bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization and measurement of cytoplasmic and nuclear oestradiol-17β-receptor proteins in benign hypertrophied human prostate
Authors: Auf G. , Ghanadian R.
Published: December 2008

The demonstration and partial characterization of a high-affinity saturable binding component for oestradiol-17β in the cytosol and nuclear extract of the benign hypertrophied human prostate is reported. This binding component was found to precipitate with protamine sulphate and to exhibit marked specificity for oestradiol and diethyl-stilboestrol (DES) but not dihydrotestosterone (DHT) or progesterone. Analysis of oestradiol-labelled cytosol on low ionic strength glycerol gradients revealed a binding component with a sedimentation coefficient of 4S which was inhibited with DES but not DHT and destroyed either by preheating labelled cytosol at 45 °C for 30 min or by treatment with the sulphydryl blocking agent, parachloromercureobenzoate. The oestradiol-binding complex precipitated by ammonium sulphate was found to have an isoelectric point (pI) of 6·3 as analysed on polyacrylamide-gel plates. The oestradiol-binding component in the nuclear extract also exhibited similar steroid specificity and sedimented with a coefficient of 2·8S on high ionic strength glycerol gradients. Isoelectric focusing of the heparin-extracted nuclear oestradiol-binding complex revealed a pI of 6·0. The dissociation constants (Kd) and the concentrations of the cytoplasmic and nuclear oestradiol-binding sites in 19 samples of benign hypertrophied prostates were estimated by Scatchard plot analyses. The mean Kd and concentration of binding sites in the cytosol were 2·9 ± 2·6 (s.d.) nmol/l and 11·7± 8·4 fmol/mg protein respectively. The corresponding values for nuclear extract were 4·1 ±7·5 nmol/l and 347·1±415·5fmol/mg DNA respectively. There was no significant difference between the mean concentration of oestradiol-binding sites in the two cellular fractions.
Induction of implantation in the rat by intraparametrial injection of uterine RNA from oestrogen-treated animals
Authors: Lejeune B. , Puissant F. , Camus M. , Leroy F.
Published: December 2008

Crude RNA preparations from uteri of oestradiol-treated rats induced the implantation of delayed blastocysts when injected into the parametrium of ovariectomized pregnant rats. Treatment of donor animals with labelled oestradiol showed that this effect could not be due to contamination of the RNA extracts by oestradiol. RNase digestion of these extracts suppressed their capacity to induce implantation. Purified poly (A)-rich RNA from oestrogen-treated uteri failed to elicit implantation although it was capable of increasing epithelial height when repeatedly injected into uterine horns of ovariectomized rats. These results suggest that uterine RNA synthesis might somehow mediate the effects of oestrogen in causing implantation and that RNAs other than messenger RNA might be involved.
3β-Hydroxy-Δ5-steroid dehydrogenase activity in the rapidly growing ovarian follicles of the domestic fowl (Gallus domesticus)
Authors: Armstrong D. G.
Published: December 2008

The total and specific activity of 3β-hydroxy-Δ5-steroid dehydrogenase, isocitrate dehydrogenase (NADP+) and glucose-6-phosphate dehydrogenase were measured in ovarian follicles from the domestic fowl. The enzymes were assayed in the five largest yolk-filled follicles which were sampled twice during the ovulatory cycle, at 1 h and 16 h before an expected ovulation. The total and specific activity of granulosa enzymes increased throughout the hierarchy and reached a maximum in the largest follicle. The relative increase in 3β-hydroxy-Δ5-steroid dehydrogenase activity was greater than that of the other two enzymes examined. The total thecal 3β-hydroxy-Δ5-steroid dehydrogenase activity reached a maximum in the third and fourth largest follicles. Thereafter its activity decreased up to the time of ovulation. The activity of 3β-hydroxy-Δ5-steroid dehydrogenase and glucose-6-phosphate dehydrogenase in follicles collected 1 h before an ovulation were significantly less than the activity in corresponding follicles collected 16 h before an ovulation.
Relationships among release of prolactin, synthesis of DNA and growth of the anterior pituitary gland of the rat: effects of oestrogen and sulpiride
Authors: Jahn G. A. , Machiavelli G. A. , Kalbermann L. E. , Szijan I. , Alonso G. E. , Burdman J. A.
Published: December 2008

The effect of daily injections of sulpiride was compared with that of a single injection of the drug in male rats which had been treated with oestradiol diundecenoate for various periods of time. We studied the effect of the different treatments on weight of the pituitary gland, concentration of prolactin and incorporation of [3H]thymidine into DNA in the pituitary gland and on serum levels of prolactin. Administration of the oestrogen produced a marked increase in the synthesis of DNA at day 7. The stimulation diminished at day 21 and was not significant at day 45. The maximum increase in the concentration of prolactin in serum and pituitary glands was observed during the first 7 days (approximately 400 and 150% respectively) and in the weight of the anterior pituitary gland after 21 days of treatment (approximately 107%).

A single injection of sulpiride markedly stimulated the release of prolactin and the synthesis of DNA at day 7. Both these effects diminished at day 21 and disappeared by day 45. Daily injections of sulpiride also produced similar changes in the release of prolactin and in the replication of DNA. The growth of the anterior pituitary gland was greater in this group than in the rats which had been treated with oestradiol diundecenoate only. After the end of treatment with oestrogen and sulpiride the pituitary weight and the concentration of prolactin in the anterior pituitary gland diminished together with levels of prolactin and oestrogen in serum. There was a good correlation between weight of the gland and serum levels of prolactin. The results further support the idea of a mechanism which controls the proliferation of lactotrophs in which the release of the hormone is accompanied by an increase in pituitary DNA synthesis.
Local action of parathyroid hormone (1–34) and (1–84) at the parotid gland of sheep
Authors: Wright R. D. , Blair-West J. R. , Nelson J. F. , Tregear G. W.
Published: December 2008

Administration of bovine parathyroid hormone (PTH) preparations increased the phosphate concentration in the parotid saliva of sheep. Data on the site of action of PTH (1–84) were obtained by (a) equimolar infusions of PTH (1–84) and (1–34) directly into the arterial blood supply of the vascularly isolated parotid gland in anaesthetized sheep, (b) intravenous infusion of PTH (1–84) at a similar rate and (c) intra-arterial infusion of PTH (1–84) with complete drainage of the venous effluent from the gland during the infusion. Results showed substantial time– and dose–response identity of the two peptides, at 10−9 to 4 × 10−9 mol/l in arterial blood, in raising salivary phosphate concentration. The effect of PTH (1–84) was not due to recirculated fragments because the response was obtained when recirculation was prevented by complete venous drainage and little or no response occurred when the same infusion was given i.v.
Plasma concentrations of prolactin during incubation and parental feeding throughout repeated breeding cycles in canaries (Serinus canarius)
Authors: Goldsmith A. R.
Published: December 2008

Concentrations of prolactin were measured in the plasma of male and female canaries serially sampled during repeated breeding cycles. Concentrations in female canaries were low during nest building and increased significantly (P < 0·05) during the first few days of incubation. Levels increased further (P < 0·01) in the middle of the incubation period to reach concentrations which were ten times higher than before breeding. Levels remained high for several days after the eggs hatched, as the young were fed in the nest. Prolactin concentrations declined gradually as the young were reared, reaching basal levels by the time the young were fledged, but always increased again in the females as they began incubating eggs in subsequent breeding cycles. Male canaries, which do not incubate but do assist in feeding the young, showed only slight increases in prolactin during the parental period. Male and female canaries which did not breed had low levels of prolactin throughout the experiment. The results show that prolactin secretion is high not only during incubation but also during the parental feeding phase in an altricial passerine bird. These findings are discussed in relation to the different patterns of prolactin secretion which occur during breeding in other birds.
Adrenocortical responses of ducks to treadmill exercise
Authors: Harvey S. , Phillips J. G.
Published: December 2008

The influence of treadmill exercise on corticosterone secretion has been determined in domestic ducks. In birds unused to such exercise the concentrations of plasma corticosterone were markedly increased (> fourfold) after 15 or 30 min of treadmill exercise (1·1 km/h at 3 ° grade) and the level remained high (between 30 and 40 ng/ml) throughout 90 min of exercise. This increase in corticosterone secretion accompanied a similar increase in colon temperature and was independent of the plasma glucose level. After exercise the corticosterone concentration declined to the pretreatment level within 60 min of recovery. In birds used to the exercise the corticosterone response to a standard (30 min) period of exercise was diminished (by 77·6% in comparison with untrained birds and was no greater than the response (1·7-fold) in stationary control birds after handling and bleeding. The diminution of the corticosterone response to exercise may be due to the trained birds becoming fitter and better able to perform the work involved.
Daily variations in serotonin metabolism in the suprachiasmatic nucleus of the rat: influence of oestradiol impregnation
Authors: Héry M. , Faudon M. , Dusticier G. , Héry F.
Published: December 2008

In order to determine the temporal relationships between variations in 5-hydroxy-tryptamine (5-HT, serotonin) metabolism in the suprachiasmatic nucleus (SCN) and the cyclic LH surge, and also to check whether implantation of oestradiol capsules might modulate 5-HT metabolism in the SCN, we carried out a parallel study of 5-HT content in the SCN and median eminence, and 5-HT metabolism in the SCN and supraoptic region in vitro. These experiments were performed on intact male rats, ovariectomized females and ovariectomized females implanted with oestradiol.

It was only in ovariectomized rats implanted with oestradiol, in which we have described the existence of a clear-cut circadian rhythm of LH secretion, that we found fluctuations in the content, synthesis and utilization of 5-HT. The content and synthesis were characterized by a peak between 12.00 and 15.00 h, whereas utilization was 50% higher at 09.00 and 19.00 h than at 15.00 h. These fluctuations in 5-HT content and metabolism were specific to the SCN; the median eminence and the supraoptic region did not show such variations. They were also specific to ovariectomized rats implanted with oestradiol, since the patterns of 5-HT content and metabolism in the SCN were the same in males and ovariectomized females and did not differ from those in the median eminence, the supraoptic region or the whole hypothalamus.

These results suggest that 5-HT terminals in the SCN play an important role in the control of cyclic LH secretion at a critical period. Moreover, oestradiol seems to be partly responsible for the fluctuations of 5-HT metabolism in the SCN of ovariectomized rats implanted with oestradiol.
Hypothalamic, pituitary and uterine cytoplasmic and nuclear oestrogen receptors and their relationship to the serum concentration of tamoxifen and its metabolite, 4-hydroxytamoxifen, in the ovariectomized rat
Authors: Bowman S. P. , Leake A. , Morris I. D.
Published: December 2008

High-affinity oestrogen receptors were measured in the cytosol and nuclei prepared from the hypothalamus, pituitary gland and uterus of the ovariectomized rat up to 16 days after a single dose of tamoxifen or 4-hydroxytamoxifen. Tamoxifen produced a dose-related fall in the concentration of cytosol receptors in the hypothalamus, pituitary gland and uterus. Minimum values were observed after 24 h; cytosol receptor concentrations were restored slowly and only reached expected control values between 4 and 8 days and 2 and 4 days for 7·0 mg/kg and 0·7 mg/kg doses of tamoxifen respectively. The nuclear receptor changes were inversely related to the cytosol receptor changes, except that hypothalamic nuclear receptor concentrations after 0·7 mg tamoxifen/kg were not changed. 4-Hydroxytamoxifen (0·14 mg/kg) depleted cytosol and raised nuclear oestrogen receptors in the pituitary gland and uterus. Receptor concentrations had returned to the expected control values by day 4. Oestrogen receptor concentrations in the hypothalamus were unchanged. The apparent resistance of the receptor system in the hypothalamus to translocation by tamoxifen and 4-hydroxytamoxifen was probably due to the blood–brain barrier since the apparent affinity of tamoxifen for the cytosol receptor was similar for all three tissues (dissociation constant 4 nmol/l).

Serum concentrations of tamoxifen and 4-hydroxytamoxifen measured after a single dose of 7·0 mg tamoxifen/kg were maximal after 24 h and undetectable by 4 days, at which time nuclear and cytosol receptor levels were still changed. Concentrations of 4-hydroxy-tamoxifen were approximately one-third those of tamoxifen. The results suggest that the receptor changes after tamoxifen are not simply related to the serum concentration of tamoxifen and its metabolites and that the retention of ligand within the target tissue may be an important determinant.
Changes in the characteristics of pulsatile luteinizing hormone secretion during the oestrous cycle and after ovariectomy and oestrogen treatment in female rats
Authors: Higuchi Takashi , Kawakami Masazumi
Published: December 2008

Changes in the characteristics of LH secretory pulses in female rats were determined in different hormonal conditions; during the oestrous cycle and after ovariectomy and oestrogen treatment. The frequency and amplitude of the LH pulses were stable during the oestrous cycle except at oestrus when a pattern could not be discerned because of low LH concentrations. These were significantly lower than those measured during other stages of the cycle. Mean LH concentrations and LH pulse amplitudes increased with time up to 30 days after ovariectomy. The frequency of the LH pulse was unchanged 4 days after ovariectomy when mean LH levels had already increased. The frequency increased 10 days after ovariectomy and then remained stable in spite of a further increase in mean serum LH concentrations. Oestradiol-17β injected into ovariectomized rats caused a decrease in LH pulse amplitude but no change in pulse frequency. One day after treatment with oestradiol benzoate no LH pulse was detectable, probably because the amplitude was too small. A generator of pulsatile LH release is postulated and an oestrogen effect on its function is discussed.
Effects of passive immunization against testosterone on the sexual activity of female rhesus monkeys
Authors: Martensz N. D. , Everitt B. J.
Published: December 2008

Active immunization of an ovariectomized rhesus monkey against testosterone-3-(O-carboxymethyl)oxime–bovine serum albumin produced an antiserum with a high degree of specificity towards testosterone. Passive immunization of ovariectomized, oestrogen-treated monkeys with this antiserum resulted in significant reductions in proceptive and/or receptive behaviours in the majority of animals. This effect could be reversed by treatment with 17α-methyltestosterone, a steroid which showed only 6% cross-reaction with the antiserum. Passive immunization caused an increase in the binding of testosterone by the γ-globulin fraction of serum isolated by treatment with 2-ethoxy-6,9-diaminoacridine lactate. The present findings emphasize the importance of androgens of adrenal origin in the regulation of sexual behaviour in the female rhesus monkey.
Oxytocin may play a role in the control of the human corpus luteum
Authors: Tan G. J. S. , Tweedale R. , Biggs J. S. G.
Published: December 2008

The effects of oxytocin on dispersed luteal cells from human corpora lutea of the menstrual cycle were studied. Oxytocin at a concentration of 4 mi.u./ml produced a slight increase in basal progesterone production. However, higher oxytocin concentrations (400 and 800 mi.u./ml) markedly inhibited both basal and human chorionic gonadotrophin-induced progesterone production. These data provide evidence for an effect of oxytocin on the human corpus luteum. In view of the inhibitory action of oxytocin, increased secretion of this hormone may be important in the demise of the corpus luteum at the end of the menstrual cycle.
Ovarian steroid concentrations in rats with spontaneous and with delayed or advanced ovulation
Authors: Toorop A. I. , Gribling-Hegge L. , Meijs-Roelofs H. M. A.
Published: December 2008

The present study examined the ovarian progesterone levels in rats during the normal 5-day oestrous cycle and in rats with an experimentally induced delayed or advanced ovulation. Ovarian androgen and oestrogen concentrations were also studied in rats with an advanced ovulation.

The ovarian progesterone concentrations during the normal cycle showed two peaks: one during metoestrus and dioestrus 1 and the second during the afternoon of pro-oestrus.

Rats treated with pentobarbitone sodium (35 mg/kg body weight) at 13.00 h on the day of pro-oestrus showed no increase in ovarian progesterone levels on that day, but did show an increase during the afternoon of the next day.

Rats injected intraperitoneally with an ovulation-inducing bolus of human chorionic gonadotrophin (hCG; 20 i.u.) at 15.00 h on the day before pro-oestrus (dioestrus 2) showed increased ovarian progesterone levels as early as 0·5 h after hCG injection. Lowered levels of ovarian androgen and oestrogen values compared with saline-injected rats were first found 2 and 6 h respectively after hCG injection.

In conjunction with data obtained previously these findings show that normal, delayed and advanced ovulations are preceded by an increase in ovarian progesterone concentrations and a subsequent decline in ovarian androgen and oestrogen levels.
Regulation of testicular human chorionic gonadotrophin binding in prolactin-deficient Snell dwarf mice
Authors: Amador A. G. , Bartke A.
Published: December 2008

The regulation of binding of 125I-labelled human chorionic gonadotrophin (hCG) to testis was studied in mutant mice with congenital deficiency of prolactin (dw/dw), in mice with prolactin deficiency induced by treatment with bromocriptine and in normal untreated mice. After injection of hCG, normal mice showed a dose-related decrease in testicular hCG binding and subsequent recovery from down-regulation, similar to previous findings in the rat. Mice with congenital prolactin deficiency had a similar dose–response curve of receptor loss after hCG administration, but recovered from down-regulation faster than the normal mice. Induction of prolactin deficiency with bromocriptine prevented down-regulation of hCG binding. The differential effects of congenital and drug-induced prolactin deficiency could be related to a difference in the duration of the deficiency or to its severity. However, this difference could also suggest direct effects of the dw mutation and/or bromocriptine on the Leydig cells.
Effects of luteinizing hormone releasing hormone on the gonadotrophs of hypogonadal (hpg) mice
Authors: McDowell I. F. W. , Morris J. F. , Charlton H. M. , Fink G.
Published: December 2008

Hypogonadal (hpg) mice lack hypothalamic luteinizing hormone releasing hormone (LH-RH); consequently the pituitary gonadotrophs, though differentiated, remain inactive. The acute and chronic responses of gonadotrophs in hpg mice to LH-RH were studied using quantitative electron microscopy, immunocytochemistry for LH and radioimmunoassay of the gonadotrophins.

Acute i.v. administration of 40 ng LH-RH to male hpg mice produced an eightfold increase in plasma LH after 5 min, but granule depletion was not detectable ultrastructurally. Vacuoles (300–600 nm) were present more frequently in gonadotrophs from hpg mice given LH-RH compared with control mice. Daily s.c. administration of 2 μg LH-RH to male hpg mice for 20 days stimulated a 63-fold increase in the pituitary content of FSH but only a twofold increase in the pituitary content of LH. Testicular weight increased fivefold but the weight of the seminal vesicles did not change. The frequency of cells immunoreactive for LH increased (× 1·6), the gonadotrophs hypertrophied (× 1·9) and the cell content of granules increased (× 2·3) to values close to the normal range. The rough endoplasmic reticulum and Golgi apparatus became more prominent. A striking result of long-term daily administration of LH-RH was the accumulation of large (1–2 μm) lipid droplets in about 40% of gonadotrophs. All these changes induced by LH-RH regressed towards the untreated hpg state when LH-RH administration was discontinued for 5 and 10 days. These results show that the gonadotrophs of hpg mice can be stimulated trophically by LH-RH, and that long-term administration stimulates the synthesis and release of the gonadotrophins but the effect on FSH is much greater than on LH.
Oestrogen receptor-like binding in the surface germinal epithelium of the rat ovary
Authors: Hamilton T. C. , Davies P. , Griffiths K.
Published: December 2008

The surface germinal epithelium of the rat ovary was isolated and grown in vitro. Cytosol from cultured cells contained a saturable component, of sedimentation coefficient 7·5–8·5S, which bound oestrogenic and antioestrogenic substances with high affinity (Kd 400 pmol/l). Nuclei isolated from cells exposed to [3H]oestradiol contained radioactivity partially susceptible to KC1 extraction. Sedimentation analysis of the KC1 extract showed that [3H]oestradiol was associated with a moiety of sedimentation coefficient 4·5–5S.
Testosterone-dependent non-copulatory behaviour in male hamsters (Mesocricetus auratus)
Authors: Steel Elizabeth
Published: December 2008

Male hamsters (intact, castrated or testosterone-treated) were tested for their response to dioestrous and to oestrous females. Response to the dioestrous female was measured in terms of proximity and olfactory investigation; response to the oestrous female was measured in terms of mounting, intromission and ejaculation. Interest in dioestrous females declined in parallel with copulatory behaviour after castration and was restored by implantation of testosterone. Six weeks of testosterone treatment failed to restore copulatory behaviour to pre-castration levels; in contrast, interest in the dioestrous female was fully restored. Different components of the behaviour towards dioestrous females changed at different rates; some were restored within a week of implantation while others took several weeks to reach pre-castration levels. As found previously, the tendencies of the male to approach and to leave the female varied independently.
Sexual experience, androgens and female choice of a mate in laboratory rats
Authors: Taylor G. T. , Regan D. , Haller J.
Published: December 2008

Sexual experience produces long-lasting changes in both the behaviour and reproductive system of a male rat. The response of the female rat to an area that had recently housed a previously mated male was investigated in three experiments. In experiments 1 and 2 females preferentially urine marked in an area vacated by a sexually experienced (SE) male relative to areas vacated by a sexually inexperienced (SI) or castrated (C) male. The density of female marks were ranked SE > SI > C > empty area. In experiment 3 female preference for an SE male with varied and multiple mating experiences was magnified when compared with an SI male. There was the suggestion that the multiple SE male was even preferred to a male with only a single mating experience. A fourth experiment demonstrated an acute increase in circulating testosterone in multiple SE males exposed to oestrous or non-oestrous females, and the increase was observable for up to 7 days after exposure to an oestrous female. The conclusion is that chronic changes in androgen-dependent urinary by-products released by the SE male mediate the discrimination and choice of a mate by the female rat.
Adrenocortical hormones, ageing and mental condition: seasonal and circadian rhythms of plasma 18-hydroxy-11-deoxycorticosterone, total and free cortisol and urinary corticosteroids
Authors: Touitou Yvan , Sulon José , Bogdan André , Reinberg Alain , Sodoyez Jean-Claude , Demey-Ponsart Emilie
Published: December 2008

The circannual rhythms of plasma 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), total and free cortisol have been documented on a circadian basis in January, March, June and October in seven young men (24 years old), six elderly men, six elderly women and six elderly demented subjects, both men and women, in their eighties. Blood samples were drawn every 4 h over a 24-h period at each sampling session and urine samples were collected at 4-h intervals only from the young men. A circadian rhythm of 17-hydroxycorticosteroids (17-OH-CS), 17-ketosteroids (17-KS), urinary free cortisol and 18-OH-DOC was defined for each of the four seasons with stable acrophases throughout the year and the same excretory profiles. A circannual rhythm was validated in young men for 17-OH-CS, urinary free cortisol and 18-OH-DOC but not for 17-KS. A circadian rhythm of plasma free cortisol, the active form of the hormone, plasma total cortisol and plasma 18-OH-DOC was validated in all groups and at all the seasons at which samples were taken. The secretory profiles of 18-OH-DOC, free and total cortisol were very similar, with no differences attributable to age, sex or mental condition except for the levels of plasma free cortisol and 18-OH-DOC which were higher and lower respectively in the elderly subjects. Whereas a circannual rhythm of plasma 18-OH-DOC was validated for all groups, a circannual rhythm of both free and total cortisol in the plasma was validated in young men but not in any group of elderly subjects. This loss of the circannual rhythmicity of cortisol in the elderly may reflect the decrease with age of the capacity to adapt to seasonal external factors.
An ocular capacity to promote photoperiodic testicular growth in the quail
Authors: Baylé J. D. , Oliver J. , Sicard B.
Published: December 2008

Disk-shaped, 0·6 × 0·2 mm pellets of radioluminous material were inserted in the anterior chamber of the eyes of sexually immature male quail on short daylengths. Two weeks later testicular weights and plasma testosterone levels were significantly increased compared with controls. The effectiveness of the ocular implants varied according to the spectrum of emission of the radioluminous material. Sectioning of the optic nerve suppressed all gonadal response to retinal photostimulation.
Growth of the endometrium and cotyledons during pregnancy in the ewe: rates of protein secretion and synthesis and nuclear and cytosol steroid hormone receptor levels
Authors: Miller B. G. , Tassell R. , Stone G. M.
Published: December 2008

The time-course of cell hypertrophy and changes in in-vitro rates of secretion and synthesis of protein in intercaruncular and caruncular endometrium and maternal and fetal cotyledonary placenta have been examined during days 0–112 of pregnancy in the ewe. The concentrations of high-affinity receptors for oestradiol and progesterone in nuclear and cytosol fractions from these tissues were also determined.

Protein secretion by intercaruncular endometrium increased 25-fold between days 0 and 84. On day 84 10−5 m-colchicine blocked 75% of total secretion. Protein secretion did not increase in the other tissues. Protein synthesis and RNA: DNA ratio in intercaruncular endometrium increased steadily between days 0 and 112, whereas they did not change in caruncular endometrium between days 0 and 28 and declined in cotyledon between days 56 and 112. The levels of cytosol receptor for oestradiol and progesterone and of nuclear receptor for oestradiol in all tissues during days 56–112 were very low in relation to the corresponding levels in caruncular endometrium on day 0. The level of nuclear progesterone receptor in caruncular endometrium increased threefold between oestrus and day 28. The level of this receptor in cotyledon remained low on days 56–112, but in intercaruncular endometrium it increased to high values on days 84–112.

The results demonstrated a major surge in secretory activity by the intercaruncular endometrium at around mid-gestation, which was associated with a marked increase in nuclear progesterone receptor levels but only a low level of nuclear oestradiol receptor. The observations do not suggest any important role for oestradiol or progesterone in the growth of fetal and maternal cotyledon.
Effect of underfeeding upon the rate of milk ejection in the lactating rat
Authors: Grosvenor C. E. , Mena F.
Published: December 2008

Lactating rats were fed at a level equivalent to 75% of the daily food consumed by controls, which had food available ad libitum, from days 4–14 or from days 4–12 post partum. The underfed mothers lost about 10% of their initial weight whereas control mothers gained weight slightly during this time. The litters (six pups) of underfed mothers gained 20% less weight than those of controls but remained healthy. The milk obtained by the pups from six glands (the remaining six glands had been ligated on day 3) during a timed suckling, plus that subsequently obtained after oxytocin injections to the mother, totalled 7·4± 0·80 g in underfed and 15± 0·62 g in control mothers on day 14, and 6 ± 0·41 g in underfed compared with 8 ±0·50 g in control mothers on day 12. The pups of underfed mothers obtained a significantly greater percentage of the total milk after 10 (30 v. 6%), 15 (84 v. 32%) and 45 (100 v. 57%) min of suckling than did those of control mothers. In two trials for the milk ejection test, the litters of control and underfed mothers were exchanged. The pups of control mothers suckled by underfed mothers in both trials obtained a significantly greater percentage of the total milk (64%) in 15 min than did the pups of underfed mothers suckled by control mothers (25%).

Oxytocin-induced intramammary pressure (IMP) responses recorded under urethane anaesthesia achieved a greater amplitude in underfed than in control mothers in response to each dose (0·4, 0·8 and 1·6 mu.) of oxytocin administered intravenously. The average slope of the dose–response curve was 1·25 cm H2O/0·1 mu. oxytocin compared with 0·75cm H2O/0·1 mu. for fed mothers. The amplitude of the IMP in response to a 1·6 mu. dose of oxytocin also was greater in underfed mothers over a range of volumes of milk added incrementally to empty glands. The difference was most striking at low volumes of milk (0·2–0·6 ml) within the gland. The data from these experiments suggest the more rapid transfer of milk from mother to pups in underfed rats is due at least in part to adaptations within the mammary gland, possibly involving reductions in the sympathetic-mediated tone of mammary ducts.
Cyproheptadine and desmethylcyproheptadine directly inhibit the release of adrenocorticotrophin and β-lipotrophin/β-endorphin activity from the neurointermediate lobe of the rat pituitary gland
Authors: Lamberts S. W. J. , Bons E. G. , Uitterlinden P. , Hackeng W. H.
Published: December 2008

Cyproheptadine and its metabolite desmethylcyproheptadine were shown to suppress directly the release of adrenocorticotrophin (ACTH) and β-lipotrophin/β-endorphin activity from the neurointermediate lobe of the pituitary gland incubated in vitro. Neither compound affected the release of ACTH from the anterior pituitary gland. Serotonin stimulated the release of ACTH and β-lipotrophin/β-endorphin activity from the neurointermediate lobe, but did not influence the (desmethyl)cyproheptadine-mediated inhibition of hormone release.

These results indicate that serotonin and cyproheptadine affect hormone release by the neurointermediate lobe by a direct action. The effect of cyproheptadine, however, might not be exerted by a serotonin receptor.
Regulation of luteal activity in adult female rats treated neonatally with testosterone propionate
Authors: van der Schoot P. , de Greef W. J.
Published: December 2008

The present study was concerned with the control of luteal activity in female rats which had been treated neonatally with 1·25 mg testosterone propionate (TP). Treatment of such rats in adulthood with 15 i.u. human chorionic gonadotrophin induced ovulation followed by a period of luteal activity. The two daily surges of prolactin secretion, typical for a period of luteal activity in the normal female rat, were not observed in TP-treated females. Instead, higher basal levels of prolactin were observed in TP-treated females than in normal female rats. Furthermore, uterine traumatization at 5 days after ovulation did not result in the formation of decidual tissue.

In intact TP-treated females luteal activity, induced and temporarily sustained by an ectopic pituitary transplant, persisted after removal of the pituitary graft. In contrast, in TP-treated females which had been ovariectomized on day 25 of age and had received an ovarian transplant before induction of the luteal phase, luteal activity ended within a week after removal of the ectopic pituitary gland. Females treated with TP which had been ovariectomized on day 25 of life had lower plasma levels of prolactin and higher levels of dopamine in hypophysial stalk plasma than intact TP-treated females when measured at 4 months of age. Treatment of ovariectomized rats with oestradiol-17β increased levels of prolactin in plasma and lowered levels of dopamine in hypophysial stalk plasma.

It is concluded that the control of luteal activity in TP-treated females shows 'male' characteristics. However, the presence of the ovaries in such rats leads to decreased hypothalamic release of dopamine and increased plasma levels of prolactin, probably due to increased oestrogen levels. These increased levels of prolactin are sufficient to maintain luteal activity.
Teat stimulation-induced prolactin release in non-pregnant and pregnant Holstein heifers
Authors: Akers R. M. , Lefcourt A. M.
Published: December 2008

The effect of manual teat stimulation (milking paradigm) on release of prolactin was studied (1) in non-pregnant heifers (six each in age groups 3,6, and 10 months), in 15 heifers at 100, 150, 200 and 250 days of gestation and at 30 and 90 days of lactation (during machine milking) and (3) simultaneously in six heifers at ≤ 100 and in six heifers at ≥200 days of gestation. Among non-pregnant heifers small increases in prolactin response to teat stimulation were measured in three of six, two of six and none of six animals at 3, 6, or 10 months of age. In contrast, prolactin responses of the 15 heifers (area under response curves and absolute peaks) were significantly greater with each progressive stage of gestation. However, prolactin responses to machine milking at 30 days of lactation were significantly less than responses to manual teat stimulation during the latter stages of pregnancy, and responses at 90 days of lactation were further diminished. The changes in prolactin response during gestation were not due to seasonal effects as prolactin responses measured simultaneously in animals at different stages of gestation showed similar trends in responsiveness.
Increased thymidine incorporation into fetal rat cartilage in vitro in the presence of human somatomedin, epidermal growth factor and other growth factors
Authors: Hill D. J. , Holder A. T. , Seid J. , Preece M. A. , Tomlinson S. , Milner R. D. G.
Published: December 2008

The incorporation of [3H]thymidine by rat costal cartilage in vitro was studied at different fetal and postnatal ages and the effect of partially purified human somatomedin, mouse epidermal growth factor, platelet secretion products, insulin and growth hormone on thymidine uptake by fetal cartilage was examined. Thymidine uptake in plasma-free medium was many times greater in late fetal life than after birth. The incorporation of [3H]thymidine into costal cartilage from 21-day fetuses was significantly (P <0·05) increased above control values in the presence of 10 μg somatomedin/l, and when cartilage was incubated in medium containing somatomedin and diluted human plasma there was a synergistic action. Epidermal growth factor at a concentration of 1 ng/l was a potent stimulator of thymidine uptake. Secretion products from human platelets after their aggregation by thrombin stimulated [3H]thymidine uptake at a concentration of 2% (v/v), but were inhibitory at high concentrations. High concentrations of platelet secretion products stimulated the incorporation of [35S]sulphate by cartilage. A pharmacological concentration of 10 mu. insulin/ml stimulated [3H]thymidine uptake, but not concentrations of 1 or 100 mu./ml. Growth hormone had no effect. The results showed that fetal cartilage had a greater endogenous mitogenic activity than postnatal cartilage. While somatomedins may be important in the regulation of fetal body growth, other protein growth factors also stimulate fetal skeletal tissues.
Effects of prolactin on steroid production by human luteal cells in vitro
Authors: Tan G. J. S. , Biggs J. S. G.
Published: December 2008

The effects of prolactin on steroidogenesis were studied in dispersed luteal cells prepared from human corpora lutea of the menstrual cycle. Prolactin, at concentrations of 0·1–1000 ng/ml, had no effect on progesterone production by luteal cells during short-term incubation (3 h). However, in two out of five corpora lutea, higher concentrations of prolactin (100 and 1000 ng/ml) significantly reduced the oestradiol-17β production induced by human chorionic gonadotrophin (hCG; 10 i.u./ml); lower doses of prolactin had little effect. In the remaining corpora lutea, prolactin failed to affect either basal or hCG-induced production of oestradiol-17β. These results are discussed in relation to the mechanism by which prolactin influences human ovarian function.
Effects of parathyroid hormone and the synthetic 1–34 amino-terminal fragment in rats and dogs
Authors: Stevenson R. W. , Parsons J. A.
Published: December 2008

Since the structural requirements for all known biological activities of parathyroid hormone (PTH(1–84)) are virtually satisfied by the amino-terminal 34 amino acid fragment, PTH(1–34), we investigated whether this fragment could elaborate the overall actions of the intact hormone in the whole animal by comparing the effects of equimolar infusions of each peptide to dogs and rats. Infusion of bovine PTH(1–84) (bPTH(1–84)) at 17 pmol/kg per h for 20 h to three dogs or at 100 and 200 pmol/kg per h to groups of six rats for 5 days produced greater hypercalcaemia (3·02±0·03, 2·52±0·07 and 3·24±0·11 mmol/l respectively) than equimolar infusions of human PTH(1–34) (hPTH(1–34)) (2·61±0·03, 2·46 ± 0·05 and 2·71 ±0·09 mmol/l respectively). A significant calcium rise was not observed in dogs until after 4 h of PTH infusion. No rise in plasma calcium was apparent in rats, however, until the third day of PTH infusion. Only in parathyroidectomized rats was there a rise in plasma calcium within 24 h of starting an infusion of PTH. The hypercalciuria and plasma phosphate responses in dogs during equimolar infusions of hPTH(1–34) and bPTH(1–84) were not significantly different. However, by day 5 of infusion in rats greater hypercalciuria was produced by bPTH(1–84). Although infusion of hPTH(1–34) and bPTH(1–84) caused rises in urinary cyclic AMP excretion (measured only in the dog) of immediate onset and equal magnitude, bPTH(1–84) tended to produce greater phosphaturia than hPTH(1–34) in both species. If the assumption is correct that the half-lives of hPTH(1–34) and bPTH(1–84) in the circulation are similar and provided that hPTH does not inherently have less biological activity than bPTH, then during equimolar infusions of these peptides into dogs and rats, the greater responses observed with bPTH(1–84) suggest that intact PTH may have a direct action of its own in vivo before being metabolized into smaller biologically active fragments.

In additional experiments using parathyroidectomized rats, the infusion rate of bPTH(1–84) required to restore normocalcaemia was 26 pmol/kg per h. Although near-normal calcaemia and intestinal calcium absorption could still be maintained when the infusion rate was increased to 39 pmol/kg per h, hypercalciuria and phosphaturia became apparent.
Effect of gliquidone on insulin binding to rabbit erythrocytes
Authors: de Gasparo M. , Hostetter G. , Desaulles P. A.
Published: December 2008

A study was made of the effects of acute or chronic treatment of rabbits with 10 mg gliquidone (Glurenorm)/kg body weight on erythrocyte insulin receptors. The binding of 125I-labelled insulin to the population of whole red blood cells was not affected by either treatment. Because of the heterogeneity of the erythrocytes, subpopulations were selected according to their specific gravity, which is directly related to cell age. The lowest-density fraction showed a 30% greater capacity of the insulin receptors without any change in affinity after chronic therapy with gliquidone, but no effects were observable after acute treatment. The highest-density fraction was not affected by either acute or chronic administration of gliquidone. Therefore, all other things being equal (blood sugar, plasma insulin levels), young erythrocytes are sensitive to sulphonylurea, whereas old ones are not. Irrespective of the compound tested, this observation suggests that receptor sensitivity might be tissue-specific or age-specific or both, and that the stage of maturation of a cell is a determining factor.
Thyrotrophin and thyroid-stimulating immunoglobulins have similar characteristics in activating human thyroid membrane adenylate cyclase
Authors: Ollis C. A. , MacNeil S. M. , Tomlinson S. , Munro D. S.
Published: December 2008

The activation of adenylate cyclase by TSH and thyroid-stimulating immunoglobulins (TSIg) was investigated in membranes prepared from non-toxic goitres. The assay conditions for maximal adenylate cyclase stimulation by TSH in the absence and presence of a cell cytosol preparation were determined. Cell cytosol had no detectable effect on the characteristics of activation by TSH although it increased the production of cyclic AMP in response to the hormone. In the presence of cell cytosol, membrane protein, pH and substrate concentration dependency of adenylate cyclase activation by both TSH and TSIg were similar. In a comparison of the time-courses of activation there was no apparent lag phase in the activation of adenylate cyclase by TSIg but the onset of activation was slower and linearity persisted longer than with TSH.
Effect of photoperiod and gonadectomy on testosterone metabolism in vitro by the prostate of the golden hamster
Authors: Lucini V. , Bottoni L. , Massa R.
Published: December 2008

Testosterone metabolism was studied in vitro in the prostate of intact and castrated golden hamsters maintained either in short days (8 h light: 16 h darkness, 8L : 16D) or in long days (14L : 10D). Testosterone was found to be converted into 17β-hydroxy-5α-androstan-3-one (5α-DHT), 5α-androstane-3α, 17β-diol, 5α-androstane-3, 17-dione and androstenedione. The mean conversion of testosterone to 5α-DHT was higher in prostates from animals maintained in long days than in short days (P < 0·0025) while that to androstenedione was higher in short days (P <0·0005); no significant changes in the formation of the other three metabolites were noted. Castration of animals maintained in short days resulted in a significant (P <0·05) decrease in the mean conversion to all four metabolites. In contrast, castration of animals kept in a long-day regime caused a significant (P <0·01) decrease in the mean formation of 5α-DHT but a significant (P <0·05) increase in the mean formation of 5α-androstane-3α, 17β-diol.
Effect of tamoxifen on growth and prolactin secretion of rat pituitary tumours
Authors: Prysor-Jones R. A. , Silverlight J. J. , Jenkins J. S.
Published: December 2008

The antioestrogenic drug tamoxifen was administered to rats bearing transplanted prolactin-secreting tumours derived from spontaneously occurring pituitary adenomas in Wistar–Furth rats. Some inhibition of tumour growth was observed but this was accompanied by an increase in plasma prolactin concentrations. Bromocriptine, however, consistently inhibited both growth and prolactin secretion of these tumours. The addition of tamoxifen to bromocriptine treatment produced no increased response to the dopamine agonist. Tamoxifen increased prolactin secretion by tumour cells in vitro but did not affect DNA synthesis. Normal rats responded to tamoxifen with a moderate increase in plasma prolactin concentrations and there was no change in pituitary DNA synthesis.
l-Thyroxine enters the rat liver cell by simple diffusion
Authors: Rao G. S. , Rao M. L.
Published: December 2008

The mode of uptake of l-[125I]thyroxine by freshly isolated rat liver parenchymal cells was studied by a rapid centrifugation technique. Using conditions for measuring initial rates of uptake, uptake by liver cells was not saturable when exposed to hormone concentrations in the incubation medium ranging from 2 pmol/l to 10 μmol/l. The Arrhenius plot was linear from 2 to 37°C; the temperature coefficient was 1·4. The uptake of l-[125I]thyroxine by liver cells was 35% when compared with that of l-[125I]tri-iodothyronine. In the presence of 2·8% bovine serum albumin the rate of uptake of l-[125I]thyroxine by liver cells was reduced by 90%. These results suggest that l-[125I]thyroxine enters the rat liver parenchymal cell by simple diffusion and only the free hormone crosses the plasma membrane.
Biphasic inhibition of bioactive hypothalamic corticotrophin releasing factor secretion in vitro by corticosterone and prevention of the second phase by various steroids
Authors: Beckford U. , Holmes M. C. , Gillham B. , Jones M. T.
Published: December 2008

The effect of various steroids on the functional activity of the rat hypothalamus in vitro was investigated. The addition of corticosterone (10−7 mol/l) for 30 min to the incubation medium inhibited immediately the release of bioactive corticotrophin releasing factor (CRF) by tissue induced by serotonin (2·6×10−8 mol/l). This was followed by a period lasting from 30 min (coincident with removal of the steroid from the medium) to 60 min when no inhibition was seen. Finally a second period of suppression of hypothalamic CRF activity in vitro was shown to be fully established 120 min after addition of the steroid. In more detailed investigations the latter inhibition was shown to occur when the tissue was exposed to the steroid (3×10−7 mol/l) for 5 or 30 min, but not for 1 min, and it was dose-related. Of other steroids investigated, progesterone in high concentrations (3 × 10−6 mol/l) suppressed to a small extent the functional activity of the hypothalamus in vitro but 17α-hydroxyprogesterone, 11α-hydroxyprogesterone, 11α,17α-dihydroxyprogesterone and 11-epicortisol had no effect on the delayed inhibition. Progesterone (10−7 mol/l) potentiated the ability of corticosterone (10−8 mol/l) to induce the delayed suppression of hypothalamic CRF activity in vitro. In contrast, 17α-hydroxyprogesterone, 11α-hydroxyprogesterone, 1 1α,17α-dihydroxyprogesterone and 11-epicortisol competitively antagonized this inhibitory action of corticosterone (3 × 10−7 mol/l) in a dose-related manner (1·5 × 10−8–3 × 10−8 mol/l). The action of the antagonist 11-epicortisol was similar whether it was added to the tissue in vitro before corticosterone or antagonist and agonist were added together. The functional characterization of steroid action on the hypothalamus may lead to a clearer understanding of the mechanism by which the compounds influence hormone release.