bluuebunny/crossref_metadata_2025_split huggingface dataset:
GLYCOSYLTRANSFERASE AND UDP-GALACTOSE PYROPHOSPHATASE ACTIVITIES IN THE ENDOMETRIUM DURING THE OESTROUS CYCLE OF THE RAT
Authors: NELSON J. D. , JATO-RODRIGUEZ J. J. , LABRIE F. , MOOKERJEA S. 
Published: December 2008

SUMMARY
UDP-galactose: glycoprotein galactosyltransferase, CMP-sialic acid: glycoprotein sialyltransferase and UDP-galactose pyrophosphatase activities were measured in the endometrium of rat uteri during the oestrous cycle. The galactosyltransferase activity started to increase at dioestrus and reached a maximum on the afternoon of pro-oestrus. The UDP-galactose pyrophosphatase activity changed in a direction opposite to that of galactosyltransferase. The sialyltransferase activity was low during metoestrus and dioestrus, but began to rise on the morning of pro-oestrus, reaching a peak on the morning of oestrus. Previously, we have shown that oestradiol administration stimulated galactosyl- and sialyltransferase and inhibited pyrophosphatase activities several-fold in the endometrium of ovariectomized rats. Progesterone prevented the oestradiol effect on the enzymes. The changes in glycosyltransferase and pyrophosphatase activities during the oestrous cycle possibly bear a direct relationship to the ovarian hormones in the rat during the normal oestrous cycle. This relationship will then be conducive to increased synthesis of glycopolymers during ovulation. Furthermore, the lag of 18 h for a maximal rise of sialyltransferase following that of galactosyltransferase is consistent with the normal sequence of glycosylation that occurs in glycoprotein secretion.
STEROID PRODUCTION BY ISOLATED RABBIT OVARIAN FOLLICLES: EFFECTS OF LUTEINIZING HORMONE FROM MATING TO IMPLANTATION
Authors: YOUNGLAI E. V. 
Published: December 2008

SUMMARY
Follicles were isolated from rabbits before and after mating and the effects of LH on steroidogenesis were studied using an incubation technique. Before mating testosterone was the major steroid produced in response to LH. Mating or administration of ovine LH in vivo caused the follicles to produce mainly progesterone and these follicles were refractory to LH in vitro. Up to 72 h after mating, LH would stimulate follicles to produce progesterone. At 96 h after mating, the testosterone response to LH was again manifest. These results suggest that the responsiveness of rabbit follicles to LH is dependent on the endocrine status of the animal when the ovaries were removed.
SITES OF STEROID PRODUCTION IN OVINE GRAAFIAN FOLLICLES IN CULTURE
Authors: MOOR R. M. 
Published: December 2008

SUMMARY
The follicular components responsible for the synthesis of oestrogen, testosterone and progesterone have been localized by studying in vitro the steroidogenic capacity of (1) intact follicles, (2) opened but undisturbed follicle walls, (3) isolated thecal shells, (4) granulosa cells and (5) co-cultures of thecal shells and granulosa monolayers.
Oestrogen was secreted throughout the five-day culture period by intact follicles and explants of follicle wall. Neither the isolated thecal shell nor the membrana granulosa alone secreted oestrogen in vitro, but granulosa cells converted exogenous testosterone to oestrogen during the first few hours after explantation. A limited and transient production of oestrogen occurred in co-cultures of theca and granulosa.
Testosterone was secreted in the presence of FSH in approximately equal amounts by intact follicle, follicle wall and thecal shells. No testosterone was secreted by the isolated granulosa cells.
Progesterone was secreted by each cellular component but the highest output occurred where granulosa cells were grown in monolayer culture.
The results indicate that the theca is the source of follicular androgen synthesis but that an interaction between theca and granulosa is required for the production of oestrogen. It is postulated that direct contact between two cell components is important in the modulation of steroidogenic function within the follicle.
HORMONAL CONTENT AND ULTRASTRUCTURE OF THE HYPOTHALAMO-NEUROHYPOPHYSIAL SYSTEM OF THE RAT AFTER INJECTION OF VINBLASTINE INTO THE MEDIAN EMINENCE
Authors: RODRÍGUEZ E. L. , CAVICHIA ECHANDÍA, J. C. , RODRÍGUEZ E. M. 
Published: December 2008

SUMMARY
The effects of an injection of vinblastine (Vbl) into the median eminence on the structure, fine structure and antidiuretic hormone (ADH) content of the hypothalamo-neurohypophysial system in the rat is reported. The animals were studied on days 3, 8 and 25 after the injection of 1 or 5 mm-Vbl (3 μl). Significant changes were observed only in the 5 mm-Vbl-injected animals. Their median eminence extracts showed a progressive accumulation of ADH whereas ADH depletion occurred in the neural lobe extracts. On day 8 after injection, the animals exhibited strong polidipsia although considerable amounts of ADH still remained within the neural lobe. The ADH content of the plasma samples was consistently below the sensitivity of the method (5 μu.). The light microscopic analysis showed accumulation of Gomori-stainable products in the median eminence and a striking depletion of this material from the neural lobe. Electron microscopy revealed accumulation of neurosecretory vesicles and other inclusions proximal to the site of injection in the median eminence together with some evidence of nerve fibre degeneration. Few neurosecretory terminals were found in the neural lobe of the 8-day experimental rats. They had been engulfed by pituicytes for digestion. Recuperation of the normal ADH content of both median eminence and neural lobe was found to occur on day 25 after the Vbl injection. Simultaneously, the neural lobe refilled with Gomori-positive materials and neurosecretory terminals reappeared. The results suggest (1) reversible blockade of axoplasmic transport at the site of the Vbl injection; (2) reversible degeneration of neurosecretory terminals and (3) reversible blockade of ADH release in the surviving terminals of the neural lobe.
SIALIC ACID CONCENTRATION IN THE REPRODUCTIVE ORGANS, PITUITARY GLAND AND URINE OF THE INDIAN LANGUR MONKEY (PRESBYTIS ENTELLUS ENTELLUS)
Authors: SHANDILYA L. N. , RAMASWAMI L. S. , SHANDILYA N. 
Published: December 2008

SUMMARY
The concentration of sialic acid was determined in the reproductive organs, pituitary gland and urine of male and female langur monkeys. In the male, sialic acid concentration was lowest in the testes and highest in the epididymides. Both caput and cauda epididymides contained almost the same concentration. Castration and subsequent androgen administration did not modify the concentration of sialic acid by comparison with intact animals, suggesting that sialic acid is not androgen-dependent in the langur.
There was no significant difference in sialic acid concentration in the uterus during the proliferative and luteal phases of the menstrual cycle. After ovariectomy, there was a decrease in the concentration of sialic acid in the uterus, cervix and vagina while oestrogen or oestrogen plus progesterone administration increased its concentration significantly, but not to the control level. However, the difference in concentration between oestrogen-treated and oestrogen plus progesterone-treated monkeys was not significant. There was a peak of sialic acid excretion in the urine on day 8 of the normal 22-day menstrual cycle, i.e. a day before the probable day of ovulation. In pregnant monkeys sialic acid excretion increased significantly 2 days before delivery compared with the values recorded 7 to 3 days before parturition. The part played by sialic acid during the menstrual cycle and pregnancy in the female is not clear.
CONCENTRATION OF OESTRADIOL, PROGESTERONE, LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE IN THE JUGULAR VENOUS PLASMA OF EWES DURING THE OESTROUS CYCLE
Authors: PANT H. C. , HOPKINSON C. R. N. , FITZPATRICK R. J. 
Published: December 2008

SUMMARY
Changes in the concentrations of ovarian steroids and pituitary gonadotrophins were measured by radioimmunoassay in the jugular plasma of six Clun Forest ewes throughout the oestrous cycle.
The concentration of oestradiol began to rise 12–14 h before the onset of oestrus from values of 11·2 ± 0·36 (s.e.m.) pg/ml during the luteal phase to 21·1 ± 2·01 pg/ml at −8 to 0 h (oestrus). There was no distinct increase during the luteal phase.
Circulating progesterone varied in a cyclic manner with the highest values at the mid-luteal phase (3·70 ± 0·28 ng/ml; n = 28). In five out of six ewes the concentration was still quite high (1·86 ± 0·43 ng/ml) at 35 h before the onset of oestrus. The concentration declined rapidly thereafter, reaching minimum values about 12 h before oestrus coincident with the increase in oestradiol concentration.
Plasma LH increased from very low values of 2·59 ± 0·09 ng/ml during the luteal phase to 75·3 ± 7·4 ng/ml about 9 h after the onset of oestrus.
Two peaks of plasma FSH concentration were detected after the onset of oestrus. The first peak (171·0± 35·5 ng/ml) coincided with the LH peak and the second (133·0 ± 10·7 ng/ml) occurred about 24 h later at a time when LH values were low. The mean FSH concentration at other times during the cycle was 61·9 ± 2·8 ng/ml.
PURIFICATION AND RADIOIMMUNOASSAY OF CHICKEN GROWTH HORMONE
Authors: HARVEY S. , SCANES C. G. 
Published: December 2008

SUMMARY
Chicken growth hormone has been isolated from adenohypophysial tissue from which the glycoprotein hormones had been removed. The procedure entailed alkali extraction, ammonium sulphate precipitation and ion-exchange chromatography on DEAE-cellulose. The resulting fraction was homogeneous, active in the rat tibia bioassay and had a similar isoelectric point, molecular weight and amino acid composition to mammalian growth hormone. A specific homologous radioimmunoassay has been developed using the avian growth hormone.
EFFECT OF LIMB ISCHAEMIA AND SCALDING ON THE CONCENTRATIONS OF GROWTH HORMONE AND CORTICOSTERONE IN RAT PLASMA
Authors: BARTON R. N. 
Published: December 2008

SUMMARY
In post-absorptive rats in a 20 °C environment, bilateral hind-limb ischaemia decreased the plasma growth hormone concentration below the very wide range found in control rats. Injection of sodium pentobarbitone increased the concentration in both control and injured rats but did not eliminate the difference between them. A 20% dorsal scald also decreased the variability of plasma growth hormone concentration but did not reduce it below the normal range. Thus growth hormone is probably not responsible for the insulin resistance seen in the severely injured rat. The plasma corticosterone concentration markedly increased after both injuries but was not altered by pentobarbitone.
URINARY STEROID EXCRETION BY THE SQUIRREL MONKEY (SAIMURI SCIUREUS)
Authors: SETCHELL K. D. R. , CHUA K. S. , HIMSWORTH R. L. 
Published: December 2008

SUMMARY
Urinary steroids and steroid conjugates were measured in the squirrel monkey (Saimuri sciureus). The principal steroids excreted were cortisol, 11β,17α,20β,21-tetrahydroxy-4pregnen-3-one (20β-dihydrocortisol), 11β,17α,20α,21-tetrahydroxy-4-pregnen-3-one (20α-dihydrocortisol), α- and β-cortol and α- and β-cortolone. The majority of the steroids were excreted unconjugated and a conspicuous feature of the pattern was the large amount of urinary free cortisol. Unlike man there was an insignificant excretion of 3α,17α,21-trihydroxy-5β-pregnane-11,20-dione (tetrahydrocortisone) and 3α,11β,17α,21-tetrahydroxy-5β-pregnan-20-one (tetrahydrocortisol). A steroid not previously identified in urine from any species was one of the major glucuronide conjugates; it was characterized as having the structure 3β,17α,20ξ,21-tetrahydroxy-5β-pregnan-11-one. Administration of dexamethasone resulted in complete suppression of steroid output, whilst the response to adrenocorticotrophic hormone was inconstant.
DYNAMICS AND MECHANICS OF CORTICOSTEROID FEEDBACK AT THE HYPOTHALAMUS AND ANTERIOR PITUITARY GLAND
Authors: JONES M. T. , HILLHOUSE E. W. , BURDEN J. L. 
Published: December 2008

SUMMARY
Corticosteroid feedback mechanisms were investigated at the hypothalamic level using the rat hypothalamus in vitro and at the pituitary level using basal hypothalamic-lesioned rats. Both fast and delayed corticosteroid feedback effects were demonstrated at the level of the hypothalamus and pituitary gland with doses of corticosteroids within or near the physiological range. These two phases of feedback were separated temporally by a 'silent period' during which no feedback was apparent.
Studies on the mechanism of action of corticosteroids at the hypothalamic level showed that the fast feedback mechanism acts by inhibition of release whilst the delayed feedback mechanism acts by inhibition of both synthesis and release. The fast feedback action of corticosterone does not appear to act by excitation of neuroinhibitory pathways since neither picrotoxin nor phentolamine prevented the feedback action of corticosteroids in vitro.
Corticosterone inhibition of corticotrophin releasing factor release was overcome by depolarization of the membrane with K+ suggesting that the mechanism of action of the fast feedback of corticosteroids is by membrane stabilization.
EFFECTS OF EXOGENOUS PROGESTERONE AND OESTRADIOL ON PROSTAGLANDIN F AND 13,14-DIHYDRO-15-OXO PROSTAGLANDIN F2α CONCENTRATIONS IN UTERI AND PLASMA OF OVARIECTOMIZED EWES
Authors: LOUIS T. M. , PARRY DILYS M. , ROBINSON J. S. , THORBURN G. D. , CHALLIS J. R. G. 
Published: December 2008

SUMMARY
The control of prostaglandin (PG) production by steroid hormones has been investigated in non-pregnant bilaterally ovariectomized sheep, prepared with indwelling utero-ovarian venous catheters and treated with physiological amounts of oestradiol and progesterone. Oestradiol treatment alone (2 × 15 μg/day for 9 days) had no effect on the prostaglandin F (PGF) concentration in uterine caruncles or intercaruncular tissue, on the release of PGF or of 13,14-dihydro-15-oxo PGF (PGFM) from these tissues during incubation in vitro, or on the concentrations of PGF in the utero-ovarian vein or PGFM in the jugular vein. However, oestradiol did accumulate in the uterine tissues. Progesterone treatment alone (2 × 10 mg/day for 9 days) provoked a significant increase in the concentration of PGF in the caruncles, a significant increase in the release of PGF from the caruncles during incubation with arachidonic acid and increased mean concentrations of PGFM in the jugular vein. When oestradiol was superimposed on a progesterone-primed system, there was a further marked increase in the PGF content of the caruncles, release of PGF into the utero-ovarian vein, and increased concentrations of PGFM in the jugular vein. The caruncles always contained more PGF than the intercaruncular area, and released more PGF and PGFM during incubation in vitro. In the progesterone+oestradiol group, there was good correlation between the PGF concentrations in simultaneous samples from the right and left utero-ovarian veins, and for all groups there was a high correlation between utero-ovarian PGF and peripheral PGFM concentrations. The caruncular epithelium of the progesterone-treated animals contained more lipid droplets than those of the other groups.
These data are consistent with a requirement for progesterone in activating 'prostaglandin synthetase' activity, and promoting PGF production, largely from the caruncles. After progesterone priming, the synthesis of PGF by the caruncles and PG release into the vascular system was increased further by oestradiol treatment, whereas oestradiol alone was without effect.
OESTRADIOL-17α AND PITUITARY RESPONSIVENESS TO LUTEINIZING HORMONE RELEASING FACTOR IN THE RAT: A STUDY USING RECTANGULAR PULSES OF OESTRADIOL-17β MONITORED BY NON-CHROMATOGRAPHIC RADIOIMMUNOASSAY
Authors: HENDERSON S. R. , BAKER CHRISTINE , FINK G. 
Published: December 2008

SUMMARY
Plasma concentrations of oestradiol-17β were measured by a non-chromatographic radioimmunoassay during the oestrous cycle, after the s.c. injection of 2·5 or 10 pg oestradiol benzoate (OB), or the s.c. implantation of Silastic capsules containing crystalline oestradiol-17β. The profile of endogenous plasma oestradiol-17β concentrations was similar to that reported by other workers, and lay between the concentrations produced by the low and high doses of OB. The rectangular pulses of increased plasma oestradiol concentrations, produced during the period of implantation of the Silastic capsules, were used to determine the time taken for oestradiol-17β to exert its facilitatory effect on the gonadotrophin response to LH-releasing factor (RF). In animals ovariectomized at dioestrus, oestradiol, at concentrations similar to those reached during the peak of the spontaneous surge, first reduced the LH response. However, after 7 h, responsiveness increased significantly to reach a peak at 12 h. The FSH response was also greatest 12 h after ovariectomy. In animals ovariectomized at metoestrus the effect of oestradiol on the LH response was significantly less than in rats ovariectomized at dioestrus, and the FSH responses were lower than those in animals bearing empty capsules and examined at the same time after ovariectomy. These findings together with the effects of long-term exposure to sodium pentobarbitone are considered with respect to the possible mechanisms, including the priming effect of LH-RF, which may produce increased pituitary responsiveness after ovariectomy and exposure to oestrogen.
STEROID SYNTHESIS IN VITRO BY THE PLACENTA OF THE GUINEA-PIG. AND PROGESTERONE CONCENTRATIONS IN SYSTEMIC AND UTERINE PLASMA
Authors: TAM W. H. 
Published: December 2008

SUMMARY
The spongy zone (SZ) syncytiotrophoblast has been identified as the principal site of progesterone synthesis in the placenta of the guinea-pig. This was evident from the relatively large amounts of progesterone synthesized by the SZ from [7α-3H]pregnenolone and the exact correlation of SZ development and the estimated progesterone secretory activity of the placenta throughout gestation. Placental progesterone secretion started between days 20–25 of gestation when the SZ was being formed. Progesterone secretion rose to a maximum by day 30 and was maintained until at least day 53, reflecting the large amount of SZ tissue present in the placenta during this period. Secretory activity decreased simultaneously with the decrease in SZ tissue, even though a decrease in progesterone concentration in systemic plasma was not evident. The results also suggested that the yolk sac was able to synthesize progesterone and metabolize steroids in vitro. Small quantities of 5-saturated C21 steroids were also synthesized by the placenta.
THE INFLUENCE OF OESTRADIOL ON THE METABOLISM OF ANDROGENS BY HUMAN PROSTATIC TISSUE
Authors: BARD D. R. , LASNITZKI ILSE 
Published: December 2008

The uptake and metabolism of testosterone, androstenedione and 5α-dihydrotestosterone (DHT) by human benign hyperplastic prostates and prostatic carcinomas have been measured in organ culture. DHT was a major metabolite of both testosterone and androstenedione in the benign tissue and the androstanediols were the principal metabolites of DHT. Over half the carcinomas produced less DHT from testosterone than the benign hyperplastic prostates, and carcinomas from the oldest patients showed an enhancement of 17β-hydroxysteroid dehydrogenation. There was no relationship between these differences in metabolism and the degree of differentiation of the carcinomas.
Oestradiol decreased the production of DHT from both testosterone and androstenedione and, at low androgen concentrations, increased the production of androstanediols from testosterone, androstenedione and DHT. Uptake of DHT, but not of the other two androgens, was stimulated by oestradiol.
INDUCTION OF THE RAT PROSTATE GLAND BY ANDROGENSIN ORGAN CULTURE
Authors: LASNITZKI ILSE , MIZUNO TAKEO 
Published: December 2008

The induction of the prostate gland by testosterone or dihydrotestosterone was studied in urogenital sinuses from Wistar rat embryos explanted in organ culture. In normal development, prostatic rudiments appeared in the urogenital sinuses of 18–19 day male foetuses as epithelial buds projecting into the mesenchyme.
Male urogenital sinuses from 17·5 and 18·5 day foetuses formed buds in control medium, and addition of testosterone or dihydrotestosterone increased their number and size. In contrast, sinuses from 15·5 and 16·5 day male foetuses did not form buds in the absence of androgens, while exposure to the hormones induced them de novo. A concentration of 0·0015 μg testosterone/ml was sufficient to elicit prostatic buds. The same effect was seen after continuous treatment with testosterone or brief exposure to the hormone followed by cultivation in control medium. The development of the buds followed the same time sequence as in the organ in situ.
Testosterone and dihydrotestosterone elicited prostatic buds in female sinuses from 15·5 to 18·5 day foetuses, but their response to androgens decreased with advancing foetal age.
Male and female sinuses from 14·5 day foetuses did not respond to testosterone but formed buds after exposure to dihydrotestosterone. This difference was considered to be due to a low content or absence of 5α-reductase at this stage.
Testes from 15·5 to 18·5 day foetuses grown in close contact with urogenital sinuses or explants of mature prostate glands induced prostatic buds or augmented the height of the prostatic epithelium.
It was concluded that androgens are necessary for the initiation of the rat prostate gland and that the effect of testosterone is mediated via 5α-dihydrotestosterone.
The onset of 5α-reductase synthesis is likely to occur between days 14 and 15 of foetal life. The early androgenic activity of the testes suggests that bud formation in the older male sinuses in the absence of androgens is due to exposure to endogenous testosterone before explantation.
DESENSITIZATION OF THE DOPAMINERGIC INHIBITION OF PITUITARY LUTEINIZING HORMONE RELEASE BY PROLACTIN IN OVARIECTOMIZED RATS
Authors: BECK W. , WUTTKE W. 
Published: December 2008

Increase of plasma prolactin in chronically ovariectomized rats by transplanting pituitary glands from male rats to the kidney capsule reduced pituitary LH output for 1 week. At the end of this time, despite the fact that prolactin remained high, plasma LH levels rose to reach the value seen in ovariectomized control rats. High plasma prolactin did not affect FSH concentrations. Treatment of ovariectomized rats with apomorphine, a dopamine-receptor stimulating drug, reduced pituitary LH release in a dose-dependent way at doses of 1, 2, 5 and 10 mg/kg body weight. Higher doses either had no effect or they stimulated pituitary LH release. Apomorphine did not reduce pituitary LH secretion in chronically hyperprolactinaemic rats at doses which significantly inhibited LH release in ovariectomized animals. Plasma FSH levels were not affected by apomorphine treatment. In both groups of animals the drug reduced plasma prolactin levels to basal values, indicating that the dopamine agonist inhibits pituitary prolactin release by direct action on the pituitary gland.
These results suggest that dopamine inhibits pituitary LH release, probably by reducing hypothalamic LH-releasing hormone release. The mechanism by which chronically high prolactin levels cause apomorphine to be less effective in reducing pituitary LH release may be a desensitization of some dopamine-receptive mechanism which is inhibitory to LH release.