bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF HYPOTHALAMIC LESIONS ON WATER METABOLISM OF THE TOAD BUFO MARINUS
Authors: BAKKER H. R. , BRADSHAW S. D.
Published: December 2008

The rate of cutaneous water uptake after dehydration was significantly depressed in functionally neurohypophysectomized toads (Bufo marinas), which consequently regained weight much more slowly than intact toads when returned to water.

Toads bearing hypothalamic lesions were able to develop an antidiuresis when removed from water to a saturated atmosphere, but the antidiuresis was solely glomerular in origin and was established more slowly than in intact animals. The fractional reabsorption of filtrate increased significantly and the relative free water clearance decreased significantly in intact toads after removal from water. These changes in tubular function, which were not seen in lesioned toads, were responsible for the development of a more rapid and effective antidiuresis in intact animals.

Injections of iso-osmotic saline, oxytocin (250 mu./100 g) and vasopressin (50 mu./100 g) had no significant effect on rates of cutaneous water uptake in both intact and lesioned toads. Injections of hyperosmotic saline, however, significantly increased rates of water uptake in both groups of toads, but to a much greater extent in the intact animals. Fluid retention arising from a marked antidiuresis occurred after the injection of vasopressin and hyperosmotic saline, and there was some evidence of an antidiuretic effect of oxytocin with the doses used here.

These results and their bearing on the question of the functional significance of the neurohypophysis in anuran amphibians are discussed.
VASOTOCIN RELEASE INTO THE CEREBROSPINAL FLUID OF CATS INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE, THYROTROPHIN RELEASING HORMONE AND GROWTH HORMONE RELEASE-INHIBITING HORMONE
Authors: GOLDSTEIN R. , PAVEL S.
Published: December 2008

Institute of Endocrinology, Bucharest, Rumania

(Received 29 March 1977)

The mammalian pineal gland contains (Pavel, 1965) and synthesizes (Pavel, Goldstein, Ghinea & Calb, 1977) the nonapeptide arginine-vasotocin (AVT). Since luteinizing hormone releasing hormone (LH–RH), thyrotrophin releasing hormone (TRH) and growth hormone release-inhibiting hormone (somatostatin, SRIF) have now been localized not only in the brain, but also in the pineal gland (White, Hedlund, Weber, Rippel, Johnston & Wilber, 1974; Pelletier, Le Clerc, Dube, Labrie, Puviani, Arimura & Schally, 1975), we investigated the effects of these peptides on the release of AVT into the cerebrospinal fluid (CSF) of cats.

Intracarotid injections of 0·1 μg LH-RH, TRH (Hoechst, Frankfurt), SRIF (Serono, Rome) or oxytocin (Syntocinon, Sandoz Ltd, Basel) in 0·5 ml saline were given to urethane-anaesthetized male cats weighing 3–4 kg. Controls received an equal volume of saline only. The pineal glands were removed 60 min after the injections, quickly homogenized, and extracted
BIOSYNTHESIS OF ALDOSTERONE FROM 18-HYDROXYLATED PRECURSORS BY RAT ADRENAL TISSUE IN VITRO
Authors: FATTAH D. I. , WHITEHOUSE B. J. , VINSON G. P.
Published: December 2008

Rat adrenal capsules incubated with [3H]18-hydroxydeoxycorticosterone (18-OH-DOC) and [3H]18-hydroxycorticosterone gave appreciable yields of aldosterone from both precursors, similar in size to those obtained from labelled corticosterone, deoxycorticosterone and progesterone under the same conditions. After feeding rats for 14 days on a flour diet deficient in sodium, aldosterone production from endogenous precursors in vitro was increased twofold compared with that by adrenal glands from animals receiving the flour diet with 1% sodium chloride added (control diet). When adrenal capsules from animals on the low-sodium flour diet were incubated with high specific activity [3H]18-OH-DOC (sp. act. 40 Ci/mmol), the yield of [3H]aldosterone was increased two- to threefold compared with that produced by capsules from animals on the control diet. When capsules were incubated with low specific activity [3H] 18-OH-DOC and [14C]corticosterone (sp. act. 52 mCi/mmol) only the yield of [14C]aldosterone was increased. Yields of labelled 18-hydroxycorticosterone from all precursors tested were increased three- to fourfold in animals receiving the low-sodium diet relative to the controls.

The results show that 18-OH-DOC can be an effective precursor for aldosterone formation by rat adrenal capsules, and that production of aldosterone and 18-hydroxycorticosterone from this precursor can be stimulated by a low-sodium diet. This suggests the existence of an alternative pathway for aldosterone biosynthesis involving 18-OH-DOC as an intermediate.
MEASUREMENT OF THYROID HORMONE IN EXPERIMENTAL THYROID TUMOURS IN RATS
Authors: AL-HINDAWI A. Y. , BLACK E. G. , BREWER D. B. , GRIFFITHS S. G. , HOFFENBERG R.
Published: December 2008

Rats treated with 131I and propylthiouracil were shown to develop thyroid tumours 7–9 months after treatment. In this group, the levels of total thyroxine and tri-iodothyronine, and free thyroxine and tri-iodothyronine in the serum were low, and that of TSH was raised. In a group of rats treated with 131I and then propylthiouracil and thyroxine, thyroid tumours were found despite normal concentrations of total and free thyroxine and tri-iodothyronine in the serum. The level of TSH in the serum was significantly raised in this group. Thyroid tumours were not found in the various control groups of rats.
CIRCADIAN RHYTHM OF LUTEINIZING HORMONE SECRETION IN THE OVARIECTOMIZED RAT IMPLANTED WITH OESTRADIOL
Authors: CHAZAL G. , FAUDON M. , GOGAN F. , HERY M. , KORDON C. , LAPLANTE E.
Published: December 2008

Implantation of a solid source of oestradiol into ovariectomized rats produced constant plasma concentrations of the hormone over a long period of time. Under these conditions, LH is released in a circadian pattern with a very marked peak in the afternoon. This circadian rhythm is synchronized to the light–darkness cycle, since it follows exactly a shift in the nycthemeral cycle. The first peak appeared on day 3 after placement of the oestrogen implant; its amplitude was constant from days 3 to 9 after implantation, and decreased gradually during prolonged implantation. The afternoon peak was not correlated with changes in the pituitary sensitivity to exogenous LH releasing hormone (LH-RH), since the LH response to increasing doses of the peptide could be superimposed in the morning and in the afternoon. However, the decreased amplitude of the rhythm observed after more than 9 days of implantation seemed to depend upon a progressive desensitization of the pituitary gland to LH-RH. Pituitary LH content also decreased as a function of implantation time. It is concluded that, under conditions of constant plasma oestradiol concentrations and of constant pituitary sensitivity to LH-RH, a daily activation of the neural trigger releasing pituitary gonadotrophins occurs.
GENETIC VARIATION IN THE SECRETION OF OESTROGEN IN THE EWE
Authors: WHEELER A. G. , BAIRD D. T. , LAND R. B. , SCARAMUZZI R. J.
Published: December 2008

A.R.C. Animal Breeding Research Organisation, The King's Buildings, West Mains Road, Edinburgh, EH9 3JQ and †M.R.C. Unit of Reproductive Biology, Department of Obstetrics and Gynaecology, University of Edinburgh, Edinburgh, EHI 2QW

(Received 12 May 1977)

It has been suggested that the sensitivity of ewes to the negative and positive feedback effects of oestrogen can be related to the rate of ovulation of the breed (Land, 1976; Land, Wheeler & Carr, 1976), and may be associated with different patterns of oestrogen secretion as inferred by Land, Thompson & Baird (1972). However, no apparent differences between the concentrations of oestrogens in jugular venous plasma from ewes with differing rates of ovulation have been reported (Bindon, Blanc, Pelletier, Terqui & Thimonier, 1975; Scaramuzzi & Land, 1976). The pulsatile nature of the ovarian secretion of oestradiol (Baird, Swanston & Scaramuzzi, 1976) and the fact that the concentrations of oestrogen in peripheral plasma are so
METABOLISM OF TESTOSTERONE BY FOREHEAD SKIN OF THE ROEBUCK (CAPREOLUS CAPREOLUS)
Authors: JOHNSON ELIZABETH , LEASK J. T. S.
Published: December 2008

Roebucks have a specialized region of skin on the forehead which contains sebaceous and apocrine glands that produce secretions used in territorial marking. These glands enlarge during the breeding season and regress after the rut as the testes regress.

The metabolism of testosterone by this forehead skin in vitro was studied in two captive roebucks over the period of glandular enlargement and subsequent regression, and compared with that of dorsal skin. In May, June and July, both areas of skin actively metabolized testosterone and the metabolites detected were androstenedione, androstanedione, dihydrotestosterone, epiandrosterone, androsterone and 5α-androstanediols. There were no major differences in testosterone metabolism between the two body sites, although dorsal skin appeared to be more active in total metabolism than forehead skin. There was a peak in the extent of metabolism in June/July, with a subsequent gradual decline to December. The decline in metabolism occurred at a time when the associated glands were still enlarged, which suggests that the availability of androgen to the skin glands is determined not only by the amount of testosterone in the circulation, but also by a decrease in the metabolizing capacity of the tissue.
AUGMENTATION OF VASOPRESSIN ANTIDIURESIS BY PROLACTIN WITH A NOTE ON THE CONTAMINATION OF INTERNATIONAL STANDARD PROLACTIN
Authors: WATERS A. K.
Published: December 2008

Department of Physiology, Charing Cross Hospital Medical School, London, W6

(Received 7 April 1977)

It has been reported (Horrobin, Burstyn, Lloyd, Durkin, Lipton & Muiruri, 1971; Buckman & Peake, 1973; Wallin & Lee, 1976) that prolactin affects salt and water metabolism. To assess any interaction of the antidiuretic hormone arginine-vasopressin (AVP) and prolactin, four experiments were performed.

The antidiuretic action of AVP was measured by the standard AVP bioassay method using the water-loaded ethanol-anaesthetized rat described by Jeffers, Livesey & Austin (1942) with the minor modifications of Forsling, Jones & Lee (1968). Male Wistar rats (150-200 g) were used with at least six preparations for each experiment. When stable antidiuretic responses to standard AVP (3rd International Standard, 1957, National Institute for Biological Standards, London) were obtained, the infusion fluid was changed to one containing the appropriate hormone for the experiment and the effect of AVP within the succeeding hour compared
CONCENTRATION OF GONADOTROPHINS IN THE PLASMA AND TESTICULAR RESPONSIVENESS TO GONADOTROPHIC STIMULATION IN ANDROGEN-DEFICIENT C57BL/10J MICE
Authors: BARTKE A. , ROBERSON C. , DALTERIO S.
Published: December 2008

Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545, U.S.A.

(Received 24 May 1977)

Deficient testicular function was suspected in male C57BL/10J mice from the observations that they have small testes (Shire & Bartke, 1972) and fail to produce the androgen-dependent pregnancy-blocking pheromone (Chapman & Whitten, 1969). Comparison with male DBA/2J mice and several other strains indicated that C57BL/10J mice have fewer spermatogonia, spermatocytes and spermatids, low testicular weight, a progressive decrease in the absolute weight of the testes after sexual maturation, excessive accumulation of esterified cholesterol in the testes and a low level of testosterone in the plasma (Bartke & Shire, 1972; Shire & Bartke, 1972; Bartke, 1974). The relative androgen deficiency of the C57BL/10J mice is also suggested by the observations of Ivanyi (1973), Hill, Clemens, Liu, Vessel & Johnson (1975) and Hoppe (1975).

To define the causes of androgen deficiency in C57BL/10J mice, the levels of gonadotrophins in
A COMPARISON OF PLASMA PROGESTERONE AND LUTEINIZING HORMONE IN GROWING HENS FROM EIGHT WEEKS OF AGE TO SEXUAL MATURITY
Authors: WILLIAMS J. B. , SHARP P. J.
Published: December 2008

Agricultural Research Council's Poultry Research Centre, King's Buildings, West Mains Road, Edinburgh, EH9 3JS

(Received 20 June 1977)

In the maturing hen the concentration of luteinizing hormone (LH) in the plasma rises to a prepubertal maximum and then declines over a 2–3 week period until the first egg is laid (Sharp, 1975). Sharp (1975) postulated that increased secretion of progesterone by the developing ovary may be responsible for this fall in the level of LH since the large, yolky follicles, which are thought to be steroidogenic (Furr, 1969), develop over a 2–3 week period before the onset of lay (Wilson & Sharp, 1975). The present experiment was designed to test this hypothesis by direct measurement of the amount of progesterone and LH in the blood of growing hens.

Variations in the level of LH in the peripheral plasma were determined by an homologous radioimmunoassay for avian LH (Follett, Scanes &
CHARACTERIZATION AND ASSAY OF THE PROGESTERONE RECEPTOR IN RAT UTERINE CYTOSOL
Authors: VU HAI M. T. , MILGROM E.
Published: December 2008

The synthetic progestogen R5020 (17,21-dimethyl-19-norpregna-4,9-diene-3,20-dione) binds with high affinity (Ka = 8·8 × 108 1/mol at 0 °C) to the progesterone receptor from rat uterine cytosol. At nanomolar concentrations, equilibrium is attained in less than 90 min. R5020 has a very low affinity for other specific steroid-binding proteins (corticosteroid-binding globulin and oestrogen receptors) present in relatively high concentrations in the uterine cytosol. The affinity of the receptor for the natural hormone progesterone is remarkably low (Ka= 1 × 108−1·7 × 1081/mol at 0 °C) which explains the instability of progesterone–receptor complexes. Advantage may be taken of this property to remove endogenous progesterone easily by charcoal treatment at 0 °C, a treatment which does not modify the concentration of receptors. A method based on these characteristics is described for the assay of the total number (progesterone-bound and unbound) of receptor sites in uterine cytosol. This assay may be used in various physiological situations where endogenous progesterone is present at unknown concentrations.
PROGESTERONE RECEPTORS IN THE RAT UTERUS: VARIATIONS IN CYTOSOL AND NUCLEI DURING THE OESTROUS CYCLE AND PREGNANCY
Authors: VU HAI M. T. , LOGEAT F. , MILGROM E.
Published: December 2008

The concentration of progesterone receptors in rat uterine cytosol and nuclei was measured during the oestrous cycle and pregnancy. The method used allowed the measurement of the total concentration of binding sites (unbound and hormone-bound).

During the oestrous cycle, the concentration of receptors in the cytosol peaked at pro-oestrus, low concentrations were observed at oestrus and metoestrus, and an increase was seen at dioestrus. In the nuclei, maximum concentrations occurred at pro-oestrus and dioestrus. The number of receptors in the cytosol was very low during the first half of pregnancy, but the concentration increased progressively after day 15 to attain a very high level (about 26 000 binding sites/cell) on day 22.

In the nuclei, the concentration of receptors was low at the beginning of pregnancy. On day 5 (day of implantation) there was a slight increase, which corresponded to a decrease in the number of cytosolic receptors and a small peak in the level of progesterone in the plasma. Maximum concentrations were attained during a 'plateau' period between days 9 and 15. Thereafter, there was a decrease in the concentration of nuclear receptors and on day 22, the mean value was very low; in some animals, probably on the verge of parturition, no receptors were detectable in the nuclei.
CIRCADIAN VARIATION IN THE SENSITIVITY OF THE PITUITARY–ADRENAL SYSTEM TO DEXAMETHASONE SUPPRESSION
Authors: DUNN J. D. , CARRILLO A. J.
Published: December 2008

Intact female rats were injected with 100 μg dexamethasone/kg body weight or saline at 12.00, 24.00 or 04.00 h. Four hours later, i.e. 16.00, 04.00 or 08.00 h respectively, a double bleeding procedure was used to obtain blood samples from stressed and unstressed rats for subsequent fluorometric determination of corticosterone levels in the plasma. The difference between the level of corticosterone in stressed and unstressed rats (the stress increment) was determined and used as an index of the response of corticosterone in the plasma to stress.

Increments in the levels of corticosterone in the plasma evoked by stress in rats injected at 12.00 h with dexamethasone and bled 4 h later were significantly (P < 0·05) less than those in rats given dexamethasone at 24.00 or 04.00 and bled at 04.00 or 08.00 h respectively. In contrast, stress-induced increments in the level of corticosterone in the plasma of rats treated with saline did not vary with the time of day.
DIURNAL VARIATION IN PLASMA TESTOSTERONE AND CORTISOL IN RHESUS MONKEYS LIVING IN SOCIAL GROUPS
Authors: ROSE R. M. , GORDON T. P. , BERNSTEIN I. S.
Published: December 2008

Concentrations of cortisol and testosterone in the plasma of adult male rhesus monkeys living in social groups were determined during a 27-h period. Capture and venipuncture of experienced, conditioned animals did not lead to a fall in the concentration of testosterone in the plasma during the 90 min immediately after removal from the group. Both plasma cortisol and plasma testosterone concentrations showed a significant fall and rise in samples collected every 3 h during a 27-h period, even though there was considerable individual variation. During the autumn breeding season, animals showed higher concentrations of testosterone at both 10.00 and 22.00 h compared with those observed at the same times during the summer. Even though animals demonstrated significant diurnal changes, testosterone samples withdrawn at the same time of day (10.00 h) on consecutive days were significantly correlated with one another (r = 0·65, n = 27, P < 0·01), suggesting the usefulness of sampling once a day to study potential environmental influences on plasma testosterone concentrations.
PRECOCIOUS 'FEMINIZATION' OF RAT LIVER ENZYMES IN THE PRESENCE OF ECTOPIC PITUITARY TISSUE
Authors: GUSTAFSSON JAN-ÅKE , SKETT PAUL
Published: December 2008

The presence of ectopic pituitary tissue (derived from an adult rat) in prepubertal male and female rats caused the immature, masculine-type hepatic steroid metabolism to develop into female-type metabolism. It is concluded that the hypothalamus–pituitary system controls the ontogenesis of sex-dependent steroid metabolism in rat liver.
EFFECTS OF ANTI-OESTROGEN TREATMENT OF NEONATAL MALE RATS ON LORDOSIS BEHAVIOUR AND MOUNTING BEHAVIOUR IN THE ADULT
Authors: SÖDERSTEN P.
Published: December 2008

Male rats were treated daily with 100 μg of the anti-oestrogen ethamoxytriphetol (MER-25) or oil during the first 10 days of life and tested for lordosis behaviour and mounting behaviour as intact adults, after castration and after castration and oestradiol benzoate or testosterone propionate treatment. The MER-25-treated rats showed higher levels of lordosis behaviour than oil-treated rats in all four treatment groups. Under each of these endocrine conditions, except after castration alone, the MER-25-treated rats showed a reduced capacity to ejaculate. Treatment of the neonatal rat with MER-25 reduced body weight in adulthood but did not change the weight of the accessory sexual glands, the testes, the number of cornified papillae on the glans penis or plasma testosterone concentrations during development. The response of the accessory sexual glands and cornified papillae on the glans penis to treatment with oestradiol benzoate or testosterone propionate after castration in adulthood was unaffected by treatment with MER-25. It is suggested that formation of oestrogen in the neonatal male rat brain from testosterone in the circulation inhibits the capacity to show lordosis behaviour and facilitates the capacity to ejaculate in response to gonadal hormone treatment in adulthood.
A CRITICAL PERIOD FOR POSITIVE FEEDBACK IN IMMATURE (21-DAY-OLD) RATS
Authors: PUIG-DURAN E. , MACKINNON P. C. B.
Published: December 2008

The concentrations of LH and prolactin in the serum in response to a single s.c. injection of oestradiol benzoate (OB, 1 μg) were studied in 21-day-old Wistar rats of different sexual status. In intact female rats, the total concentration of oestrogen in the serum reached a maximum level within 30 min of the injection, whereas the level of LH fell and remained low until a surge occurred 54 h later. However, the amount of prolactin in the serum increased within 1 h of injection of OB and thereafter showed diurnal fluctuations with evening peaks. Male rats castrated within 24 h of birth showed increases in the serum level of both LH and prolactin in response to OB, which were similar in timing to those seen in intact female rats. However, intact male rats failed to show an increase in the level of either LH or prolactin after treatment with OB, while neonatally androgenized female rats, although failing to show an increase in the level of LH, exhibited a prolactin response which was similar to that observed in intact female rats.

A further study was undertaken in rats which had received an initial injection of OB and a subsequent injection of progesterone 5 h before the expected female-type LH surge. In intact female rats, progesterone augmented the oestrogen-stimulated surge of LH, but this effect was not observed in either intact male or neonatally androgenized female rats. In all three groups, however, the level of prolactin in the serum was increased when compared with control animals which had received OB only.

The effect of progesterone, injected at various times after priming with OB, on the output of LH and prolactin was also studied in female rats killed 5 h after the second injection. Up to 21 h after injection of OB, progesterone had no effect on the level of LH or prolactin. If, however, progesterone was then injected during the middle of the light period, but not in the dark period, the concentrations of LH and prolactin increased. Thus there are critical times during a 24 h period when the gonadotrophin output of the oestrogen-primed female rat is responsive to the stimulatory effects of progesterone.
DEGRADATION OF CALCITONIN DURING INCUBATION WITH THYROID SLICES IN VITRO
Authors: PENTO J. T. , ANDERSON C. C.
Published: December 2008

Division of Pharmacodynamics and Toxicology, College of Pharmacy, 644 Northeast 14th Street, Health Sciences Center, Oklahoma City, Oklahoma 73104, U.S.A.

(Received 30 September 1977)

The secretion of calcitonin in vitro has recently been examined in various mammalian and submammalian species. It appears that calcium and other calcitonin secretagogues produce a much greater secretory response in vivo than in vitro (Bell, 1970; Feinblatt, Raisz & Kenny, 1973; Gautvik & Tashjian, 1974; Selawry, Becker, Bivins, Snider & Silva, 1975). We have previously suggested that the relative unresponsiveness observed in vitro may be due to calcitonin-induced self-inhibition resulting from the accumulation of calcitonin in a closed incubation system in vitro (Orme & Pento, 1976), However, another possible explanation for the secretory unresponsiveness in vitro may be the occurrence of tissue-induced degradation of the secreted calcitonin. Therefore, the present study examined the influence of thyroid tissue from various species on the degradation of calcitonin
LEVELS OF IMMUNOGLOBULINS G AND M AND TRI-IODOTHYRONINE IN CORD BLOOD AND THE DIAGNOSIS OF NEONATAL THYROID DISEASE
Authors: DISSANAYAKE S.
Published: December 2008

Department of Biochemistry, Faculty of Medicine, Peradeniya Campus, Peradeniya, Sri Lanka

(Revised manuscript received 10 October 1977)

During pregnancy, the level of tri-iodothyronine (T3) in the maternal serum is raised but this increase is not reflected in cord blood (Editorial Comment, 1973; Burke & Eastman, 1974; Walfish, 1976). To what extent the T3 content and the composition of cord blood are interdependent or related is not clear and this study was undertaken to investigate the relationship between the levels of T3 and immunoglobulins in cord blood.

Cord blood was collected from 53 subjects in the General Hospital, Kandy, Sri Lanka, at the time of delivery. Blood samples were allowed to clot and the serum was separated and stored at −20 °C. The concentrations of immunoglobulins G (IgG) and M (IgM) were determined by single radial immunodiffusion in agarose gels (2% for IgG; 1% for IgM) with reference to WHO standard
EFFECTS OF ADRENALECTOMY AND PREDNISOLONE ON THE ABSORPTION AND PHOSPHORYLATION OF THIAMINE IN RATS
Authors: LAZAROV JONCHO
Published: December 2008

After adrenalectomy, the absorption of [35S]thiamine in the small intestine of rats was significantly reduced. Injection of Δ1,4-pregnadiene-11β,17α,21-triol-3,20-dione (prednisolone) restored this absorption to some extent, but not to the value found in control (unoperated) rats. Treatment with 1% saline had no effect. Adrenalectomy also reduced the amount of [35S]thiamine that accumulated in the intestinal mucosa and liver compared with that found in controls, but treatment with prednisolone increased the retention of thiamine in these tissues. One per cent NaCl raised the retention of thiamine in the liver but not in the mucosa of the jejunum. The loss in body weight that occurred after adrenalectomy was not, however, corrected after treatment with either saline or steroid.

In adrenalectomized rats, the concentrations of thiamine mono- and diphosphates in the intestinal mucosa and the liver were lower than in the control animals. The concentration of thiamine triphosphate was, however, higher in the intestinal mucosa after adrenalectomy, but remained unchanged in the liver. Treatment with prednisolone increased the concentrations of thiamine mono-, di- and triphosphates in both of these tissues in adrenalectomized rats, compared with unoperated control animals.
PITUITARY–THYROID FUNCTION IN THE RHESUS MONKEY (MACACA MULATTA)
Authors: BELCHETZ P. E. , GREDLEY GLENYS , HIMSWORTH R. L.
Published: December 2008

The mean concentration of thyroxine (T4) in the plasma of the rhesus monkey Macaca mulatta (53 ± 8 (s.d.) nmol/l) is less than the lower limit of the range of concentrations normally found in man; conversely, the mean concentration of tri-iodothyronine (T3) in monkey plasma (2·45 ± 0·52 (s.d.) nmol/l) is at the upper end of the normal human range. The basal concentrations of TSH in the plasma, as measured by radioimmunoassay, were comparable in the two species (mean concentration of TSH in monkey plasma 1·53 mu./l; range 0·2–2·6 mu./l). The administration of radioactive iodine (13–15 mCi Na131I) to these monkeys regularly induced hypothyroidism. The concentration of TSH in the plasma began to rise 3 weeks after the administration of radioactive iodine and reached a maximum and sustained level (30–300 mu./l) after 3 months, at which time the concentrations of T4 and T3 in the plasma were immeasurable. Other pituitary and adrenal functions were unaffected by the hypothyroid state.

Protracted sedation of normal monkeys with phencyclidine hydrochloride resulted firstly within hours in a decline in the concentration of T3 in the plasma without any corresponding alteration in the concentration of T4 and secondly, after 24 h, in a marked rise in the concentrations of both T4 and TSH. The connection between these changes is not clear but phencyclidine does not seem to be a suitable sedative for prolonged studies of the pituitary– thyroid system in normal monkeys. In contrast, sedation with phencyclidine did not affect the concentration of TSH in the plasma of hypothyroid monkeys provided that their body temperature was maintained near normal; the level of TSH fell if the monkey became cold when sedated and rose if it became overheated.

The rise in the level of TSH in the plasma of normal monkeys after administration of synthetic thyrotrophin releasing hormone (TRH) was less than that observed in man, although the effect of the increase upon the plasma T3 concentration was similar in the two species. The response of monkeys to incremental doses of TRH showed that a maximum response was obtained at a lower equivalent dose (1·0 μg/kg body weight) than in man, but administration of this dose (or a greater one) to hypothyroid monkeys caused only small increases in the concentration of TSH in the plasma.

The rapid intravenous injection of 0·2 or 2·0 μg T3 had no effect on the level of TSH in the plasma of hypothyroid monkeys, but 20 μg caused a progressive decline which reached a nadir 35% below the baseline at 5 h; the level of TSH returned to its basal value after 24 h. The raised concentration of TSH in the plasma of hypothyroid monkeys could be reduced to the normal range by the repeated administration of 20 μg T3 over 3 or 4 days.
PREPARATION OF ANTISERA TO THREE INDIVIDUAL RAT NEUROPHYSINS AND THEIR USE FOR RADIOIMMUNOASSAYS
Authors: MCPHERSON MARGARET A. , PICKERING B. T.
Published: December 2008

A number of antisera have been raised against individual rat neurophysins. One of these proved suitable for the specific radioimmunoassay of rat vasopressin–neurophysin and data validating such a use are presented. Use of this antiserum showed that vasopressin–neurophysin is present in rat neurohypophyses in equimolar amounts to vasopressin, while in the hypothalamus the assay detected twice as much neurophysin-like material as hormone. A number of partially specific antisera for rat oxytocin–neurophysin have been obtained and the best of these was raised against the minor neurophysin.
SEPARATION OF RELAXIN ACTIVITIES IN EXTRACTS OF OVARIES OF PREGNANT SOWS BY POLYACRYLAMIDE GEL ELECTROPHORESIS
Authors: OLIVER R. M. , FIELDS P. A. , LARKIN L. H.
Published: December 2008

Polyacrylamide gel electrophoresis has been employed to separate three fractions that have relaxin activity from crude extracts of ovaries of pregnant sows. Bioassays indicated that all fractions had the ability to inhibit spontaneous uterine contractions in vitro and to induce formation of interpubic ligaments in oestrogen-primed mice. The presence of the various fractions in crude extracts of sow ovaries was monitored with the polyacrylamide gel system on days 40, 70 and 100 of pregnancy. Both the total amount and the relative proportions of the fractions were found to change as pregnancy progressed.
RELATIONSHIP BETWEEN FOLLICLE-STIMULATING HORMONE, ANDROSTENEDIONE AND OESTRADIOL IN HUMAN FOLLICULAR FLUID
Authors: MCNATTY K. P. , BAIRD D. T.
Published: December 2008

The concentrations of FSH, oestradiol and androstenedione in the follicular fluid of normal and cystic human follicles were measured at different stages of the menstrual cycle. In addition, the number of granulosa cells in the follicles was determined.

In follicles in which FSH was detectable, the concentration of oestradiol was greater than that of androstenedione, irrespective of the stage of the cycle. In contrast, in those follicles in which FSH was undetectable and in all cystic follicles irrespective of the level of FSH, the concentration of androstenedione was greater than that of oestradiol. In follicles containing FSH there was a highly significant linear correlation between the number of granulosa cells and the concentration of follicular oestradiol (P < 0·001).

It is suggested that in human ovaries up to 90% of the oestradiol in follicular fluid may originate from the granulosa cells.
EFFECTS OF OVARIAN STEROIDS AND PROLACTIN ON THE CONTRACTILITY AND SODIUM PUMP SITE DENSITY OF GUINEA-PIG MYOMETRIUM
Authors: LIPTON A. , LEAH J. , PARKINGTON H. C.
Published: December 2008

Ovariectomized guinea-pigs were given a single dose of oestrogen or progestogen or the two steroids combined. Controls were given 0·9% saline. Four days after the injection, myometrial contractility in response to spasmogens was measured isometrically in isolated tissue baths, both before and after incubation in Kreb's solution with or without added prolactin. Further myometrial strips were also incubated with or without prolactin and the density of Na+/K+ ATPase 'pump' sites on the surface of the myometrial cell was estimated by labelling with tritiated ouabain.

Incubation with prolactin significantly reduced the contractility of myometrial tissue from guinea-pigs given saline alone, progestogen alone or progestogen plus oestrogen, but not in tissue from animals pretreated with oestrogen. When myometrial strips from animals pretreated with oestrogen or progestogen were incubated without prolactin in the medium, there was a significant increase in the density of pump sites compared with the number in saline-pretreated animals; incubation with prolactin did not further modify this effect. When both steroids were administered together there was a significant increase only when prolactin was present in the incubation medium. There was also a significant increase in the density of pump sites after incubation of myometrium from the control (saline-pretreated) animals in the presence of prolactin.
POSSIBLE ROLE OF GAMMA-AMINOBUTYRIC ACID SYNTHESIS IN THE MECHANISM OF DEXAMETHASONE FEEDBACK ACTION
Authors: ÁCS Z. , STARK E.
Published: December 2008

Specific inhibition of glutamic acid decarboxylase (GAD, EC 4.1.1.15; the main enzyme involved in the synthesis of γ-aminobutyric acid) by mercaptopropionic acid interferes with the effect of dexamethasone on both the resting and stress-induced secretion of ACTH. It is postulated that dexamethasone may, at least in part, inhibit the secretion of ACTH via the induction of GAD, thereby raising the level of γ-aminobutyric acid in the central nervous system.
VASOTOCIN BIOSYNTHESIS BY CULTURED PINEAL GLANDS FROM ADULT MALE RATS
Authors: PAVEL S. , GHINEA ELENA , GOLDSTEIN R. , MATULEVIČIUS V.
Published: December 2008

Institute of Endocrinology, Bucharest, Romania

(Received 20 September 1977)

We have previously reported that the pineal gland of the mammalian foetus, which comprises mainly specialized secretory ependymal cells (Anderson, 1965), synthesizes the nonapeptide arginine-vasotocin (AVT; Pavel, Dorcescu, Petrescu-Holban & Ghinea, 1973; Pavel, Goldstein, Ghinea & Calb, 1977). However, in contrast with the foetal pineal gland, the predominant cell type in the pineal gland of the adult mammal is the parenchymal cell or pinealocyte (Quay, 1965); there is a marked reduction in the number of ependymal cells and they are restricted to the pineal recess (Anderson, 1965), which shows the same secretory characteristics as the subcommissural organ (Palkovits, 1965). Since we have postulated the ependymal origin of mammalian AVT (Pavel, 1971; Pavel et al. 1973; Pavel, 1975; Pavel et al. 1977), it seemed worthwhile to investigate the synthesis of AVT in the adult pineal gland in order to elucidate, if only
EFFECT OF GLUCOSE AND AMINO ACIDS ON FOETAL RAT PANCREATIC GROWTH AND INSULIN SECRETION IN VITRO
Authors: DE GASPARO M. , MILNER G. R. , NORRIS P. D. , MILNER R. D. G.
Published: December 2008

Foetal rat pancreatic rudiments explanted on day 14 of gestation were grown for 6 days in organ culture in medium containing glucose (5·5 or 16·5 mmol/l) and amino acids at the 'physiological' or seven times the 'physiological' concentration. At the end of the period of culture, the rudiments were compared with normal 20-day foetal pancreas for DNA content, insulin concentration and quantitative morphology. The secretion of insulin from the explants was tested during 2 h incubations in medium containing glucose (5·5 or 16·5 mmol/l).

Amino acid, but not glucose enrichment of the culture medium stimulated cellular growth of the rudiment which remained, nevertheless, smaller than that occurring in vivo. All culture conditions produced a smaller proportion of exocrine cells and a greater proportion of β and duct cells than were found in normal 20-day foetal pancreas. Enrichment with amino acids favoured the development of exocrine cells at the expense of duct cells. Glucose had no effect on the development of any type of cell. Enrichment with amino acids resulted in a higher concentration of insulin per β cell but the highest value observed in vitro was only one sixth of that occurring in vivo. The absolute number of β cells cultured in amino-acid-enriched medium was twice that occurring in vivo. Culture in a glucose-enriched medium had no effect on the ability of the explant to respond to an acute glucose challenge during a short incubation, but the basal and glucose-stimulated release of insulin from cultures grown in amino-acid-enriched medium were significantly greater.
PLASMA TESTOSTERONE PROFILES IN MALE MACROPODID MARSUPIALS
Authors: LINCOLN G. A.
Published: December 2008

Serial blood samples were collected over a 3·5–8 h period from ten adult male macropodid marsupials belonging to five different species to study the pattern of testosterone secretion. The concentration of testosterone in the plasma ranged from 0·5 to 9·5 ng/ml, and in each animal the levels declined progressively during the study; this effect was attributed to the stress effects of handling. Injection of 5 μg synthetic luteinizing hormone releasing hormone induced a rapid and substantial increase in the level of testosterone.
EFFECTS OF SUBCUTANEOUS IMPLANTS OF PROGESTERONE ON THE INDUCTION AND DURATION OF SEXUAL RECEPTIVITY IN OVARIECTOMIZED RATS
Authors: HANSEN S. , SÖDERSTEN P.
Published: December 2008

Ovariectomized rats, pre-implanted with elastomer capsules containing oestradiol, became sexually receptive after exposure to progesterone (implanted in elastomer capsules) for 4–6 h. Implantation of progesterone capsules facilitated receptivity in oestradiol-implanted rats independently of both previous exposure to progesterone implants and the presence of progesterone at the time of implantation.

The duration of sexual receptivity in ovariectomized rats implanted with oestradiol and progesterone capsules was dependent upon the length of both the oestradiol and progesterone capsules, but the decline in sexual behaviour of receptive rats was independent of the continued presence of either oestradiol or progesterone. Repeated implantation of progesterone capsules at 6 hourly intervals prevented the decline of sexual receptivity.
EFFECTS OF DEXAMETHASONE ON THE RESPONSES OF LUTEINIZING HORMONE AND TESTOSTERONE TO TWO INJECTIONS OF LUTEINIZING HORMONE RELEASING HORMONE IN YOUNG POSTPUBERTAL BULLS
Authors: CHANTARAPRATEEP P. , THIBIER M.
Published: December 2008

Six young postpubertal bulls were studied in two experiments, 3 months apart. In experiment 1, three bulls received i.m. injections of dexamethasone (20 mg) and 5 h later these animals plus three control bulls received i.m. injections of luteinizing hormone releasing hormone (LH-RH, 250 μg). In experiment 2, the controls from experiment 1 received dexamethasone and the treated animals from experiment 1 acted as controls for experiment 2. All bulls also received an i.m. injection of 250 μg LH-RH on day 2 of each experiment. The concentrations of LH and testosterone in samples of jugular blood were determined by radioimmunoassay. There were no significant differences in the patterns of testosterone and LH release between the two experiments. On day 1, the response of LH to LH-RH was significantly (P < 0·05) reduced by dexamethasone, but on day 2 values in the control and treated groups were similar although significantly (P<0·05) lower than values on day 1. The response of testosterone to LH-RH was not affected by dexamethasone.

These results are discussed in terms of the site of action at which dexamethasone may act to depress the release of LH.
EFFECT OF OVARIAN STEROIDS ON PREPUTIAL GLAND ODOURS IN THE FEMALE RAT
Authors: THODY A. J. , DIJKSTRA H.
Published: December 2008

Sexually experienced male rats were used to test for whole body and preputial gland odours of female rats. The male rats clearly preferred whole body odours of intact female rats to those of preputialectomized female rats. The male rats also preferred the odour of preputial gland tissue of intact female rats to that of ovariectomized female rats and were especially attracted to the preputial gland odours of female rats in pro-oestrus and oestrus. The preputial gland odours of ovariectomized rats that had received oestradiol benzoate for 7 days were attractive to male rats, although similar treatment with progesterone was ineffective. However, a single injection of progesterone given 72 h after a single injection of oestradiol benzoate not only made ovariectomized rats receptive, but also made their preputial gland odours attractive to male rats.

The results suggest that the preputial gland of the female rat is responsible for odours that serve to attract sexually experienced male rats. Ovarian steroids, as well as controlling receptivity in the female rat, would also appear to control the production of sex attractants in the preputial gland. There was no relationship between the size of the preputial glands and their ability to attract male rats which suggests that preputial gland growth and production of sex attractants are not under the same hormonal control.
EFFECTS OF GONADAL STEROIDS AND CYCLOHEXIMIDE ON THE RELEASE OF GONADOTROPHINS BY RAT PITUITARY CELLS IN CULTURE
Authors: DEBELJUK LUCIANO , KHAR ASHOK , JUTISZ MARIAN
Published: December 2008

The effects of oestradiol-17β, testosterone and progesterone alone and together with cycloheximide on the basal and gonadotrophin releasing hormone (GnRH)-induced release of gonadotrophins were studied in cultured dispersed rat pituitary cells. In the control group (no steroid treatment), GnRH significantly stimulated the release of LH and FSH; cycloheximide partially inhibited this response, although it had no effect on the basal secretion of gonadotrophins. A dose of 5 ng oestradiol/ml had no significant effect on the response to GnRH; at a dose of 100 ng/ml the GnRH-induced release of LH was significantly augmented whereas the release of FSH was inhibited. Cycloheximide blocked the augmenting effect of oestradiol. The basal release of LH was slightly but significantly inhibited in response to 10 ng testosterone/ml and increased in response to progesterone (200 ng/ml). Testosterone at both dose levels and progesterone significantly inhibited the GnRHinduced release of LH and FSH and in testosterone and progesterone-treated groups, the response to GnRH was inhibited by cycloheximide, but not beyond the levels observed in the control group. It is concluded that steroids can act directly on the pituitary cells, that oestradiol stimulates the GnRH-induced release of LH and that cycloheximide blocks this stimulatory effect. Testosterone and progesterone, on the other hand, partially inhibit the response to GnRH.
LEVELS OF ARGININE-VASOPRESSIN AND OXYTOCIN IN THE PITUITARY GLAND AND INDIVIDUAL HYPOTHALAMIC NUCLEI OF THE GENETICALLY OBESE ZUCKER RAT
Authors: CROWLEY W. R. , GEORGE J. M. , JACOBOWITZ D. M.
Published: December 2008

Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Maryland 20014, U.S.A. and *Department of Medicine, Ohio State University, College of Medicine, Columbus, Ohio, U.S.A.

(Received 20 September 1977)

The genetically obese Zucker rat exhibits several endocrine disorders, including defects of the female reproductive system such as delayed puberty, irregular oestrous cycles, failure to mate and refractoriness to pseudopregnancy-inducing stimuli (Saiduddin, Bray, York & Swerdloff, 1973). Zucker rats show hyperdipsia, increased plasma osmolality and excrete a large volume of urine with a decreased osmolality and an increased protein content, suggesting a deficiency in the regulation of body fluids (York & Bray, 1971, 1973; Bray, York & Swerdloff, 1973). These considerations, plus the recent findings that in Zucker rats the concentration of noradrenaline is reduced in the hypothalamic paraventricular nucleus and increased in the median eminence (Cruce, Thoa & Jacobowitz, 1976), prompted us to measure levels of arginine-vasopressin (AVP) and
DIFFERENCES IN THE RELEASE OF MELANOCYTE-STIMULATING HORMONE IN VITRO BY RAT PITUITARY GLANDS COLLECTED AT VARIOUS TIMES DURING THE OESTROUS CYCLE
Authors: VIVAS ADRIANA , CELIS MARÍA ESTER
Published: December 2008

The release of melanocyte-stimulating hormone (MSH) into the medium during incubation and the pituitary tissue content of MSH were measured separately using pituitary glands collected from rats at various stages of the oestrous cycle. The MSH was measured by a biological assay using a synthetic α-MSH as standard. The release of MSH was maximal during the pro-oestrous phase and MSH content of the pituitary gland was highest during dioestrus. The influences of the tripeptide Pro-Leu-Gly-NH2, which inhibits MSH secretion in vivo, and of progesterone on the release of MSH in vitro were studied with tissue collected at various phases of the oestrous cycle. Pro-Leu-Gly-NH2 was effective in inhibiting MSH release both at pro-oestrus and oestrus but not at dioestrus. Progesterone overcame this inhibition.
PURIFICATION OF HUMAN PARATHYROID HORMONE: RECENT STUDIES AND FURTHER OBSERVATIONS
Authors: KEUTMANN H. T. , HENDY G. N. , BOEHNERT M. , O'RIORDAN J. L. H. , POTTS J. T.
Published: December 2008

During the isolation of human parathyroid hormone there is an extensive loss of immunoassayable hormone over the successive extraction steps, due in part to the presence of fragments that are soluble in 4% trichloroacetic acid. These fragments are derived from both the amino- and carboxyl-terminal regions of the hormone.

The hormonal fractions precipitated with trichloroacetic acid were further purified by gel filtration and ion-exchange chromatography. At the final ion-exchange purification step, some preparations of the hormone eluted in multiple fractions. When the various components were characterized separately by immunoassay, amino acid composition, enzymic cleavage and partial sequence analysis, they were found to be closely comparable, although the most acidic fraction contained a blocked terminal amino group.

Extraction of a number of batches of tissue permitted revision of the amino acid composition of human parathyroid hormone. Biosynthetic studies with labelled amino acids confirmed the absence of tyrosine and the presence of phenylalanine and threonine and localized these residues to definite regions of the molecule.
COMPARISON OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE SECRETION AFTER ELECTRICAL STIMULATION OF THE PREOPTIC PART OF THE HYPOTHALAMUS IN FEMALE RATS ANAESTHETIZED WITH ETHYL CARBAMATE OR SODIUM PENTOBARBITONE
Authors: DYER R. G. , TER HAAR M. B. , MAYES LINDA C.
Published: December 2008

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

(Received 17 January 1978)

For over 30 years, the method by which the brain regulates the secretion of gonadotrophic hormones has been studied by electrical stimulation of those parts of the central nervous system thought to be implicated in the control process. Much of the work has been performed on the female rat. In this species, anaesthetic doses of sodium pentobarbitone, administered immediately before the pro-oestrous 'critical period', block the preovulatory surge of luteinizing hormone (LH) for 24 h. The same treatment also reduces the early phase of the pro-oestrous secretion of follicle-stimulating hormone (FSH; Daane & Parlow, 1971). Electrical stimulation of the preoptic part of the hypothalamus can overcome this blocking effect and analysis of the optimum parameters required to restore normal secretion of gonadotrophins may give some insight into the endogenous process (e.g. Everett, 1965; Fink & Aiyer, 1974;