bluuebunny/crossref_metadata_2025 huggingface dataset:
FACTORS INFLUENCING THE SECRETION OF LUTEINIZING HORMONE AND OVULATION IN RESPONSE TO ELECTROCHEMICAL STIMULATION OF THE PREOPTIC AREA IN RATS
Authors: VELASCO M. E. , ROTHCHILD I.
Published: December 2008

Factors affecting luteinizing hormone (LH) secretion in response to stimulation of the preoptic area (POA) of the forebrain in rats were explored by determining serum LH levels after electrochemical stimulation of the POA. In rats made anovulatory by exposure to constant light (CLA rats), peak concentrations of LH in serum were found 2 h after stimulation with 5–15 mC, and 1 h after stimulation with 0·5–1 mC. The peak levels increased with increasing doses between 0·5 and 15 mC. The incidence of rats ovulating and the mean number of ovulations/rat were roughly proportional to the stimulating dose, but a plateau was reached between 5 and 10 mC. A threshold level of serum LH seemed to be necessary for ovulation, and the incidence of ovulations of six ova or more/rat increased with the increase in peak serum LH level.

Preoptic-roof section, which cuts dorsal afferents to the POA, enhanced the increase in serum LH in response to POA stimulation in CLA rats, while sodium pentobarbitone anaesthesia decreased the response. In both cases, the incidence of ovulation and the number of ovulations/rat were not different from values found in POA-stimulated control CLA rats showing the same peak serum LH level.

In normal cyclic rats the response of serum LH to stimulation was much greater on the morning of pro-oestrus than on that of oestrus; at prooestrus a second rise occurred between 17.00 and 19.00 h. Three days after ovariectomy the basal level of LH increased; these ovariectomized rats showed a small increase in response to a dose of 5 mC. Treatment with 20 μg oestradiol benzoate at the time of ovariectomy, however, resulted in a lowered basal LH level, but the peak response to 5 mC was almost as great as that found in similarly stimulated intact CLA rats. In intact males and in neonatally androgen-treated females the peak levels of serum LH in response to doses of 5 or 15 mC were equivalent to those in CLA females in response to doses of only 1–5 mC.
ANOMALOUS EFFECTS OF PROGESTERONE ON THE MATURATION AND SURVIVAL OF SPERMATOZOA IN THE EPIDIDYMIS OF THE GOLDEN HAMSTER
Authors: LUBICZ-NAWROCKI C. M.
Published: December 2008

The effect of progesterone on the maturation and viability of epididymal spermatozoa was tested in golden hamsters. The corpus epididymidis and ductus deferens were unilaterally ligated so that mature spermatozoa were isolated in the left cauda epididymidis whilst the contralateral epididymis was left intact. Fertility trials showed that after eight daily consecutive injections of progesterone (1·0 mg) spermatozoa on both sides retained normal fertilizing ability. Treatment with progesterone (0·25 and 1·0 mg) for 12 days, however, decreased the fertilization rate of retained spermatozoa to 44·4% and 0%, respectively, whereas fertilizing ability of spermatozoa from the intact cauda epididymidis remained unimpaired. In addition, progesterone (1·0 mg/day) did not influence passage of spermatozoa through the epididymis. Male hamsters treated with progesterone (0·25 mg/day) in combination with testosterone, 5α-dihydrotestosterone (5α-DHT) or 3α-androstanediol (all at 50 μg/day for 12 days revealed that 3α-androstanediol and 5α-DHT (but not testosterone) antagonized the antifertility effect of progesterone on retained epididymal spermatozoa. Furthermore, treatment of castrated hamsters with testosterone, 5α-DHT or 3α-androstanediol (100, 75 and 12·5 μg/day, respectively) in combination with progesterone (1·0 mg/day) showed that progesterone inhibited the stimulatory effect of testosterone but not that of 5α-DHT and 3α-androstanediol. The dissimilar effect of progesterone on fertilizing ability of spermatozoa in ligated and intact epididymides is discussed.
BIOSYNTHESIS OF ADRENOCORTICAL STEROIDS BY MONOTREMES: ECHIDNA (TACHYGLOSSUS ACULEATUS) AND PLATYPUS (ORNITHORHYNCHUS ANATINUS)
Authors: WEISS MAGDA
Published: December 2008

The formation of corticosteroids from [14C]pregnenolone or [14C]progesterone by platypus and echidna adrenal homogenates was studied. Corticosteroids were assayed in the peripheral blood plasma of the platypus. In the platypus nine labelled conversion products were identified. The combined yields of cortisol and cortisone averaged 70% and the combined yields of corticosterone and 11-dehydrocorticosterone averaged 14%. Aldosterone was identified in each experiment in yields below 0·1%. In the echidna ten labelled conversion products were identified. Those in highest yield were 11-deoxycorticosterone and 11-deoxycortisol which contained, respectively, an average of 35 and 11% of the added substrate. The yield of corticosterone was always less than 1% and that of cortisol was consistently lower. Aldosterone was identified in all cases in yields below 0·05%.

The yields of total 11β-hydroxylated conversion products from platypus adrenal exceeded 80%, whereas they were below 1% from glands of male echidnas and 7% from female echidna.

The yield—time curves for labelled conversion products from [14C]-pregnenolone indicated that the biosynthetic pathways of corticosteroid production by the monotreme adrenal are similar to those in eutherian mammals.

From stored endogenous precursors of a platypus adrenal incubated for 30 min, corticosteroids were formed in the following amounts (per 100 mg adrenal): cortisone, 5·1 μg; cortisol, 1·3 μg; 11-dehydrocorticosterone, 1·5 μg. In the peripheral plasma of platypus the concentration of combined cortisol and cortisone was 14 μg/100ml and the combined corticosterone and 11-dehydrocorticosterone was 1·8 μg. The mean ratio of adrenal weight (mg) to body weight (kg) was 39·5 in the echidna and 257 in the platypus. The marked contrast in adrenocortical biosynthetic capacity of the two monotremes is discussed and a comparison of the results is made in relation to higher mammals.
A QUANTITATIVE STUDY OF GENETIC DIFFERENCES IN THE INCIDENCE OF OESTRUS, OVULATION AND PLASMA LUTEINIZING HORMONE CONCENTRATION IN THE SHEEP
Authors: LAND R. B. , PELLETIER J. , THIMONIER J. , MAULÉON P.
Published: December 2008

Seasonal variation in the ovulation rate and incidence of ovulation was examined in 15 Romanov and 15 Solognote ewes by endoscopy. The ovulation rate of the Romanovs was found to be related to the incidence of ovulation (r = 0·78) and to the incidence of oestrus as measured by daily teasing with aproned entire rams (r = 0·83). The ovulation rate of the Romanovs was greater than that of the Solognotes, and was 2·6 and 1·1 corpora lutea in the two breeds, respectively, in the autumn. The durations of the breeding season and of oestrus of the Romanovs exceeded those of the Solognotes.

The characteristics of the preovulatory discharge of luteinizing hormone (LH) and the daily plasma LH levels were studied by radioimmunoassay in the Romanov and Solognote ewes and in ewes of the Berrichon and Berrichon × Romanov breeds. The interval between the onset of oestrus and the discharge of LH was greater in the Romanovs (17·6 h) than in the other breeds (mean = 7·5 h). The total release of LH, however, was not related to the number of corpora lutea formed.
THE EFFECTS OF SYNTHETIC GONADOTROPHIN RELEASING FACTOR ON THE RELEASE OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE FROM OVINE PITUITARY TISSUE IN VITRO
Authors: CRIGHTON D. B.
Published: December 2008

A synthetic decapeptide gonadotrophin releasing factor was tested for effects on the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) using an ovine pituitary incubation system. The effects of other synthetic peptides used at similar doses were studied.

The synthetic decapeptide consistently provoked significant increases in the LH content of the incubation medium at doses equal to or in excess of 0·5 ng/flask (0·2 ng/ml medium). Significant increases in the FSH content of the incubation medium at doses equal to or in excess of 0·25 ng/flask (0·1 ng/ml medium) were observed. The other synthetic peptides failed to influence LH or FSH release in vitro even at a dose 20–40 times greater.

The results demonstrate that the decapeptide releases both LH and FSH from sheep pituitary tissue, suggesting that it may play a role in the release of both hormones in vivo in the sheep.
ANALYSIS OF THE ZINC-BINDING PROTEIN DERIVED FROM THE HUMAN BENIGN HYPERTROPHIC PROSTATE
Authors: HEATHCOTE J. G. , WASHINGTON R. J.
Published: December 2008

Preliminary analysis of the zinc-binding protein isolated from the human benign hypertrophic prostate gland was carried out using a micro method. The most interesting feature of the amino acid composition of the protein hydrolysate appears to be the large molar proportion of histidine which is present. This might account for the binding of divalent cations.
ROLE OF THE ADRENAL CORTEX IN THE ADAPTATION OF THE MONOTREME TACHYGLOSSUS ACULEATUS TO LOW ENVIRONMENTAL TEMPERATURE
Authors: AUGEE M. L. , McDONALD I. R.
Published: December 2008

When exposed to a low ambient temperature of 5 °C, adrenalectomized echidnas were able to increase their metabolic rate and to maintain their body temperature within the normal range for no more than 48 h — less than 12 h in five out of six animals. Thereafter, activity, metabolic rate, cardiac rate and body temperature declined and the animals became torpid.

When maintained with daily i.m. injections of 1–2 mg cortisol acetate/kg, adrenalectomized echidnas maintained activity and normal body temperature in the cold environment indefinitely. When cortisol injections were withheld and exposure to cold continued, normal body temperature was maintained for a further 10 days, after which it declined rapidly.

The onset of torpor was always preceded by a marked fall in plasma glucose concentration, as occurred in normal, but fasted, echidnas after prolonged exposure to cold. Both cortisol and corticosterone have glucocorticoid activity in echidnas, and torpor was prevented in adrenalectomized echidnas by preventing the fall in plasma glucose with either intermittent injections or constant rate infusions of glucose solutions.

The adrenal glands of normal echidnas exposed repeatedly to low environmental temperatures showed marked hypertrophy and increase in lipid content.

It is concluded that adrenocortical secretions are necessary for the metabolic response to cold stress in these prototherian mammals, and a major role of the corticosteroids is in maintenance of normal blood glucose concentrations, presumably by enhancing hepatic gluconeogenesis.
PROPERTIES OF A SIMPLIFIED BIOASSAY FOR ADRENOCORTICOTROPHIC ACTIVITY USING THE STEROIDOGENIC RESPONSE OF ISOLATED ADRENAL CELLS
Authors: LOWRY P. J. , McMARTIN C. , PETERS JUDY
Published: December 2008

A reproducible method for isolating intact cells from the adrenal glands of a small number of rats (four to six) is described. The incubation conditions and fluorometric corticosteroid assay were modified to enable a large number of incubations to be carried out with each batch of cells. Linear regression analysis of log-dose—response curves for adrenocorticotrophin (ACTH) analogues yields potency ratios with 95% confidence limits which are usually less than ± 20%. The ED50 of the assay is about 50 pg/ml for natural ACTH and 7 pg/ml for corticotrophin-(1–24)-tetracosapeptide. Insulin and prostaglandin E2 had no effect on the steroidogenic response to ACTH while cyclic AMP at high doses was steroidogenic but gave a much steeper log-dose—response curve than ACTH. α- and β-melanocytestimulating hormone (MSH) were both agonists but only at concentrations 1 × 106 times higher than those of ACTH. Cells isolated from rabbit adrenals were similar to those from the rat in their responsiveness to ACTH but were unresponsive to amounts of MSH sufficient to stimulate rat adrenal cells.
SOME PROPERTIES OF THE HYDRO-OSMOTIC VASOPRESSIN 'EFFECTOR': INTERACTIONS WITH N-ETHYLMALEIMIDE
Authors: BENTLEY P. J.
Published: December 2008

N-Ethylmaleimide (NEM) prevents the hydro-osmotic response to vasopressin. It has no significant effects on osmotic water movement in the absence of the hormone. The hydro-osmotic effects of cyclic AMP and hyperosmotic mannitol solutions are also reduced by NEM.

After exposure to vasopressin, cyclic AMP, or hyperosmotic mannitol, the osmotic permeability declines to the preincubation level but after exposure to NEM this was prevented. This effect was seen after exposure to 10−4 and 10−5 m-NEM, i.e. concentrations that do not alter the onset of the response.

The increased osmotic permeability after treatment with NEM is not due to a non-specific effect caused by a 'fixation' of the tissue in a distorted condition (such as occurs during rapid water transfer) since it was seen even after treatment of the tissue under conditions when no osmotic water movement was occurring, that is with iso-osmotic Ringer solution on both sides.

The effect of NEM could not be mimicked by exposure of the bladder to 20 mm-Ca2+, 0·1 mm-Zn2+ or 1 mm-l-cysteine.
THE EPISODIC NATURE OF CHANGES IN OVINE PLASMA CORTISOL LEVELS AND THEIR RESPONSE TO ADRENALINE DURING ADAPTATION TO A NEW ENVIRONMENT
Authors: McNATTY K. P. , THURLEY D. C.
Published: December 2008

Large and rapid variations were found in the plasma cortisol levels of housed and cannulated sheep. Adrenaline injected i.v. caused increased plasma levels of cortisol that were proportionate to the dose. This response of cortisol to adrenaline was larger when sheep were newly housed, than when the sheep had been housed and sampled for 2 weeks. Response to adrenocorticotrophin also diminished over 2 weeks. Dexamethasone abolished the response to adrenaline. Tyrosine and DOPA had little effect on cortisol levels, dopamine and noradrenaline had some effect, but none had as great an effect as adrenaline.
METABOLISM OF RNA AND PYRIMIDINE NUCLEOTIDES IN THE UTERUS DURING THE EARLY DECIDUAL CELL REACTION
Authors: MILLER B. G.
Published: December 2008

Changes in the metabolism of pyrimidine 5′-nucleotides and RNA in the mouse uterus during the oil-induced decidual cell reaction were investigated. During the first 20 h after the intraluminal injection of 10 μl sesame oil the amounts of HClO4-soluble nucleotides and uridine 5′-nucleotides in the treated horn increased by 55% and 115%, respectively. During the same interval RNA increased by 101%, while the increase in protein was much smaller, and the amount of DNA remained almost unchanged.

Doses of [2-14C]uridine, [5-3H]cytidine and [5-3H]orotic acid were administered to mice 20 min before killing. After [2-14C]uridine injection the specific activity of the uridine 5′-nucleotide fraction 20 h after the oil stimulus had not changed, while the specific activity of RNA increased by 43% during the 20-h interval. Similar results were obtained when [5-3H]-cytidine was injected. In contrast, after an injection of [5-3H]orotic acid the specific activities of both the uridine 5′-nucleotide and RNA fractions decreased with increasing time after the intraluminal injection of oil. When approximate rates of RNA synthesis were calculated independently from the data for [2-14C]uridine and [5-3H]orotic acid incorporation in these two fractions, the results agreed well, and indicated that the rate of synthesis of RNA in the decidualizing uterus increased by 64% and 163% at 8 and 20 h respectively after the intraluminal administration of sesame oil.
INFLUENCE OF THE ADRENAL GLAND ON PROSTATIC ACTIVITY IN ADULT RATS
Authors: MOBBS B. G. , JOHNSON I. E. , CONNOLLY J. G.
Published: December 2008

The weight of the accessory sex glands, and the citrate and nucleic acid content of the ventral prostate (VP) glands, were examined in animals which had been adrenalectomized 30 days previously and in intact control rats. Adrenalectomy greatly reduced the citrate content, but did not affect the nucleic acid content of the VP. It was concluded that the adrenals stimulated prostatic function rather than growth.

The concentration of radioactivity in the accessory sex glands of adrenalectomized and/or castrated animals after the injection of [3H]testosterone was compared with that in sham-operated controls. Radioactivity was related to the DNA content of the VP of the four groups. It was concluded that adrenalectomy facilitated the uptake and/or retention of androgen.

[3H]Corticosterone was not retained by any of the accessory sex glands of animals adrenalectomized and castrated 2 days previously. It seems unlikely that the glands should be considered 'target organs' for corticosterone in the accepted sense of the term, but it is suggested that corticosteroids may help to maintain the balance between differentiation and growth in the VP by influencing the metabolism of androgens by the prostate gland.
MASCULINIZING EFFECTS OF A TESTICULAR INTERSTITIAL CELL TUMOUR GRAFT ON FEMALE RATS
Authors: POURREAU-SCHNEIDER NATALIE
Published: December 2008

An androgen-producing testicular interstitial cell tumour of rats was grafted into intact and spayed female rats. The tumour inhibited luteinization, produced follicular atresia, stimulated the uterine myometrium and endometrium, and caused vaginal mucus formation. Anoestrus set in and mating behaviour disappeared, rendering gestation impossible. After surgical removal of the tumour, the masculinization disappeared rapidly. With the return of vaginal oestrus (sometimes only 4 days after removal of the tumour) most of the rats mated and gave birth to normal young. When a palpable nodule reappeared, the reproductive function was again lost. The tumour produced similar changes in the target organs of spayed females. The inhibitory action of the endocrine tumour on pituitary gonadotrophic hormone production was shown by the absence of castration cells in the pituitary of the tumour-bearing spayed female.
THE EFFECT OF STILBOESTROL ANALOGUES ON THE METABOLISM OF STEROIDS BY THE TESTIS AND PROSTATE OF THE RAT IN VITRO
Authors: DANUTRA VARAPAN , HARPER MAUREEN E. , GRIFFITHS K.
Published: December 2008

Male Sprague—Dawley rats were injected (i.m.) daily for 10 days with 100 μg of either oestradiol-17β, diethylstilboestrol (DES), dl-dihydrodibutylstilboestrol (dl-DHBS) or meso-dihydrodibutylstilboestrol (meso-DHBS) in 0·2 ml sesame oil. After 10 days, the testicular tissue was removed and incubated simultaneously with [7α-3H]dehydroepiandrosterone and [4-14C]17α-hydroxyprogesterone. Less testosterone was synthesized by the testicular tissue from animals treated with oestradiol-17β, DES and meso-DHBS than by the controls or animals treated with dl-DHBS. The decreased synthetic activity was related to the decreased activity of both the 17β-hydroxysteroid dehydrogenase and 17α-pregnene-C17, 20-lyase enzyme systems.

Prostatic tissue was also incubated with [7α-3H]testosterone. Administration of DES, oestradiol-17β or meso-DHBS increased the metabolism of testosterone by the prostatic tissue with a marked effect on the 5α-reductase enzyme system.
PITUITARY SECRETION OF PROLACTIN, LUTEINIZING HORMONE AND FOLLICLESTIMULATING HORMONE IN ADULT FEMALE RATS TREATED NEONATALLY WITH OESTROGEN
Authors: NAGASAWA HIROSHI , YANAI REIKO , KIKUYAMA SAKAE , MORI JUNICHI
Published: December 2008

The serum and pituitary levels of prolactin, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were determined by radioimmunoassay in adult female rats treated neonatally with oestrogen and were compared with levels in normal cyclic rats at 90, 150 and/or 180 days of age. The serum level of prolactin was significantly higher and its pituitary content and concentration were lower in oestrogenized rats than in control rats at early prooestrus and on the 2nd day of dioestrus. The level of LH in the serum of oestrogenized rats was similar to the level in control rats at pro-oestrus and was higher than that of the controls at dioestrus. Pituitary levels of LH were lower in oestrogenized rats than in control rats at both pro-oestrus and dioestrus. The serum and pituitary levels of FSH in the oestrogenized rats were intermediate between the values found at dioestrus and at pro-oestrus in the controls. The results demonstrate that the pituitary of the neonatally oestrogenized female rat constantly secretes considerable amounts of these hormones.
EFFECTS OF TESTOSTERONE AND FOLLICLE-STIMULATING HORMONE ON SPERMATOGENESIS IN ADULT MICE DURING TREATMENT WITH OESTRADIOL
Authors: DAVIES A. G. , COUROT M. , GRESHAM P.
Published: December 2008

Adult male mice were treated with oestradiol for 10 weeks and for the last half of this period they were given relatively large daily doses of testosterone and highly purified human pituitary follicle-stimulating hormone (FSH), singly and in combination.

Oestradiol treatment reduced and testosterone restored the yields of mature (step 16) spermatids from round (step 7) spermatids, round spermatids from pachytene primary spermatocytes and pachytene from preleptotene spermatocytes. At the dose level used FSH was not effective alone but appeared to augment the effect of testosterone on the yield of round spermatids from preleptotene spermatocytes.
EFFECT OF ERGOT ALKALOIDS UPON LUTEAL FUNCTION IN THE FERRET
Authors: BLATCHLEY F. R. , DONOVAN B. T.
Published: December 2008

Since ergocornine is believed to block prolactin secretion in several species, the drug was given to pseudopregnant ferrets in an attempt to define the rôle of the hormone in the control of luteal function. The effects of ergocornine, and of the more potent analogue 2-bromo-α-ergocryptine, were followed by assay of the progestin content of the blood and histological examination of the ovaries. Ergocornine was given at the time of induction of pseudo-pregnancy by an injection of luteinizing hormone (day 0), on day 1, days 0 and 1, days 0, 2, 4 and 6, or day 7, and 2-bromo-α-ergocryptine on days 0, 1, 2 and 3, or 7, 8, 9 and 10. A lasting depression of plasma progestin content occurred after the injection of ergocornine on days 0 and 1, perhaps because of interference with the formation of the luteal bodies. Other injection régimes had little effect on progestin secretion.
CENTRAL NERVOUS BLOCKADE OF OESTRADIOL-STIMULATED RELEASE OF LUTEINIZING HORMONE IN THE EWE
Authors: RADFORD H. M. , WALLACE A. L. C.
Published: December 2008

The injection of oestradiol benzoate (OB) into the ovariectomized ewe induced a biphasic response in circulating luteinizing hormone (LH). There was a fall in concentration during the first 8–12 h after injection, and then a rapid increase in concentration during the next 12 h. Sodium pentobarbitone anaesthesia, begun either at the time of injection of OB, or 8 or 16 h later, did not affect the first phase, but prevented the second phase of this response. The injection of synthetic luteinizing hormone releasing factor caused a release of LH that was similar both in anaesthetized and conscious ewes. The results indicated a non-nervous site for the inhibitory action of oestrogen on circulating LH, and a central nervous site of action of oestrogen in stimulating LH release.
PITUITARY CONTENT AND PLASMA LEVELS OF GROWTH HORMONE IN FOETAL AND WEANLING RATS
Authors: RIEUTORT M.
Published: December 2008

Pituitary and plasma growth hormone were measured in foetal and weanling rats. Growth hormone was first detected in the pituitary (66 ± 8 ng) and plasma (26 ± 2 ng/ml) of 19·5-day-old foetuses. Pituitary growth hormone content increased rapidly up to the end of gestation and after birth. Plasma levels were high after 21·5 days of gestation (147 ± 8 ng/ml) and a further increase was observed at birth. The plasma growth hormone level fell to that of adult levels 5–10 days after birth. An early modulation of growth hormone secretion is discussed since newborn rats aged 2 h showed a rapid decrease in plasma levels at 25 °C while there was no such decrease in newborn animals maintained at 37 °C.
THE EFFECT OF INTRAVENTRICULAR ADMINISTRATION OF 6-HYDROXYDOPAMINE ON PHOTO-INDUCED TESTICULAR GROWTH IN JAPANESE QUAIL
Authors: DAVIES D. T. , FOLLETT B. K.
Published: December 2008

The intraventricular infusion into quail of 6-hydroxydopamine, a drug known to cause degeneration of adrenergic neurones, prevented the subsequent photoperiodic stimulation of testicular growth. This effect was seen in about 20% of the treated birds only but in these, the testicular weight and histology as well as the plasma luteinizing hormone (LH) concentration were similar to the same parameters in non-photostimulated birds. 6-Hydroxydopamine inhibited plasma LH significantly within one day of infusion. The results implicate adrenergic pathways in the photoperiodic control of reproduction.
THE HORMONAL INDUCTION OF OVULATION OR OF LUTEINIZATION IN THE INTACT OR HYPOPHYSECTOMIZED GUINEA-PIG
Authors: DONOVAN B. T. , LOCKHART A. N.
Published: December 2008

The induction of ovulation and follicular luteinization in the guinea-pig by follicle-stimulating (FSH) and luteinizing (LH) hormones was studied in the intact and in the hypophysectomized animal. Follicular luteinization could be produced as early as day 8 of the oestrous cycle by 250 mu. FSH, but not before day 10 by 400 mu. LH, while either FSH or LH caused ovulation when given on day 12 or later. When injected on day 13, luteinization could be induced with 62·5 mu. FSH or 200 mu. LH. Luteinization of follicles also occurred when 400 mu. LH or 250 mu. FSH was given immediately after hypophysectomy on day 13, but when hormone treatment was delayed for 4·5 h after surgery the incidence of luteinization was greatly reduced. Combined treatment with 200 mu. LH and 125 mu. FSH, by contrast, readily caused luteinization. It is concluded that ovarian follicles are resistant to luteinization during the first half of the oestrous cycle and that the response to LH late in the cycle is dependent upon the maintenance of follicular responsiveness by endogenous gonadotrophin.
DEVELOPMENTAL STUDY OF PITUITARY-ADRENOCORTICAL RESPONSE IN MICE: PLASMA AND BRAIN CORTICOSTERONE DETERMINATION AFTER HISTAMINE STRESS
Authors: KAKIHANA RYOKO , BLUM STEPHEN , KESSLER SEYMOUR
Published: December 2008

The development of the pituitary-adrenocortical stress response was studied in CBA/J × DBA/2J hybrid mice. On the basis of the plasma corticosterone response 15 min after a subcutaneous injection of histamine dihydrochloride (50 mg/kg), the first three neonatal weeks could be divided into stress-nonresponsive (3–211 days) and stress-responsive 16–21 days) periods. During the former period, corticosterone levels in the brains of the non-stressed control mice were 63% higher than those of comparable mice during the latter period. Histamine stress significantly increased corticosterone concentrations in the brain during both these periods, but the increase was much greater (88%) during the stress-responsive period than during the stress-nonresponsive period (29%).
PURIFICATION AND CHARACTERIZATION OF CAPRINE PROLACTIN
Authors: McNEILLY A. S. , ANDREWS P.
Published: December 2008

Prolactin was isolated from frozen goat pituitary glands by a simple procedure involving gel filtration and chromatography on DEAE-cellulose. The major product (yield, 2·5 mg/g pituitary tissue) had high pigeon crop sac-stimulating activity (27 i.u./mg) and was free of growth hormone and other pituitary hormones. The molecular weight was similar to that of ovine prolactin.

Caprine prolactin was immunologically indistinguishable from ovine prolactin in radioimmunoassays, in which ovine prolactin antiserum and either ovine or caprine prolactin labelled with 125I were used.

The results indicate that caprine and ovine prolactin are closely related and that radioimmunoassay for ovine prolactin may be used to estimate caprine prolactin in serum.
OESTRADIOL-17β AND TESTOSTERONE IN RAT TESTIS TISSUE: EFFECT OF GONADO-TROPHINS, LOCALIZATION AND PRODUCTION IN VITRO
Authors: de JONG F. H. , HEY A. H. , van der MOLEN H. J.
Published: December 2008

Concentrations of oestradiol-17β and testosterone were estimated in testicular tissue from intact and hypophysectomized rats. Within 30 min after intravenous injection of human chorionic gonadotrophin (HCG) or follicle-stimulating hormone (FSH) to intact animals the tissue concentrations of both steroids were not significantly changed. Prolonged s.c. administration of HCG (5 days) caused an increase in the tissue levels of both steroids, which was further increased when the prolonged treatment was followed by an intravenous injection with this trophic hormone. FSH had no influence on tissue concentrations of oestradiol-17β or testosterone in hypophysectomized rats.

Assay of separated seminiferous tubules and interstitial tissue indicated that oestradiol-17β and testosterone were mainly localized in the interstitial tissue. Incubations of these constituents showed that oestradiol-17β was produced in the seminiferous tubules, while testosterone was produced in the interstitial compartment.
EFFECTS OF THYROIDECTOMY ON THE CHEQUERED WATER-SNAKE, NATRIX PISCATOR
Authors: THAPLIYAL J. P. , GUPTA S. C. , GARG R. K.
Published: December 2008

Thyroidectomy decreased the body weight and the height of the cells lining the sex-segment of the kidney of the Chequered Water-snake, Natrix piscator maintained at 30 °C; at 40 °C the liver, kidney and gonad were also affected. At the higher temperature, thyroidectomy influenced significantly protein, carbohydrate and lipid metabolism. At 30 °C, only a decrease in the rate of esterification of the free fatty acids in the liver and of their release from the adipose tissue was observed. The difference in the effect of thyroidectomy at 30 and 40 °C is explained by suggesting that thyroid activity was low in animals maintained at the lower temperature and high in those kept at the higher temperature.
A RE-EXAMINATION OF THE TADPOLE IN METAMORPHIC STASIS AS A RECIPIENT IN A BIOASSAY FOR THYROID-STIMULATING HORMONE
Authors: CHING MELVIN
Published: December 2008

The tadpole, in metamorphic stasis, has been used as a bioassay recipient for thyroid-stimulating hormone (TSH). The validity of its use for this purpose, however, has not been tested critically, particularly with respect to the effect of other hormones, most notably, growth hormone (GH) and luteinizing hormone (LH). Growth hormone has been shown to influence thyroid function and LH is a common contaminant of pituitary TSH preparations. Tadpoles of Rana pipiens, arrested at a particular metamorphic stage, received various concentrations of LH alone, a combination of doses of GH and TSH, or GH and rat anterior pituitary extract. Growth hormone was ineffective in re-inducing metamorphosis in 78% of cases, whereas LH stimulated metamorphosis in the tadpoles.
PLASMA CORTICOSTERONE CONCENTRATIONS AND PITUITARY PROLACTIN CONTENT IN LATE PREGNANCY AND THEIR WITHIN-DAY FLUCTUATIONS IN THE RAT
Authors: ÔTA KATUAKI , ÔTA TAKAO , YOKOYAMA AKIRA
Published: December 2008

Levels of plasma corticosterone and of pituitary prolactin were studied in the mornings (10.00–10.30 h) and evenings (17.00–18.00 h) during the last week of pregnancy in the rat. Morning levels of plasma corticosterone started to rise on day 19 and reached a peak on day 21. The concentration of corticosterone in plasma on the morning of day 21 was about 2·3 times higher than that on day 15. Both content and concentration of prolactin in the pituitary began to fall on the morning of day 19 of pregnancy and the minimum values for both content and concentration were reached on the morning of day 21. Plasma corticosterone concentration and pituitary prolactin content measured in the evening, however, remained high throughout the period examined and there were no appreciable changes in the levels at the different stages of pregnancy.

The results obtained on day 22 of pregnancy, the expected day of parturition, indicated that a surge of pituitary prolactin secretion and a temporary depression of corticosterone secretion occurred at about the time of parturition.
INDUCTION BY GONADAL HORMONES OF HEPATIC LIPOGENIC ENZYME ACTIVITY IN IMMATURE PULLETS
Authors: BALNAVE D. , PEARCE J.
Published: December 2008

The effect of gonadal hormone administration on hepatic lipogenic enzyme activity, and some physiological parameters was investigated in immature pullets.

Pullets (aged 4 weeks) were allocated to treatment groups and received intramuscular injections of oestradiol, testosterone, progesterone or oestradiol + testosterone (all in 0·3 ml corn oil) or corn oil alone (control group). There was no evidence of any hormone-induced changes in the specific activity of hepatic ATP-citrate lyase 1, 3, 6 and 12 h after hormone administration. NADP-malate dehydrogenase exhibited significant variations in specific activity over this period of time and it is probable that these changes reflected an increased requirement for NADPH for synthetic purposes in hormone-treated birds.

The effect of 1, 2, 4 and 9 days of hormone administration was also investigated. In testosterone-treated birds there were significant increases in the specific activities of both lipogenic enzymes after 1 day of hormone treatment whereas for birds receiving oestradiol the maximum specific activities were found on the second day. Similarly, the liver lipid content of oestradioltreated birds showed a substantial increase on day 2. After 9 days of hormone administration no significant differences in the specific activity of ATP-citrate lyase were observed between treatments but the specific activity of NADP-malate dehydrogenase was significantly reduced in oestradiol- or mixed hormone-treated birds; it is possible that the reduced enzyme activity is associated with a reduced requirement for NADPH and in this connexion there were no further increases in liver lipid content or liver weight after 4 days of hormone administration. The liver RNA:DNA ratio tended to be greatest in birds receiving oestradiol or oestradiol + testosterone.

Studies utilizing inhibitors of RNA and protein synthesis showed that such compounds abolished the increases in lipogenic enzyme activity following hormone administration suggesting that these increases were hormone-induced effects.

These results are discussed in relation to the effects of the various hormones on liver lipid metabolism and also in relation to the situation in the mature laying hen.
RELATIONSHIP BETWEEN THE SEX OF THE FOETUS AND THE AMOUNT OF HUMAN CHORIONIC GONADOTROPHIN IN PLACENTAE FROM THE 10TH TO THE 20TH WEEK OF PREGNANCY
Authors: WIDE LEIF , HOBSON BRUCE
Published: December 2008

Sixty-seven placentae were obtained by abdominal hysterotomy, between the 10th and 20th weeks of pregnancy, from women who had had a therapeutic abortion. Human chorionic gonadotrophin (HCG) in extracts from these placentae was assayed by a biological and a radioimmunological method. When the concentration and total amount of HCG in placentae was related to the sex of the foetus no significant difference between 'male' and 'female' placentae was found. This is contrary to findings at term when there is a significant (P < 0·005) difference in the concentration of HCG/g and/placenta in 'male' and 'female' placentae. The amount of biologically active HCG in 'female' placentae significantly increased but was unchanged in 'male' placentae when the periods 10–20 and 37–41 weeks were compared. Similarly, the amount of immunologically active HCG in 'female' placentae was unchanged but in 'male' placentae it decreased. The possible reasons for the different results obtained with the biological and the radioimmunological assays are discussed.
EFFECT OF NEONATAL ADMINISTRATION OF DIFFERENT ANDROGENS IN THE FEMALE RAT: CORRELATION BETWEEN AROMATIZATION AND THE INDUCTION OF STERILIZATION
Authors: McDONALD P. G. , DOUGHTY CYNTHIA
Published: December 2008

Groups of neonatal female rats were treated once daily for the first 5 days of life with oil, 1 μg testosterone propionate, or 10 μg of one of the following androgens; androstenedione-enol-propionate, 19-hydroxytestosterone propionate, 5α-dihydrotestosterone propionate, 5α-androstanedioneenol-propionate, androsterone propionate, 5α,3α-androstenediol dipropionate, 5α,3β-androstanediol dipropionate. A final group was given 100 μg 5α,3β-androstanediol dipropionate as a single injection on day 1 of life. Only those androgens which are aromatizable were effective in preventing cyclicity whilst the 5α-reduced androgens were ineffective or only partially effective. All treatments significantly increased the ano-genital distance compared with oil-treated control animals. There were no clear relationships between aromatization and the effects on suppressing sexual behaviour after oestrogen and progesterone treatment. The results are discussed in terms of the role of aromatization in the hormonal control of hypothalamic differentiation.
DIURNAL VARIATIONS IN THE ACTION OF INSULIN ON MUSCLE GLYCOGEN SYNTHESIS
Authors: GAGLIARDINO J. J. , PESSACQ MARÍA TERESA
Published: December 2008

The effect of a single dose of insulin i.u./kg, i.p.) injected every 4 h during a 24-h period was studied in normal mice. The glycogen content of the diaphragm muscle and serum glucose levels were determined every 15 min throughout a period of 60 min after the hormone injection. Although insulin always produced an increase in glycogen and a decline in serum glucose, neither the sequential changes observed during the 60 min after injection nor the magnitude of these changes were constant throughout the 24 h of the day. The two circadian variations in the action of insulin (on glycogen and glucose) did not display any well-defined relationship, i.e. the most marked decline in glucose was not followed by a correspondingly marked increase in glycogen. These observations suggest that the results obtained from the administration of a single dose of insulin at an arbitrary time of day might be misleading. The circadian variations found could represent another component of the complex homeostatic mechanisms in which insulin is involved.
METABOLIC FATE OF HUMAN CALCITONIN IN THE DOG
Authors: CLARK MARY B. , WILLIAMS CLAIR C. , NATHANSON BRENDA M. , HORTON RIMA E. , GLASS H. I. , FOSTER G. V.
Published: December 2008

The metabolism of human calcitonin by the liver and kidneys was studied in dogs. Hormone was infused into anaesthetized animals and plasma samples for radioimmunoassay collected from catheters placed in the aorta, hepatic and renal veins. Compared with arterial levels, 30·1 ± 3·3 (S.E.M.)% less hormone was measured in renal vein samples and 8·3 ± 3·0% less in hepatic vein samples. From estimates of blood volume and renal blood flow, it was calculated that the kidneys removed 8% of the circulating hormone/min. Further studies demonstrated that (i) removal of the kidneys prolonged the disappearance of the hormone, (ii) less than 0·3% of infused stable hormone appeared in urine, (iii) radioactivity in kidneys of dogs infused with 131I-labelled calcitonin was concentrated in the cortex, (iv) this uptake of radioactivity was decreased by prior perfusion with stable hormone, and (v) unlabelled hormone disappeared when incubated with homogenates of kidney. From these findings, it is concluded that the kidney plays the major role in the clearance of human calcitonin from the blood and that this clearance is due probably to enzymic degradation.
RELATIONSHIP OF PROLACTIN AND GROWTH HORMONE TO MAMMARY FUNCTION DURING PREGNANCY AND LACTATION IN THE C3H/ST MOUSE
Authors: SINHA Y. N. , SELBY F. W. , VANDERLAAN W. P.
Published: December 2008

The secretion of prolactin and growth hormone (GH) in C3H/St mice, a strain having a high incidence of spontaneous mammary tumours, was studied at intervals throughout pregnancy and lactation. Serum and pituitary concentrations of prolactin and GH were measured by specific, homologous radioimmunoassays. Crude extracts of mouse placentae did not cross-react in these assays, indicating that the assay systems measured prolactin and GH of hypophysial origin. Except for a small, brief rise on day 5, prolactin secretion was low throughout most of pregnancy; the serum concentration of prolactin increased appreciably only near term. During lactation, prolactin in serum averaged from 5 to 10 times basal levels (30–40 ng/ml) until day 15 of lactation, after which the concentration declined. In contrast, GH secretion increased early in pregnancy, the concentration rising both in serum and in the pituitary gland consistently after day 5. The serum concentrations reached 3–10 times basal levels (8–12 ng/ml) between days 10 and 20 of pregnancy. There were successive decreases in serum GH concentration after parturition; the concentration reached basal levels on day 5, but it increased thereafter and was maintained at over three times basal levels for the remainder of lactation. The levels of GH in serum were highly correlated with mammary DNA and RNA contents during pregnancy, while prolactin concentration was more strongly correlated with mammary function during lactation.
EFFECT OF RELAXIN ON OESTROGEN-INDUCED UTERINE LUMINAL FLUID ACCUMULATION IN THE OVARIECTOMIZED RAT
Authors: KENNEDY T. G.
Published: December 2008

Uterine luminal fluid accumulation (ULFA) was induced in ovariectomized rats by twice daily treatment for 3 days with 0·5 μg oestradiol-17β. At the end of this treatment, rats were given a single subcutaneous injection of 0·2 ml 0·9% saline containing 0, 0·1, 1, 10, or 100 guinea-pig units (GPU) of relaxin, and ULFA was determined 15–17 h thereafter. It was reduced in animals receiving ≥ 1 GPU relaxin. This reduction in ULFA commenced 12 h after treatment of rats with 10 GPU relaxin, and was completed by 24 h. Ligation of the cervical end of the uterus prevented the loss of fluid in response to a single injection of relaxin, indicating the cervix as the route of fluid loss. Uterine luminal fluid accumulation was reduced to a greater extent by treatment of rats with 1 mg progesterone than by 10 GPU relaxin. Given concomitantly with oestrogen, relaxin had no effect on ULFA in horns which were ligated at the cervical end, indicating that relaxin did not inhibit luminal fluid formation. It is concluded from these results that the effects of progesterone on ULFA are not mediated by relaxin. The results, however, do not allow rejection of the hypothesis that the effect of prolactin on ULFA is mediated by relaxin.
DNA SYNTHESIS AND THE SECRETION OF PROLACTIN AND GROWTH HORMONE BY THE PITUITARY GLAND OF THE MALE RAT: EFFECTS OF DIETHYLSTILBOESTROL AND 2-BROMO-α-ERGOCRYPTINE METHANESULPHONATE
Authors: DAVIES CAROL , JACOBI JOAN , LLOYD H. M. , MEARES J. D.
Published: December 2008

The effects of 2-bromo-α-ergocryptine methanesulphonate on the response of the pituitary gland of the male rat to diethylstilboestrol dipropionate were studied by radioimmunoassay of prolactin and growth hormone and measurements of DNA synthesis. Given before diethylstilboestrol, 2-bromo-α-ergocryptine prevented the oestrogen-induced rise in serum prolactin and partly inhibited pituitary DNA synthesis. Given on days 4–6 of a 6-day period after a single dose of diethylstilboestrol, 2-bromo-α-ergocryptine rapidly increased pituitary prolactin concentration, diminished serum prolactin, reduced pituitary DNA synthesis and did not affect the growth hormone response to oestrogen.
THE HYPERCALCAEMIC RESPONSE TO PARATHYROID HORMONE IN JAPANESE QUAIL
Authors: KENNY A. D. , DACKE C. G.
Published: December 2008

The nature of the rapid hypercalcaemic response in birds to intravenously administered parathyroid hormone (PTH) has been studied using the Japanese quail and, to a lesser extent, the chicken. The response has been examined in acutely 45Ca-labelled birds. Parathyroid hormone, synthetic (Beckman 1–34 peptide) bovine PTH, was given with or without the simultaneous administration of a calcium load of 51 mm-CaCl2. It is concluded that the hypercalcaemic response in birds is complex involving two or more underlying mechanisms. The initial phase (30 min or less) is characterized by an increase in plasma 45Ca levels; interpretation of this response in terms solely of bone resorption is difficult. It is suggested that inhibition of bone accretion is the basis for the initial phase. The later phase (30 min or longer) can be interpreted as being largely due to bone resorption. In calciumloaded birds, which were used in recently described avian bioassay methods for PTH, similar results, and therefore interpretations, pertain. No immediate hypocalcaemic response to PTH was found in immature Japanese quail or chickens.
INVOLVEMENT OF NEURONES CONTAINING 5-HYDROXYTRYPTAMINE IN THE MECHANISM OF PROLACTIN RELEASE INDUCED BY OESTROGEN
Authors: CALIGARIS L. , TALEISNIK S.
Published: December 2008

Oestradiol benzoate (OB) injected into spayed rats induced high levels of serum prolactin (measured by radioimmunoassay) in the afternoon of the third day after the injection. When progesterone was injected into spayed rats primed 3 days before with OB, a release of prolactin was observed in the morning. These rises in serum prolactin were prevented either by treatment with p-chlorophenylalanine (PCPA), a compound which depletes 5-hydroxytryptamine (5-HT) from the brain or by injecting the 5-HT antagonist methysergide, into the third ventricle. The blockade of prolactin release by PCPA treatment of OB-injected rats was partially reversed by the administration of 5-hydroxytryptophan. These results indicate that 5-HT containing neurones mediate the effect of ovarian steroids on prolactin release. Further support of this view was provided by experiments showing that the injection of 5-HT into the third ventricle raised serum prolactin levels.

The rise in serum prolactin observed after the ovarian steroid treatment was blocked to a great extent by the injection of picrotoxin or strychnine. Picrotoxin also blocked the rise in serum prolactin induced by the injection of 5-HT into the third ventricle but failed to affect the rise in serum prolactin after i.v. injection of thyrotrophin-releasing hormone or α-methyl-p-tyrosine treatment. The results suggest that an inhibitory neuronal mechanism mediated by 5-HT neurones is involved in the release of prolactin induced by ovarian steroids.
NEUROPHYSIN-LIKE PROTEIN IN BOVINE PINEAL GLAND
Authors: REINHARZ A. C. , CZERNICHOW P. , VALLOTTON M. B.
Published: December 2008

Neurophysin-like proteins have been extracted and purified from bovine pineal glands and were found to share the biochemical and immunological properties of neurophysin I and neurophysin II respectively, and to be associated with at least one biologically and immunologically active neurohormone, probably vasotocin.
EFFECT OF BETAMETHASONE ON THE PRODUCTION OF GLUCOSE FROM PROPIONATE BY SHEEP
Authors: FORD E. J. H. , WINCHESTER J. G.
Published: December 2008

Primed continuous intraruminal infusions of tracer amounts of [2-14C]propionate were used to measure propionate production and the incorporation of propionate carbon into glucose by six sheep on a diet of 1000 g chopped hay/day. Primed continuous intravenous infusions of [U-14C]glucose were used to measure the rate of glucose entry in the same sheep. The measurements were repeated 24 h after a single intramuscular injection of betamethasone.

Maximum hyperglycaemia and a significant increase in glucose entry occurred after 24 h but there was no significant change in propionate production or in the synthesis of glucose from propionate.

It is concluded that the increase in glucose entry must arise from substrates other than propionate such as amino acids.