bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prolactin-dependent accumulation of α-lactalbumin in mammary gland explants from the pregnant tammar wallaby (Macropus eugenii)
Authors: Nicholas K. R. , Tyndale-Biscoe C. H. 
Published: December 2008

ABSTRACT
The minimal hormonal requirements for the in-vitro accumulation of α-lactalbumin have been investigated in a marsupial, the tammar (Macropus eugenii). Mammary gland explants from 24-day pregnant tammars cultured in medium containing bovine insulin, cortisol and ovine prolactin showed a progressive increase in accumulation of α-lactalbumin during 4 days of incubation. No increment was observed if prolactin was omitted from the medium. However, a similar rate of increase was observed after 3 days of culture in medium containing prolactin alone. This induction of α-lactalbumin was maximal at a prolactin concentration of approximately 0·02 mg/l, which corresponds to physiological levels during pregnancy and early lactation. The absence of an effect of bovine insulin on tammar explants is not due to a general unresponsiveness to this hormone since insulin-stimulated DNA synthesis and amino acid uptake was evident after 3 days of culture. The inclusion of tri-iodothyronine and raised concentrations of cortisol in culture media have been shown to modulate α-lactalbumin synthesis in eutherian mammals but were without effect in the tammar. In addition, increased levels of progesterone did not inhibit the induction of α-lactalbumin, confirming an earlier invivo study suggesting that progesterone withdrawal may not be the lactogenic trigger in this species. Thus the pregnant tammar is the only species yet described in which α-lactalbumin is induced maximally in vitro in response to a single hormone.
J. Endocr. (1985) 106, 337–342
Oestrogens in fetal and maternal fluids throughout pregnancy in the pig and comparisons with the ewe and cow
Authors: Robertson H. A. , Dwyer R. J. , King G. J. 
Published: December 2008

ABSTRACT
In order to correlate the concentrations of oestrogens in the fetal fluids of the pig with those observed in the maternal blood and urine, changes in the concentrations of oestrone, oestradiol-17β, oestrone sulphate, oestradiol sulphates and oestrone glucuronide were assessed throughout pregnancy in the fetal and maternal fluids. In general, the pattern of change was similar for all oestrogens measured in both fetal and maternal fluids. Since the concentration of oestrogens in allantoic fluid during early pregnancy is reflected in the concentration of these steroids in maternal plasma and excreted in the maternal urine, the rise and fall of oestrogen concentrations around day 30 is suggestive of synthesis followed by a virtual cessation of oestrogen production until the fetus or placenta again produce increasing amounts detectable after day 45. These findings contrast sharply with those in the cow and the ewe where, although similar peaks in oestrogen concentrations are observable in allantoic fluid during early pregnancy, they are not reflected in blood.
J. Endocr. (1985) 106, 355–360
Effect of intraventricular injection of 5,6-dihydroxytryptamine on spermatogenesis and plasma testosterone levels in the rat
Authors: Das T. K. , Mazumder R. , Biswas N. M. 
Published: December 2008

ABSTRACT
Quantitative evaluation of spermatogenesis at stage VII of the cycle of the seminiferous epithelium and radioimmunoassay of plasma testosterone were performed in adult Wistar rats after intraventricular injection of 5,6-dihydroxytryptamine (5,6-DHT). The rats were killed 2, 10 and 21 days after injection. Brain 5-hydroxytryptamine (5-HT) and plasma testosterone levels were found to be significantly lower in all rats treated with 5,6-DHT. A significant reduction in step 7 spermatid count was also observed after 10 and 21 days. Supplementation with human chorionic gonadotrophin for 21 days in rats injected with 5,6-DHT partially prevented the step 7 spermatid degeneration and increased testosterone levels without producing any effect on brain concentrations of 5-HT. These results suggest that changes in testicular steroidogenesis and spermatogenesis are secondary to pituitary gonadotrophin release which, in turn, is under the influence of brain 5-HT neurones.
J. Endocr. (1985) 106, 395–400
REAPPEARANCE OF THYMUS OF AGEING RATS AFTER ORCHIDECTOMY
Authors: Fitzpatrick F.T.A. , Kendall M.D. , Wheeler M.J. , Adcock I.M. , Greenstein B.D. 
Published: December 2008

ABSTRACT
There was no visible thymus in ageing rats of 18 months, and 7 days after orchidectomy there was still no evidence of a thymus. By 30 days after the operation, however, there was a well-defined and well developed bilobular thymus overlying the heart, although it was smaller than those observed in 10-week-old rats. Histologically, the tissue appeared normal, was well vascularized, filled with lymphocytes and several mitotic figures were also seen. When compared with sham-operated animals, blood from these animals had a significantly higher lymphocyte count. These results have important implications for the possible enhancement of the immune system with associated improvement of health during ageing.
Calmodulin regulation of cellular cyclic AMP production in response to arginine vasopressin, prostaglandin E2 and forskolin in rat renal papillary collecting tubule cells in culture
Authors: Ishikawa S. , Saito T. , Kuzuya T. 
Published: December 2008

ABSTRACT
The effect of calmodulin on the stimulation of cyclic AMP production by arginine vasopressin (AVP), prostaglandin E2 (PGE2) and forskolin was examined in cultured renal papillary collecting tubule cells of the rat. In the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine submaximal concentrations of AVP (1 nmol/l), PGE2 (20 nmol/l) and forskolin (240 nmol/l) significantly increased cellular cyclic AMP accumulation by 2·3-, 6·0- and 8·4-fold respectively. Two chemically dissimilar inhibitors of calmodulin, namely trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7), attenuated the AVP-, PGE2- and forskolin-stimulated cellular production of cyclic AMP in a dose-related manner. Cellular production of cyclic AMP was inhibited by 50% (ID50) by doses ranging from 16 to 28 μmol trifluoperazine/1 and 35 to 44 μmol W-7/1. Basal accumulation of cellular cyclic AMP was also decreased by treatment with either trifluoperazine or W-7, but the effective dose was higher than that which inhibited cellular cyclic AMP production stimulated by AVP, PGE2 and forskolin. Since forskolin directly activates adenylate cyclase at a site of the catalytic unit and the cellular action of AVP to activate adenylate cyclase is mediated through receptor-guanine nucleotide regulatory-catalytic units, the present study indicates calmodulin regulation of basal, AVP-, PGE2-and forskolin-activated adenylate cyclase in the papillary collecting tubule cells. The inhibition of AVP- or PGE2-induced cellular cyclic AMP production by treatment with either Ca2+-free medium or verapamil, a blocker of cellular Ca2+ uptake, was demonstrated and suggests that an increase in cytosol Ca2+, which interacts with calmodulin to form an active complex is, at least in part, due to the increased cellular influx of Ca2+ from the extracellular space.
J. Endocr. (1985) 107, 15–22
Changes in ovarian steroidogenesis in prepuberal rats induced to ovulate by low doses of human chorionic gonadotrophin
Authors: Uilenbroek J. Th. J. , Meijs-Roelofs H. M. A. , Woutersen P. J. A. , Kramer P. , van Cappellen W. A. , Gribling-Hegge L. A. , de Greef W. J. 
Published: December 2008

ABSTRACT
To determine whether the decrease in ovarian 5α-reduced androgen production before first ovulation might be caused by an increase in serum LH, prepuberal female rats were injected at 28–31 days of age with low doses of human chorionic gonadotrophin (hCG) (0·05–0·075 i.u., four times daily). This treatment resulted in ovulation of six to ten ova per rat on day 32 in all animals.
Treatment with hCG resulted in a gradual decrease in ovarian content and production (i.e. content in ovary and medium after 4 h of incubation) of 5α-dihydrotestosterone (DHT) and 5α-androstane-3α,17β-diol. The ovarian content of DHT and the production of 5α-androstane-3α,17β-diol decreased within 24 h after the first injection of hCG. Oestradiol content and production increased between 24 and 48 h after the start of treatment and was maximal on day 31 (day of pro-oestrus).
Activities of 5α-reductase and aromatase were measured in ovarian homogenates obtained on days 29–31. Activity of 5α-reductase in hCG-treated rats was lower than that in control rats on all days studied. Aromatase activity in hCG-treated rats increased between days 29 and 31.
It was concluded that multiple injections of low doses of hCG, which may induce ovulation, cause a decrease in 5α-reduced androgen production, which is probably due to a decrease in 5α-reductase activity. The subsequent increase in oestradiol production corresponds with an increase in aromatase activity. The results indicate that the decrease in 5α-reductase activity as observed in ovaries of spontaneously ovulating rats might be caused by the gradual increase in serum LH, which has been found to occur during the last week before first ovulation.
J. Endocr. (1985) 107, 113–119
An androgen-independent mechanism maintains photorefractoriness in male tree sparrows (Spizella arborea)
Authors: Wilson F. E. 
Published: December 2008

ABSTRACT
A series of experiments was performed to clarify whether photorefractoriness in male tree sparrows is maintained by an androgen-dependent mechanism. Castration did not raise plasma LH in photorefractory males held under a daily photoperiod of 20 h light: 4 h darkness (20L: 4D). Castrated photorefractory males were implanted with the antiandrogen cyproterone or injected s.c. with the antiandrogen flutamide to determine whether androgens which may be resistant to castration inhibit LH secretion. Neither cyproterone nor flutamide raised plasma LH above values found in castrated control birds. Castrated photorefractory males were treated with testosterone to determine whether plasma LH in photorefractory males is androgen-suppressible. Concentrations of plasma LH were independent of plasma testosterone over a wide range of concentrations. The lack of LH response to castration, to castration coupled with antiandrogen therapy, and to castration coupled with testosterone replacement argues that photorefractoriness in male tree sparrows is maintained by an androgen-independent mechanism.
J. Endocr. (1985) 107, 137–143
Effects of maternal sodium depletion on the composition of ovine fetal fluids
Authors: Bell R.J. , McDougall J.G. , Wang X. , Wintour E.M. 
Published: December 2008

ABSTRACT
Effects of maternal sodium depletion on the composition of ovine fetal fluids were studied. Maternal Na depletion was achieved by 48-h drainage of parotid saliva. There was a significant decrease in both maternal and fetal plasma Na concentration, indicating that both mother and fetus had experienced the Na-depletion stimulus. There was a significant increase in maternal blood aldosterone but the change in fetal blood aldosterone was not significant. In animals where there was an increase in fetal blood aldosterone the increase could be accounted for by transfer of aldosterone across the placenta from the mother. There was a significant decrease in fetal urinary Na concentration and Na excretion and the urinary Na/K ratio fell in seven out of eight studies. These observations are consistent with the hypothesis that fetal Na depletion sensitizes the fetal kidney to the action of circulating aldosterone as in the adult.
J. Endocr. (1985) 107, 177–182
Developmental changes in the rate of production of an unusual testosterone metabolite, 4-androstene-3α,17β-diol, by chick liver microsomes
Authors: Darby N. J. , Spencer S. , Lodola A. , Burnet F. R. 
Published: December 2008

ABSTRACT
Testosterone is produced by the chick embryo testis from the 13th day of incubation. We have investigated the ability of microsomes prepared from the fetal and neonatal liver to metabolize testosterone and have found that the principal metabolite generated by microsomes in the presence of NADPH is 4-androstene-3α,17β-diol. The rate of production of this metabolite declined sharply over the time of hatching. Conversely, 16α-hydroxytestosterone production increased transiently just after hatching. Our findings indicate that chick liver microsomes contain a 3α-hydroxysteroid dehydrogenase (3α-hydroxysteroid: NAD(P) oxidoreductase, EC 1.1.1.50) whose activity changes during development.
J. Endocr. (1985) 107, 205–209
Comparison of glucose-induced changes in electrical activity, insulin release, lactate output and potassium permeability between normal and ob/ob mouse islets: effects of cooling
Authors: Scott A. M. , Dawson C. M. , Gonçalves A. A. 
Published: December 2008

ABSTRACT
A comparison has been made between the glucose-induced changes in electrical activity, insulin release, lactate output and potassium permeability in normal and ob/ob obese (Norwich strain) mice. The electrical response of the islet membrane to high glucose (22·2 mmol/l) stimulation was different in the two types of mice, generating continuous spike activity in normal but producing bursts of activity in ob/ob mouse islets. The absolute amounts of insulin and lactate produced by ob/ob islets in response to both basal and high glucose concentrations were greater than the absolute amounts produced by normal islets, though the ratio of the amount produced in high glucose concentrations to the amount produced in basal glucose concentrations was not significantly different between normal and ob/ob islets for both parameters. Glucose-induced changes in potassium permeability were smaller in ob/ob than in normal mice. Cooling from 37 to 27 °C, during steady-state glucose stimulation, reduced both lactate output and insulin release, the temperature coefficients being similar in both types of mice. The effect of temperature reduction on electrical activity was more marked in the islets of ob/ob mice than in those of normal mice; spike frequency was unaffected in normal but reduced in ob/ob mice, whereas spike amplitude was decreased in both. Cooling-induced inhibition of potassium permeability was greater in the islets of ob/ob mice than in those of normal mice. These results show that this new colony of ob/ob mice (Norwich strain) is comparable to normal mice in terms of the dynamics of insulin release and lactate output in response to glucose, but that the response of the β-cell membrane electrical activity and potassium permeability to glucose is different.
J. Endocr. (1985) 107, 265–273
A chronic technique for high frequency blood sampling/transfusion in the freely behaving rat which does not affect prolactin and corticosterone secretion
Authors: Wiersma J. , Kastelijn J. 
Published: December 2008

ABSTRACT
A blood sampling/blood transfusion technique is described for chronically cannulated freely behaving rats. The procedure permits high frequency sampling for several hours at a maximum rate of one blood sample per min. Prolactin and corticosterone were used as indicators of stress.
In male rats the prolactin concentration in blood obtained by rapid decapitation was not significantly different from that obtained through a cannula. A blood volume reduction of 1 or 2 ml did not affect prolactin or corticosterone secretion; however, a reduction of 3 ml or more increased corticosterone secretion but did not consistently increase prolactin secretion. When blood volume reduction was compensated for by blood transfusion, frequent blood sampling did not affect prolactin or corticosterone secretion in dioestrous rats. The surges of prolactin secretion during the afternoon of pro-oestrus and pseudopregnancy were also unaffected by high frequency blood sampling.
It is therefore concluded that the blood sampling/ transfusion procedure described does not stress the animals. Its advantages include not only the possibility of following individual hormone profiles, but also the economic and ethical aspects of reducing the number of animals needed for experimentation.
J. Endocr. (1985) 107, 285–292
Changes in total and free concentrations of steroid hormones in the plasma of women throughout pregnancy: effects of medroxyprogesterone acetate in the first trimester
Authors: Willcox D. L. , Yovich J. L. , McColm S. C. , Schmitt L. H. 
Published: December 2008

ABSTRACT
The total (protein-bound plus free) and free concentrations of progesterone, oestradiol-17β and cortisol were measured serially throughout pregnancy in the plasma of two groups of women whose pregnancies went to term. Group A (n = 53) experienced an uneventful low-risk pregnancy with a spontaneous abortion rate of 8·6%. Women in group B (n = 22) were treated orally with medroxyprogesterone acetate (MPA; 80–120 mg daily) until 18 weeks gestation for threatened abortion within the first 6 weeks of pregnancy.
In both groups of women the proportion of each hormone circulating in the free or unbound form remained constant despite the overall increases which occurred in total circulating hormone concentrations as pregnancy progressed. The steroid hormonal profiles in the first half of pregnancy were similar in both groups of women. However, from weeks 20 to 40 total and free progesterone concentrations were significantly (P < 0·05 in each case) higher in group B compared with group A. Conversely, total and free oestradiol-17β concentrations were lower (P < 0·005 and P < 0·01 respectively) in group B. At this stage it is not known if these differences were attributable to the administration of MPA to women in group B or to altered placental steroidogenesis as a result of earlier uterine bleeding.
J. Endocr. (1985) 107, 293–300
Circadian rhythm of melatonin in the pineal gland of the Japanese quail (Coturnix coturnix japonica)
Authors: Cockrem J. F. , Follett B. K. 
Published: December 2008

ABSTRACT
Melatonin was measured by radioimmunoassay in homogenates of pineal glands from quail (Coturnix coturnix japonica) kept under different photoperiods and in darkness. Under 8-, 12- and 16-h daylengths melatonin levels were increased during the dark period, the duration of the increase depending on the duration of the dark period. As the daylength was increased the peak occurred closer to lights-off, reflecting the more rapid melatonin rise under the longer photoperiods. The pineal melatonin rhythm continued in darkness with an amplitude relative to that seen under a light/dark cycle of slightly less than one-half after 2 days in darkness and one-third after 6 days in darkness. The corresponding average periods of the rhythm were 25·5 h and 25·7 h. These results show that there is a circadian rhythm of melatonin in the pineal gland of the quail which is entrained by light/dark cycles and which continues in darkness.
J. Endocr. (1985) 107, 317–324
Increased dopaminergic inhibition of prolactin in the hypoprolactinaemic IPL nude rat
Authors: Cohen H. , Sabbagh I. , Guillaumot P. , Bertrand J. 
Published: December 2008

ABSTRACT
In this study, aimed at investigating whether dopaminergic regulation of prolactin could be implicated in the hypoprolactinaemia observed in the IPL nude rat, dopaminergic inhibition of prolactin was suppressed using a catecholamine synthesis inhibitor α-methyltyrosine (MT) and a dopaminergic antagonist sulpiride.
Adult male rats (IPL nude and normal) were injected through implanted atrial cannulae with either MT (250 mg/kg) or physiological saline (control). Rats were decapitated 2 h after the injection. Plasma prolactin levels, compared with basal values, increased by 15·6 ± 1·9 (s.e.m.)- and 5·89 ± 0·6-fold in IPL nude and normal rats respectively. This difference was highly significant. The pituitary prolactin content was decreased in both groups.
In a second experiment, adult male IPL nude or normal rats were injected with either sulpiride (1 mg/kg) or saline and decapitated 2, 4, 8, 12, 14 and 24 h later. Plasma prolactin levels, compared with basal values, were increased in rats injected with sulpiride by 9·2 ± 1·8 and 3·4 ± 0·7-fold in IPL nude and normal rats respectively. The pituitary prolactin content was reduced more in IPL nude than in normal sulpiride-injected rats. These data suggest that prolactin secretion, as well as synthesis, is under an increased dopaminergic inhibition in the male IPL nude rat.
J. Endocr. (1985) 107, 325–329
In-vivo activity of the LH-releasing hormone pulse generator in castrated and intact male rats
Authors: Dluzen D. E. , Ramirez V. D. 
Published: December 2008

ABSTRACT
The in-vivo LH-releasing hormone (LHRH) output from the mediobasal hypothalamus of conscious freely moving sham-castrated, acutely castrated (immediately after castration) and long-term castrated (> 20 days after castration ) adult male rats has been studied. Five rats in each of the three conditions were perfused for an 8-h period (11.00–19.00 h). One animal in each condition was perfused for a 24-h period. In the sham-castrated and acutely castrated, but not in the long-term castrated rats, apparently random surges of LHRH output (> 5·6 pmol/l), separated by periods of non-detectable activity, were observed throughout the perfusion period. The LHRH output of the long-term castrated rats was characterized by an extremely low overall mean release and markedly attenuated pulse amplitudes, with both parameters significantly lower than those of the sham-and acutely castrated rats. These results indicate that the raised blood levels of LH in long-term castrated rats do not appear to be the consequence of high amplitude and high overall release of LHRH.
J. Endocr. (1985) 107, 331–340
An enzyme-linked immunosorbent assay for the measurement of thyroglobulin in human serum using mouse monoclonal antibodies
Authors: Kilduff P. , Black E. G. , Hall R. , McGregor A. M. 
Published: December 2008

ABSTRACT
A robust, rapid, sensitive and specific enzyme-linked immunosorbent assay (ELISA), using an in-house immunoglobulin-A-sub-class mouse monoclonal human-thyroglobulin antibody (WNSM2), with a sensitivity of 1·51 pmol/l has been established for the measurement of thyroglobulin in serum. Standard curves in varying dilutions of human serum were similar to standard curves obtained in serum-free medium, thus demonstrating no significant cross-reactivity with any serum proteins other than thyroglobulin. Levels of serum thyroglobulin detected by ELISA correlated significantly (r = 0·93, P < 0·001) with those from a standardized and well-characterized radioimmunoassay. The coefficients of variation within and between ELISA assays were 3·9 and 7·1% respectively. Thyroglobulin was detectable in 87% of 54 normal subjects who had no history of thyroid or autoimmune disease, the mean (±s.d.) for this group being 15 ± 6·6 pmol/l with a range of 1·51–53 pmol/l. Using this assay, levels of thyroglobulin were shown to be significantly (P < 0·002) increased in patients with untreated hyperthyroid Graves' disease compared with normal subjects.
J. Endocr. (1985) 107, 383–387