bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECTS OF OXYTOCIN AND VASOPRESSIN DURING THE OESTROUS CYCLE AND PREGNANCY ON THE UTERUS OF A MARSUPIAL SPECIES, THE QUOKKA (SETONIX BRACHYURUS)
Authors: HELLER H.
Published: December 2008

Uteri of the marsupial species Setonix brachyurus suspended in a solution with a cation concentration similar to that of Setonix plasma ultrafiltrate, responded to oxytocin, arginine-vasopressin (AVP) and arginine-vasotocin at all stages of the oestrous cycle (28 days) and gestation (27 days). In cyclic intact non-pregnant animals the potency of AVP in evoking contractile responses of the uterus was greater than that of oxytocin when the myometrium was oestrogen-dominated, i.e. from about day 19 to about 2 days after oestrus. In contrast, during the luteal phase (day 7–18) the uterine muscle was much more responsive to oxytocin than to AVP, although the threshold concentration for oxytocin was raised. The uteri of bilaterally ovariectomized quokkas responded more markedly to AVP than to oxytocin after treatment of the animal in vivo with an oestrogen. The responsiveness of uteri of progesterone-treated ovariectomized quokkas to vasopressin was equal to or less than their responsiveness to oxytocin.

The response of the pregnant Setonix uterus to oxytocin was always greater than that to AVP, even late in pregnancy when at the corresponding stage of the oestrous cycle in the non-pregnant quokka (day 19–23) the myometrium was more responsive to AVP than to oxytocin. At earlier stages of pregnancy there were indications of a similar degree of progesterone block to oxytocin as during the luteal phase in non-pregnant Setonix.

It has frequently been assumed that the endocrine milieu in marsupials is the same during the oestrous cycle and in pregnancy. The present results suggest that there are differences.
A SIMPLIFIED METHOD FOR MEASURING THYROIDAL UPTAKE OF TECHNETIUM99m USING DIRECTIONAL COUNTING
Authors: GRAY H. W. , HOOPER L. A. , GREIG W. R.
Published: December 2008

The uptake of technetium-99m (99mTc) by the thyroid was measured 15 min after injection using a directional counting technique. The 'washout' of thyroidal 99mTc after intravenous perchlorate injection was quantitated so that separate measurement of the extrathyroidal activity of 99mTc was unnecessary.

In normal subjects the thyroidal uptake was 1·28 ± 0·61% of the administered dose (mean ± 1 s.d.); in primary myxoedema 0·26 ± 0·28%, in simple goitre 2·18 ± 2·10%, in thyrotoxicosis 11·0 ± 5·4%, in hypothyroid patients with Hashimoto's disease 4·50 ± 3·70% and in three patients with Pendred's syndrome the mean uptake was 9·3%.

The technique has been evaluated and its advantages as a simple alternative to quantitative scintiscanning are discussed.
STEROID METABOLISM BY AN OESTROGEN-DEPENDENT INTERSTITIAL-CELL TUMOUR OF A RAT TESTIS
Authors: JULL J. W. , McCLELLAN D. , COUPEY S.
Published: December 2008

Steroid metabolism by a unique, transplantable, oestrogen-induced, hormone-dependent interstitial-cell tumour of a rat testis was investigated. After incubation of the minced tumour in medium without substrate the presence of 3α-androstanediol, 3-epiandrosterone and androsterone was shown. There was inconclusive evidence for the presence of smaller amounts of 3β-androstanediol, and no evidence for testosterone. [14C]Pregnenolone substrate was shown to be metabolized after 2 h to androstenedione, androsterone and a small amount of testosterone. Epi- and dehydroepiandrosterone were probably formed from [14C]pregnenolone, but were incompletely characterized.
THE BIOLOGICAL HALF-LIVES OF RIBOSOMAL AND TRANSFER RNA IN THE MOUSE UTERUS
Authors: MILLER B. G.
Published: December 2008

Estimates were obtained of the half-lives of ribosomal RNA (rRNA) and transfer RNA (tRNA) in the uteri of ovariectomized mice receiving daily doses of 6 or 25 ng oestradiol, or no oestrogen injections. Apparent half-lives were calculated from data for the loss of radioactivity from rRNA and tRNA fractions after a single intravenous injection of [methyl-3H]l-methionine. The half-life of rRNA in mice which received no oestradiol injections was about 7 days and decreased to about 4 days in mice that received either 6 or 25 ng oestradiol daily. The half-life of tRNA after all treatments was about 3 days.
MITOGENIC ACTION OF OESTRADIOL-17β ON HUMAN MYOMETRIAL AND ENDOMETRIAL CELLS IN LONG-TERM TISSUE CULTURES
Authors: CHEN LOUISE , LINDNER H. R. , LANCET M.
Published: December 2008

Dispersed human endometrial and myometrial cells grown for up to 4 months as monolayer cultures responded to addition of oestradiol-17β (1 × 10−9 mol/l) to the medium by increased [3H]thymidine incorporation into DNA, and an increased rate of cell division. Cultures derived from uterine leiomyomata showed a less consistent mitotic response to the hormone.

Normal endometrial and myometrial cells grown in the oestradiolenriched medium showed a significantly higher efficacy of colony formation (increases of about 60 and 90%, respectively) than cells grown in control medium throughout the experimental period. Exposure to the hormone for 3–4 days was sufficient to induce this effect, which suggests that it does not depend on selection of hormone-sensitive cells. The mitogenic effect of oestradiol, as expressed by increased cloning efficacy, persisted for several days after transfer of the cells to a hormone-free medium. Cultures of foetal rat skeletal muscle failed to respond to oestradiol-17β in the cloning test, and oestradiol-17α was without effect on uterine cells.

It is concluded that oestradiol-17β exerts a direct mitogenic action on some cellular components of the human endometrium and myometrium in vitro.
A STUDY OF THE ANDROGEN RECEPTORS IN A VARIETY OF ANDROGEN-SENSITIVE TISSUES
Authors: MAINWARING W. I. P. , MANGAN F. R.
Published: December 2008

A search has been conducted for specific, 5α-dihydrotestosterone-binding proteins in a wide variety of tissues and cells upon which androgenic steroids have pronounced morphological and biochemical effects. High affinity binding proteins of this nature have been identified in cytoplasmic and nuclear extracts from a diversity of accessory sexual glands of many species, mouse kidney, testis and certain experimental androgen-dependent tumours. They are notably absent in most types of skeletal muscle and in soluble extracts prepared from prokaryotic organisms. The implications of these findings to the mechanism of action of androgenic steroids are discussed. While the selective binding of 5α-dihydrotestosterone indubitably plays a role of paramount importance in the mechanism of action of androgens in many accessory sexual glands throughout life, this process may be of importance in other tissues only during the period of early growth and development. A severe limitation to the importance of the binding of 5α-dihydrotestosterone in certain adult tissues is imposed by the very low activity of the enzyme, 5α-reductase, responsible for the formation of 5α-dihydrotestosterone.
IMMUNORADIOMETRIC AND TWO-SITE ASSAY OF HUMAN FOLLICLE-STIMULATING HORMONE
Authors: READHEAD CAROL , ADDISON G. M. , HALES C. N. , LEHMANN H.
Published: December 2008

An immunoradiometric assay for human follicle-stimulating hormone (FSH) is described. A non-specific antiserum to human FSH was purified by incubation of the antiserum with human luteinizing hormone and thyroid-stimulating hormone before its reaction with an immunoadsorbent containing human FSH. The specific antibodies to human FSH isolated on immunoadsorbent were iodinated and used for the FSH assay. The sensitivity of the assay was improved by the extraction of plasma FSH onto antibody-coated polyethylene tubes before its reaction with iodinated FSH antibodies producing a two-site assay. Optimal conditions for the preparation and use of antibody-coated tubes in such a procedure are described. Using serial extraction a sensitivity of 11 pg/ml (0·1 mu./ml) was achieved. There was good agreement between the results obtained with this method and those obtained with radioimmunoassay. The advantages of the increased sensitivity of this new method are discussed.
PITUITARY AND PLASMA GONADOTROPHIN LEVELS AND SPERMATOGENESIS IN THE GOLDFISH CARASSIUS AURATUS AFTER METHALLIBURE TREATMENT
Authors: BRETON B. , JALABERT B. , BILLARD R.
Published: December 2008

The level of gonadotrophin measured by radioimmunoassay in fully mature male goldfish was about 15 ng carp gonadotrophic hormone (c-HG)/ml plasma and 30 μg c-HG/g pituitary (wet weight). After treatment for 35 days with methallibure (added to the water at the rate of 2 p.p.m./day), the level of gonadotrophin in the blood was very low and remained at the pretreatment level in the pituitary. This suggested that releasing factor might control either synthesis or discharge of gonadotrophin from the pituitary. These results have also shown that type B spermatogonia and meiosis were gonadotrophin dependent but that the development of spermatocytes into spermatids did not require high concentrations of gonadotrophin. Spermiation was suppressed when the concentration of c-HG dropped below 10 ng/ml plasma.
SEX DIFFERENCES AND HORMONAL CONTROL OF TESTOSTERONE METABOLISM IN RAT PITUITARY AND BRAIN
Authors: DENEF CARL , MAGNUS CAREW , McEWEN B. S.
Published: December 2008

The in-vitro conversion of testosterone to 17β-hydroxy-5α-androstan-3-one (5α-dihydrotestosterone, DHT) and 3α, 17β-dihydroxy-5α-androstane (3α-androstanediol, DIOL) in pituitary and slices of brain regions was compared between male and female rats. Intact pituitaries from male rats formed 2·5 times more DHT and 1·5 times more DIOL than those of females. A small sex difference was also detected in the hypothalamus, males again being higher than females. No sex differences could be detected in other brain regions. However, DHT formation in the brain was regionally differentiated with higher conversion rates in hypothalamus than in cortex, hippocampus, amygdala, pineal gland or cerebellum. The highest transformation, however, was found in the mid-brain. Metabolism in the pre-optic area was as low as that in the cortex.

5α-Dihydrotestosterone and DIOL formation in the pituitary increased several-fold after gonadectomy in both sexes and the sex difference disappeared. Little or no increase occurred after thyroidectomy or adrenalectomy. The increase in pituitary DHT formation after gonadectomy could be attenuated or prevented both by treatment with testosterone propionate and with oestradiol benzoate. Replacement therapy, particularly with oestradiol benzoate, gave rise to a sex difference reminiscent of that of normal animals. No significant change in pituitary DHT formation occurred in adult females which had been treated with testosterone propionate on the 4th day of life.

The results suggested a close relationship between DHT formation and activity of gonadotrophin secretion, particularly at the level of the pituitary.
THE EFFECT OF d-ALDOSTERONE AND SPIRONOLACTONE ON THE CONCENTRATION OF SODIUM AND POTASSIUM IN THE MILK OF RATS
Authors: YAGIL R. , ETZION Z. , BERLYNE G. M.
Published: December 2008

The effects of d-aldosterone and spironolactone on the sodium and potassium concentrations in the milk of rats were determined. d-Aldosterone caused a highly significant fall in the milk sodium concentration and the Na:K ratio when compared with control animals. The administration of spironolactone shortly before aldosterone gave results not significantly different from control animals. It is concluded that aldosterone has a specific sodium-lowering action in the milk of the lactating rat.
STEROID METABOLISM IN VITRO BY AN INTERSTITIAL CELL TUMOUR AND THE ATTACHED PREPUBERTAL TESTIS
Authors: RICHARDS GWEN , NEVILLE A. MUNRO
Published: December 2008

A virilizing interstitial cell tumour and the attached testicular tissue from a 4-year-old boy were incubated in vitro with [7α-3H]pregnenolone and [4-14C]progesterone, or [4-14C]androstenedione and [7α-3H]5α-dihydrotestosterone. Ring A saturated steroids were produced from 4-ene precursors by the prepubertal testis, but this tissue was unable to convert pregnenolone or progesterone to 17α-hydroxylated C21 steroids, or to C19 steroids.

The virilizing interstitial cell tumour metabolized pregnenolone and progesterone to 17α-hydroxyprogesterone, androstenedione and testosterone. In addition, dehydroepiandrosterone was detected as a product of pregnenolone. The tumour lacked 4-ene-5α-steroid reductase activity.

5α-Dihydrotestosterone was metabolized to 5α-androstane-3,17-dione, androsterone, isoandrosterone, 5a-androstane-3α,17β-diol and 5α-androstane-3β,17β-diol in both the normal and tumour tissue.

The significance of these metabolic pathways is discussed.
INCREASED SENSITIVITY OF SEMINAL VESICLES TO TESTOSTERONE IN A MOUSE STRAIN WITH LOW PLASMA TESTOSTERONE LEVELS
Authors: BARTKE A.
Published: December 2008

In male mice of the C57BL/10J (C57) strain the testicular weight, sex drive and aggression are low compared with a number of other strains, indicating androgen deficiency. In contrast, DBA/2J (DBA) males were 'normal' in all studied parameters of testicular function. The weight of the seminal vesicles is similar in both strains.

Plasma testosterone levels, and the responsiveness of the seminal vesicles to injected testosterone propionate in C57 and DBA animals were compared. Plasma testosterone levels were 1·3 ± 0·4 ng/ml in C57 and 4·6 ± 1·0 ng/ml in DBA mice. The increase in weight of the seminal vesicles after administration of testosterone propionate to castrated male mice was, however, considerably greater in C57 than in DBA mice. In order to restore the weight of the seminal vesicles to normal it was necessary to administer twice as much testosterone propionate to DBA than to C57 males.
HISTOLOGICAL AND ULTRASTRUCTURAL CHANGES IN THE PARS DISTALIS OF THE RABBIT PITUITARY IN ORGAN CULTURE
Authors: PATHAK S. , FISK A.
Published: December 2008

Typical histological and ultrastructural changes that occur in the pars distalis of the rabbit pituitary after different periods of organ culture are described. The best technique for the maintenance of the maximum proportion of the explant was assessed by comparing cultures grown under different conditions. Explants in air with a medium buffered with N-2-hydroxyethylpiperazine-N1-2-ethanesulphonic acid (HEPES), not previously used in organ culture, proved more satisfactory than explants in carbogen with bicarbonate-buffered 199, and cultures were maintained for more than 3 weeks.

The survival of cells was assessed on the basis of their cytological integrity; DNA- and RNA-fluorescence with acridine orange was a valuable indicator. Prolactin cells, which were few in uncultured controls, became the most common type of granular cell in long-term cultures.

Cell modifications during culture included the development of a peripheral epithelioid layer and the appearance of numerous microvilli. Microfibrils, coated or smooth vesicles, lytic bodies, desmosomes and intranuclear rods became more common and intranuclear rodlets (fibrous or membranous structures) were identified. Cells often became more electron dense during long-term culture.

Though there was an increase in the number of agranular cells during culture, identifiable granules were retained by many cells throughout culture.
CHANGES IN LEYDIG CELL HYDROXYSTEROID DEHYDROGENASES INDUCED BY ADMINISTRATION OF TESTOSTERONE PROPIONATE TO NORMAL MEN
Authors: MORSE H. C. , HELLER C. G.
Published: December 2008

By the employment of an improved histochemical technique, frozen sections from human testicular biopsy specimens were examined for 3β-and 17β-hydroxysteroid dehydrogenase (HSD) activity, before, during, and after administration of 25 or 50 mg testosterone propionate per day to normal men. This administration strongly suppressed Leydig cell HSD activity and caused these cells to be transformed into fibroblast-like cells. After cessation of administration, the Leydig cells recovered morphologically and so did, simultaneously their 3β- and 17β-HSD activity. It is concluded that histochemically detectable 3β- and 17β-HSD are under gonadotrophin control and change with alterations in Leydig cell function. The morphology or 3β- and 17β-HSD are therefore probably acceptable as indicators of Leydig cell function in reproductively normal men.
OESTROGEN AND PROGESTERONE INFLUENCE ON THE RELEASE OF PROLACTIN IN OVARIECTOMIZED RATS
Authors: CALIGARIS L. , ASTRADA J. J. , TALEISNIK S.
Published: December 2008

The concentration of prolactin in serum after oestrogen and progesterone injection into spayed rats was measured by radioimmunoassay.

After a single injection of 5 μg oestradiol benzoate (OB) into long-term ovariectomized rats, serum prolactin concentrations showed a circadian rhythm with high levels in the afternoon and almost no changes in the morning. Peaks of prolactin occurred 2, 3 and 4 days after the injection. Below a dose of 1 μg OB, the response was dose-dependent, but the response was then maximal.

In spayed rats primed with 5 μg OB, the injection of 2 mg progesterone 2, 3 or 4 days later resulted in a significant increase in serum prolactin. This response, in contrast to that of oestrogen, occurred in the morning and in the evening and was found to be dose-dependent. The rise in serum prolactin after injection of 1 mg progesterone also showed a close relationship to the priming dose of OB. Progesterone had no effect in spayed, untreated animals. Maximal levels of prolactin were attained 3–4 h after the s.c. injection of progesterone. The release of prolactin which can be induced either by OB or by progesterone was blocked by the administration of progesterone injected 1 day before the expected release would occur. These results indicate that progesterone exerts both facilitatory and inhibitory effects on prolactin secretion. Male rats were found to be less sensitive to the ovarian steroid treatment.

It is suggested that oestrogen could be responsible for the rise in prolactin observed at pro-oestrus and progesterone for the increase in prolactin in pseudopregnancy and pregnancy.
OESTRONE, OESTRADIOL-17β AND OESTRIOL LEVELS IN HUMAN FOETAL PLASMA DURING GESTATION AND AT TERM
Authors: SHUTT D. A. , SMITH I. D. , SHEARMAN R. P.
Published: December 2008

Marked rises in both unconjugated and sulphoconjugated oestrone, oestradiol-17β and oestriol were observed in human foetal plasma between mid-gestation and term. Significant arterio-venous differences for the individual oestrogens in the unconjugated form were found in the umbilical cord plasma. No consistent arterio-venous differences were found for the oestrogen sulphates. This indicates that all three oestrogens are secreted from the placenta into the foetal circulation in the unconjugated form. Mean unconjugated oestrogen (oestrone + oestradiol-17β + oestriol) levels rose from 22·7 ng/ml at 17–20 weeks of gestation to 108·9 ng/ml at term in umbilical venous plasma and from 4·3 ng/ml to 23·3 ng/ml in umbilical arterial plasma. This represents a secretion rate of approximately 30 mg oestrogen/day into the umbilical vein at term. Mean oestrogen sulphate levels rose from 128 ng/ml to 313 ng/ml in the cord plasma during the same period. Of the three oestrogens measured, oestriol was quantitatively the major oestrogen in foetal plasma. It consistently represented about 78% of the unconjugated fraction and 95% of the sulphate fraction at all stages of gestation.

The method of delivery did not have a significant effect on the oestrogen levels in uncomplicated pregnancies. Similar oestrogen levels were found in foetal heart blood after either hysterotomy or spontaneous abortion at 16–20 weeks of gestation, and no significant differences were found for oestrogen levels in cord plasma after elective Caesarean section at 38–39 weeks when compared with oestrogen levels after normal delivery at term.

A significant rise in foetal unconjugated oestrogens at a time when foetal corticosteroids are increasing may be of physiological importance for foetal maturation in women.
THE INFLUENCE OF OVARIAN HORMONES UPON THE MOTILITY AND PROSTAGLANDIN PRODUCTION OF THE PREGNANT RAT UTERUS IN VITRO
Authors: HARNEY P. J. , SNEDDON J. M. , WILLIAMS K. I.
Published: December 2008

The output of prostaglandin-like material and the spontaneous contractions of the pregnant rat uterus in vitro have been studied during the last 6 days of pregnancy and for 3 days post partum. Both prostaglandin release and uterine activity were minimal on days 17–18 of pregnancy but both parameters gradually increased, reaching a peak on day 22, the expected day of delivery. Post partum both uterine prostaglandin release and spontaneous activity declined. Progesterone (25 mg, i.m.) given to rats from days 16–21 of pregnancy did not alter uterine activity or prostaglandin output when compared with uteri taken on day 22 from animals which had received ethyl oleate over the same period. On day 22 the spontaneous activity of uteri in vitro taken from animals ovariectomized on day 17 was very low compared with that seen in preparations from sham-operated controls, although prostaglandin release in these groups was not significantly different. Oestrogen (1 μg, i.m.) was given to one group of ovariectomized animals on days 19 and 20; uterine activity was determined on day 21 of pregnancy and found to be of greater intensity and amplitude than that seen in an ovariectomized control group. Prostaglandin output was similar in these groups. Thus although exogenous progesterone and oestrogen do not influence uterine prostaglandin release at term, oestrogen appears essential for the occurrence of spontaneous contractions. It is concluded that, in the pregnant rat uterus in vitro, prostaglandin release may contribute to uterine activity but oestrogen is essential for this to become apparent.
EFFECTS OF MICROQUANTITIES OF TESTOSTERONE ON THE EPIDIDYMIS AND ACCESSORY GLANDS OF THE CASTRATED RHESUS MONKEY, MACACA MULATTA
Authors: DINAKAR N. , ARORA RENU , PRASAD M. R. N.
Published: December 2008

Release of testosterone from silastic implants over a period of 90 days resulted in variable stimulation of the epididymis and accessory glands of reproduction in the castrated rhesus monkey. While the weights of the seminal vesicles, prostate gland and bulbo-urethral glands were maintained at the same level as the intact control animals by four or eight implants of testosterone, those of the epididymis and ductus deferens were not affected by either dose of testosterone.

Fructose in the seminal vesicles was stimulated significantly above intact control levels by eight implants of testosterone.

There was no regional variation in the levels of sialic acid in the caput, corpus and cauda epididymides, but the concentrations of phospholipid and total lipid were significantly higher in the caput epididymidis.

Our observations suggest there may be differential threshold requirements of androgens for the maintenance of the epididymis and accessory glands in the male rhesus monkey.
EFFECT OF ANGIOTENSIN II ON ALDOSTERONE SECRETION IN THE CONSCIOUS RAT
Authors: COLEMAN T. G. , McCAA R. E. , McCAA CONNIE S.
Published: December 2008

Aldosterone secretion has been shown to increase in response to exogenous angiotensin II in man and many experimental animals. However, the rat adrenal has traditionally shown little or no response to angiotensin in experimental protocols using either angiotensin added to incubating adrenal tissue or angiotensin infused into anaesthetized rats. In this study, changes in plasma aldosterone concentration in response to a 20 min infusion of small amounts of angiotensin II into conscious rats were compared with the changes produced in sodium pentobarbitone anaesthetized rats. Both groups showed typical arterial pressure increases in response to infusion: 5 ng angiotensin/kg/min producing approximately a 12 mmHg pressure increase and 20 ng angiotensin/kg/min producing approximately a 25 mmHg increase. Plasma aldosterone concentration increased in anaesthetized rats only at the higher infusion rate, reaching a value 37 ± 6v. 17 ± 2 (s.e.m.) ng/100 ml (n = 5) in anaesthetized control animals. In contrast, plasma aldosterone concentration in conscious rats increased to 69 ± 24 and 106 ± 43 ng/100 ml at the two infusion rates, respectively, v. 13 ± 5ng/100ml in conscious controls. This marked sensitivity indicates that the acute response of the rat to angiotensin infusion is similar to that of other experimental animals and man; however, the response is severely attenuated by anaesthesia and surgical preparation.
ALTERATION OF 3β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN RAT OVARIES DURING THE OESTROUS CYCLE
Authors: GAWIENOWSKI A. M. , CLARK J. N. , SRINIVASAN C. N.
Published: December 2008

The activity of 3β-hydroxysteroid dehydrogenase has been determined during various stages of the oestrous cycle in rats. The enzyme activity was high during pro-oestrus and oestrus but low during dioestrus I and II.
PLACENTAL TRANSFER OF OXYTOCIN IN THE GUINEA-PIG AND ITS RELEASE DURING PARTURITION
Authors: BURTON A. M. , ILLINGWORTH D. V. , CHALLIS J. R. G. , McNEILLY A. S.
Published: December 2008

Oxytocin levels in pregnant and parturient guinea-pigs were studied by means of a sensitive and specific radioimmunoassay. Oxytocin was released from the maternal pituitary in substantial amount only during the expulsive phase of labour, when the mean concentration in carotid arterial blood in five animals was 503 pg/ml plasma (range 96–2900 pg/ml). Oxytocin was not found in the plasma of the first born at the moment of birth, but was usually detected in amounts ranging from 96 to 455 pg/ml in those born subsequently. The mean half-time of oxytocin in the maternal circulation during late pregnancy was 62 ± 7·5 (s.e.m., n = 5) s. In-vivo experiments showed that the placenta was permeable to oxytocin in both directions.
MODIFICATIONS IN OVARIAN AND PITUITARY FUNCTION IN THE HYSTERECTOMIZED PREGNANT HAMSTER
Authors: GREENWALD G. S.
Published: December 2008

When hamsters were hysterectomized on day 1 of pregnancy, ovulation occurred 17 days later. On day 12 of this prolonged pseudopregnancy, plasma levels of progesterone were approximately half of those of intact animals on the same day of pregnancy. The concentration of follicle-stimulating hormone in the pituitary of the hysterectomized animals was only half that of the pregnant group, but luteinizing hormone concentrations were similar. The massive proliferation of antral follicles characteristic of pregnant hamsters on day 12 was not found in the hysterectomized animals; injection of 20 i.u. human chorionic gonadotrophin (HCG) on day 12 resulted in the ovulation of 31 and 6 ova respectively, but priming the hysterectomized hamsters with pregnant mare serum gonadotrophin (before HCG) resulted in superovulation.

After hysterectomy on day 9 of pregnancy, by day 12 there was a rapid decline in luteal activity as shown histologically by the onset of structural luteolysis and a concomitant fall in luteal weight, and luteal and plasma levels of progesterone. These effects were partially or completely reversed by daily injection of 1 mg prolactin on days 9–11.

The results indicate that hysterectomy before the establishment of the placenta results in the sustained release by the pituitary of prolactin and gonadotrophins, but most likely at lower levels than in pregnant animals. However, hysterectomy on day 9 abruptly removes the placental source of a prolactin-like hormone and the pituitary cannot respond in time to prevent luteolysis.
CHANGES IN CELL PROLIFERATION RATE IN MOUSE UTERINE EPITHELIUM DURING CONTINUOUS OESTROGEN TREATMENT
Authors: LEE AUDREY E. , ROGERS L. A. , TRINDER GAIL
Published: December 2008

Fraction of labelled mitoses (FLM) curves were constructed for mouse uterine luminal epithelium during oestradiol treatment; on day 2 when mitosis was high, and on days 4 and 9 when mitosis was low. No difference was found between the duration of DNA synthesis on these 3 days. The distance between the first and second peaks, usually taken as an estimate of the mean cell cycle time, did not change significantly between days 2 and 4, although the labelling index fell from 38 to 8%. The second peaks of the FLM curves became progressively lower on the three days examined, which was consistent with the interpretation that there was a reduction in the probability of transition of cells from G1 (the post-mitotic period) into the replicative phase of the cell cycle, resulting in the observed fall in mitotic index.
THE INHIBITION OF FERTILIZING ABILITY OF EPIDIDYMAL SPERMATOZOA BY THE ADMINISTRATION OF OESTRADIOL BENZOATE TO TESTOSTERONE-MAINTAINED HYPOPHYSECTOMIZED OR CASTRATED HAMSTERS
Authors: LUBICZ-NAWROCKI C. M.
Published: December 2008

Experiments were designed to discover if oestradiol benzoate induces loss of fertilizing ability of hamster epididymal spermatozoa by acting directly on the cauda epididymidis. Spermatozoa were retained in the cauda epididymidis by ligating the distal corpus epididymidis and proximal ductus deferens and fertilizing ability was compared in oestrogen-treated, intact hamsters and in castrated or hypophysectomized animals maintained with testosterone. Fertility tests showed that 12 daily s.c. injections of 3·5 or 5 μg oestradiol benzoate reduced fertilizing ability to 35·2 and 0%, respectively; supplementary testosterone did not prevent the adverse effect of oestrogen and reduced fertilizing ability was shown not to be related to a deficiency of circulating testosterone as judged by fructose concentration in the seminal vesicles. Daily treatment of androgen-maintained castrated or hypophysectomized hamsters with 3·5 μg oestradiol benzoate for 12 days reduced fertilizing ability to 43·7 and 31·3%, respectively. The results suggest that oestradiol benzoate reduces fertilizing ability in hamsters by acting directly on the cauda epididymidis and inhibiting the effect of testosterone.
RADIOIMMUNOASSAY OF ENDOGENOUS AND EXOGENOUS PROLACTIN IN MILK OF RATS
Authors: McMURTRY J. P. , MALVEN P. V.
Published: December 2008

Immunoreactive rat prolactin was detected in rat milk. Increasing volumes of milk decreased the percentage of 131I-labelled rat prolactin bound to antiserum in a manner parallel to the decreases produced by increasing log doses of standard hormone and blood serum. Rats suckling litters of 4, 8 or 12 pups were milked at various stages of lactation and prolactin concentrations (ng/ml) in milk varied significantly both with stage of lactation and with litter size. Mean prolactin levels were maximal on day 4 to day 15 and they decreased sharply near the end of lactation. At every stage of lactation litter size tended to influence prolactin concentrations with larger litters always being associated with more prolactin per millilitre of milk. Intraperitoneal injection of 1 mg bovine prolactin into lactating rats promptly caused the appearance of high levels of this foreign hormone in rat milk without significantly affecting the concentration of the native hormone.
PROGESTERONE CONCENTRATION, INTRALUMINAL PRESSURE AND ELECTRICAL ACTIVITY OF THE GUINEA-PIG UTERUS
Authors: PORTER D. G. , YOSHINAGA K. , FORD J.
Published: December 2008

The electrical activity of the myometrium and the intra-uterine pressure were recorded by means of suction electrodes and intraluminal balloons respectively from anaesthetized, oestrogen-primed, ovariectomized guinea-pigs treated with progesterone (25 mg, s.c. twice, 16 h apart). No loss of intra-uterine pressure occurred after progesterone treatment and electrical activities in the balloon-containing and intact horns were indistinguishable. Furthermore, the concentration of progesterone in the uteri of these animals was 0·32 ± 0·05 (S.E.M.) μg (balloon-containing horn) and 0·43 ± 0·06 μ/g wet tissue (intact horn). These values greatly exceed the levels found in uteri of pregnant animals (0·07 ± 0·03 μ/g wet tissue). Thus the failure of progesterone to reduce myometrial activity in the guinea-pig is real and is not due to interference from the balloon, or to failure of the steroid to reach the uterine muscle or to lack of oestrogen priming.
PRODUCTION OF PROSTAGLANDINS BY THE EARLY PREGNANT GUINEA-PIG UTERUS IN VITRO
Authors: WALKER FELICITY M. MAULE , POYSER N. L.
Published: December 2008

The amounts of prostaglandins F2α (PGF2α) and E2 (PGE2) produced by homogenized, incubated, pregnant and non-pregnant guinea-pig uteri were compared. The sizes of the corpora lutea from these animals were considered in relation to the amounts of prostaglandins produced by their uteri.

The amount of PGF2α produced by the uteri from day-15 bilaterally pregnant guinea-pigs was significantly less than that produced by uteri from guinea-pigs on day 15 of the oestrous cycle. Corpora lutea from the pregnant animals were maintained but those from the day 15 non-pregnant animals had regressed. There was no significant difference between the results obtained for PGE2. Results from day 15 unilaterally pregnant animals and day 25 bilaterally pregnant animals are also presented and their implications discussed. The findings reported here may well explain how, in the guinea-pig, the conceptus is able to neutralize the luteolytic effects of the uterus.
A COMPARATIVE STUDY OF PROGESTERONE- AND CORTISOL-BINDING ACTIVITY IN THE UTERUS AND SERUM OF PREGNANT AND NON-PREGNANT WOMEN
Authors: GUÉRIGUIAN J. L. , SAWYER M. E. , PEARLMAN W. H.
Published: December 2008

The 105000 g supernatant fraction (soluble proteins) of homogenates of human uterine tissue, essentially myometrium, and peripheral blood serum, were assayed for progesterone- and cortisol-binding activity by batchwise use of Sephadex G-25 in test tubes (not gel filtration) under equilibrium conditions; the results were expressed empirically as the reciprocal of the protein concentration, 1/P, at 50% steroid binding. The steroid-binding activity of the uterine soluble proteins was due apparently to a single component closely resembling corticosteroid-binding globulin (CBG) with respect to equilibrium association constants, steroid ligand specificity, and elution behaviour on hydroxylapatite chromatography and Sephadex G-100 filtration. Therefore, the mean 1/P values for steroid-binding activity were converted to the apparent CBG content (nmol/g total soluble protein). Comparison of the mean ratio (about 0·2) of the respective total binding activity, uterus (g): serum (ml), with the mean ratio (0·03) of the total iron content, uterus:serum, indicated that the high CBG content of the uterus could not be attributed to retention of blood; the apparent CBG levels in skeletal muscle (pectoral) were very low. The mean values for the apparent CBG content of uterine soluble protein were almost as high as those for the CBG content of serum protein; the mean value for the apparent CBG content of uterine soluble protein was slightly higher for pregnant women (mostly in early pregnancy) than that for non-pregnant women with various gynaecological complications. On polyacrylamide gel electrophoresis, soluble protein from the uterus resembled that of serum in the areas corresponding to serum albumin and transferrin; the electrophoretic patterns were distinctly different, however, in the area between the origin and the transferrin band.

It is suggested that CBG may accumulate in interstitial fluid of the myometrium, thereby regulating the local concentration of bound and unbound progesterone and cortisol, and influencing hormone action on the respective target cells, muscle and fibroblast. A more extensive study of levels of progesterone- and cortisol-binding activity in serum was carried out also. It was concluded that the progesterone-binding activity of human serum, as in the case of human myometrium, is due largely to CBG.
RENAL DIURESIS AFTER INJECTIONS OF THE FRESHWATER EEL AND ANTIDIURESIS ARGININE VASOTOCIN IN (ANGUILLA ANGUILLA L.)
Authors: HENDERSON I. W. , WALES N. A. M.
Published: December 2008

The renal responses of the freshwater-adapted eel, Anguilla anguilla L. to arginine vasotocin ([8-arginine]-oxytocin) have been examined. The quality of the responses to the intravenously administered peptide was found to vary with the dose. Less than 0·1 ng/kg body weight reduced glomerular filtration rate, free water clearance and rate of urine production for up to 60 min. Doses greater than 1·0 ng/kg body weight induced a 'glomerular diuresis', i.e. increased rates of urine production, glomerular filtration and free water clearance for 40–60 min. Neither the diuretic nor the antidiuretic doses produce changes in urinary composition, and no obvious direct tubular actions of the peptide were found. Arterial blood pressure, measured in the dorsal aorta, increased with some of the diuretic doses, whilst the lower doses (less than 10 ng/kg body weight) had little or no cardiovascular actions. The mechanisms involved in these dose—response characteristics are discussed with particular regard to the renal function of lower vertebrates. It is suggested that arginine vasotocin plays a primary or secondary role in the modulation of 'glomerular intermittency'.
EFFECTS OF FRESHWATER ADAPTATION AND OF PROLACTIN ON SODIUM-POTASSIUMACTIVATED ADENOSINE TRIPHOSPHATASE ACTIVITY IN THE URINARY BLADDER OF TWO FLOUNDER SPECIES
Authors: UTIDA S. , KAMIYA MIE , JOHNSON D. W. , BERN H. A.
Published: December 2008

Sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) activity increased in the urinary bladder of the euryhaline teleost Platichthys stellatus after transfer from sea-water to fresh water. This increase also occurred after injection of prolactin into seawater Platichthys, simulating the results of freshwater transfer. In Kareius bicoloratus, which does not survive transfer to fresh water, prolactin does not increase bladder Na-K-ATPase activity. The differences in response of these two species to prolactin may be related to the degree of their euryhalinity. There may be a relationship between adaptability to fresh water and responsiveness of bladder Na-K-ATPase to prolactin.
IMMUNOCHEMICAL AND CHROMATOGRAPHIC SIMILARITY OF RAT, RABBIT, CHICKEN AND SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONES
Authors: JEFFCOATE S. L. , SHARP P. J. , FRASER H. M. , HOLLAND D. T. , GUNN A.
Published: December 2008

Luteinizing hormone releasing hormone (LH-RH) was detected in hypothalamic extracts of rats, rabbits and chickens using a radioimmunoassay for synthetic LH-RH decapeptide. The mobilities of the immunologically active fraction and of synthetic LH-RH were the same in various chromatographic systems (gel filtration on Sephadex, thin-layer chromatography on silica gel and ion-exchange chromatography on carboxymethylcellulose) suggesting that mammalian, avian and synthetic LH-RH's are closely related.
EFFECT OF PERINATAL HYPOTHYROIDISM ON PITUITARY SECRETION OF GROWTH HORMONE AND PROLACTIN IN RATS
Authors: KIKUYAMA SAKAE , NAGASAWA HIROSHI , YANAI REIKO , YAMANOUCHI KOREHITO
Published: December 2008

Female Sprague—Dawley rats were fed 6-propyl-2-thiouracil (PTU) in their diet during late pregnancy and lactation. The growth and gonadal development of their pups were inhibited and in females the day of vaginal opening and onset of oestrous cycles were delayed; thyroid glands were hypertrophied. Treatment of the pups with thyroxine largely reversed these changes. The effect on body weight persisted even after treatment with PTU had stopped. At 20 days of age, the anterior pituitary glands of the pups of PTU-treated mothers contained significantly less growth hormone (GH) and prolactin than those of normal pups of both sexes. These changes persisted at 60 days of age. If the pups of PTU-treated mothers were given thyroxine from day 1 to day 20 of age, pituitary GH and prolactin content on day 20 had returned towards normal values. Thyroid deficiency was found to suppress the synthesis and release of prolactin and the synthesis of GH by the pituitary in vitro.

These findings suggest that thyroxine influenced the maturation of the pituitary directly and/or through the hypothalamus and that thyroxine deficiency in early life brought about persistent alteration of the pituitary secretion of GH and prolactin.
INFLUENCE OF PROLONGED GLUCOSE INFUSIONS ON PLASMA INSULIN AND GROWTH HORMONE CONCENTRATIONS OF FOETAL LAMBS
Authors: BASSETT J. M. , MADILL DENISE
Published: December 2008

Chronically cannulated foetal lambs close to term were infused intravenously with glucose at rates of 40 or 70 mg/min for up to 5 days. Infusion at these rates increased the foetal plasma glucose concentration to values in the ranges 35–45 and 60–80 mg/100 ml respectively. There were related increases in plasma fructose and lactate concentrations.

Foetal plasma insulin concentrations increased within the first hour and remained raised throughout infusion. Plasma insulin concentrations were significantly correlated with plasma glucose concentrations. The secretory response of insulin to subsequent glucose infusions at a rate of 140 mg/min was not increased by the previous prolonged glucose infusions.

Glucose infusion resulted in decreased plasma growth hormone concentrations in three of the lambs infused, but over the total number of observations plasma glucose and growth hormone concentrations were not significantly correlated.
THE HORMONAL MECHANISM OF IMMUNOPOTENTIATION IN MICE AFTER ORCHIDECTOMY
Authors: CASTRO J. E.
Published: December 2008

Orchidectomy of Balb C mice aged between 4 and 6 weeks delayed the normal rate of thymic involution. Testosterone replacement after orchidectomy prevented this relative thymic enlargement and testosterone supplements given to intact mice accelerated the normal rate of thymic involution.

When hypopituitary, dwarf mice were given somatotrophin and thyroxine alone there was no significant difference in the thymic weights of control or orchidectomized mice. When replacement therapy included gonadotrophin, orchidectomy was associated with significant thymic hypertrophy. Passive transfer of serum from previously orchidectomized mice did not change the thymic weight of normal recipient mice.

These experiments suggest that testosterone exerts a constant moderating effect on the thymus and the immunological effects of orchidectomy are due to the direct effects of androgen withdrawal.
EFFECTS OF NADPH, NADP+, SUCCINATE AND CYCLIC AMP ON PROGESTERONE SYNTHESIS IN SUBCELLULAR FRACTIONS OF RABBIT OVARIAN INTERSTITIAL TISSUE
Authors: SCOON V. , MAJOR PATRICIA W.
Published: December 2008

The effects of NADPH, NADP+, succinate and cyclic AMP on progestational steroid synthesis have been investigated in subcellular fractions of rabbit interstitial tissue. Production of progesterone and 20α-hydroxy-4-pregnen-3-one increased during incubation of mitochondria with NADPH and NADP+ respectively, and an increase in 20α-hydroxy-4-pregnen-3-one was observed after incubation of microsomes with NADP+. No changes in progestational steroid production were observed in individual cell fractions after incubation with cyclic AMP or succinate. However, a small but significant increase in progesterone synthesis occurred in a combined fraction containing mitochondria, microsomes and cytosol when incubated with cyclic AMP.
SHORT-TERM EFFECTS OF OESTRADIOL BENZOATE IN NORMAL, HYPOPHYSECTOMIZED AND ALLOXAN-DIABETIC MALE RATS
Authors: GOODMAN M. N. , HAZELWOOD R. L.
Published: December 2008

Studies were undertaken to determine the effects and possible mode of action of 17β-oestradiol benzoate (OEB) in alloxan-diabetic male rats. Adlibitum or pair-fed normal, diabetic, and hypophysectomized rats received daily subcutaneous injections of 10 μg OEB for 10 days. In normal rats, OEB decreased plasma glucose, increased plasma immunoreactive insulin, growth hormone and corticosteroid levels, increased pancreatic β-cell granulation, and enhanced glucose stimulation of insulin release in vitro. In alloxan-diabetic rats, OEB treatment decreased urinary glucose excretion, increased plasma growth hormone and corticosteroid levels and slightly enlarged the pancreatic islets of Langerhans. In hypophysectomized rats, OEB decreased plasma glucose, increased plasma insulin levels, and slightly enlarged the pancreatic islets of Langerhans.

These results suggest that OEB affects experimental diabetes by a direct action on the pancreas, promoting insulin formation, and possibly by an indirect action mediated through hypophysial secretions.
EFFECT OF DEXAMETHASONE ON CELL POPULATION KINETICS IN THE ADRENAL CORTEX OF THE PREPUBERTAL MALE RAT
Authors: WRIGHT N. A. , APPLETON D. R. , MORLEY A. R.
Published: December 2008

The effect of a single injection of dexamethasone on adrenocortical cell proliferation was studied in prepubertal male rats using tritiated thymidine. After a short latent period, all zones of the adrenal cortex showed a rapid decrease in both labelling and mitotic indices. After a prolonged period when very low indices were apparent, there was a rapid rise in both proliferative indices with most zones showing a considerable increase above control values.

A more detailed study of the initial depression showed that after a latent period of about 5 h the labelling index fell approximately 8 h before the mitotic index. This differential response in the labelling and mitotic indices was consistent with a block in the cell cycle late in the pre-DNA synthetic interval of the cell cycle (G1), with cells being prevented from entering DNA synthesis. This hypothesis was also supported by an experiment involving continuous labelling of control and dexamethasone-treated animals; again after a latent period of 5–6 h, the rate of increase of the continuous labelling index fell as cells became blocked in late G1.

By analogy with other tissues, results are interpreted in terms of a direct action of dexamethasone on adrenocortical cells; this steroid-sensitive step in the cell cycle may be important in the control of growth in the adrenal cortex.
GLUCOSE-INDUCED INCREASE OF PLASMA INSULIN IN THE RAT FOETUS IN UTERO
Authors: KERVRAN A. , GIRARD J. R.
Published: December 2008

The effect of glucose on the release of insulin from the pancreas of 18·5 to 21·5-day-old rat foetuses has been studied in utero. Foetal hyperglycaemia was induced by a 1 h glucose infusion into pregnant rats.

In foetuses from mother rats infused with saline, the blood glucose and the plasma insulin concentrations increased up to day 21·5 of gestation. The blood glucose level of the foetuses never exceeded that of the mothers which remained stable from day 18·5 to day 21·5 of gestation.

The infusion of glucose raised the foetal blood glucose concentration to that of the mothers and induced a significant increase of plasma insulin levels both in the mothers and their foetuses. The enhanced plasma insulin concentration observed in the 18·5-day-old foetuses of glucose-infused pregnant rats became greater each day up to 21·5 days.