bluuebunny/crossref_metadata_2025 huggingface dataset:
CHANGES IN THE SECRETION OF OVARIAN STEROIDS AND PITUITARY LUTEINIZING HORMONE IN THE PERI-OVULATORY PERIOD IN THE EWE: THE EFFECT OF PROGESTERONE
Authors: BAIRD D. T. , SCARAMUZZI R. J.
Published: December 2008

The secretion rates of oestradiol, androstenedione and progesterone and the peripheral plasma concentration of LH were measured in 12 ewes with ovarian autotransplants before and after luteal regression induced by a single intramuscular injection of a synthetic prostaglandin (PG) analogue, 16-aryloxyprostaglandin F2α (I.C.I. 80996). Luteal regression was followed by a fourfold rise in the basal concentration of LH and increased secretion of oestradiol. In five out of six ewes there was a discharge of LH with the peak occurring 36–78 h after the injection of the PG analogue. The secretion of oestradiol declined from 3·68± 1·08 to 0·33± 0·6 (s.e.m.) ng/min in the 24 h following the LH peak (P < 0·001). In the remaining six ewes in which progesterone was implanted subcutaneously 24 h after the injection of PG analogue, follicular development was suppressed as indicated by the low secretion of oestradiol and androstenedione. The basal concentration of LH fell to values similar to those observed during the luteal phase after the implant of progesterone. The secretion of androstenedione followed a similar pattern to that of oestradiol in those ewes which showed presumptive evidence of ovulation. These results suggest that progesterone reinforces the negative feedback effects of oestrogen in the ewe.
BRANCHIAL SODIUM EXCHANGE IN SEAWATER-ADAPTED TILAPIA MOSSAMBICA: EFFECTS OF PROLACTIN AND HYPOPHYSECTOMY
Authors: DHARMAMBA M. , MAETZ J.
Published: December 2008

The effects of exogenous prolactin and hypophysectomy were tested on Na exchange across the gills of Tilapia mossambica adapted to sea-water.

Exogenous prolactin produced a 75% decrease of both total Na influx and Na efflux. Total Na influx was measured simultaneously with the drinking rate. Water ingestion stopped almost completely in prolactin-treated fish. Thus branchial net excretion flux of Na was reduced 75% by prolactin.

Hypophysectomy produced a 50% inhibition of Na efflux across the gill.
COMPARISON BETWEEN THE BINDING OF 19-NORTESTOSTERONE, 5α-DIHYDROTESTOSTERONE AND TESTOSTERONE IN RAT PROSTATE AND BULBOCAVERNOSUS/LEVATOR ANI MUSCLE
Authors: KRIEG M. , DENNIS M. , VOIGT K. D.
Published: December 2008

Specific binding of [3H]19-nortestosterone in the 100000 g cytosol of the rat bulbocavernosus/levator ani muscle (BCLA) and prostate was demonstrated by agargel electrophoresis at low temperature and compared qualitatively and quantitatively with the binding of tritiated testosterone and 5α-dihydrotestosterone (5α-DHT). Both tissues showed a greater binding affinity for 5α-DHT than for 19-nortestosterone, with testosterone binding the least well of the three. The relative binding affinities in the BCLA and prostate were: 19-nortestosterone: testosterone = 1·4, 19-nortestosterone: 5α-DHT = 0·7. The differences were statistically significant (P < 0·02). The concentrations of receptor sites for 5α-DHT were 171 ± 20 (s.d.) fmol/mg prostatic cytosol protein and 24 ± 4 (s.d.) fmol/mg BCLA cytosol protein. The in-vitro metabolism of the three steroids in both tissues was also investigated by thin-layer chromatography. After incubating for 2 h at 0 °C the prostate was shown to reduce 26% of the 5α-DHT to androstanediols whilst the BCLA showed a 5% conversion. Testosterone was converted by the prostate to 5α-DHT (10%) and the androstanediols (6%) whilst the BCLA showed little activity in this respect. Comparing these in-vitro data with in-vivo findings from the literature, in both organs there is a positive correlation of the extent of binding in vitro to the stimulation of growth in vivo, bearing in mind that testosterone is metabolized to 5α-DHT in the prostate whilst in the BCLA, 5α-reductase is essentially absent.
ENDOCRINE EFFECTS OF MASTURBATION IN MEN
Authors: PURVIS K. , LANDGREN B.-M. , CEKAN Z. , DICZFALUSY E.
Published: December 2008

The levels of pregnenolone, dehydroepiandrosterone (DHA), androstenedione, testosterone, dihydrotestosterone (DHT), oestrone, oestradiol, cortisol and luteinizing hormone (LH) were measured in the peripheral plasma of a group of young, apparently healthy males before and after masturbation. The same steroids were also determined in a control study, in which the psychological anticipation of masturbation was encouraged, but the physical act was not carried out. The plasma levels of all steroids were significantly increased after masturbation, whereas steroid levels remained unchanged in the control study. The most marked changes after masturbation were observed in pregnenolone and DHA levels. No alterations were observed in the plasma levels of LH.

Both before and after masturbation plasma levels of testosterone were significantly correlated to those of DHT and oestradiol, but not to those of the other steroids studied. On the other hand, cortisol levels were significantly correlated to those of pregnenolone, DHA, androstenedione and oestrone.

In the same subjects, the levels of pregnenolone, DHA, androstenedione, testosterone and DHT in seminal plasma were also estimated; they were all significantly correlated to the levels of the corresponding steroid in the systemic blood withdrawn both before and after masturbation.

As a practical consequence, the results indicate that whenever both blood and semen are analysed, blood sampling must precede semen collection.
STIMULATION OF INTRA-UTERINE GROWTH IN RAT BY α-MELANOCYTE-STIMULATING HORMONE
Authors: SWAAB D. F. , VISSER M. , TILDERS F. J. H.
Published: December 2008

We have studied whether endogenous α-MSH has a function in stimulating intra-uterine growth in the rat. The approach used was to determine whether or not this hormone is present during the intra-uterine growth spurt, and if binding of endogenous foetal α-MSH by antibodies would inhibit this growth.

Antibodies against α-MSH or ACTH 1-24, either purified or non-purified, induced immunofluorescence in the intermediate lobe of adult male control rats. Using purified anti-α-MSH, fluorescence appeared in the foetal intermediate lobe on day 18 of pregnancy, the day that biologically active MSH was first seen. A negative correlation was observed between the pituitary MSH content and foetal body weight only on day 19 of pregnancy. Injection of purified anti-α-MSH induced a drop in foetal body weight, but no effect on placental weight was observed. Purified anti-ACTH 1-24 had no effect upon body weight but caused an increase in placental weight.

These results support our previous findings and indicate that endogenous MSH has a function in the stimulation of foetal growth.
BINDING OF HUMAN GROWTH HORMONE TO HEPATIC LACTOGENIC BINDING SITES: REGULATION BY OESTROGENS AND ANDROGENS
Authors: HERINGTON A. C. , BURGER H. G. , VEITH NOELLE M.
Published: December 2008

The binding of 125I-labelled human growth hormone (HGH) to the 'lactogenic' binding sites of rat liver membranes has been shown to be highly dependent on the oestrogen and androgen status of the animal from which the membranes were prepared. Oestradiol treatment of either male or female rats induced a highly significant rise in HGH binding. The minimum effective dose used was 2–5 μg/day and the rise in HGH binding was apparent after 4 days of treatment. Following cessation of oestradiol treatment of male rats HGH binding declined with a half-time of approximately 9 days. In contrast to the stimulatory effect of oestrogen, treatment of female rats with testosterone propionate (minimum effective dose 100–200 μg/day) led to a marked reduction in HGH binding. The influence of both oestrogens and androgens was confirmed following the removal of endogenous sex steroids by adrenalectomy–ovariectomy of female rats and castration of male rats. Scatchard analysis showed that, with the possible exception of adrenalectomy–ovariectomy, all pharmacologically and physiologically induced changes in HGH specific binding reflected changes in binding site capacity; there were no changes in binding affinity. While earlier studies have indicated that the oestrogen effect is primarily indirect and is mediated by the pituitary gland, the mode of action of the androgens is currently unknown. The relatively slow response of HGH binding to hormonal changes would support an indirect action for both the sex steroids. The stimulatory effect of oestrogens and the inhibitory effect of androgens may provide an explanation for the marked sex difference in HGH binding to rat liver membranes.
THE INTERRELATIONSHIP BETWEEN PROGESTERONE AND LUTEINIZING HORMONE DURING THE OVULATION CYCLE OF THE HEN (GALLUS DOMESTICUS)
Authors: ETCHES R. J. , CUNNINGHAM F. J.
Published: December 2008

The existence of a circadian rhythm in the sensitivity of the hypothalamus of the laying hen to stimulation by progesterone was investigated by injecting 0·5 mg progesterone subcutaneously during the proposed period of maximum insensitivity. Following this treatment increases in plasma concentrations of both LH and progesterone were observed which were comparable to the spontaneous preovulatory rises in the plasma levels of the hormones.

The ability of either progesterone or luteinizing hormone releasing hormone (LH-RH) to induce premature ovulation varied according to the stage of follicular development. Neither hormone was more than 28% effective when injected within 6·5 h of the previous ovulation, whereas both hormones were 100% effective approximately 27 h after the terminal ovulation of a clutch sequence. Failure to ovulate in response to LH-RH given 6·5 h after ovulation was associated with a lack of progesterone secretion.

Both LH and progesterone were secreted when ovulation was induced by injections of either LH-RH or progesterone, and LH was secreted in response to progesterone given 6·5 h after ovulation. These results demonstrate that progesterone stimulates the secretion of LH and LH stimulates the secretion of progesterone. The precise physiological role of these two hormones, however, was not established.
BIOLOGICAL EFFECTS OF 131I AND 125I ISOTOPES OF IODINE IN THE RAT
Authors: DONIACH I. , SHALE D. J.
Published: December 2008

From the differences in radiation profiles between 131I and 125I isotopes of iodine it would be expected that they would show different effects on thyroid function. The differences should lead to lower rates of thyroid gland destruction with 125I and hence less post-irradiation hypothyroidism. This difference in biological effect has been demonstrated in rats by indirect assessment of thyroid function. In this report the long-term effects of a range of similar doses of 131I and 125I were compared, in male and female rats, by direct assessment of thyroid function. Seventeen months after receiving 25 and 125 μCi of 131I, male and female rats showed significant elevation of serum TSH concentration and a reduction in 3 h radioiodine uptake. Rats receiving 1 and 5 μCi of 131I and all doses of 125I showed no significant changes in thyroid function. These findings confirm the previously reported differences in effect between the 131I and 125I isotopes of iodine in the rat.
CONGENITAL GOITRE IN SHEEP: ISOLATION OF THE IODOPROTEINS WHICH REPLACE THYROGLOBULIN
Authors: DOLLING C. E. , GOOD B. F.
Published: December 2008

Immunological and chromatographic studies of proteins from the congenital goitre of South Australian Merino sheep revealed that normal thyroglobulin is absent from the thyroid glands of these sheep. However, a thyroglobulin-immunoreactive iodoprotein was isolated by affinity chromatography on agarose gel to which antibody against thyroglobulin had been covalently bound. Sucrose-gradient ultracentrifugation indicated that this iodoprotein had a sedimentation coefficient of 8S and a molecular weight of approximately 175000. This iodoprotein is therefore about one quarter the size of normal thyroglobulin (19S; 660000) and is similar in size to the subunit of thyroglobulin (3-8S; 165000) although this has usually been described as non-iodinated except when derived by reductive fission.

In addition the goitre extract contained iodoproteins which had the immunological properties of serum albumin and immunoglobulin G.

Determination of the iodine and iodoamino acid content of the hydrolysed iodoproteins revealed that they contained iodothyronines which were able to contribute to the production of thyroid hormones although the total iodothyronine content of the goitrous gland was less than that of the normal sheep thyroid gland.
OUTPUT OF OESTROGENS, TESTOSTERONE AND THEIR PRECURSORS BY ISOLATED HUMAN ADRENAL CELLS AS COMPARED WITH THAT OF GLUCOCORTICOSTEROIDS
Authors: KEYMOLEN V. , DOR P. , BORKOWSKI A.
Published: December 2008

The output of oestrogens, testosterone and their precursors was compared with that of glucocorticosteroids under standardized conditions, in a suspension of isolated human adrenal cells. Cortisol, corticosterone, androstenedione, dehydroepiandrosterone and its sulphate all increased in the same proportions after ACTH stimulation. The response to the logarithm of ACTH concentrations had a sigmoid shape but was fairly linear between 5 and 100 to 1000 μu./ml.

The output of dehydroepiandrosterone plus that of its sulphate was of the same order of magnitude as the production of cortisol; the output of free dehydroepiandrosterone averaged half that of the sulphate indicating that the adrenal cortex is capable, under certain conditions, of producing large amounts of the free steroid.

The output of androstenedione was very low, on average 35 times lower than that of cortisol, suggesting by extrapolation that the adrenal secretion may not be the main source of androstenedione in vivo or that ACTH is not the unique stimulus to adrenal androstenedione secretion.

The output of testosterone was small to negligible and that of oestrogens was practically absent.

In three additional experiments the influence of prolactin, prostaglandins, FSH and HCG was explored: no selective stimulation of androgen or oestrogen output was observed except in one experiment in which HCG stimulated adrenal testosterone production.
INFLUENCE OF 16-ARYLOXYPROSTAGLANDINS ON THE PRODUCTION OF PROGESTERONE BY HUMAN GRANULOSA CELLS IN VITRO
Authors: HENDERSON K. M.
Published: December 2008

16-Aryloxy analogues of prostaglandin F2α(PGF2α) are potent luteolysins in laboratory and farm animals. When their effect on progesterone production by luteinized human granulosa cells in tissue culture was investigated inhibition of both basal and gonadotrophin-stimulated progesterone production was observed, so revealing characteristics expected of potential human luteolysins. The analogues were, however, unable to inhibit progesterone production stimulated by PGE2, suggesting that like PGF2α these compounds may act by specifically blocking LH-activated adenylate cyclase.

The 16-aryloxyprostaglandins similarly inhibited progesterone production by porcine granulosa cells, so that the effects observed with the 16-aryloxyprostaglandins in vitro may be indicative of their potential in vivo.
PRODUCTION OF MALE PSEUDOHERMAPHRODITISM IN RATS BY TWO NEW INHIBITORS OF STEROID 17α-HYDROXYLASE AND C 17-20 LYASE
Authors: GOLDMAN A. S. , EAVEY R. D. , BAKER MARY K.
Published: December 2008

Two new synthetic steroid analogues, (I) 16β-bromo-3β,17α-dihydroxy-5α-pregnane-11,20-dione and (II) 17β-ureido-1,4-androstadien-3-one have been shown to give kinetic patterns consistent with active-site-directed irreversible inhibition of adult rat testicular microsomal steroid 17α-hydroxylase and C17-20 lyase in vitro. Administration of both analogues to adult male rats for 24 h produced potent inhibition of these testicular enzymes in vivo. Given to pregnant rats during the critical period of male organogenesis they produced hypospadias: a characteristic of the syndrome in man in which these enzymes are defective genetically. Given to male rat pups during the first 9 days of life, inhibitor II produced significantly smaller prostates and seminal vesicles in adulthood, indicating the usefulness of this inhibitor in studies on the role of testosterone in neonatal programming of target organ size in adulthood. Thus, two new enzyme inhibitors have been shown to block testosterone production in the foetal and neonatal rat selectively at the site of the hydroxylase without other apparent hormonal effects or influence on adrenal size.
INTERACTIONS OF OESTRADIOL-17β AND TAMOXIFEN IN THE UTERUS OF THE PREGNANT RAT
Authors: MAJOR J. S. , GREEN B. , HEALD P. J.
Published: December 2008

Measurement of the uptake and retention of a radioactive post-coital antifertility agent tamoxifen, by reproductive tissues of the rat have shown that the ovary retained more radioactivity than did any other reproductive organ. Studies have also been made of the uptake and distribution of [3H]tamoxifen and [3H]oestradiol-17β in the uterus of the pregnant rat on days 2–6 post coitum. Twenty-four hours after administration of tamoxifen, either i.v. or orally, 40–50% of the radioactivity was in the high speed pellet, 10–20% in the nuclear fraction, and 15–30% in the cytosol. An equivalent dose of [3H]oestradiol-17β yielded distributions of 5%, 5% and 82% respectively. Fractionation of uteri from animals given 0·2 mg tamoxifen/kg on Day 2 of pregnancy followed by [3H]oestradiol 60 min before death showed little difference in total uptake of oestradiol or distribution in the subcellular fraction on Days 4, 5 and 6. Although uptake of oestradiol by uterine nuclei was reduced on Day 3 by previous administration of tamoxifen on Day 2, appreciable quantities were still bound to the nuclear receptors. Treatment of ovariectomized animals with tamoxifen at doses up to 40 μg/rat (i.e. 0·2 mg/kg) led to the accumulation of oestrogen–receptor complex in the nucleus.

It is concluded that the antifertility properties of tamoxifen (under the conditions of these experiments) cannot be ascribed to the suppression of uptake and binding of oestradiol by the uterus.
EFFECT OF BRAIN STIMULATION ON ALDOSTERONE SECRETION IN THE RHESUS MONKEY (MACACA MULATTA)
Authors: FRANKEL R. J. , JENKINS J. S. , WRIGHT J. J. , KHAN M. U. A.
Published: December 2008

The lateral hypothalamus, and various sites within the limbic system and frontal lobe of the rhesus monkey brain were electrically stimulated using chronically implanted electrodes. A considerable increase in plasma aldosterone levels was observed after stimulation of the lateral hypothalamic area, certain localized sites in the cingulate area, and lower medial parts of the frontal lobe. Inactive sites included most of the amygdala, hippocampus, and basal ganglia, together with other areas within the frontal lobe and cingulate gyrus. Stimulation of all active areas was followed by an increase in plasma renin activity. Plasma cortisol also increased considerably after hypothalamic stimulation but in the case of extra-hypothalamic sites the cortisol response was much less.
EFFECTS OF PROPRANOLOL ON CHANGES IN HEART RATE, HEART WEIGHT, KIDNEY WEIGHT, URINARY HYDROXYPROLINE AND WEIGHT GAIN INDUCED BY LARGE DOSES OF THYROXINE IN THE RAT
Authors: GOULDING A. , McCHESNEY R. , STEWART R. D. H.
Published: December 2008

The effects of the β-adrenergic receptor blocking agent, dl-propranolol, and of the antithyroid drug, carbimazole, upon some manifestations of thyroxine (T4)-induced changes in peripheral metabolism were studied in rats. Propranolol lowered the heart rate, but did not alter the following changes induced by T4: increment in heart rate, increase in heart or kidney weight, increase in urinary hydroxyproline, decrease in body weight gain or increase in serum T4. Carbimazole administration lowered serum T4 and reduced weight gain, but had no effect upon heart rate or hydroxyproline excretion.
LUTEINIZING HORMONE RELEASE AFTER TWO INJECTIONS OF SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE IN THE EWE
Authors: CRIGHTON D. B. , FOSTER J. P.
Published: December 2008

Anoestrous ewes were given two injections of 30 μg synthetic luteinizing hormone releasing hormone (LH-RH) separated by one of the following intervals: 1·5, 3, 6, 12 or 24 h. The first injection caused an increase in the plasma LH concentration in each animal. The response to the second injection was dependent on the interval between the injections. When the second injection was administered 1·5 h after the first it caused a further increase in the LH concentration to maximal levels which were significantly greater than those induced in the other anoestrous groups. When the second injection was administered 3 h after the first, there was no significant difference between the responses to the two injections although the time to reach the maximal LH concentration was shorter and the height of the LH peak was greater in each animal following the second injection. When the second injection was administered 6,12 or 24 h after the first, the LH response was significantly less, in terms of height and area of the induced peak, than following the first injection. The LH response to the second injection was particularly low in the 12 and 24 h groups. Two injections of 30 μg synthetic LH-RH were also administered at 1·5 h intervals to ewes on either day 10 of the oestrous cycle or at onset of oestrus. The pattern of LH responses in all these animals was similar to that observed in anoestrous ewes injected at 1·5 h intervals. The total LH release, as assessed in terms of area of the induced peaks, was significantly greater in the onset of oestrus group than in the day 10 group or any of the anoestrous groups.

Presumably the sensitization–desensitization sequence of the pituitary gland to LH-RH which has been demonstrated, together with the effects of sex steroid hormones, must play an important part in the development and decay of the natural preovulatory LH peak.
IN-VITRO STUDIES OF NORMAL HUMAN THYROID CELLS: RESPONSES TO THYROTROPHIN AND DIBUTYRYL CYCLIC AMP
Authors: BIDEY S. P. , MARSDEN P. , ANDERSON J. , McKERRON C. G. , BERRY H.
Published: December 2008

Follicular cells isolated from normal human thyroid tissue have been cultured for up to 140 h with bovine thyrotrophin (TSH) or dibutyryl cyclic AMP (DBcAMP). Both compounds induced marked reorganization of the cells into three-dimensional follicular structures, whilst non-supplemented cells assumed a monolayer form.

Cultures treated initially with TSH or DBcAMP showed a greater iodide uptake capacity, in comparison with unsupplemented cultures, in which iodide uptake was markedly diminished after 24 h.

The release of tri-iodothyronine (T3) and thyroxine (T4) into the medium was determined by radioimmunoassay. Both TSH- and DBcAMP-treated cells showed a significant increase in iodothyronine output compared with unsupplemented control cells.

In contrast to the 'classical' TSH-induced depression of the T4:T3 ratio in vivo, an increase in the ratio was observed for both TSH- and DBcAMP-supplemented cells in vitro. The ratio was also significantly greater after TSH than after DBcAMP, and possible implications of this finding are discussed.
OESTROGEN-INDUCED CHANGES IN THE SECRETION OF LUTEINIZING HORMONE CAUSED BY CONTINUOUS INFUSIONS OF LUTEINIZING HORMONE RELEASING HORMONE IN THE LONG-TERM OVARIECTOMIZED RAT
Authors: SCHUILING G. A. , GNODDE H. P.
Published: December 2008

Oestrogen-induced changes in luteinizing hormone secretion, caused by continuous infusions of luteinizing hormone releasing hormone (LH-RH), appear to depend on the duration of exposure of the pituitary gland to the releasing hormone.

The initial oestrogen-induced depression of the potential response of the pituitary gland to LH-RH, which always seems to occur, does not necessarily turn into an enhancement of this potential response. It is suggested that this may be due to the fact that the response of the pituitary gland to LH-RH infusions is a continuously changing parameter influenced by oestrogen.
IMMUNOCHEMICAL CHARACTERIZATION OF GASTRIN IN PANCREATIC ISLETS OF NORMAL AND GENETICALLY OBESE MICE
Authors: DOCKRAY G. J. , BEST L. , TAYLOR I. L.
Published: December 2008

Material with gastrin-like immunoreactivity has been extracted from micro-dissected islets and from antral mucosa of normal and genetically obese mice. The islet and antral extracts cross-reacted with antisera specific for the CO2H-terminal portion of human heptadecapeptide gastrin, but did not cross-react with antisera specific for the NH2-terminal region or with an antiserum specific for the entire, intact, molecule. With the antiserum showing highest cross-reactivity, the concentration of immunoreactive gastrin in normal islet tissue (138 pmol/g, standard human G17-I) was approximately 50% that in obese mouse islets (204 pmol/g) and 2% that in normal antral mucosa (6·1 nmol/g). Following fractionation on Sephadex G-50 the principal forms of gastrin in the islet and antral extracts had similar elution volumes to human heptadecapeptide gastrin, although other, probably smaller, forms of gastrin were also noted in the islet extracts.
AN ANALYSIS OF SPECIFIC STIMULI CAUSING THE RELEASE OF PROLACTIN AND GROWTH HORMONE AT MILKING IN THE GOAT
Authors: HART I. C. , LINZELL J. L.
Published: December 2008

Experiments to investigate the relative importance of the tactile, conditioned and possible metabolic components of the milking stimulus on the release of prolactin and growth hormone (GH) from the anterior pituitary of the goat are described. A comparison of the hormonal responses to milking the auto-transplanted mammary gland (i.e. denervated gland) with that obtained by milking the intact mammary gland of the same goat showed that the concentration of prolactin in the plasma increased only after milking the intact gland, whereas in two out of four goats an increase in plasma GH was detected several minutes after milking the transplanted gland. In the intact animal significantly more prolactin (P < 0·01) was released in response to milking both teats for 6 min as compared with that released by milking only one teat for the same time. No significant difference (P > 0·1) was found for GH. Similar quantities of prolactin and GH were released by goats milked when conscious or under anaesthesia. A comparison of the hormonal responses to teat stimulation in the same anaesthetized goats with and without the removal of milk from the mammary gland showed a significant reduction (P < 0·001) in the quantity of prolactin and GH released in the absence of milk removal. The significance of these results is discussed.
PROTEIN BIOSYNTHESIS IN VITRO BY THE PARS INTERMEDIA OF THE MOUSE PITUITARY GLAND
Authors: ISHERWOOD H. , THORNTON V. F.
Published: December 2008

During short-term incubations of isolated posterior pituitary glands of the mouse, isotopically labelled amino acids were incorporated into protein by the cells of the pars intermedia. Using labelled leucine, 5–10% of incorporated label was found in a protein (P1), with a molecular weight of about 75000. Protein P1 could be isolated from both fresh and incubated tissue, and was a normal and indeed major, secretory product of the pars intermedia, constituting more than 50% of the protein present.
DECIDUALIZATION AND OVUM-IMPLANTATION IN SPAYED MICE TREATED WITH OESTRIOL
Authors: MARTIN L.
Published: December 2008

Single injections of oestriol were partially effective in sensitizing the uterus to a decidual stimulus and inducing ovum-implantation in progesterone-treated spayed mice, whereas two injections (6 h apart) were fully effective. It seems that in the progestational uterus, as in the non-progestational organ, oestriol can induce a full oestrogenic response provided that its level in the target organ is maintained. It is also concluded that ovum-implantation is not triggered by some transient early effect of oestrogen, but requires about 12 h of sustained oestrogen action for its successful completion.
SEASONAL AND CIRCADIAN CHANGES IN THE EPISODIC RELEASE OF FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE AND TESTOSTERONE IN RAMS EXPOSED TO ARTIFICIAL PHOTOPERIODS
Authors: LINCOLN G. A. , PEET M. J. , CUNNINGHAM R. A.
Published: December 2008

Six rams of an ancient breed of domesticated sheep (Soay) were subjected to an artificial light régime of alternating periods of long days (16 h light:8 h darkness) and short days (8 h light: 16 h darkness) which induced seasonal development and regression of the testes during a period of 36 weeks. Over 2000 blood samples were taken, and the changes in plasma levels of FSH, LH and testosterone were related to the cycle of testicular activity. During long days plasma levels of gonadotrophins became very low and the testes regressed to about 20% of their maximum size; there was a corresponding reduction in plasma testosterone levels. When the rams were returned to short days reproductive development was again stimulated after 2–3 weeks with a progressive increase in plasma FSH and LH levels and consequent hypertrophy of the testes. It took about 16 weeks of short days for testicular activity to become maximal.

Blood samples collected at hourly intervals for 24 h on ten occasions during the study revealed transitory peaks in plasma FSH and LH levels indicative of episodic release. Changes in gonadotrophin secretion were modulated primarily by alterations in the frequency of episodic release; < 1 spike per 24 h during long days increased to a maximum of 10 spikes/24 h under short daylengths. The peaks of FSH release were of smaller amplitude than those of LH, although during periods of frequent episodic release basal levels of FSH were increased to a greater extent than those of LH.

A circadian rhythm was observed in the plasma levels of FSH, LH and testosterone, which was related to increased gonadotrophin release during the dark phase of the 24 h cycle; changes in blood haematocrit were also observed. The circadian changes appeared to be correlated with the activity cycle of the animals which in turn was dictated by daylight. A possible interrelationship between the circadian cycle and the seasonal cycle is discussed.
IN-VITRO METABOLISM OF [3H]TESTOSTERONE BY SCALP AND BACK SKIN: CONVERSION OF TESTOSTERONE INTO 5α-ANDROSTANE-3β,17β-DIOL
Authors: STEWART MARY ELLEN , POCHI P. E. , STRAUSS J. S. , WOTIZ H. H. , CLARK S. J.
Published: December 2008

The in-vitro metabolism of [3H]testosterone by human scalp and back skin was examined for possible differences in enzyme activity in skin from these two areas, both of which contain large sebaceous glands but only one of which, the back, is prone to develop acne. Punch biopsy specimens of skin, obtained from the scalp and back of adult men, were minced and incubated with [3H]testosterone. The metabolic products were diluted with carrier steroids, then separated and measured by thin-layer chromatography and by gas chromatography on an instrument equipped with a splitter. The results showed that of the 5α-reduced metabolites identified, a major one in both the scalp and back skin incubations was 5α-androstane-3β,17β-diol. Formation of the androstanediol was especially pronounced in scalp skin where it accounted for up to 50% of the 5α-reduced metabolites produced. This finding that 5α-androstane-3β,17β-diol is a major product of testosterone metabolism in vitro by human skin containing sebaceous glands, supports the possibility, previously suggested by studies in the rat, that this steroid can stimulate sebum secretion.
METABOLIC CLEARANCE OF RAT PROLACTIN IN THE LACTATING AND NON-LACTATING RAT
Authors: GROSVENOR C. E. , MENA F. , WHITWORTH N. S.
Published: December 2008

The metabolic clearance of rat prolactin, assessed by the continuous infusion to equilibrium method, increased from 0·77 to 2·15 ml/min in lactating and from 0·65 to 1·75 ml/min in non-lactating rats as the infusion rate was increased from 100 to 472 ng/min. The clearance rate of rat prolactin did not increase when large doses of ovine prolactin were infused simutaneously with rat prolactin. The clearance rates computed from equilibrium levels of immunoreactive 131I-labelled rat prolactin in plasma were highly correlated with, but were considerably greater than, those computed from unlabelled rat prolactin which was infused simultaneously. In lactating and non-lactating rats, the clearance of each prolactin tested (RP-1, B-1, Nicoll's secreted and 131I-labelled) increased and had stabilized within the 30–35 min of infusion of each new higher dose of the hormone. The ability of the rat to clear quickly greater amounts of prolactin from the circulation as the infusion rate increases implies that plasma prolactin concentrations do not necessarily mirror the rate of prolactin secretion from the pituitary.
GLYCOSYLTRANSFERASE AND UDP-GALACTOSE PYROPHOSPHATASE ACTIVITIES IN THE ENDOMETRIUM DURING THE OESTROUS CYCLE OF THE RAT
Authors: NELSON J. D. , JATO-RODRIGUEZ J. J. , LABRIE F. , MOOKERJEA S.
Published: December 2008

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

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

The follicular components responsible for the synthesis of oestrogen, testosterone and progesterone have been localized by studying in vitro the steroidogenic capacity of (1) intact follicles, (2) opened but undisturbed follicle walls, (3) isolated thecal shells, (4) granulosa cells and (5) co-cultures of thecal shells and granulosa monolayers.

Oestrogen was secreted throughout the five-day culture period by intact follicles and explants of follicle wall. Neither the isolated thecal shell nor the membrana granulosa alone secreted oestrogen in vitro, but granulosa cells converted exogenous testosterone to oestrogen during the first few hours after explantation. A limited and transient production of oestrogen occurred in co-cultures of theca and granulosa.

Testosterone was secreted in the presence of FSH in approximately equal amounts by intact follicle, follicle wall and thecal shells. No testosterone was secreted by the isolated granulosa cells.

Progesterone was secreted by each cellular component but the highest output occurred where granulosa cells were grown in monolayer culture.

The results indicate that the theca is the source of follicular androgen synthesis but that an interaction between theca and granulosa is required for the production of oestrogen. It is postulated that direct contact between two cell components is important in the modulation of steroidogenic function within the follicle.
HORMONAL CONTENT AND ULTRASTRUCTURE OF THE HYPOTHALAMO-NEUROHYPOPHYSIAL SYSTEM OF THE RAT AFTER INJECTION OF VINBLASTINE INTO THE MEDIAN EMINENCE
Authors: RODRÍGUEZ E. L. , CAVICHIA ECHANDÍA, J. C. , RODRÍGUEZ E. M.
Published: December 2008

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

The concentration of sialic acid was determined in the reproductive organs, pituitary gland and urine of male and female langur monkeys. In the male, sialic acid concentration was lowest in the testes and highest in the epididymides. Both caput and cauda epididymides contained almost the same concentration. Castration and subsequent androgen administration did not modify the concentration of sialic acid by comparison with intact animals, suggesting that sialic acid is not androgen-dependent in the langur.

There was no significant difference in sialic acid concentration in the uterus during the proliferative and luteal phases of the menstrual cycle. After ovariectomy, there was a decrease in the concentration of sialic acid in the uterus, cervix and vagina while oestrogen or oestrogen plus progesterone administration increased its concentration significantly, but not to the control level. However, the difference in concentration between oestrogen-treated and oestrogen plus progesterone-treated monkeys was not significant. There was a peak of sialic acid excretion in the urine on day 8 of the normal 22-day menstrual cycle, i.e. a day before the probable day of ovulation. In pregnant monkeys sialic acid excretion increased significantly 2 days before delivery compared with the values recorded 7 to 3 days before parturition. The part played by sialic acid during the menstrual cycle and pregnancy in the female is not clear.
CONCENTRATION OF OESTRADIOL, PROGESTERONE, LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE IN THE JUGULAR VENOUS PLASMA OF EWES DURING THE OESTROUS CYCLE
Authors: PANT H. C. , HOPKINSON C. R. N. , FITZPATRICK R. J.
Published: December 2008

Changes in the concentrations of ovarian steroids and pituitary gonadotrophins were measured by radioimmunoassay in the jugular plasma of six Clun Forest ewes throughout the oestrous cycle.

The concentration of oestradiol began to rise 12–14 h before the onset of oestrus from values of 11·2 ± 0·36 (s.e.m.) pg/ml during the luteal phase to 21·1 ± 2·01 pg/ml at −8 to 0 h (oestrus). There was no distinct increase during the luteal phase.

Circulating progesterone varied in a cyclic manner with the highest values at the mid-luteal phase (3·70 ± 0·28 ng/ml; n = 28). In five out of six ewes the concentration was still quite high (1·86 ± 0·43 ng/ml) at 35 h before the onset of oestrus. The concentration declined rapidly thereafter, reaching minimum values about 12 h before oestrus coincident with the increase in oestradiol concentration.

Plasma LH increased from very low values of 2·59 ± 0·09 ng/ml during the luteal phase to 75·3 ± 7·4 ng/ml about 9 h after the onset of oestrus.

Two peaks of plasma FSH concentration were detected after the onset of oestrus. The first peak (171·0± 35·5 ng/ml) coincided with the LH peak and the second (133·0 ± 10·7 ng/ml) occurred about 24 h later at a time when LH values were low. The mean FSH concentration at other times during the cycle was 61·9 ± 2·8 ng/ml.
PURIFICATION AND RADIOIMMUNOASSAY OF CHICKEN GROWTH HORMONE
Authors: HARVEY S. , SCANES C. G.
Published: December 2008

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

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

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

Corticosteroid feedback mechanisms were investigated at the hypothalamic level using the rat hypothalamus in vitro and at the pituitary level using basal hypothalamic-lesioned rats. Both fast and delayed corticosteroid feedback effects were demonstrated at the level of the hypothalamus and pituitary gland with doses of corticosteroids within or near the physiological range. These two phases of feedback were separated temporally by a 'silent period' during which no feedback was apparent.

Studies on the mechanism of action of corticosteroids at the hypothalamic level showed that the fast feedback mechanism acts by inhibition of release whilst the delayed feedback mechanism acts by inhibition of both synthesis and release. The fast feedback action of corticosterone does not appear to act by excitation of neuroinhibitory pathways since neither picrotoxin nor phentolamine prevented the feedback action of corticosteroids in vitro.

Corticosterone inhibition of corticotrophin releasing factor release was overcome by depolarization of the membrane with K+ suggesting that the mechanism of action of the fast feedback of corticosteroids is by membrane stabilization.
EFFECTS OF EXOGENOUS PROGESTERONE AND OESTRADIOL ON PROSTAGLANDIN F AND 13,14-DIHYDRO-15-OXO PROSTAGLANDIN F2α CONCENTRATIONS IN UTERI AND PLASMA OF OVARIECTOMIZED EWES
Authors: LOUIS T. M. , PARRY DILYS M. , ROBINSON J. S. , THORBURN G. D. , CHALLIS J. R. G.
Published: December 2008

The control of prostaglandin (PG) production by steroid hormones has been investigated in non-pregnant bilaterally ovariectomized sheep, prepared with indwelling utero-ovarian venous catheters and treated with physiological amounts of oestradiol and progesterone. Oestradiol treatment alone (2 × 15 μg/day for 9 days) had no effect on the prostaglandin F (PGF) concentration in uterine caruncles or intercaruncular tissue, on the release of PGF or of 13,14-dihydro-15-oxo PGF (PGFM) from these tissues during incubation in vitro, or on the concentrations of PGF in the utero-ovarian vein or PGFM in the jugular vein. However, oestradiol did accumulate in the uterine tissues. Progesterone treatment alone (2 × 10 mg/day for 9 days) provoked a significant increase in the concentration of PGF in the caruncles, a significant increase in the release of PGF from the caruncles during incubation with arachidonic acid and increased mean concentrations of PGFM in the jugular vein. When oestradiol was superimposed on a progesterone-primed system, there was a further marked increase in the PGF content of the caruncles, release of PGF into the utero-ovarian vein, and increased concentrations of PGFM in the jugular vein. The caruncles always contained more PGF than the intercaruncular area, and released more PGF and PGFM during incubation in vitro. In the progesterone+oestradiol group, there was good correlation between the PGF concentrations in simultaneous samples from the right and left utero-ovarian veins, and for all groups there was a high correlation between utero-ovarian PGF and peripheral PGFM concentrations. The caruncular epithelium of the progesterone-treated animals contained more lipid droplets than those of the other groups.

These data are consistent with a requirement for progesterone in activating 'prostaglandin synthetase' activity, and promoting PGF production, largely from the caruncles. After progesterone priming, the synthesis of PGF by the caruncles and PG release into the vascular system was increased further by oestradiol treatment, whereas oestradiol alone was without effect.