bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneity in the luteal population following superovulation with pregnant mare serum gonadotrophin and human chorionic gonadotrophin in the sheep
Authors: Hunter M. G. , Southee J. A. 
Published: December 2008

ABSTRACT
In order to investigate the development and possible heterogeneity in the luteal population following superovulation, anoestrous ewes were induced to ovulate using progestagen priming followed by injections of pregnant mare serum gonadotrophin (1000 IU) and hCG (1000 IU). Ovaries were recovered from ewes on each of days 2, 4, 6, 8, 10, 12 and 15, and the weight, progesterone content, 125I-labelled hCG binding and progesterone synthesis in vitro of the individual corpora lutea measured. The results obtained showed that plasma progesterone concentrations on the day of slaughter were significantly correlated with time (P<0·05), total weight of luteal tissue (P< 0·001) and number of corpora lutea (P<0·05). The number of corpora lutea recovered per animal ranged from two to 12 and was significantly (P<0·05) correlated with the day after hCG injection until day 10. There was much variation between individual corpora lutea, particularly in terms of weight and progesterone content, although both were significantly (P<0·001) correlated with day of recovery until day 10. 125I-Labelled hCG binding was significantly (P<0·001) correlated with time until day 15. There was a significant (P<0·001) effect of age of the tissue on progesterone production in vitro, with output declining throughout the luteal phase.
These results show that the number of corpora lutea induced by superovulation in anoestrous ewes was very variable, and suggest that ovulation may have continued to occur during the luteal phase. Moreover, there was much variation between individual corpora lutea recovered from the same animal, and thus it should not be assumed that an individual corpus luteum is representative of the entire population.
Journal of Endocrinology (1989) 121, 459–465
Dexamethasone induces an increased biosynthesis of chromogranin A in rat pituitary gland
Authors: Fischer-Colbrie R. , Wohlfarter T. , Schmid K. W. , Grino M. , Winkler H. 
Published: December 2008

ABSTRACT
The influence of dexamethasone on the regulation of the biosynthesis of chromogranins A and B, two proteins originally described in adrenal chromaffin granules, was investigated in the rat pituitary gland. Dexamethasone increased chromogranin A levels and its corresponding mRNA in a dose-dependent manner. Induction of chromogranin A occurred with a time-lag of 24 h. As shown by immunohistochemistry, chromogranin A was present in control and dexamethasone-treated rats in gonadotrophic cells only. Chromogranin B, secretogranin II and the respective pituitary hormones co-stored with chromogranin A were not changed by dexamethasone. Thus dexamethasone selectively increased chromogranin A levels in gonadotrophic cells.
Journal of Endocrinology (1989) 121, 487–494
The effect of 5-methoxytryptamine on golden hamster gonads is not a consequence of its acetylation into melatonin
Authors: Raynaud F. , Miguel J. L. , Vivien-Roels B. , Masson-Pévet M. , Pévet P. 
Published: December 2008

ABSTRACT
Radioimmunoassay and high performance liquid chromatography were used to determine if the gonadal atrophy induced by late afternoon injections of 5-methoxytryptamine (5-MT) in golden hamsters kept under long photoperiod could be due to the acetylation of this compound into melatonin. An increase in plasma concentrations of melatonin (10–13 nmol/l) was detected 15 min after injection of 130 nmol 5-MT. An injection of 4·3 nmol melatonin generated a similar plasma concentration of melatonin. 5-MT (130 nmol) and melatonin (4·3 nmol) were then injected daily in the late afternoon to golden hamsters kept under long photoperiod. After 8 weeks, 5-MT induced total testicular regression, while melatonin induced partial atrophy only. Thus under these experimental conditions, 5-MT had a physiological activity independent of that of melatonin.
Journal of Endocrinology (1989) 121, 507–512
Growth hormone and testosterone can independently stimulate the growth of hypophysectomized prepubertal lambs without any alteration in circulating concentrations of insulin-like growth factors
Authors: Young I. R. , Mesiano S. , Hintz R. , Caddy D. J. , Ralph M. M. , Browne C. A. , Thorburn G. D. 
Published: December 2008

ABSTRACT
Castrated prepubertal lambs were hypophysectomized and then treated with GH and testosterone either alone or in combination over a series of 3-week treatment periods. Hypophysectomy resulted in a rapid reduction in skeletal growth rate which could be reversed by the administration of either GH (4IU three times a week for 3 weeks) or testosterone propionate (10 mg daily for 3 weeks). When GH or testosterone treatment was withdrawn, skeletal growth fell to the post-operative rate. Combined treatment with both GH and testosterone was no more or less effective than either hormone given singly. The order of administration did not have any effect on the growth rate. Circulating concentrations of insulin-like growth factor-I (IGF-I) were reduced by hypophysectomy, but neither GH nor testosterone treatment, alone or in combination, had any effect on IGF-I concentrations. Concentrations of IGF-II rose following hypophysectomy, and again were not affected by any of the hormonal replacement treatments.
In conclusion, both GH and testosterone could stimulate skeletal growth in the hypophysectomized lamb without any alteration of circulating IGF concentrations, and testosterone can clearly stimulate skeletal growth in the complete absence of GH.
Journal of Endocrinology (1989) 121, 563–570
The role of hypothalamic vasoactive intestinal polypeptide in the maintenance of prolactin secretion in incubating bantam hens: observations using passive immunization, radioimmunoassay and immunohistochemistry
Authors: Sharp P. J. , Sterling R. J. , Talbot R. T. , Huskisson N. S. 
Published: December 2008

ABSTRACT
The role of chicken vasoactive intestinal polypeptide (cVIP) as a prolactin-releasing factor was investigated in incubating bantam hens. Specific antibodies were raised against cVIP (anti-cVIP) for passive immunization studies, to develop a radioimmunoassay and to localize VIP neurones immunohistochemically in the hypothalamus. The concentration of plasma prolactin decreased after i.v. injection of anti-cVIP: this low concentration being maintained by daily injection of anti-cVIP. Incubating hens injected daily with anti-cVIP deserted their nests after 4·5 ± 0·6 days and returned to lay after 20 ± 1 days. This disruption of incubation behaviour with anti-cVIP was prevented by concomitant, twice daily, injections of 30IU ovine prolactin. The concentration of plasma LH was not immediately affected after injection of anti-cVIP but increased when the hens deserted their nests.
The amount of cVIP, measured by radioimmunoassay, was significantly higher in the median eminence (P < 0·01) and medial basal hypothalamus (P = 0·05) in incubating than in laying hens. No differences were seen in the amounts of cVIP in the preoptic hypothalamus or in a part of the forebrain including the nucleus accumbens, between laying and incubating hens.
Morphological observations were made on immunohistochemically identified cVIP cell bodies in the medial basal hypothalamus. These showed that cVIP cell number, cell area and density of immunoreactive product were significantly (P < 0·05) greater in incubating than in laying hens. Further, the density of cVIP reaction product in the anterior median eminence was also significantly (P < 0·01) greater in incubating than in laying hens.
These observations are consistent with the view that hypothalamic VIP is a physiologically important prolactin-releasing hormone in incubating bantam hens.
Journal of Endocrinology (1989) 122, 5–13
Gonadotrophin-releasing activity of neurohypophysial hormones: II. The pituitary oxytocin receptor mediating gonadotrophin release differs from that of corticotrophs
Authors: Evans J. J. , Catt K. J. 
Published: December 2008

ABSTRACT
Neurohypophysial hormones stimulate gonadotrophin release from dispersed rat anterior pituitary cells in vitro, acting through receptors distinct from those which mediate the secretory response to gonadotrophin-releasing hormone (GnRH). The LH response to oxytocin was not affected by the presence of the phosphodiesterase inhibitor, methyl isobutylxanthine, but was diminished in the absence of extracellular calcium and was progressively increased as the calcium concentration in the medium was raised to normal. In addition, the calcium channel antagonist, nifedipine, suppressed oxytocin-stimulated secretion of LH. It is likely that the mechanisms of LH release induced by GnRH and neurohypophysial hormones are similar, although stimulation of gonadotrophin secretion is mediated by separate receptor systems. Oxytocin was more active than vasopressin in releasing LH, but less active in releasing ACTH. The highly selective oxytocin agonist, [Thr4,Gly7]oxytocin, elicited concentration-dependent secretion of LH but had little effect on corticotrophin secretion. The neurohypophysial hormone antagonist analogues, [d(CH2)5Tyr(Me)2]-vasopressin, [d(CH2)5Tyr(Me)2,Orn8]vasotocin and [d(CH2)5d-Tyr(Et)2Val4,Cit8]vasopressin, inhibited the LH response to both oxytocin and vasopressin. However, [d(CH2)5Tyr(Me)2]vasopressin was much less effective in inhibiting the ACTH response to the neurohypophysial hormones, and [d(CH2)5Tyr-(Me)2,Orn8]vasotocin and [d(CH2)5d-Tyr(Et)2,Val4, Cit8]vasopressin exhibited no inhibitory activity against ACTH release. Thus, agonist and antagonist analogues of neurophypophysial hormones display divergent activities with regard to LH and ACTH responses, and the neuropeptide receptor mediating gonadotroph activation is clearly different from that on the corticotroph. Whereas the corticotroph receptor is a vasopressin-type receptor an oxytocin-type receptor is responsible for gonadotrophin release by neurohypophysial hormones.
Journal of Endocrinology (1989) 122, 107–116
Effect of serotonin on α-melanocyte-stimulating hormone secretion from perifused frog neurointermediate lobe: evidence for the presence of serotonin-containing cells in the frog pars intermedia
Authors: Lamacz M. , Tonon M. C. , Leboulenger F. , Héry F. , Idres S. , Verhofstad A. J. , Pelletier G. , Vaudry H. 
Published: December 2008

ABSTRACT
We have examined the presence of 5-hydroxytryptamine (serotonin; 5-HT) in the intermediate lobe of the frog pituitary and investigated the effect of exogenous 5-HT on α-melanocyte-stimulating hormone (α-MSH) release from the perifused neurointermediate lobe (NIL). Using a specific antiserum against 5-HT, the indirect immunofluorescence technique revealed the presence of 5-HT-like immunoreactivity (5-HT-LI) in discrete cells, generally gathered in small clusters among parenchymal cells, and in numerous neurites surrounding melanotrophic cells. At the electron microscopic level, using a silver-gold intensification procedure, 5-HT-LI was localized in dense-core secretory vesicles within specific pituitary cells which appear to be different from pituitary melanotrophs. Dense accumulation of gold particles was also observed in nerve fibres running between parenchymal cells. A combination of high-performance liquid chromatography analysis and electrochemical detection showed the presence of both 5-HT and its metabolite 5-hydroxyindol acetic acid (5-HIAA) in frog NIL extracts (534 ± 40 and 1245 ± 65 (s.e.m.) pg/mg wet tissue respectively). Administration of graded doses of 5-HT (from 1 to 30 μmol/l) to perifused frog NIL induced a dose-dependent inhibition of α-MSH release. Repeated pulses of 5-HT (10 μmol/l each) induced a reproducible inhibition of α-MSH without any desensitization phenomena. The inhibitory effect of 5-HT was partially blocked by the serotonergic antagonists methysergide and ICS-205-930 (10 μmol/l each). Concomitant administration of methysergide and ICS-205-930 (10 μmol/l each) totally abolished 5-HT-evoked inhibition of α-MSH. Fenfluramine, a releaser of 5-HT, induced a slight but significant reduction of α-MSH secretion. While 5-HT caused a marked inhibition of α-MSH release from intact NIL, 5-HT was devoid of effect on acutely dispersed pars intermedia cells suggesting that 5-HT does not exert a direct action on pituitary melanotrophs. We have examined the effect of specific dopaminergic, GABAergic and α-adrenergic antagonists on 5-HT-induced α-MSH inhibition. We observed that sulpiride and SR 95531 (10 μmol/l each) did not affect the response of NIL to 5-HT while yohimbine (10 μmol/l) suppressed the inhibitory action of 5-HT.
Taken together, our results indicate that discrete cells of the frog pars intermedia contain the neurotransmitter 5-HT which may act locally to inhibit α-MSH release. Our data also suggest that the inhibitory effect of 5-HT is mediated via presynaptic stimulation of catecholamine (possibly norepinephrine) release from adrenergic nerve endings terminating in the intermediate lobe of the frog pituitary.
Journal of Endocrinology (1989) 122, 135–146
Towards an antigenic map of human thyroglobulin: identification of ten epitope-bearing sequences within the primary structure of thyroglobulin
Authors: Dong Q. , Ludgate M. , Vassart G. 
Published: December 2008

ABSTRACT
The aim of this study was to define, at the molecular level, epitopes of thyroglobulin recognized by heterologous antibodies and autoantisera.
One hundred thousand clones from a λgt11 human thyroid cDNA library were screened using a rabbit antibody to human thyroglobulin at a 1:2000 dilution. Twenty clones were plaque-purified to homogeneity, and characterization and sequencing of their cDNA inserts showed that they represented four distinct regions of the thyroglobulin molecule, one of them being the 22 carboxyl-terminal amino acids. Rescreening of the library with the same rabbit antibody to human thyroglobulin absorbed with peptides encoded by the carboxyl-terminal clone, led to the definition of six further epitope-bearing fragments of thyroglobulin. The ten regions that we have identified were recognized by ten further rabbit antibodies to human thyroglobulin, showing that they are representative of the repertoire of heterologous epitopes.
In contrast, none of the ten heteroepitope-bearing fragments was recognized by sera from ten patients with autoimmune thyroid disease with various titres of thyroglobulin antibodies. Screening of 2 × 106 clones from the library using a pool of ten autoantisera (individual sera diluted to 1:1000), and of 1 × 106 clones using a single autoantiserum of very high antithyroglobulin titre (diluted 1:400) resulted in no thyroglobulin clones being isolated. The significance of these results to the immune process is discussed.
Journal of Endocrinology (1989) 122, 169–176
Expression of an intercellular adhesion molecule, ICAM-1, by human thyroid cells
Authors: Weetman A. P. , Cohen S. , Makgoba M. W. , Borysiewicz L. K. 
Published: December 2008

ABSTRACT
Intercellular adhesion molecule-1 (ICAM-1), hitherto identified on activated B cells, macrophages, dendritic cells, endothelia and certain epithelial cells, serves as a ligand for the lymphocyte function-associated antigen-1 (LFA-1). ICAM-1 binding by LFA-1 enhances the efficiency of lymphocyte-target cell and lymphocyte-accessory cell interactions. We have investigated the in-vitro expression of ICAM-1 by cultured thyroid cells from five patients with Graves' disease using indirect immunofluorescence analysis, and found that 30 ± 11% (mean ± s.d.) of cells were ICAM-1 positive under basal conditions. The proportion of cells which were ICAM-1 positive and the amount of ICAM-1 per cell (assessed by fluorescence intensity) were both increased in all cases by the cytokines γ-interferon, interleukin-1 and tumour necrosis factor. Immunohistochemical analysis of frozen sections from thyroidectomy specimens demonstrated ICAM-1 on thyroid follicular cells in areas of lymphocytic infiltration in patients with Graves' disease (n = 2) or Hashimoto's thyroiditis (n = 2). ICAM-1 was not found in specimens from a patient with a toxic multinodular goitre or a patient with Graves' disease without focal lymphocytic accumulation. These results suggest that the thyroid epithelium may express ICAM-1 as well as major histocompatibility complex class II antigens, such as HLA-DR, in response to locally synthesized cytokines. The enhanced expression of ICAM-1 may render these cells more susceptible as targets for lymphocytemediated cytotoxicity, and together with HLA-DR antigen expression may increase the accessory cell capability of the thyroid follicular cells.
Journal of Endocrinology (1989) 122, 185–191
Regulation of the onset of the breeding season of the ewe: importance of long days and of an endogenous reproductive rhythm
Authors: Malpaux B. , Robinson J. E. , Wayne N. L. , Karsch F. J. 
Published: December 2008

ABSTRACT
Three experiments were conducted to evaluate the role that the increasing day lengths of late winter and spring play in timing the breeding season of the Suffolk ewe. In the first experiment, ewes were denied their normal complement of increasing day length by maintaining them on the photoperiod experienced at the winter solstice. This prevented the breeding season from occurring the subsequent autumn. In the second experiment, ewes were exposed to increases in day length at different time-intervals after the winter solstice: the normal time, later than normal or earlier than normal. Once the summer solstice photoperiod was reached, it was maintained until the end of the study. When increasing photoperiod was provided early, the breeding season was advanced; when it was provided late, reproduction was delayed. In the third experiment, ewes were exposed to a continuously increasing photoperiod matching the maximal rate of rise in natural conditions; this treatment was begun on the spring equinox and continued until mid-autumn. The steadily increasing photoperiod did not alter the time of reproductive onset in the autumn.
These findings support the following conclusions for timing of the breeding season of the Suffolk ewe. (1) The lengthening photoperiod between the winter and summer solstices is required for the occurrence of the breeding season in the autumn. (2) The time of initial exposure to this lengthening photoperiod provides an important cue for determining when the reproductive period occurs. (3) The time of onset of the breeding season does not depend upon the decreasing photoperiod after the summer solstice, nor does it require the photoperiod to stop increasing as the summer solstice approaches. These findings have been incorporated into a conceptual model for temporal regulation of the annual reproductive cycle of the ewe. An important component of this model is a critical role for increasing photoperiod to initiate a process in the late winter–spring which ultimately leads to an obligatory reproductive onset in the autumn.
Journal of Endocrinology (1989) 122, 269–278
Dynamics of testosterone secretion by the rat testis: implications for measurement of the intratesticular levels of testosterone
Authors: Maddocks S. , Sharpe R. M. 
Published: December 2008

ABSTRACT
Testosterone concentrations have been measured in testicular interstitial fluid (IF), and in blood plasma sampled from various parts of the rat testis and spermatic cord, to assess (1) the most accurate method for determination of the intratesticular levels of testosterone, and (2) the route of secretion of testosterone from the testis. In untreated adult rats, testosterone concentrations were highest in blood collected from veins on the surface of the testis (269·50 ± 30·63 (s.e.m.) nmol/l), but were reduced by 56% on average in blood collected from veins at the proximal end of the spermatic cord (123·06±24·75 nmol/l), and were reduced considerably in peripheral venous blood (4·55 ± 0·55 nmol/l). Similar changes occurred in adult rats in which steroidogenesis was either stimulated (by treatment with human chorionic gonadotrophin; hCG) or inhibited (by treatment with aminoglutethimide; AMG), and in rats of various ages during sexual maturation. The reduction in testosterone levels during passage of blood from the testis up the spermatic cord is probably due mainly to dilution by incoming arterial blood which transfers to venous blood via anastomoses in the spermatic cord. Venous-arterial transfer of testosterone in the cord contributed to this in only a minor way. Concentrations of testosterone in testicular IF were always greater than testicular venous concentrations in control, developing and hCG-stimulated rats, but were comparable in rats treated with AMG to suppress Leydig cell steroidogenesis. These and other results demonstrate that the method of drip-collection of IF results in over-estimation of the actual intratesticular levels of testosterone. However, the present study also suggests that testicular venous blood probably provides the most accurate indication of the concentrations of testosterone in IF (and therefore in the testis) at any given time.
Journal of Endocrinology (1989) 122, 323–329