: possible androgen regulation of glucocorticoid receptor sites in the rat
Authors: DuBois D. C. , Almon R. R. 
Published: December 2008

ABSTRACT
The glucocorticoid receptor population of the androgen-dependent levator ani–bulbo cavernosus muscle complex in response to both androgen withdrawal and androgen replacement was examined in rats. (1) After castration the concentration of receptor sites more than doubled. The increase in the sites began within the first 24 h after castration and reached a plateau level within 7 days. (2) Parallel dry weight studies demonstrated that no loss in muscle mass is observed until 48 h after castration. (3) In a second series of experiments, both the regrowth of the muscle and the number of receptor sites in response to androgen injections were examined. By day 11 of injection, the muscle had increased in dry weight to a point where it was equal to the size of this muscle in normal intact male controls. (4) During this process, the concentration of receptor sites began to decline 5 days after the beginning of injections and reached control or below control values by 11 days.
J. Endocr. (1984) 102, 225–229
Effects of prolactin, progesterone and ovariectomy on metabolic activities and insulin receptors in the mammary gland and adipose tissue during extended lactation in the rat
Authors: Flint D. J. , Clegg R. A. , Knight C. H. 
Published: December 2008

ABSTRACT
Prolactin implants prevented the decline in milk yield and the resumption of oestrous cycles which occurred between days 22 and 28 in untreated lactating rats. Ovariectomy and progesterone implants only partially prevented the decline in milk yield despite preventing the occurrence of oestrous cycles. All three treatments increased total RNA content of the mammary gland compared with controls. In untreated rats there were no changes in mammary DNA content or the number of insulin receptors whereas lipoprotein lipase (LPL) activity decreased significantly during the declining phase of lactation. In contrast, the number of insulin receptors, LPL activity and glucose incorporation into lipid increased in adipose tissue. Prolactin prevented the increase in insulin receptors and lipid synthesis and significantly decreased LPL activity in adipose tissue. Progesterone stimulated LPL activity in the mammary gland and also prevented the increase in lipid synthesis and insulin receptors in adipose tissue but was without effect on LPL activity whereas ovariectomy stimulated LPL activity in the mammary gland but prevented only the increase in the number of insulin receptors in adipose tissue.
The results show that raising the serum prolactin concentration can prevent the decline in milk yield during extended lactation and whilst part of this effect may be due to a direct effect on the mammary gland and an indirect effect due to inhibition of oestrous cycles, prolactin may also produce part of its effect on milk synthesis by inhibiting competitive metabolic processes in tissues such as adipose tissue.
J. Endocr. (1984) 102, 231–236
Evidence for the participation of a melanin-concentrating hormone in physiological colour change in the eel
Authors: Gilham I. D. , Baker B. I. 
Published: December 2008

ABSTRACT
The hormonal and nervous control of colour change in the eel has been investigated. The only bioactive forms of MSH found in eel pituitary extracts or secreted by eel pituitary cultures were forms of α-MSH; no β-MSH was detected. After transfer of eels from a black to a white background, the melanin concentration in skin melanophores was accompanied by a rapid decline in plasma α-MSH titres. Hypophysectomy resulted in melanin concentration, and pituitary extracts injected into hypophysectomized eels caused melanin dispersion. This effect was eliminated if the pituitary extracts were first incubated with a specific α-MSH antiserum or if the antiserum was injected into the hypophysectomized eel. However, injection of α-MSH antiserum into intact, black-adapted eels failed to result in melanin concentration although the same antiserum was effective in causing pallor in black-adapted toads. Partially purified preparations of teleost melanin-concentrating hormone (MCH), free from catecholamines, induced melanin concentration when injected into black-adapted eels and this effect was significantly potentiated by injections of α-MSH antiserum. The denervation of melanophores on the pectoral fin had only a slight effect on the responses of the melanophores to humoral agents. It is concluded that the control of physiological colour change in the eel is largely hormonal, and involves the antagonistic effects of α-MSH and a melanin-concentrating agent which is probably MCH.
J. Endocr. (1984) 102, 237–243
Some effects of parathyroidectomy on cell-mediated immune responses in the rat
Authors: Perris A. D. , Edwards D. J. , Atkinson M. J. 
Published: December 2008

ABSTRACT
Xenografts of mouse tail skin to the rib cages of normal and sham-parathyroidectomized rats caused an increase in plasma calcium concentration and concomitant increase in bone marrow mitosis. Neither was elicited in aparathyroid rats and graft survival was prolonged in these animals.
No hypercalcaemic episode was associated with the delayed hypersensitivity response induced by painting rat ears with oxazolone. Compared with the response in sham-parathyroidectomized rats, that in parathyroidectomized rats was enhanced although both responses were less than that in normal rats.
Parathyroidectomy of parental donors did not affect the ability of their splenic lymphocytes to mount a graft-versus-host response in F1 hybrid recipients. When sham-operated and aparathyroid parents were sensitized with F1 hybrid lymphocytes no differences were observed in a subsequent graft-versus-host response in F1 recipients. However, when aparathyroid F1 recipients were employed a marked reduction in the graft-versus-host reaction was observed.
Thus the clonal expansion of cells with specific reactivity to certain antigens in secondary lymphoid tissue, which is driven by those same specific antigens, is not affected or only moderately affected by the parathyroid status of the animal. However, the more general increase in lymphocyte numbers promoted by non-specific mitogenic lymphokines is markedly impaired in the hypocalcaemic parathyroidectomized rat. Furthermore, the parathyroid gland is essential for the development of a hypercalcaemic episode which follows antigenic challenge and causes cell proliferation in primary lymphoid tissues. This surge of mitosis could serve to replenish the depleted pools of virgin T and B lymphocytes in the secondary lymphoid tissue which occur as a result of their response to antigens.
J. Endocr. (1984) 102, 257–263
The use of salivary progesterone assays in the assessment of ovarian function in postmenarcheal girls
Authors: Read G. F. , Wilson D. W. , Hughes I. A. , Griffiths K. 
Published: December 2008

ABSTRACT
Menstrual cycle profiles of salivary progesterone were derived from daily samples obtained from 75 postmenarcheal girls aged between 12 and 17 years. Data were analysed to establish the proportion of girls exhibiting ovulatory cycles in each of several age groups following menarche or in groups based solely on chronological age. 'Luteal'-phase profiles of salivary progesterone, which were similar in shape to those characteristic of mature premenopausal women, were taken to indicate the probable occurrence of ovulation. The percentage of cycles in those subjects judged to be ovulatory, grouped according to gynaecological age, rose from 14% in the first year to 56% in the fourth year. Those classified according to chronological age, and where sufficient data permitted reliable estimates of the percentage of subjects ovulating, rose from 11% at 12 years of age to 64% for girls aged 16. These data are in reasonable concordance with published data using plasma progesterone and urinary methods for establishing ovulatory incidence, and indicate the value of salivary progesterone measurements in studies of ovarian function in adolescence.
J. Endocr. (1984) 102, 265–268
Varying sensitivity to the negative oestrogen feedback during the ovarian cycle of female rats: evidence for the involvement of oestrogen and the medial preoptic area
Authors: Döcke F. , Rohde W. , Gerber P. , Chaoui R. , Dörner G. 
Published: December 2008

ABSTRACT
The gonadotrophic response to a single injection of oestradiol benzoate (OB) was studied in acutely ovariectomized adult rats during the different stages of a 4-day ovarian cycle. The results showed a sudden decline of the sensitivity to the gonadotrophin-inhibiting effect of OB between metoestrus and dioestrus. This desensitization to the negative oestrogen feedback was probably caused by an oestrogen action on the medial preoptic area (MPOA). In rats ovariectomized and implanted with OB in the MPOA in metoestrus, an s.c. injection of OB on the presumptive day of pro-oestrus did not lower the circulating LH and FSH levels, whereas a clear suppression of gonadotrophin secretion was seen in females implanted with cholesterol in the MPOA or implanted with OB in the hypothalamic ventromedial–arcuate region. Similar findings were obtained in rats which had been ovariectomized 3–4 weeks before implantation. A final experiment demonstrated that bilateral lesioning of the MPOA also reduced the sensitivity to the negative feedback action of oestrogen in long-term ovariectomized rats. In all experiments performed, diminution of the oestrogen-induced inhibition of LH secretion was more marked than that of suppression of FSH secretion. It is proposed that desensitization to the negative oestrogen feedback, probably resulting from an inhibitory oestrogen action on medial preoptic neurones, is a prerequisite for adequate gonadotrophic support of preovulatory follicle maturation in the presence of a continuously rising oestrogen concentration in the blood.
J. Endocr. (1984) 102, 287–294
Progesterone interaction with eosinophils and with responses already induced by oestrogen in the uterus
Authors: Grunert G. , Porcia M. , Neumann G. , Sepúlveda S. , Tchernitchin A. N. 
Published: December 2008

ABSTRACT
Progesterone pretreatment decreases oestrogen-induced uterine eosinophilia and other non-genomic responses that are possibly mediated by eosinophils. To investigate the mechanisms of this interaction, the present study describes the effects of progesterone on oestrogenic responses already induced by oestrogen treatment and the in-vivo and in-vitro effects of progesterone on blood eosinophils.
Progesterone treatment of oestrogen-pretreated animals potentiated uterine eosinophilia 24 h after progesterone treatment but decreased it at later times and increased eosinophil degranulation in vivo. In addition, progesterone degranulated blood eosinophils in vitro. These findings demonstrate interaction of progesterone with oestrogenic responses mediated by eosinophils.
Progesterone interaction with other oestrogenic responses was analysed for comparison; evidence is shown suggesting a role of eosinophils in oestrogeninduced uterine luminal fluid accumulation.
J. Endocr. (1984) 102, 295–303
Interaction of prostaglandin E2 and β-adrenergic catecholamines in the regulation of uterine smooth muscle motility and adenylate cyclase in the rat
Authors: Krall J. F. , Barrett J. D. , Jamgotchian N. , Korenman S. G. 
Published: December 2008

ABSTRACT
Prostaglandin E2 (PGE2) increased the force of the spontaneous contractions of the rat myometrium and decreased the sensitivity of the uterus to the relaxing effects of the specific β-adrenergic catecholamine agonist isoprenaline. Prostaglandin E2, at concentrations above 10 μmol/l, increased cyclic AMP production by intact muscle strips. The muscle strips were far more sensitive, however, to the inhibitory effect PGE2 had on isoprenaline-dependent cyclic AMP production (threshold <0·001 nmol/l). Both PGE2 and isoprenaline stimulated adenylate cyclase activity of a myometrial subcellular (particulate) fraction in a guanyl nucleotide-requiring manner. When present in saturating concentrations (100 μmol/l), the stimulatory effects were not additive, suggesting that the receptors for the two agonists competed for the same catalytic subunit of adenylate cyclase or for the same guanyl nucleotide-requiring factor which couples receptors and enzyme. If muscle strips were incubated with PGE2 before the preparation of the adenylate cyclase-containing particulate fraction, the enzyme became less responsive to stimulation by guanyl nucleotide and by isoprenaline and PGE2 in the presence of guanyl nucleotide. The PGE2 receptor may therefore interact with the β-adrenoreceptor to inhibit isoprenaline-dependent cyclic AMP production by intact muscle cells by desensitizing adenylate cyclase, possibly at the level of the guanyl nucleotide-dependent coupling step.
J. Endocr. (1984) 102, 329–336
Evaluation of the biological properties of parathyroid hormone and analogues in a vascularly isolated parotid gland-based assay
Authors: Wright R. D. , Blair-West J. R. , Nelson J. F. , Tregear G. W. , Rosenblatt M. 
Published: December 2008

ABSTRACT
Infusion of bovine parathyroid hormone (bPTH) preparations into the arterial blood supply of the vascularly isolated parotid gland in anaesthetized sheep increases salivary phosphate concentration and gland blood flow rate with rapid onset and offset of action. These responses have been used as a bioassay for PTH and PTH analogues and for assessing the properties of an in-vitro inhibitory analogue [Nle-8, Nle-18, Tyr-34]bPTH-(3–34)amide. [Nle-8, Nle-18, Tyr-34]bPTH-(1–34)amide at 10− 9 to 10 −8 mol/l was four to five times more potent than bPTH(1–34) on both salivary phosphate and blood flow assays. Human PTH(1–34) was not significantly more potent than bPTH(1–34). The [Nle-8, Nle-18, Tyr-34]bPTH-(3–34)amide analogue had very slight agonist activity at 3 × 10−7 mol/l and at a 100:1 ratio of analogue to PTH it completely inhibited the action of bPTH(1–34) on phosphate secretion and gland blood flow. It caused partial inhibition at 10:1 and had no evident effect at 1:1. These results differ from previous in-vitro results and indicate that the preparation may be valuable for evaluation of agonist and antagonist analogues of PTH. The vascularly isolated parotid gland of the sheep permits repeated random testing of analogues in a control–test–control sequence and the results indicate high sensitivity to PTH in a rapidly reactive invivo system with two responding parameters.
J. Endocr. (1984) 102, 375–379
Effect of insulin on free fatty acid uptake by hepatocytes in the duck
Authors: Gross R. , Mialhe P. 
Published: December 2008

ABSTRACT
To elucidate the hypolipacidaemic effect of insulin in ducks, its action on the uptake of free fatty acids (FFA) by duck hepatocytes was determined. At low doses (10 mu./l) insulin stimulated FFA uptake. This effect was not observed with higher doses of insulin (20, 30 and 50 mu./l). Growth hormone at physiological concentrations and corticosterone (14·4 nmol/l) decreased basal activity, probably by reducing glucose metabolism and consequently α-glycerophosphate (α-GP) supply. Insulin was able to reverse the inhibition induced by GH and corticosterone on both FFA uptake and α-GP production. These results therefore suggest that the hypolipacidaemic effect of insulin may be partly mediated by its action on hepatic FFA uptake.
J. Endocr. (1984) 102, 381–386
Further characterization of corticotrophin releasing factor activity from a bronchial tumour
Authors: Kirkland S. C. , Lumsden J. L. , Ellison M. L. 
Published: December 2008

ABSTRACT
The nature of corticotrophin releasing factor (CRF) activity secreted by a human bronchial carcinoid cell line was investigated. The CRF activity in incubation media exposed to bronchial tumour cells was concentrated by preparative high pressure liquid chromatography (HPLC). Analytical HPLC resolved the CRF activity into several different forms.
The incorporation of [3H]leucine and other [3H]amino acids into materials which co-eluted with CRF activity when fractionated by analytical HPLC suggested that the bronchial carcinoid cells were secreting peptide CRF(s). The most abundant radioactive material was shown to have a molecular weight of 12 000 by sodium dodecyl sulphate gel electrophoresis. This radioactive fraction also stimulated ACTH secretion by rat pituitary cell cultures in a dose-responsive manner.
J. Endocr. (1984) 103, 91–96
Prolactin stimulates steroidogenesis by human luteal tissue in vitro
Authors: Hunter M. G. 
Published: December 2008

ABSTRACT
Human luteal tissue recovered from varying stages of the luteal phase was minced and incubated for 3 h and the effect of human chorionic gonadotrophin (hCG), prolactin and hCG + prolactin on progesterone and oestradiol production measured. While hCG generally enhanced both progesterone and oestradiol synthesis, prolactin alone at either 20 or 200 μg/l had no significant effect on steroidogenesis. When prolactin was added along with hCG in four of six corpora lutea, however, progesterone production significantly increased and in three of six corpora lutea oestradiol production was increased above that induced by hCG alone. It is concluded that prolactin may play some role in the control of steroidogenesis by the human corpus luteum.
J. Endocr. (1984) 103, 107–110
Studies on the control of prostaglandin production by the hypothalamus in relation to LH release in the rat
Authors: Brown C. G. , Poyser N. L. 
Published: December 2008

ABSTRACT
Prostaglandin (PG) and thromboxane (TX) synthesis by homogenates of the hypothalamus of rats has been measured in relation to the preovulatory surge of LH. Prostaglandin and TX production by the median eminence (ME) was five to ten times higher than that by the anterior hypothalamus/preoptic area (AH-POA). Prostaglandin E2 and PGF2α were the major prostaglandins synthesized by the ME and AH-POA respectively. During the 4-day oestrous cycle, the PG-and TX-synthesizing capacity of the ME showed daily changes, being high at 06.00 and 22.00 h and, with the exception of pro-oestrus, low at 18.00 h. There was an additional peak of PGE2 production by the ME at 18.00 h on pro-oestrus coincident with the preovulatory LH surge. Progesterone treatment stimulated PGE2 synthesis by the ME of long-term ovariectomized, oestradiol-primed rats but not by the ME of acutely ovariectomized, oestradiol-primed rats. 2-Hydroxyoestradiol had no effect on PG and TX production by the ME at 18.00 h on dioestrus or 18.00 h on pro-oestrus. Noradrenaline stimulated PG and TX synthesis by the ME at the former time but not at the latter time.
Prostaglandin F2α-synthesizing capacity of the AH-POA peaked at 22.00 h on each day of the 4-day cycle. There was also an additional peak at 14.00 h on each day except dioestrus. Similar peaks occurred in the production of PGE2 and TXB2, except on pro-oestrus when the production of each compound remained low. There was no association between increased PGE2 production by the AH-POA and the preovulatory surge of LH. Noradrenaline, but not 2-hydroxy-oestradiol, stimulated PG and TX production by the AH-POA at 18.00 h on both dioestrus and pro-oestrus. Progesterone stimulated PGE2, PGF2α and 6-oxo-PGF1α production by the AH-POA of acute, ovariectomized, oestradiol-primed rats but not of long-term ovariectomized, oestradiol-primed rats.
Flurbiprofen, a cyclo-oxygenase inhibitor, prevented the preovulatory LH surge in two rats and delayed the LH surge by 2 h in four rats. It also reduced PG and TX production by the ME and AH-POA. Overall, the present studies show that there is an increase in PGE2-synthesizing capacity of the ME at the time of the preovulatory LH surge in the rat, and that the administration of an inhibitor of prostaglandin synthesis interferes with the timing of the LH surge.
J. Endocr. (1984) 103, 155–164
Evidence for episodic but not circadian activity in plasma concentrations of adrenocorticotrophin, cortisol and thyroxine in dogs
Authors: Kemppainen R. J. , Sartin J. L. 
Published: December 2008

ABSTRACT
Concentrations of immunoreactive (i) ACTH, cortisol and thyroxine were determined in plasma samples obtained at 20-min intervals for 25 h in nine normal and two adrenalectomized dogs. The dogs were exposed to a 12 h light:12 h darkness photoperiod for 30 days before the sampling period. Episodic secretion of iACTH and cortisol was evident in each normal dog, with an average of 9·0 iACTH peaks and 10·1 cortisol peaks in a 24-h period. Levels of iACTH and cortisol were significantly correlated in each normal dog, but periods of dissociation between levels of the two hormones were apparent. A sex difference in 24-h mean iACTH and cortisol levels, numbers of cortisol peaks, and amplitude of iACTH peaks was observed, with females showing higher mean levels and greater peak frequency and amplitude in each instance. Adrenalectomy resulted in a 50- to 150-fold increase in mean iACTH concentrations with an apparent increase in iACTH peak amplitude. Cortisol levels were unchanging in the adrenalectomized dogs.
Thyroxine concentrations showed episodic variation in each of the normal dogs, but the mean number of peaks (3·3/24-h period) was considerably less than for iACTH or cortisol. Female dogs had significantly higher 24-h mean levels of thyroxine than did males. No circadian rhythmicity was obvious for the plasma levels of any of the three hormones measured.
J. Endocr. (1984) 103, 219–226
Blockade of LH and FSH secretion by LH-releasing hormone, by the LH-releasing hormone analogue, buserelin, and by combined treatment with LH-releasing hormone and oestradiol benzoate
Authors: Schuiling G. A. , Pols-Valkhof N. , van der Schaaf-Verdonk G. C. J. , Koiter T. R. 
Published: December 2008

ABSTRACT
The LH and FSH release-stimulating (experiment 1) and -blocking (experiment 2) effects of LH-releasing hormone (LHRH) and of the LHRH analogue d-Ser(But)6-des-Gly10-LHRH-ethylamide (buserelin), as well as the effect of combined treatment with LH RH and oestradiol benzoate (OB; experiment 3) on the 'supra-maximally' LHRH-stimulated release of LH and FSH were studied in rats ovariectomized for 2 weeks. Pretreatment with LHRH (250 or 500 ng/h) or buserelin (250 ng/h) for 6 days was effected by means of subcutaneously implanted Alzet osmotic minipumps; control rats received a 'sham pump', i.e. a piece of silicone elastomer with the dimensions of a minipump. Oestradiol benzoate (3 μg/injection) or solvent was injected subcutaneously 75 and 27 h before the induction of LH/FSH responses.
Experiment 1 revealed that after infusion of LHRH and buserelin, both at the rate of 1 μg/h, plasma LHRH concentrations were established which were about twice as low as the plasma buserelin concentrations. This might suggest that buserelin has a longer half-life than LHRH. As an LH and FSH release-stimulating substance, however, it appeared that buserelin was about as effective as LHRH. Experiment 2, however, suggested that as an LH/FSH release-blocking agent buserelin was much more effective than LHRH. In addition, after buserelin pretreatment the pituitary glands contained much less LH and FSH than after LHRH pretreatment at both dose levels used. However, this may also (at least partly) be due to the fact that buserelin has a longer half-life so that after infusion of buserelin and LHRH at the same rate the plasma concentrations of buserelin are higher than those of LHRH; after buserelin infusion the pituitary gland is therefore stimulated at a higher intensity.
Experiment 3 showed that in OB-injected, sham-implanted rats the LHRH-stimulated secretion of LH and FSH was significantly higher than in the oil-injected, sham-implanted rats. In the LHRH-pretreated rats (LHRH: 250 ng/h for 6 days), however, the already depressed LHRH-stimulated secretion of LH and FSH was still further depressed by OB treatment.
These latter results suggest that the increase of the pituitary LHRH responsiveness during exposure to oestrogen requires a reduction of the LHRH stimulation, which is normally caused by the negative feedback of oestrogen on the hypothalamus.
J. Endocr. (1984) 103, 301–309