bluuebunny/crossref_metadata_2025_split huggingface dataset:
INDUCTION OF PROLACTIN AND LUTEINIZING HORMONE RELEASE BY HISTAMINE IN MALE AND FEMALE RATS AND THE INFLUENCE OF BRAIN TRANSMITTER ANTAGONISTS
Authors: DONOSO A. O. 
Published: December 2008

The levels of prolactin and LH in the plasma of rats were determined at various times after intraventricular injection of histamine. Doses of 5 and 60 μg histamine (free base) in male rats, anaesthetized with ether, induced an increase in the level of prolactin in the plasma, whilst producing a slight decrease in the concentration of LH. Injection of 5 μg histamine at 14.00 h into female rats at all stages of the oestrous cycle caused prolactin to be released; the effect was greatest at oestrus and at day 1 of dioestrus. Histamine also gave rise to a marked increase in the level of LH in the plasma when administered to pro-oestrous rats, but had no effect when injected at the other stages of the oestrous cycle.
The effect of histamine on the release of prolactin in ovariectomized, oestradiol benzoate: progesterone-primed (OVX,OB:P) rats was found to be dose-related, and the level of LH in the plasma was increased by as little as 1·25 μg.
Pretreatment with adrenergic (phenoxybenzamine and propranolol) and cholinergic (atropine) antagonists failed to block the stimulatory effects of histamine on prolactin secretion, but pretreatment with methysergide (serotonin antagonist) increased the histamine-induced release of prolactin in male rats. Antagonists did not modify the response of prolactin to histamine in OVX,OB:P-primed rats. The histamine-induced release of LH in OVX,OB:P-primed rats was slightly reduced by pretreatment with phenoxybenzamine, propranolol and atropine, but not by methysergide.
These results indicate that histamine facilitates the release of prolactin. The stimulatory action of histamine on both pro-oestrous and OVX,OB:P-primed but not male rats suggests that histamine may be involved in LH release in the rat.
Results obtained in animals pretreated with transmitter antagonists, which were unable to prevent histamine-induced hormone release, suggest that the actions of this amine are not mediated by cholinergic, noradrenergic or serotonergic mechanisms.
EFFECTS OF INHIBITORS OF CATECHOLAMINE SYNTHESIS AND CATECHOLAMINE AGONISTS ON MORPHINE- AND HYPOGLYCAEMIA-INDUCED RELEASE OF GROWTH HORMONE IN THE RAT
Authors: BLUET-PAJOT M. T. , SCHAUB C. 
Published: December 2008

Unité de Neuroendocrinologie, INSERM, U.159, 2 ter Rue d'Alesia, 75014 Paris, France
(Received 16 August 1977)
It is known that catecholamines play an important role in the regulation of growth hormone (GH) secretion, but the effects of dopamine and alpha- and beta-adrenergic agonists on the release of GH in the rat are controversial (Collu, Fraschini, Visconti & Martini, 1972; Kato, Dupre & Beck, 1973; Durand, Martin & Brazeau, 1977). It has been proposed (Bluet-Pajot, Schaub & Nassiet, 1976; Bluet-Pajot & Schaub, 1977; Durand et al. 1977) that the conflicting data obtained in the rat may be due to the anaesthesia; most of the GH responses reported to be atypical in the rat, compared with those of primates, were obtained under urethane anaesthesia, which is known to result in long-lasting and irreversible endocrine imbalance.
In contrast, neurotransmitters or experimental hypoglycaemia do not appear to induce paradoxical GH responses in rats treated
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
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

SUMMARY
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

SUMMARY
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.
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.
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

SUMMARY
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.