bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sexual dimorphism of messenger RNA isolated from neonatal rat brain
Authors: Adcock I. M. , Greenstein B. D. 
Published: December 2008

ABSTRACT
The rat brain is sexually dimorphic with respect to structure and function, and there is evidence that these differences are effected in the fetus through changes in protein synthesis, some of which may result from the intervention of gonadal steroids. To investigate this, messenger RNA (mRNA) from the limbic system and cerebellum of neonatal rats was prepared, translated in a rabbit reticulocyte system in vitro and the products were analysed by two-dimensional electrophoresis and fluorography. Some of the results were further analysed using image analysis. There was a striking sexual dimorphism in the patterns of incorporation of [35S]methionine into proteins using mRNA from the limbic system, in that groups of proteins were apparently present in male-but not in female-derived fluorograms and vice versa. One protein, tentatively identified from its coordinates as α-tubulin, was more abundant in male-derived fluorograms. Although there were no clear-cut qualitative sex differences using mRNA derived from the cerebellum, that derived from the male cerebellum appeared to be consistently more active. These results provide direct evidence for a sexual dimorphism at the transcriptional level in the neonatal limbic system of the rat.
J. Endocr. (1986) 109, 23–28
Central adrenergic activity in the mediobasal hypothalamus is temporally related to surge outputs of gonadotrophins in oestrogen-stimulated infant female rats
Authors: Clement E. M. , MacKinnon P. C. B. , Sheaves R. 
Published: December 2008

ABSTRACT
In the mediobasal hypothalamus (MBH) of prooestrous rats or acutely ovariectomized oestrogentreated adults a marked but short-lived increase in adrenergic activity occurs at 16.00 h, 2 h before the oestrogen-dependent surge of gonadotrophins at 18.00 h. In this study oestrogen-stimulated (noon on day 1) 22-day-old female rats were used which are known to produce surge levels of prolactin at 18.00 h on day 2 and surges of both prolactin and LH at 18.00 h on day 3; although similar treatment of 18-day-old animals or oil-treated 22-day-old rats failed to produce these effects. Radioenzymatic assays of adrenaline concentrations and of the activity of its synthesizing enzyme (phenylethanolamine-N-methyl transferase; PNMT, EC 2.1.1.28) in the MBH of oestrogen-treated 22-day-old rats showed significant (P< 0·05–0·01) increases in both parameters at 16.00 h (i.e. 2 h before surge levels of gonadotrophins) on days 2 and 3 when compared with other times of day. Such effects were not seen in oil-treated 22-day-old animals or in oestrogen-treated 16-day-old rats. Noradrenaline and dopamine concentrations in the MBH of oestrogen-treated 22-day-old rats remained at baseline levels on days 2 and 3 with the exception of noradrenaline at 17.00 h on day 3 when levels appeared higher (P<0·05) than at either 15.00 or 16.00 h. Subsequent measurements of PNMT activity in oestrogen-treated 22-day-old rats at 4-hourly intervals throughout days 2 and 3 showed the presence of a clear circadian rhythm with peak levels occurring at 16.00 h. In conclusion, a temporal relationship (not necessarily specific) exists between increased adrenergic activity in the MBH of oestrogen-treated 22-day-old rats and a surge of gonadotrophins (LH and/or prolactin) 2 h later. This relationship apparently depends on an oestrogen-stimulated circadian rhythm of PNMT activity.
J. Endocr. (1986) 109, 45–51
Myosin light chain kinase and cyclic AMP-dependent protein kinase activities and calmodulin levels in placental and non-placental regions of the rabbit myometrium
Authors: Matsui K. , Higashi K. , Yoshimura T. , Ito M. , Miyamoto E. 
Published: December 2008

ABSTRACT
Myosin light chain kinase activity in the placental region of the rabbit myometrium on day 28 of gestation was 4·7±0·1 (mean ± s.e.m.) nmol/min per mg protein, which was significantly higher than that (3·6 ± 0·1 nmol/min per mg protein) in the non-placental region. The amount of calmodulin in the placental region was 4·2 ± 0·1 μg/mg protein, which was significantly higher than that (3·2 ± 0·1 μg/mg protein) in the non-placental region. In contrast, cyclic AMP-dependent protein kinase activities showed no difference between the two regions.
These findings suggest that calcium- and calmodulin-dependent protein phosphorylation is activated mainly in the placental region, and uterine contractions can occur more strongly in this part than in the non-placental region. Such enzymatic phenomena may be related to the mechanism whereby the placenta separates from the myometrium after delivery of the fetus.
J. Endocr. (1986) 109, 97–100
Morphological changes in the pituitary and thyroid of the rat in hypobaric hypoxia
Authors: Gosney J. R. 
Published: December 2008

ABSTRACT
When a group of adult male Wistar rats was exposed to a barometric pressure of 380 mmHg for 28 days in an hypobaric chamber, profound changes occurred in their hypothalamic-pituitary-thyroidal axes in comparison with normobaric controls. The thyroid glands of the hypoxic animals had an inactive appearance, comprising large colloid-filled follicles lined by low epithelium. The thyrotrophs of the pars distalis of the pituitary glands were markedly decreased in number. They occupied only 0·41% of the total cell population in contrast with 1·34% in the controls (P<0·001); a total population which is itself decreased in the hypoxic animals. Classical 'thyroidectomy cells' were not seen. These observations support previous studies which indicate suppression of thyroid function in an hypoxic environment, and tend to suggest that this is a consequence of a direct effect of hypoxia on the hypothalamus or pituitary gland, rather than on the thyroid itself.
J. Endocr. (1986) 109, 119–124
A testosterone-independent reduction in net photoperiodic drive triggers photorefractoriness in male tree sparrows (Spizella arborea)
Authors: Wilson F. E. 
Published: December 2008

ABSTRACT
An experiment was performed to determine whether photorefractoriness in male tree sparrows is triggered by a testosterone-independent reduction in net photoperiodic drive or by a photoperiod-induced hypersensitivity of the hypothalamic-pituitary axis to testosterone negative feedback. Photosensitive male tree sparrows were transferred from 8 h light: 16 h darkness (8L: 16D) to 20L: 4D. Birds were castrated bilaterally on day 28 of photostimulation. Beginning on day 33 and weekly thereafter until day 54, birds were given replacement testosterone (0–1·49 μmol) in s.c. polydimethylsiloxane capsules. Plasma samples collected on days 36, 43, 50 and 57 were assayed for LH. Plasma LH concentrations in birds without replacement testosterone were regarded as reflecting net photoperiodic drive in the absence of testosterone feedback, and the slopes of curves relating the logarithm of plasma LH concentration to dose of replacement testosterone were taken as quantitative measures of testosterone feedback sensitivity. The results showed that a testosterone-independent reduction in net photoperiodic drive beginning between days 43 and 50 preceded any change in sensitivity to testosterone negative feedback. Such results provide compelling evidence that a testosterone-independent mechanism triggers the photorefractory state in male tree sparrows.
J. Endocr. (1986) 109, 133–137
Varying the patterns and concentrations of gonadotrophin-releasing hormone stimulation does not alter the ratio of LH and FSH released from perifused sheep pituitary cells
Authors: McIntosh J. E. A. , McIntosh R. P. 
Published: December 2008

ABSTRACT
Our aim was to determine whether release of LH and FSH can be controlled differentially by the characteristics of applied signals of stimulatory gonadotrophin-releasing hormone (GnRH) alone, free of the effects of steroid feedback or other influences from the whole animal. The outputs of both gonadotrophins were significantly correlated (r≈0·90; P<0·0005) when samples of freshly dispersed sheep pituitary cells were perifused in columns for 7 h with medium containing a range of concentrations of GnRH in various patterns of pulses. Hormone released in response to the second, third and fourth pulses from every column was analysed in detail. Dose–response relationships for both LH and FSH were very similar when cells were stimulated with 5–8500 pmol GnRH/1 in 5-min pulses every hour. When GnRH was delivered in pulses at a maximally stimulating level, the outputs of both hormones increased similarly with increasing inter-pulse intervals. Efficiency of stimulation (release of gonadotrophin/unit stimulatory GnRH) decreased (was desensitized) with increasing pulse duration in the same way for both hormones. Thus, varying the dose, interval and duration of GnRH pulses did not alter the proportions of LH and FSH released in the short-term from freshly dissociated cells. However, the same cell preparations released more LH relative to FSH when treated with maximally stimulating levels of GnRH for 3 h in the presence of 10% serum from a sheep in the follicular phase of its ovulatory cycle compared with charcoal-treated serum. Because there was no gonadotrophin synthesis under the conditions used in vitro these results suggest that changes in the LH/FSH ratio seen in whole animals are more likely to result from differential clearance from the circulation, ovarian feedback at the pituitary, differential synthesis in intact tissue or another hormone influencing FSH secretion, rather than from differences in the mechanism of acute release controlled by GnRH.
J. Endocr. (1986) 109, 155–161
Thyrotrophin-releasing hormone does not accumulate glycosylated thyrotrophin, but changes heterogeneous forms of thyrotrophin within the rat anterior pituitary gland
Authors: Mori M. , Kobayashi I. , Kobayashi S. 
Published: December 2008

ABSTRACT
We have investigated the effect of TRH on the accumulation of glycosylated TSH in the rat anterior pituitary gland. Hemipituitaries from adult male rats were incubated in medium containing [3H]glucosamine in the presence of TRH. [3H]Glucosamine-labelled TSH in media and pituitaries was measured by immunoprecipitation and characterized by isoelectric focusing after affinity chromatography. Incorporation of [3H]glucosamine into immunoprecipitable TSH in the media and pituitaries increased progressively with the period of incubation. Although the release of [3H]glucosamine-labelled and unlabelled TSH into media was stimulated by the addition of TRH in a time- and dose-dependent manner, TRH administration did not alter the amounts of labelled or unlabelled TSH in the anterior pituitary lobes. The anterior pituitaries were found, by isoelectric focusing analysis, to be composed of four major component peaks of [3H]glucosamine-labelled TSH. Administration of TRH caused profound changes in the radioactivity of these components and evoked new radioactive peaks, resulting in the appearance of six components in total. The present data provide evidence that TRH significantly changes the heterogeneity of glycosylated TSH in the anterior pituitary without altering the amount of the glycosylated form.
J. Endocr. (1986) 109, 227–231
Changing renin substrates in human pregnancy
Authors: Tetlow H. J. , Broughton Pipkin F. 
Published: December 2008

ABSTRACT
Renin substrate of high molecular weight was identified in plasma from pregnant women, non-pregnant subjects and in samples of umbilical arterial and venous plasma, using gel filtration chromatography. The proportion existing in the high molecular weight form in pregnant women was significantly increased above that of non-pregnant subjects by 11 weeks after the last menstrual period and continued to rise to term. In contrast, the proportion in fetal plasma was significantly lower than that of the non-pregnant group. High molecular weight renin substrate was itself heterogeneous and appeared to consist of four sub-groups. In non-pregnant adults the first peak, eluting near the void volume of the column, was the largest. In the fetus this profile was reversed. The elution profile in maternal plasma had changed markedly by as early as 8 weeks of gestation. Thereafter, it was possible to see increasing dominance of the minor 'intermediate' peaks visible in the non-pregnant adult until, in the third trimester, the high molecular weight form was eluted as a large broad band with little evidence of the individual peaks. Oestrogens are the most likely stimulus for the increased production of the high molecular weight renin substrate in pregnant women. In the fetus, although the same form of renin substrate is stimulated, the actual amount in the high molecular weight range is very small. This may be because oestrogens are sulphated in the fetus or because the fetal liver is not very responsive to the stimulation. The similarity between the profiles of mother and fetus may indicate a common source of production of renin substrate in the feto-placental unit.
J. Endocr. (1986) 109, 257–262
Lactogenic response of cultured mouse mammary epithelial cells to mouse placental lactogen
Authors: Thordarson G. , Villalobos R. , Colosi P. , Southard J. , Ogren L. , Talamantes F. 
Published: December 2008

ABSTRACT
The ability of mouse placental lactogen (mPL), mouse prolactin (mPRL), mouse GH (mGH) and ovine prolactin (oPRL) to stimulate synthesis of α-lactalbumin was tested in a primary culture of mouse mammary gland epithelial cells. Mammary tissue was obtained from 10-day pregnant Swiss Webster mice, enzymatically dissociated and the cells were cultured on floating collagen gels for 5 days. The basic culture medium consisted of Nutrient Mixture F12/Dulbecco's Modified Eagle's Medium (1:1, v/v), containing 10 mg insulin/1, 5 mg cortisol/l, 10 μg epidermal growth factor/l, 5 g bovine serum albumin/l and 50 mg gentamycin/l. Mouse PL, mPRL, mGH and oPRL were added to the basic medium in concentrations from l μg/l to l mg/l. Accumulation of α-lactalbumin in the culture medium was measured. For that purpose, mouse α-lactalbumin was purified from mammary tissue obtained from lactating Swiss Webster mice and a radioimmunoassay was developed. Mouse PL, mPRL and oPRL stimulated a dose-dependent increase in α-lactalbumin secretion. Mouse GH also caused a significant, but dose-independent, increase in α-lactalbumin secretion. Mouse PL showed the greatest activity in stimulating α-lactalbumin secretion. It was concluded that mPL is an important lactogenic hormone in the latter half of pregnancy in the mouse, when circulating mPRL concentrations are low.
J. Endocr. (1986) 109, 263–274
Androgen regulation of the androgen receptor of the quail uropygial gland: application of a [3H]mibolerone exchange assay
Authors: Amet Y. , Abalain J.-H. , di Stefano S. , Daniel J.-Y. , Tea K. , Floch H. H. , Robel P. 
Published: December 2008

ABSTRACT
An exchange assay for androgen receptors in the quail uropygial gland using [3H]mibolerone was established. The most efficient exchange conditions were 3 days of incubation at 15 °C. Under these conditions, androgen receptors were stable in the presence of sodium molybdate, and the exchange of [3H]mibolerone with endogenous testosterone bound to cytosolic or nuclear androgen receptors was maximal. Less than 5% of [3H]mibolerone-binding sites occurred in the extracted nuclear pellets. Using this exchange technique, it was shown that androgen receptors in the uropygial gland of photostimulated male quail or castrated quail treated with testosterone were activated and that their concentrations in both cytosolic and nuclear fractions were increased. These results confirm the androgen dependency of the quail uropygial gland, and show that it is an organ which can be used as a model for the study of androgen action in sebaceous glands.
J. Endocr. (1986) 109, 299–306
Effect of epidermal growth factor on the membrane potential of cultured porcine thyroid cells
Authors: Bourke J. R. , McGrath P. A. , Huxham G. J. , Waters M. J. , Manley S. W. 
Published: December 2008

ABSTRACT
Cultured porcine thyroid cells maintained in media containing TSH exhibited a membrane potential of −50 mV, and hyperpolarized by about 10 mV within 1 h of the addition of epidermal growth factor (EGF; 10 ng/ml). Follicle cells had depolarized to −45 mV after 4 h of exposure to EGF. Cells maintained in dibutyryl cyclic AMP (dbcAMP) did not alter their membrane potential when exposed to EGF for up to 4 h. Cultures washed to remove the TSH or dbcAMP hyperpolarized to − 75 mV within 30 min, and a reversible depolarization to − 60 mV was observed on addition of EGF. It was concluded that EGF acts as a physiological antagonist of TSH and also exerts a separate depolarizing influence on cultured thyroid cells.
J. Endocr. (1986) 109, 321–324
Circulating insulin-like growth factor-binding proteins in fetal, neonatal and adult sheep
Authors: Butler J. H. , Gluckman P. D. 
Published: December 2008

ABSTRACT
A specific radioimmunoassay for insulin-like growth factor I (IGF-I) has been used to study the distribution of circulating IGF-I on its carrier proteins in sheep. Serum or plasma samples obtained from fetal, neonatal and adult sheep were chromatographed at neutral pH on Sephadex G-200 columns. IGF-I eluted primarily in the 20 000–100 000 dalton region and to a lesser extent in the 20 000–100 000 dalton region in the adult. In the fetus, IGF-I eluted primarily in the 20 000–50 000 dalton region. Studies in the neonatal lamb showed IGF-I activity to fluctuate between different size binding proteins but by 7 days after birth the pattern was similar to that of the adult. When labelled IGF-I and IGF-II were added to serum which was chromatographed over Sephadex G-200 at a neutral pH, binding was displayed in the 50 000– 100 000 dalton region for both adult and fetus. However in the fetus, but not in the adult, binding of 125I-labelled IGF-II was also found at > 200 000 daltons. These studies demonstrate that the distribution of IGF-binding proteins varies between the adult and the fetal lamb. The appearance of the 150 000 dalton binding protein is coincidental with the appearance of the somatogenic receptor in the infant liver and is consistent with the GH-dependent nature of this form of binding protein in other species. The marked developmental changes in the circulating form of IGF-I in the perinatal lamb may be of functional significance and lead to altered biological availability of circulating IGF-I.
J. Endocr. (1986) 109, 333–338
Purification of dispersed rat adrenal zona glomerulosa cells by Percoll density gradient centrifugation and the isolation of a population of cells highly responsive to adrenocorticotrophin
Authors: Chu F. W. , Hyatt P. J. 
Published: December 2008

ABSTRACT
Percoll density gradient centrifugation is a simple, inexpensive and convenient method to eliminate contaminating zona fasciculata (ZF) cells from unpurified rat adrenal capsular glomerulosa (ZG) cell preparations (with less than 0·1% ZF cells in the final cell preparation). Basal steroid (aldosterone and corticosterone) output by the purified (PG) cells was unchanged. These purified cells, although free from ZF contamination, were more highly responsive than expected to ACTH (3 nmol/l). When PG cells were further separated by Sephadex column filtration, the filtered PG cells exhibited the steroidogenic response of ZG cells purified by unit gravity sedimentation and Sephadex column filtration, i.e. reduced basal steroid output and an ACTH response reduced to that stimulated by K+ (8·4 mmol/l). Although the cells retained in the column resembled the filtered PG cells ultrastructurally, they showed unchanged basal steroid output and a high ACTH response with increased latepathway activity (the conversion of corticosterone to aldosterone). By combining Percoll density gradient centrifugation and Sephadex column filtration we have a method for the isolation and study of both the high-and low-response rat ZG cells which are free from ZF contamination.
J. Endocr. (1986) 109, 351–358
Tri-iodothyronine and phenytoin reduce prolactin messenger RNA levels in cultured rat pituitary cells
Authors: Davis J. R. E. , Lynam T. C. , Franklyn J. A. , Docherty K. , Sheppard M. C. 
Published: December 2008

ABSTRACT
Thyroid hormones may regulate prolactin gene transcription. We have previously found that phenytoin inhibits tri-iodothyronine (T3) nuclear binding, and have suggested that phenytoin may act as a partial T3 agonist. We have therefore investigated the effects of phenytoin and T3 on prolactin release and gene transcription, using the technique of cytoplasmic dot hybridization with complementary DNA probes to estimate prolactin messenger (m) RNA concentrations in cytoplasm from cultured rat pituitary cells.
Tri-iodothyronine treatment led to a small but significant fall in prolactin release by 72 h, but caused marked dose- and time-dependent reductions in prolactin mRNA levels at 48–72 h. Phenytoin, however, caused more rapid falls in both prolactin release and mRNA concentrations. Neither T3 nor phenytoin significantly altered GH mRNA levels. These studies suggest effects of phenytoin similar, but not identical, to those of T3 in the lactotroph.
J. Endocr. (1986) 109, 359–364
Cytoplasmic progesterone receptors in uterine tissue of the snapping turtle (Chelydra serpentina)
Authors: Mahmoud I. Y. , Colás A. E. , Woller M. J. , Cyrus R. V. 
Published: December 2008

ABSTRACT
A high affinity progesterone-binding component was detected in the cytosol of the uterus of the snapping turtle, Chelydra serpentina. Density gradient centrifugation indicated that binding of [3H]progesterone and [3H]promegestone (R5020) was to a fraction with a heavier sedimentation coefficient than bovine serum albumin (BSA) appearing as a broader peak in the 6–7 S region; it was not affected by excess cortisol. Another binding peak, lighter than BSA and appearing with [3H]R5020 and [3H]progesterone near the 4 S region, was affected by excess cortisol. Excess progesterone decreased both the heavier and lighter peaks. Analysis of steroid specificity revealed that, of the natural steroids, progesterone had the highest affinity for the uterine cytosol. This was followed by deoxycorticosterone, 5α-pregnanedione, testosterone, oestradiol-17β, corticosterone, 5α-dihydrotestosterone and cortisol. Non-linear regression analysis of saturation data indicated the presence of two classes of high affinity binding sites: progesterone-binding sites (R-sites) with equilibrium association constants (Ka) of 2·9 ± 0·28 litres/nmol (mean ± 95% confidence limit) for [3H]R5020 and 0·34 ± 0·20 litres/nmol for [3H]progesterone, and corticosteroid-binding globulin-like sites (G-sites) with Ka of 4·5 ± 1·6 litres/nmol for progesterone. The concentration of R-sites was between 0·66 ± 0·10 and 2·6 ± 0·55 pmol/mg protein while that of G-sites was between 0·73 ± 0·05 and 5·0 ± 0·27 pmol/mg protein. DEAE-cellulose filtration assay also confirmed the presence of R-sites and G-sites in the cytosol. R-sites were detectable without oestrogen priming during the preovulatory and vitellogenic phases (low progesterone, high oestrogen concentrations) when the ovarian follicles are mature (18–22 mm diameter). During the early postovulatory phase (high progesterone, low oestrogen concentrations), when the ovarian follicles are immature (5–7 mm diameter) and active corpora lutea are present, the R-sites were undetectable even after oestrogen priming. This indicates that progesterone might have an inhibitory and oestrogen a stimulatory role in the regulation of R-sites.
J. Endocr. (1986) 109, 385–392