bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF LUTEINIZING HORMONE RELEASING HORMONE ON ACCUMULATION OF PITUITARY CYCLIC AMP AND GMP IN VITRO
Authors: RIGLER G. L. , PEAKE G. T. , RATNER A.
Published: December 2008

Departments of Physiology and Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, U.S.A.

(Received 19 August 1977)

Cyclic AMP has been increasingly implicated as an important intracellular mediator regulating the secretion of peptide hormones (Vale, Grant & Guillemin, 1973), but there is controversy concerning its role in the regulation of the luteinizing hormone releasing hormone (LH-RH)-stimulated secretion of luteinizing hormone (LH; Labrie, Pelletier, Borgeat, Drouin, Ferland & Belanger, 1976; Ratner, Wilson, Srivastava & Peake, 1976; Sundberg, Fawcett & McCann, 1976). Although less clearly established, the guanyl cyclase–cyclic GMP system may also play an important role in regulating cellular events (Goldberg, O'Dea & Haddox, 1973). Studies with a highly purified growth hormone (GH) releasing factor suggested the involvement of cyclic GMP in the mediation of GH release from the somatotrope (Wilson, Steiner, Dhariwal & Peake, 1974). This communication describes studies which suggest a role for the guanylate
DETECTION OF HIGH-AFFINITY GLUCOCORTICOID BINDING IN RAT BONE
Authors: MANOLAGAS S. C. , ANDERSON D. C.
Published: December 2008

Department of Medicine, Manchester Royal Infirmary, Manchester, M13 9WL

(Received 17 October 1977)

Recently Feldman, Dziak, Koehler & Stern (1975) have detected high-affinity gluco corticoid receptors in cytosol from isolated foetal rat calvarial bone cells. They estimated the binding constant (Kd) to be 7×10−9 mol/l for [3H]dexame[unk]hasone; however, their estimates were based on a maximum bound: free ratio of only 1%. Their data from cell cultures suggest that such binding may nevertheless be of physiological importance (Chen, Aronow & Feldman, 1977). The very small amount of binding might be due to a low initial concentration of binding sites, to their destruction during or after the trypsin–collagenase digestion, to their high dilution or to a combination of all three factors. We report here a much simpler method whereby we have greatly increased the percentage binding by setting up the incubation in intact calvaria.

Calvaría were dissected from foetal rats (19–21 days
LORDOSIS BEHAVIOUR IN MALE RATS: EFFECT OF DEAFFERENTATION IN THE PREOPTIC AREA AND HYPOTHALAMUS
Authors: YAMANOUCHI K. , ARAI Y.
Published: December 2008

Department of Anatomy, Juntendo University School of Medicine, Hongo, Tokyo 113, Japan

(Received 18 October 1977)

Differentiation of sexual behaviour patterns in male rats is dependent on the internal secretion of the testes during neonatal life. Removal of the testes at this time causes feminization and results in male rats which display female patterns of sexual behaviour (Gorski, 1971). Female patterns of behaviour are usually rare in normal male rats but recently we found that transection of the dorsal afferent neurones to the preoptic and anterior hypothalamic areas potentiated the display of lordosis in hormonally primed male rats (Yamanouchi & Arai, 1975). In the present study, further neuroanatomical analysis was carried out to clarify the localization of the afferent pathway involved in the regulation of lordosis behaviour.

Anterior or posterior roof deafferentation (ARD or PRD) was performed by lowering an L-shaped Halasz knife (2-5 mm horizontal blade) to the level
URINARY EXCRETION OF NEUROPHYSINS IN PATIENTS WITH KIDNEY DISEASE
Authors: LEGROS J. J.
Published: December 2008

The mean rate of excretion of neurophysins in the urine of 16 patients with kidney disease but without tubular dysfunction was 0·48 ± 0·14 (s.e.m.) ng/min, whereas the rate in 16 patients with tubular dysfunction was 3·64 ± 1·56 ng/min (significantly different; 2P < 0·01). In the whole group of 32 patients there was a relationship (r = 0·57) between the rate of excretion of neurophysins in the urine and the clearance of lysozyme. The increased rate of urinary excretion of neurophysins observed in some patients with kidney disease therefore appears to be related to a disorder of renal tubular function. It is shown that the raised levels of neurophysins observed in the serum of some patients with kidney disease are not attributable to a decrease in the urinary clearance of neurophysins.
RESPONSE OF CHONDROCYTES ISOLATED FROM HUMAN FOETAL CARTILAGE TO PLASMA SOMATOMEDIN ACTIVITY
Authors: ASHTON I. K. , FRANCIS M. J. O.
Published: December 2008

Plasma somatomedin activity enhanced the incorporation of [3H]thymidine into chondrocytes isolated from human foetal cartilage during weeks 13–21 of gestation. Human growth hormone (0·1–20 μu./ml), human placental lactogen (0·1–5 μg/ml) and insulin (0·25– 10 μu./ml) had no direct effects on the synthesis of DNA in these chondrocytes, although insulin at concentrations of 2·5–100 mu./ml increased [3H]thymidine incorporation by up to 400%.
EFFECT OF PROGESTERONE ON INSULIN SECRETION IN THE RAT
Authors: ASHBY J. P. , SHIRLING D. , BAIRD J. D.
Published: December 2008

Implants of progesterone resulted in an increased amount of insulin in plasma in response to intravenous administration of glucose in the rat. Isolated islets of Langerhans from progesterone-treated animals showed a greater maximum secretory response to glucose than islets from control animals but their sensitivity to low concentrations of glucose was unchanged. Theophylline increased glucose-induced secretion of insulin to a greater extent in progesterone-treated than in control rats and also produced a greater increase in the concentration of cyclic AMP in isolated islets from hormone-treated animals. These results suggest that the effect of progesterone on insulin secretion may be mediated by a change in cyclic AMP levels in the β cell. The possible role of progesterone in increasing the secretion of insulin in pregnancy is discussed.
RELATIONSHIP BETWEEN THE SUCKLING-INDUCED RELEASE OF OXYTOCIN AND PROLACTIN IN THE URETHANE-ANAESTHETIZED LACTATING RAT
Authors: WAKERLEY J. B. , O'NEILL DONNA S. , TER HAAR M. B.
Published: December 2008

The effects of changes in the intensity of the suckling stimulus on the reflex release of oxytocin and prolactin were compared in urethane-anaesthetized lactating rats. Mothers which had previously suckled 12 pups (Group 1) showed a graded increase in the amount of oxytocin released during a 3 h suckling test when the number of pups applied to the nipples was increased from six to eight or ten. Mothers which had suckled six pups during their lactation (Group 2) appeared to show a maximum frequency of milk ejection whether six, eight or ten pups were applied to the nipples.

The release of prolactin was not elicited from either Group 1 or Group 2 mothers when six pups were applied to their nipples. With eight pups suckling, the Group 1 mothers again showed no evidence of prolactin release. In contrast, the Group 2 mothers showed a significant increase in the level of prolactin in the plasma during the 3 h suckling test. With ten pups suckling the release of prolactin was evident in both groups of mothers, although the response was earlier and more pronounced in Group 2 than Group 1.

These results suggest that in the urethane-anaesthetized rat, the threshold for the suckling-induced reflex release of oxytocin is distinct from the threshold for the release of prolactin and that these thresholds are, at least in part, set by the preceding suckling experience of the mothers. In those animals which showed both reflex milk ejection and prolactin release there was a linear relationship between the magnitude of the two endocrine responses.
PLASMA CONCENTRATIONS OF PROLACTIN AND THYROTROPHIN DURING SUCKLING: EFFECTS OF STIMULATION OF THE MEDIAN EMINENCE
Authors: WAKERLEY J. B. , TER HAAR M. B.
Published: December 2008

A.R.C. Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT

(Received 1 November 1977)

Thyrotrophin releasing hormone (TRH) can have a stimulatory effect on the release of both prolactin and thyrotrophin (TSH; Deis & Alonso, 1973), although in the rat, supraphysiological doses of TRH are required to affect the secretion of prolactin (Burnet & Wakerley, 1976). A more important factor in the control of the release of prolactin is considered to be prolactin release inhibiting factor (PIF), which is thought to act through the catecholamine, dopamine (MacLeod, 1976). Stimuli which cause the concomitant release of TSH and prolactin are thought to have a direct effect at the hypothalamic level such that neurones releasing TRH are excited, whereas those releasing PIF are inhibited. In the present work, we have tested this hypothesis using the suckling stimulus to elicit the simultaneous release of prolactin and TSH (Blake, 1974; Burnet & Wakerley, 1976). If
BIOCHEMICAL CHARACTERIZATION OF PITUITARY-DEPENDENT HYPERADRENOCORTICISM IN THE DOG
Authors: MEIJER J. C. , DE BRUIJNE J. J. , RIJNBERK A. , CROUGHS R. J. M.
Published: December 2008

The biochemical characterization of 22 cases of pituitary-dependent hyperadrenocorticism in the dog, is reported. The principal characteristics of the disease include excessive and non-rhythmic production of cortisol, decreased sensitivity of the hypothalamic-pituitary system to the suppressive effects of dexamethasone, decreased responsiveness of the pituitary-adrenocortical system to the stimulus of insulin-induced hypoglycaemia and increased responsiveness of the system to stimulation with lysine-vasopressin. From these observations it is concluded that pituitary-dependent hyperadrenocorticism in the dog is a valid model for study of the pathogenesis of the disease in man.

For the diagnosis of hyperadrenocorticism itself, the measurement of the concentration of corticosteroids in a single sample of plasma obtained 8 h after intravenous injection of 0·01 mg dexamethasone/kg was sufficient. The level of 11-hydroxycorticosteroids was less than 140 nmol/l plasma in normal dogs, whereas higher values were found in dogs with hyperadrenocorticism. For purposes of differential diagnosis, measurement of the level of corticosteroids in the plasma both before and 4h after intravenous injection of 0·05 mg dexamethasone/kg is adequate: suppression is obtained only in cases of pituitary-dependent hyperadrenocorticism.
DNA SYNTHESIS AND DEPLETION OF PROLACTIN IN THE PITUITARY GLAND OF THE MALE RAT
Authors: LLOYD H. M. , JACOBI J. M. , MEARES J. D.
Published: December 2008

Haloperidol, bromocriptine and diethylstilboestrol dipropionate were given in various régimes to male rats to determine their effects on pituitary DNA synthesis, prolactin secretion and growth hormone secretion.

Haloperidol increased serum prolactin but did not stimulate pituitary DNA synthesis or reduce pituitary prolactin concentrations. Haloperidol potentiated the effects of oestrogen on serum prolactin and on pituitary DNA synthesis; pituitary prolactin concentrations were greatly reduced, and growth hormone secretion was slightly inhibited.

The inhibitory effects of bromocriptine in oestrogen-stimulated rats were demonstrated by smaller pituitary weights and decreased DNA synthesis; serum prolactin levels were lowered and pituitary prolactin concentrations were increased. Haloperidol, given to rats treated with oestrogen and bromocriptine, reversed the inhibitory effects of bromocriptine on DNA synthesis and serum prolactin; pituitary prolactin concentrations fell to well below normal. The results suggest that the haloperidol potentiation of oestrogeninduced pituitary DNA synthesis may depend upon stimulation of prolactin secretion together with reduction of intracellular prolactin levels.
STEROIDAL CONTROL OF PLASMA LUTEINIZING HORMONE, COMB GROWTH AND SEXUAL BEHAVIOUR IN MALE CHICKS
Authors: BALTHAZART J. , HENDRICK J. C.
Published: December 2008

Laboratoire de Biochimie et Laboratoire de Radioimmunologie, Université de Liège, 17 Place Delcour, B-4020 Liège, Belgium

(Received 31 October 1977)

It is well known that the concentration of luteinizing hormone (LH) in the plasma is higher in male than in female chickens (Sharp, 1975) and quail (Nicholls, Scanes & Follett, 1973), probably as a result of greater steroid feedback in the female birds (Davies, 1976). Guichard, Cédard, Mignot, Scheib & Haffen (1977) have shown that embryonic female chick gonads secrete at least ten times more oestradiol than gonads from embryonic male chicks.

We have therefore investigated the relative effectiveness of androgens and oestrogens in the control of the level of LH in the male chick and whether non-aromatizable 5α-reduced androgens could depress this level, as has recently been shown in the adult quail (Massa, Davies & James, 1978).

Nine groups of between three and seven 1-day-old male chicks were injected
PROLACTIN AND GROWTH HORMONE SECRETION AND MAMMARY GLAND GROWTH DURING PSEUDOPREGNANCY IN THE MOUSE
Authors: SINHA Y. N. , WICKES M. A. , BAXTER S. R.
Published: December 2008

Pseudopregnancy was induced in 61% of C57BL/St mice that were stimulated cervically with a glass rod for 30 s on the day of oestrus. Within 60 min of stimulation, the concentration of prolactin in the serum increased threefold and appeared to be released in a phasic manner. Subsequently, prolactin was secreted at an enhanced rate for approximately two-thirds of pseudopregnancy, as the level in the serum rose and the level in the pituitary gland dropped. The concentrations of growth hormone (GH) in the serum showed only a minor increase 8 h after cervical stimulation, with no significant rise during the course of pseudopregnancy. Pituitary GH concentrations increased between early and late pseudopregnancy. The DNA and RNA contents of the mammary glands, indices of mammary gland growth and metabolic activity, were both enhanced during pseudopregnancy and paralleled the increases in the secretion of prolactin, whereas mammary gland weight generally followed changes in the level of GH in the pituitary gland.

Administration of the prolactin inhibitor 2-bromo-α-ergocryptine reduced the incidence of pseudopregnancy, but neither an inhibitor of GH release, somatostatin, nor an antiserum to mouse GH had any appreciable effects. Injections of ovine prolactin and mouse GH induced the dioestrous state in mice, but only ovine prolactin stimulated the growth of corpora lutea. These results suggest that prolactin is the main hormone involved in the induction and maintenance of pseudopregnancy in the mouse. Injections of ovine prolactin or mouse GH suppressed endogenous levels of the respective hormone; however, prolactin also reduced the level of GH and GH reduced the level of prolactin, suggesting that pituitary hormones can influence not only their own secretion but that of other pituitary hormones as well.
PHOTOPERIODIC REGULATION OF COPULATORY BEHAVIOUR IN THE MALE HAMSTER
Authors: MORIN L. P. , ZUCKER I.
Published: December 2008

The influence of daylength on copulatory behaviour was assessed by comparing male hamsters exposed to long or short photoperiods (14 or 2 h light/24 h). Copulation declined in animals transferred from long to short days; 13 out of 14 hamsters ceased to ejaculate within 9 weeks and many no longer intromitted in tests with sexually receptive female hamsters.

The decline in copulation in hamsters experiencing short days was associated with atrophy of the gonads and flank glands. Behavioural changes in these animals were far more gradual than those observed in hamsters after surgical castration. There was significantly more mating behaviour in tests during the subjective night of the hamsters than during their subjective day.

Exogenous testosterone was more effective in restoring copulation in castrated hamsters exposed to long days than in castrated animals experiencing short days. This suggests that in short days the substrate for copulatory behaviour is relatively refractory to androgens. Photoperiodically mediated changes in behaviour, physiology and morphology may each contribute directly to the reproductive quiescence presumed to occur in the field during the short days of autumn and winter.
A DAILY RHYTHM IN THE BEHAVIOURAL SENSITIVITY OF THE FEMALE RAT TO OESTRADIOL
Authors: HANSEN S. , SÖDERSTEN P. , SREBRO B.
Published: December 2008

Ovariectomized rats were implanted with oestradiol-filled elastomer capsules which were removed at various times after implantation. Sexual receptivity was tested after implantation of a progesterone-filled elastomer capsule 42 h after the onset of treatment with oestradiol. Exposure to oestradiol for about 32 h was required for induction of receptivity. Intact rats with regular 4 day oestrous cycles, and exposed to oestradiol-filled elastomer capsules for 6 h, showed sexual receptivity 24 h after the onset of oestradiol treatment. The behavioural effects of oestradiol in both ovariectomized and intact rats depended on when during the light–darkness (LD) cycle stimulation with oestradiol occurred; maximum effects were seen only if the oestradiol capsules were implanted at 16.00 h (4 h after lights off in the 12 h L: 12 h D cycle). The behavioural effect of progesterone implants, however, did not depend on the phase of the LD cycle. The LD-dependent rhythm in oestradiol sensitivity was eliminated by lesions in the suprachiasmatic nuclei of the hypothalamus.
ABSENCE OF PYROGLUTAMYL-N3im-METHYL-HISTIDYL-PROLINEAMIDE (METHYL-THYROTROPHIN RELEASING HORMONE) IN THE RAT HYPOTHALAMUS
Authors: PEKARY A. E. , MORLEY J. E. , HERSHMAN J. M.
Published: December 2008

Pyroglutamyl-N3im-methyl-histidyl-prolineamide (methyl-thyrotrophin releasing hormone, methyl-TRH) is a potent synthetic analogue of TRH. N3im-Methyl-histidine is present in mammalian brain and it has been suggested that methyl-TRH is a physiological releasing hormone normally present in the hypothalamus. A non-gradient cation-exchange chromatography system that uses SP-Sephadex C-25 and completely resolves methyl-TRH and TRH has been developed. Because methyl-TRH cross-reacts in the immunoassay for TRH, this assay was used to measure TRH and methyl-TRH in the chromatographic fractions. By this means it has been demonstrated that the amount of methyl-TRH present in the rat is less than 0·025 ng/hypothalamus.
LOSS OF IMMUNOREACTIVE ARGININE-VASOPRESSIN AFTER ELECTRICAL STIMULATION WITH SILVER ELECTRODES
Authors: DUTTON ANGELA , DYER R. G. , YATES J. O.
Published: December 2008

A.R.C. Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT

(Received 19 January 1978)

Vasopressin is present in nerve terminals of the median eminence (e.g. Silverman & Zimmerman, 1975) and the hormone may possess corticotrophin releasing activity (Pearlmutter, Rapino & Saffran, 1974, 1975). Thus, in experiments designed to investigate the release of peptides from nerve terminals of the median eminence by application of electric stimuli to synaptosomes prepared from mediobasal hypothalamic tissue, we also hoped to establish that vasopressin was secreted from these nerve-endings.

Synaptosomes were prepared from tissue obtained from groups of 40 female rats (Gray & Whittaker, 1962) and incubated for 40 min in aerated Locke solution containing 2 mm-bacitracin to minimize peptidase activity. The incubation chamber consisted of an oxygen electrode (Rank Bros, Bottisham, Cambridge) modified to enclose the incubation medium between two silver electrodes. Pulsed stimuli were delivered between these electrodes (5–50 Hz; 1 ms duration; monopolar;
ENDOGENOUS STEROID LEVELS IN THE HUMAN PROSTATE FROM BIRTH TO OLD AGE: A COMPARISON OF NORMAL AND DISEASED TISSUES
Authors: HAMMOND G. L.
Published: December 2008

The levels of steroids in prostatic tissues were determined by radioimmunoassay after solvent extraction of a single (300–600 mg wet tissue) sample and chromatography of extracts on hydroxyalkoxypropyl Sephadex microcolumns. In normal adult prostates (n = 18) the concentrations of steroids (mean±s.e.m. ng/g wet tissue) were: testosterone, 0·25 ± 0·04; androstenedione, 0·13 ± 0·03; 5α-androstane-3, 17-dione (5α-androstanedione), 1·31 ± 17β-hydroxy-5α-androstan-3-one (5α-dihydrotestosterone, DHT), 1·22± 0·14; 5α-androstane-3α, 17β-diol (3α-androstanediol), 4·32 ± 0·49; androsterone, 4·15± 1·07; progesterone, 0·39 ± 0·07; 17α-hydroxyprogesterone, 0·42 ± 0·06. Concentrations of steroids in tissues from outer-gland regions were within the ranges found in the periurethral regions. In the prostates of newborn boys, the concentrations of all steroids were high, including progesterone and 17α-hydroxyprogesterone. Apart from 3α-androstanediol, the levels of which tend to increase after this age, the concentrations of all steroids were lower in the infant and pubertal prostates, but most were re-established to a variable extent in the adult tissues. This was particularly evident with respect to 5α-androstanedione and androsterone, and it is suggested that these two androgens may have a functional role in the mature prostate.

The concentrations of testosterone, androstenedione, 5α-androstanedione, progesterone and 17α-hydroxyprogesterone in tissues taken from ten patients with benign prostatic hypertrophy (BPH) were similar to those in normal adult tissue. The concentration of DHT was markedly raised (5·33 ± 0·46 ng/g) and the levels of 3α-androstanediol and androsterone were reduced (1·40 ± 0·12 and 0·80 ± 0·12 ng/g respectively) in adenomatous compared with normal tissue. The concentrations of various androgens displayed remarkable inter-relationships which characterize normal and BPH tissues.

The concentrations of testosterone, androstenedione, DHT and 3α-androstanediol were particularly high in the untreated prostatic carcinomatous tissue sample investigated, whereas the concentrations of 5α-androstanedione and androsterone were very low. After oestrogen treatment, testosterone and androstenedione virtually disappeared, while reduced but significant concentrations of their metabolites remained in similar proportions to those observed in the untreated carcinomatous tissue. Under the conditions of therapy, oestrogens are suggested to influence the uptake of androgens.
DOSE-RELATED EFFECTS OF NON-STEROIDAL ANTIOESTROGENS AND OESTROGENS ON THE MEASUREMENT OF CYTOPLASMIC OESTROGEN RECEPTORS IN THE RAT AND MOUSE UTERUS
Authors: JORDAN V. C. , ROWSBY LINDA , DIX C. J. , PRESTWICH G.
Published: December 2008

The dose-related effects of non-steroidal antioestrogens and oestrogens on the measurement of cytoplasmic oestrogen receptors in the rat uterus have been determined. The simultaneous administration of tamoxifen or monohydroxytamoxifen and oestradiol on three consecutive days resulted in dose-dependent decreases in both the wet weight of the uterus and the number of available cytoplasmic oestrogen receptors. The oestrogenic triphenylethylenes ICI 47 699 and ICI 3188 both produced dose-dependent decreases in the number of available cytoplasmic oestrogen receptors. Increasing doses of ICI 47 699 resulted in increasing concentrations of oestrogen receptors within the nucleus. The effects of tamoxifen and oestradiol-17β were compared in the ovariectomized mouse; replenishment of uterine oestrogen receptors was less evident in tamoxifen-treated animals than in animals receiving oestradiol, although increases in uterine weight were similar. A single large dose of tamoxifen (50 μg) produced a prolonged depletion of cytoplasmic oestrogen receptors whilst stimulating rises in uterine weight and DNA and protein content. The results demonstrate that the depletion of the uterine cytoplasmic oestrogen receptor pool is a function of the dose administered for any compound with the ability to translocate oestrogen receptors to the nucleus and as such is not an exclusive characteristic of non-steroidal antioestrogens.
EVIDENCE THAT INHIBITION OF MYOMETRIAL ACTIVITY BY OESTRADIOL IN THE RAT IS MEDIATED BY AN RNA SYNTHETIC PATHWAY
Authors: DOWNING SANDRA J. , PORTER D. G.
Published: December 2008

Within some 14 h of treatment with oestradiol benzoate (5 μg), the intra-uterine pressure cycles in ovariectomized puerperal rats were almost abolished. However, treatment with 600 μg actinomycin D 30 min before the administration of oestradiol benzoate interfered significantly with the inhibition of uterine mechanical activity during the following 14 h. Treatment of rats with actinomycin D alone produced no significant fall in the frequency of pressure cycles. These results suggest that oestrogen inhibits myometrial activity in the rat through a mechanism which involves the synthesis of protein.
SEPARATION OF RAT PITUITARY THYROTROPHIC CELLS
Authors: TAL E. , SAVION S. , HANNA N. , ABRAHAM M.
Published: December 2008

A method for the enrichment of live thyrotrophic pituitary cells is described. Pituitary glands of young male rats were removed into Earle's solution and dispersed in a 0·1% trypsin solution containing 0·5% bovine serum albumin, pH 7·2.

Nylon fibres (25 μm) were used for the separation of the thyrotrophic cells, by stringing them across a plastic frame which fitted a plastic Petri dish containing the cell suspension. The fibres were washed with light petroleum (b.p. 60–80 °C) and carbon tetrachloride, hydrolysed with 3 m-HCl for 30 min at room temperature and washed with distilled water and phosphate-buffered saline (pH 7·2). The fibres were treated with thyrotrophin releasing hormone (TRH) alone or in the presence of soluble carbodiimide solution. After incubation for 1 h at room temperature, the fibres were transferred to a new Earle's medium and cells were released from the fibres by plucking them with a needle. The separated thyrotrophic cells were identified by radioimmunoassay and by electron microscopy.

Using the above-mentioned methods, enrichment of thyrotrophic cells was obtained. Thus, the amounts of TSH, prolactin, LH and GH released, during 2 h of incubation, by 1·5 × 106 unseparated cells were 6·8 ± 0·65, 4·1 ± 0·47, 4·8 ± 0·52 and 5·2 ± 0·68 μg respectively, while the same number of purified thyrotrophic cells released 76·1 ± 0·42, 1·2 ± 0·3, 0·6 ± 0·35 and 1·6 ± 0·22 μg of the same hormones (means ± s.e.m.).
CHANGES IN OESTRADIOL-17β BINDING IN THE HYPOTHALAMI AND PITUITARY GLANDS OF PERSISTENTLY INFERTILE EWES PREVIOUSLY EXPOSED TO OESTROGENIC SUBTERRANEAN CLOVER: EVIDENCE OF ALTERATIONS TO OESTRADIOL RECEPTORS
Authors: TANG B. Y. , ADAMS N. R.
Published: December 2008

The binding of [3H]oestradiol-17β to the hypothalamus and pituitary gland of cloveraffected permanently infertile and control ovariectomized ewes was compared in vivo and in vitro. When [3H]oestradiol-17β was infused into the carotid artery (10 ng/min), the total homogenate and the nuclear and protamine-precipitable cytosol fractions of hypothalami and pituitary glands from clover-affected ewes bound significantly more [3H]oestradiol than those of the controls. Cytoplasmic oestradiol-17β receptors from the pituitary glands of clover-affected ewes showed a significantly lower apparent association constant and a higher number of binding sites/mg protein in vitro. It is suggested that the hypothalami and pituitary glands of ewes made permanently infertile by oestrogenic clover are less sensitive to feedback regulation of oestradiol-17β at physiological levels.
REVERSAL OF BETAMETHASONE-INDUCED INHIBITION OF INTESTINAL CALCIUM ABSORPTION BY 1α-HYDROXYCHOLECALCIFEROL
Authors: FOX J. , CARE A. D. , MARSHALL D. H.
Published: December 2008

The intestinal absorption of calcium has been studied in conscious, unstressed pigs, using a modification of the double isotope technique. The oral administration of betamethasone (1 mg/day) to four pigs (25–33 kg) for 4 weeks reduced the calcium absorption coefficient, calculated after the intravenous and oral administration of 47Ca2+, by a mean value of 66%. The oral administration of 1α-hydroxycholecalciferol (2 μg/day) in combination with betamethasone (1 mg/day) for a further 4 weeks returned the absorption coefficient to the control value.
ACTION OF PROSTAGLANDIN E2 ON THE RELEASE OF CATECHOLAMINES FROM THE CANINE ADRENAL GLAND AND ITS INTERACTION WITH ACETYLCHOLINE
Authors: YAMASHITA K. , MIENO M. , SHIMIZU T. , YAMASHITA ER.
Published: December 2008

The effect of prostaglandin E2 (PGE2) on the secretion of adrenaline and noradrenaline by the adrenal gland and the interaction between PGE2 and acetylcholine in the adrenal medulla were examined in anaesthetized dogs. In splanchnicotomized dogs, i.v. injection of PGE2 failed to induce any secretion of catecholamines from the adrenal gland, whereas administration of PGE2 into the lumboadrenal artery resulted in a slight, approximately dose-dependent increase in catecholamine secretion within 2 min of the injection. This effect of PGE2 was unaffected by i.v. administration of atropine. Intravenous administration of acetylcholine 1 min after the administration of PGE2 into the lumboadrenal artery of splanchnicotomized atropine-treated dogs had a markedly greater effect on adrenal catecholamine secretion; the resultant output was about twice that evoked by acetylcholine in the absence of PGE2. The effect was more than additive, since the response to acetylcholine was at least one order of magnitude greater than that to PGE2. This indicates that PGE2 and acetylcholine may act synergistically in the adrenal medulla.
BIOCHEMICAL CHANGES IN THE CORPORA LUTEA OF PREGNANT AND LACTATING HAMSTERS
Authors: CHATTERJEE SUDHA , GREENWALD G. S.
Published: December 2008

Progesterone was secreted by hamster corpora lutea between days 1 and 15 of pregnancy; on day 14, the concentration in the peripheral plasma reached a maximum. A pronounced fall in luteal weight began on the day after parturition and the corpora lutea had virtually disappeared by days 4–5 post partum. The concentration of protein and the weights of the corpora lutea reached peak levels on days 12 and 14 respectively. The highest levels of luteal RNA were reached on days 12–13. The concentration of DNA in the corpora lutea was constant throughout pregnancy, indicating that hypertrophy rather than hyperplasia accounted for the increase in luteal weight.

Luteal concentrations of cholesterol and its esters were unchanged between days 1 and 14 of pregnancy except for a significant decline in the level of cholesteryl ester on days 8 and 13. During the final stages of regression of the corpora lutea during lactation, the luteal concentrations of free and esterified cholesterol rose to three and ten times respectively, the values obtained on day 2 of pregnancy. A significant increase in the concentration of acid and alkaline phosphatase began on day 16 of pregnancy correlated with the onset of structural luteolysis.

The activity of luteal glucose-6-phosphate dehydrogenase peaked on days 2 (comparable to the value on day 2 of the oestrous cycle) and 13 of pregnancy and day 3 of lactation. The high levels on these days may be associated either with luteal steroidogenesis during pregnancy or with lipid metabolism during the post-partum involutional phase. The activity of luteal 3β-hydroxysteroid dehydrogenase was relatively constant except for significant decreases on days 10 and 13 of pregnancy.

The results indicate that the activities of all of the biochemical variables in the corpora lutea of pregnancy were highest between days 11 and 13.
STEROID FEEDBACK ON LUTEINIZING HORMONE SECRETION DURING SEXUAL MATURATION IN THE PIG
Authors: ELSAESSER F. , PARVIZI N. , ELLENDORFF F.
Published: December 2008

The effects of gonadal secretions on the release of LH and the stimulation of LH secretion by oestradiol have been investigated in newborn male and female miniature pigs; the differences in the feedback action of testosterone in newborn and pubertal male pigs were also studied.

Hemi-orchidectomy or orchidectomy of 1-week-old pigs had no effect on the level of LH in the plasma; total orchidectomy significantly reduced the levels of testosterone (P<0·01) and progesterone (P<0·05). In female pigs ovariectomized at 1 week of age, the concentration of LH in the plasma decreased, with a strong negative correlation between the level of LH and age (r = −0·41; P < 0·05). The plasma concentration of progesterone was generally low and unaffected by ovariectomy. Orchidectomy and treatment of male pigs, at 1 week of age, with testosterone (6 mg/kg body weight) had no effect on the plasma concentration of testosterone 24 h after treatment. If testosterone propionate was given rather than testosterone, the level of LH was significantly reduced (P< 0·001) 24 h after the injection and the concentration of testosterone in the plasma corresponded to that found in the intact adult male pig. Treatment with oestradiol or oestradiol benzoate did not affect the concentration of LH. Orchidectomy and treatment of pubertal male pigs with testosterone propionate resulted in a significantly (P < 0·001) higher concentration of testosterone in the plasma, compared with newborn pigs treated similarly, but the level of LH was unchanged. This suggests that there is a more rapid rate of clearance of testosterone in the newborn than in the pubertal male miniature pig and that the negative feedback of testosterone is not mediated by aromatization in the newborn animal and it declines before or during puberty.

Treatment of newborn intact male and female and gonadectomized male pigs with oestradiol benzoate produced similar variations in the plasma level of oestradiol in all groups of animals. In the female pigs, however, a surge-like release of LH was observed 60–72 h after the injection of oestradiol benzoate, suggesting that the stimulatory feedback mechanism can operate soon after birth and that the response is sexually dimorphic.
ACTIVITY OF THE PITUITARY-ADRENOCORTICAL SYSTEM AND THYROID GLAND DURING THE OESTROUS CYCLE OF THE RAT
Authors: BUCKINGHAM JULIA C. , DÖHLER K.-D. , WILSON CATHERINE A.
Published: December 2008

The concentrations of LH, progesterone, ACTH, corticosterone and thyroxine in the plasma were estimated at various times during the oestrous cycle of the rat. The well-established patterns of LH and progesterone secretion were confirmed. On each day of the cycle the plasma concentrations of ACTH and corticosterone were lowest in the morning and rose in the afternoon. Conversely, during oestrus and dioestrus, the plasma concentrations of thyroxine were higher in the morning than in the evening. However, during the afternoon of pro-oestrus the concentrations of ACTH, corticosterone and thyroxine in the plasma rose and, like the concentrations of LH and progesterone, all reached levels far higher than those attained at any other time of the cycle.
CULTURED ADRENOCORTICAL CELLS IN VARIOUS STATES OF DIFFERENTIATION: ELECTRON MICROSCOPIC CHARACTERIZATION AND ULTRASTRUCTURAL RESPONSE TO ADRENOCORTICOTROPHIN
Authors: SLAVINSKI-TURLEY E. A. , AUERSPERG N.
Published: December 2008

The ultrastructure and response to ACTH of subcultured rat adrenocortical cells in two morphological and functional states are described. Fibroblastic cortical cells, which produce low levels of corticosterone, resembled myoid cells from the adrenal capsule: they formed fibrous extracellular matrix and basement membranes and contained dilated rough endoplasmic reticulum (RER), cytofilaments resembling those of smooth muscle and lamellar mitochondrial cristae. Stimulation with ACTH for 3 days increased steroid production from 0·01 to 0·56 μg 106 cells−1 24 h−1, increased the amount of smooth endoplasmic reticulum (SER) and greatly reduced the amounts of RER, cytofilaments, basement membranes and extracellular matrix, but did not change the mitochondrial structure. Different culture conditions produced epithelial cells which secreted high levels of corticosterone, lacked extracellular matrix, basement membranes and cytofilament accumulations but contained large lipid inclusions, SER and many mitochondria with lamellar or tubulolamellar cristae and electron-dense mitochondrial matrix bodies. Stimulation with ACTH for 3 days caused an increase in steroid production from 2·3 to 30·4 μg 106 cells−1 24 h−1, an increase in the number of Golgi complexes and the amount of SER as well as a reduction in the number of mitochondrial matrix bodies and lipid inclusions. However, no ultrastructural change occurred in the mitochondrial cristae. In both forms of cell, ACTH induced a transient increase in gap junctions. These and previous results suggest that subcultured adrenocortical cells in the fibroblastic form represent stem cells, possibly originating from the capsule, whose level of differentiation can be increased by ACTH as well as by specific culture conditions.
EFFECT OF SOMATOSTATIN ON THE CONCENTRATION OF GROWTH HORMONE IN THE PLASMA OF FOETAL SHEEP
Authors: McMILLEN I. C. , JENKIN G. , THORBURN G. D. , ROBINSON J. S.
Published: December 2008

Nuffield Institute for Medical Research and Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, Headington, Oxford, 0X3 9DU

(Received 6 April 1978)

Growth hormone (GH) has been located in the ovine foetal pituitary gland by day 50 of gestation (Stokes & Boda, 1968). The concentration of GH in the plasma of foetal sheep is ten times higher than the postnatal value, increasing from 40 ng/ml on day 100 of gestation to 100–120 ng/ml on day 140 (Bassett, Thorburn & Wallace, 1970). After foetal hypophysectomy, the concentration of GH falls to < 2 ng/ml, indicating that it originates in the foetal pituitary gland (Wallace, Stacey & Thorburn, 1973). Labelled GH does not cross the ovine placenta (Wallace et al. 1973). After sectioning the foetal pituitary stalk, the concentration of GH in the foetal plasma drops to approximately 5 ng/ml (Wallace et al. 1973), which implies that the secretion of GH
STIMULATION OF ADRENAL 5-ENE,3β-HYDROXYSTEROID DEHYDROGENASE BY CORTICOTROPHIN IN VITRO
Authors: LOVERIDGE N. , ROBERTSON W. R.
Published: December 2008

Division of Cellular Biology, The Mathilda and Terence Kennedy Institute of Rheumatology, Bute Gardens, London, W6 7DW

(Received 24 April 1978)

It is well established (Chayen, Daly, Loveridge & Bitensky, 1976) that segments of guineapig adrenal gland can be maintained in vitro and will respond to low concentrations (0·005– 5·0 pg/ml) of corticotrophin (ACTH). The response measured in the cytochemical bioassay of ACTH is the loss of ascorbate from the zona reticularis (Chayen, Loveridge & Daly, 1972), which is directly related to secretion of cortisol by these segments (Chayen, Bitensky, Chambers, Loveridge & Daly, 1974). However, because both major zones of the adrenal cortex are involved in steroidogenesis (see, e.g., Symington, 1969; Hyatt, Bell, Gould, Tait & Tait, 1976), the lack of a response in the zona fasciculata seems to be anomalous. To test whether the cells of the zona fasciculata in guinea-pig adrenal segments can respond to low concentrations
AN IMPROVED METHOD FOR ESTIMATING CHOLECYSTOKININ IN HUMAN SERUM
Authors: MARSHALL C. E. , EGBERTS E. H. , JOHNSON A. G.
Published: December 2008

Because of difficulties encountered in setting up radioimmunoassays for cholecystokinin (CCK) a sensitive and reliable biological method for estimating this hormone is still needed. The principles of such a biological technique and an improvement to it have already been described, but the serum levels of CCK reported were high and the technique required further refinement and validation.

The strips of rabbit gall-bladder used to estimate the concentration of CCK increased in sensitivity to standard solutions of CCK over a 6–8 h period before stabilizing, but a single sample of serum increased the sensitivity of the strips of gall-bladder to their maximum immediately. These two problems were eliminated by 'priming' the strips of gall-bladder by exposure to two serum samples before exposure to the standard solutions used for production of a dose–response curve.

Thirdly, it was discovered that some non-peptide substances in serum possessed CCK-like activity; by extracting all the small peptides from serum with dextran-coated charcoal the residual activity could be measured and subtracted from the total CCK activity. Finally, the activity of CCK in the serum increased during processing before freezing. This increase was eliminated by taking the blood samples into aprotinin which has been shown to cause dramatic reduction in CCK activity in some experiments.

When all these factors were taken into account and the technique suitably modified, the mean level of CCK in the serum of ten normal fasting subjects was found to be 28 milli Ivy Dog units/ml (2·4 pmol/ml), which is only one third of that reported previously.
DISTRIBUTION OF ANDROGEN METABOLIZING ENZYMES IN ISOLATED TISSUES OF HUMAN FOREHEAD AND AXILLARY SKIN
Authors: HAY J. B. , HODGINS M. B.
Published: December 2008

The distribution of androgen metabolism in human skin was studied using tissues isolated either by direct dissection of axillary skin or by dissection of collagenase-digested forehead and axillary skin. All tissues (epidermis, sweat glands, sebaceous glands, hair follicles and dermis) were found to contain 17β-, 3β- and 3α-hydroxysteroid dehydrogenase (HSD) activities, 3β-hydroxysteroid dehydrogenase-Δ4–5 isomerase (Δ5-3β-HSD) activity and 5α-reductase activity. All tissues converted testosterone into 5α-dihydrotestosterone. In confirmation of previous histochemical studies, over 90% of the Δ5-3β-HSD of forehead skin was found in the sebaceous glands. In forehead skin, 40–66% of the 5α-reductase activity was in the sebaceous glands, while in axillary skin 50–70% was in the sweat glands, especially the apocrine glands. There was a more even distribution of 17β-HSD activity in skin tissues than histochemical studies have indicated previously. Knowledge of the distribution of these enzymes has helped in the understanding of the function of androgen metabolism in skin.
CIRCADIAN VARIATIONS IN THE PLASMA CONCENTRATION OF PROLACTIN IN THE ADULT MALE RAT
Authors: MATTHEIJ J. A. M. , SWARTS J. J. M.
Published: December 2008

The occurrence of circadian variations in the concentration of prolactin in the plasma of 6- to 9-month-old male rats has been assessed in animals exposed to light for 14 h/day (lights on 06.00–20.00 h). Blood samples were obtained after decapitation, or from individual rats at regular intervals via a permanent cannula. Care was taken to limit stress during sampling. The concentration of prolactin in the plasma was significantly lower between 07.00 and 15.00 h than at other times. Between 15.00 and 20.00 h (during the light period), the concentration of prolactin was significantly higher in comparison with the preceding period, or with the remainder of the 24 h period. During the night, the concentration fluctuated, probably because of episodic releases of the hormone. The possible physiological significance of a circadian rhythm in the plasma concentration of prolactin and the implications for endocrine experimentation are discussed briefly.
EFFECTS OF HUMAN THYROID-STIMULATING HORMONE AND IMMUNOGLOBULINS ON ADENYLATE CYCLASE ACTIVITY AND THE ACCUMULATION OF CYCLIC AMP IN HUMAN THYROID MEMBRANES AND SLICES
Authors: HOLMES S. D. , DIRMIKIS SUSAN M. , MARTIN T. J. , MUNRO D. S.
Published: December 2008

The activation of adenylate cyclase and the accumulation of cyclic AMP resulting from the action of human thyroid-stimulating hormone (TSH), long-acting thyroid stimulator (LATS) or LATS-protector (LATS-P) have been investigated in preparations of human thyroid membranes and slices.

Human TSH significantly increased adenylate cyclase activity in membranes from non-toxic goitres whereas LATS and LATS-P had no consistent effect. However, pre-incubation of goitrous membranes with LATS–immunoglobulin G inhibited the effect of TSH on adenylate cyclase. When thyroid membranes were prepared from the glands of patients with Graves's disease neither TSH nor thyroid-stimulating immunoglobulins (TSIg) stimulated adenylate cyclase significantly.

Whether from non-toxic goitres or thyrotoxic tissue, the concentration of TSH needed to induce half of the maximum response was lower in thyroid slices than in membranes. Both LATS and LATS-P significantly stimulated the accumulation of cyclic AMP in slices of goitrous tissue but thyrotoxic tissue slices did not respond.

In goitrous slices, submaximum concentrations of TSH and TSIg caused additive responses in the accumulation of cyclic AMP but TSIg did not increase the maximum response to TSH.
SITE OF BLOOD SAMPLING IN RATS AS A POSSIBLE SOURCE OF ERROR IN HORMONE DETERMINATIONS
Authors: DÖHLER K.-D. , WONG C. C. , GAUDSSUHN D. , VON ZUR MÜHLEN A. , GÄRTNER K. , DÖHLER URSULA
Published: December 2008

Abteilung für Klinische Endokrinologie, Department für Innere Medizin und Zentrales Tierlabor, Medizinische Hochschule, 3000 Hannover 61, Federal Republic of Germany

(Received 8 May 1978)

The application of a blood sampling technique which by itself has little or no influence on the concentrations of hormones in the circulation of the rat is of utmost importance in experimental hormone research. It has recently been demonstrated that the type of anaesthesia and probably also the site of withdrawal of blood from the body may become critical parameters when the determination of unaltered hormone levels is required (Döhler, von zur Mühlen, Gärtner & Döhler, 1977b). That the site of blood sampling may act as an interfering parameter is questionable, since cage transport, handling and possible differences in the intensity of anaesthesia may also influence the variability of individual hormone levels (Baldwin, Colombo & Sawyer, 1974; Krulich, Hefco, Illner & Read, 1974; Euker, Meites &
ANDROGEN DEPENDENCE OF RAT PROSTATIC 3α-HYDROXYSTEROID DEHYDROGENASE
Authors: MASSA R. , MAS GARCIA M. , MARTINI L.
Published: December 2008

Department of Endocrinology, University of Milan, Via A. del Sarto 21, 20129 Milan, Italy

(Received 8 May 1978)

It is well established that the rat prostate gland converts testosterone mainly into 5α-androstan-17β-ol-3-one (5α-dihydrotestosterone, 5α-DHT) and to a lesser extent into 5α-androstan-3α,17β-diol (5α-tetrahydrotestosterone, 5α-THT). This occurs, both in vivo and in vitro, through the action of a 5α-reductase and a 3α-hydroxysteroid dehydrogenase system (Baulieu, Lasnitzki & Robel, 1968; Bruchovsky & Wilson, 1968; Gloyna & Wilson, 1969; Kniewald, Massa & Martini, 1971). It has also been recognized that, although the 5α-reduction of testosterone is an irreversible reaction, the reduction of 5α-DHT to 5α-THT is reversible (Becker, Grabosch, Hoffmann & Voigt, 1973; Cresti & Massa, 1977). Consequently, the question has been raised as to whether the biological actions of 5α-THT are attributable to the compound as such or to 5α-DHT. At the anterior pituitary level, 5α-reductase activity is increased by castration and decreased
HYPOTHALAMIC CORTICOTROPHIN RELEASING FACTOR ACTIVITY IN DOGS WITH PITUITARY-DEPENDENT HYPERADRENOCORTICISM
Authors: MEIJER J. C. , MULDER G. H. , RIJNBERK A. , CROUGHS R. J. M.
Published: December 2008

Hypothalamic corticotrophin releasing factor (CRF) activity was determined in five dogs with spontaneous hyperadrenocorticism and in three control animals (one untreated, one treated with high doses of ACTH for 2 months and one treated with high doses of cortisone for 2 months). Hypothalamic CRF activity was low or undetectable in four dogs with spontaneous pituitary-dependent hyperadrenocorticism and was reduced in one dog with Cushing's syndrome due to an adrenocortical tumour. The results are compatible with a pituitary origin for pituitary-dependent hyperadrenocorticism in the dog but are not conclusive; direct information about the rates of hypothalamic CRF secretion is required.
EFFECTS OF A LONG-ACTING PROGESTIN ON REPRODUCTIVE FUNCTION IN FEMALE MICE
Authors: FINN C. A. , MARTIN L.
Published: December 2008

The duration of activity of a long-acting progestin, medroxyprogesterone acetate, was compared using three tests for progestational activity: the induction of stromal mitosis in the endometrium, implantation of blastocysts and inhibition of ovulation. The duration of activity was similar in each test and was longer when higher doses were given.