bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECTS OF VASOPRESSIN, CYCLIC AMP, AND THEOPHYLLINE ON OXYGEN CONSUMPTION OF TOAD BLADDER 'SACS'
Authors: PARISI M. , BENTLEY P. J.
Published: December 2008

The oxygen consumption of toad urinary bladders was lower in preparations made up as sacs than in pieces of tissue freely suspended in Ringer solution.

Vasopressin stimulated uptake of oxygen by both types of preparation. This probably reflects facilitated sodium transport from the mucosal to serosal side of the tissue since exclusion of this ion from the fluid bathing the mucosa (inside) abolished this effect.

When water transfer across the bladder is promoted by vasopressin (in the presence of an osmotic gradient; inside hypo-osmotic) there is a reduction (by about 50%) in usage of oxygen. Cyclic AMP had a similar action.

Theophylline and cyclic AMP failed to influence oxygen uptake by pieces of toad bladder tissue freely bathed in sodium—Ringer solution. In preparations made as sacs containing iso-osmotic sodium—Ringer solution the nucleotide stimulated while, paradoxically, the xanthine depressed oxygen consumption. This action of cyclic AMP (like that of vasopressin) is dependent on the presence of sodium at the mucosal side of the tissue since it is not seen in sacs filled with choline—Ringer solution. However, the reduction in O2 consumption produced by theophylline was still seen in the absence of sodium.
INACTIVATION AND DEGRADATION OF PORCINE CALCITONIN BY RAT LIVER, AND RELATIVE STABILITY OF SALMON CALCITONIN
Authors: de LUISE M. , MARTIN T. J. , MELICK R. A.
Published: December 2008

Slices and homogenates of a number of rat tissues inactivated porcine calcitonin labelled with 125I; the most active tissue was the liver. Maximal activity was found in rat liver supernatant. The reaction was pH- and dose-dependent, the active principle was non-diffusible, inhibited by p-chloromercuribenzoate and EDTA, and destroyed by heat. Biological activity of calcitonin was lost parallel with the breakdown of the labelled calcitonin (as measured by loss of trichloroacetic acid precipitability). Salmon ultimobranchial calcitonin was much less susceptible to inactivation by rat liver supernatant than the porcine hormone, which may explain the high potency and prolonged action of the salmon hormone in the rat.
DIHYDROTESTOSTERONE IN TESTICULAR TISSUE, AND ITS ANDROGENIC POTENCY IN VIVO
Authors: JEFFCOATE W. J. , SHORT R. V.
Published: December 2008

An attempt was made to isolate dihydrotestosterone (5α-androstan-17β-ol-3-one) from samples of testicular tissue taken from a 3-yr-old stallion and a mature bull. The extracts were quantitated by gas—liquid chromatography. In neither case was it possible to detect dihydrotestosterone.

In addition, the androgenic potency of dihydrotestosterone in vivo was compared with that of testosterone. Castrated rats received 14 daily injections subcutaneously of 300 μg of steroid in 0·1 ml arachis oil. After treatment, the rats were killed and the ventral prostates, seminal vesicles and coagulating glands were removed from each rat and weighed. Each gland was subsequently examined histologically. The fructose content of the coagulating glands was measured. The glands taken from rats treated with dihydrotestosterone differed in no way from those of rats treated with testosterone.
OVARIAN FOLLICULAR ACTIVITY IN LATE PREGNANCY
Authors: GOVAN A. D. T.
Published: December 2008

A histological study was made of ovaries obtained from patients in the latter half of pregnancy; the duration of pregnancy ranged from 26 to 40 weeks. During the first 7 weeks of this period there was little evidence of follicular activity. From 33 weeks to term new Graafian follicles, rarely exceeding 4 mm in diameter, appeared in progressively increasing numbers. This may be a critical stage in follicular development when the follicle must either go on to complete maturity or suffer atresia. Luteinization of the granulosa layer occasionally occurred in these follicles but it was not accompanied by proliferation of granulosa cells; the surrounding thecal cells frequently showed no sign of luteinization and were sometimes atrophic. The factors responsible for granulosa luteinization seem not to be the same as those necessary for theca luteinization, nor are they identical with the mechanisms responsible for luteal proliferation.
ADRENOCORTICAL FUNCTION IN THE HORSE
Authors: JAMES V. H. T. , HORNER MARIAN W. , MOSS M. S. , RIPPON A. E.
Published: December 2008

Evidence for the presence of cortisol and corticosterone in equine plasma and cortisol in equine urine is presented. The mean morning concentration of plasma cortisol was 7 μg/100 ml, and that of corticosterone 0·5 μg/100 ml. A diurnal rhythm of small amplitude was found.

Administration of corticotrophin, induction of hypoglycaemia and surgery produced marked increases in plasma cortisol levels, but only small increases were seen after normal exercise. The changes in plasma cortisol were not invariably accompanied by significant alteration of the eosinophil count.

It is concluded that the mechanisms of control of adrenocortical function in the horse are not dissimilar to those described for other mammalian species.
THE EFFECT OF LOW ENVIRONMENTAL TEMPERATURE ON PLASMA CORTICOSTEROID AND GLUCOSE CONCENTRATIONS IN THE NEWBORN CALF
Authors: KHAN MUSTAQ A. , DICKSON W. M. , MEYERS K. M.
Published: December 2008

Exposure of newborn Holstein and Jersey calves to −4 °C did not significantly increase the plasma corticosteroids (cortisol and corticosterone) concentrations compared with calves kept at 16 °C. Two Holstein calves exposed to −12 °C showed a slight decrease of plasma corticosteroid concentrations and one Holstein calf at −18° C responded with a marked increase in both hormones during cold exposure. In the animals at 16 and −4 °C the plasma cortisol and corticosterone concentrations fell steadily during the sampling period. There was also a marked, and almost linear, decrease in the packed cell volume during the sampling period; this occurred in all groups. That this was not due entirely to the withdrawal of blood was shown by a similar decrease in two calves from which only small quantities of blood had been taken. Thus, the decrease in plasma corticosteroids may have resulted to some extent from haemodilution.

An increase in glucose concentration was observed in both the control and cold-exposed calves. There was no correlation between the changes in plasma glucose and plasma corticosteroids.
ROLE OF OESTROGENS AND GONADOTROPHINS IN PERPHENAZINE-INDUCED MAMMOGENESIS
Authors: DANON A. , WELLER C. P. , SULMAN F. G.
Published: December 2008

Treatment of intact or recently (1 day) ovariectomized female rats with 5 mg perphenazine (Trilafon)/kg/day for 5 days resulted in marked lobulo—alveolar differentiation of the mammary glands. Perphenazine failed to stimulate mammogenesis in chronically (12 days) ovariectomized rats, unless they had been primed with oestradiol. However, mammogenic effects in chronically ovariectomized rats were obtained after implantation of minute amounts (2 μg) of oestradiol into the median eminence, or after treatment for 16 days with the non-steroid pituitary gonadotrophin-inhibitor methallibure (ICI 33828; 20 mg/kg/day).

Since these latter procedures counteract the gonadotrophin surge after ovariectomy, it would appear that inhibition of gonadotrophin secretion is necessary before prolactin secretion can be stimulated by perphenazine.

Castrated male rats responded to perphenazine with lobulo—alveolar differentiation similar to that in intact males. The implications of this difference with regard to the mechanism of pituitary response to gonadectomy are discussed.
ULTRASTRUCTURE OF THE NEUROHYPOPHYSIS AS SHOWN BY FREEZE-ETCHING
Authors: LIVINGSTON A.
Published: December 2008

Freeze-etched preparations of rabbit neurohypophysis and isolated hormone granules from cow neurohypophyses were examined electron microscopically. Many features seen in conventionally prepared sections were also apparent in freeze-etched replicas, particularly the neurosecretory nerve-endings containing elementary granules and elongated pituicyte processes.

Measurements of diameters of both isolated and hormone-containing granules in situ indicated that they were slightly larger in freeze-etched material than in that prepared by conventional electron microscopic techniques.

Fractures through the cores of hormone-containing granules showed a lamellar internal structure of 4 nm periodicity in both species examined.
A STUDY OF PROLACTIN-LIKE ACTIVITY IN INDIVIDUAL HUMAN PITUITARY GLANDS
Authors: NICHOLSON PATRICIA M.
Published: December 2008

Polyacrylamide disc gel electrophoresis of aqueous extracts of individual human anterior pituitary glands failed to identify a protein with lactogenic activity which was characteristic of pregnancy and the post-partum period. Lactogenic activity, determined by a semi-quantitative rabbit mammary gland organ culture assay, was largely associated with the growth hormone fraction. The total prolactin activity of individual anterior pituitary glands was determined by a 'local' intradermal pigeon crop sac method. The glands from pregnant and parturient women did not contain a higher concentration of prolactin than those of men or non-pregnant non-lactating women. These results do not provide any evidence for the existence of a human pituitary prolactin distinct from growth hormone. Reasons for this are discussed.
THE EFFECT OF PROMETHAZINE AND CLOMIPHENE ON GONADOTROPHIN SECRETION IN THE RAT
Authors: KOCH Y. , DIKSTEIN S. , SUPERSTINE E. , SULMAN F. G.
Published: December 2008

Promethazine and promethazine sulphoxide selectively inhibited gonadotrophin secretion in female rats. The effects obtained were: decrease in ovarian weight, reduction in the number of follicles and corpora lutea in the ovary, prolongation of the oestrous cycle and reduced amounts of gonadotrophin-releasing factors in the hypothalamus.

Very small doses of clomiphene citrate (1–100 ng/kg) increased gonadotrophin secretion in female rats, as shown by an increase in ovarian weight, increase in the number of corpora lutea, shortening of the oestrous cycle and increased amounts of gonadotrophin-releasing factors in the hypothalamus. Higher doses of clomiphene citrate (1 μg—2 mg/kg) produced the well-known inhibition of gonadotrophin secretion.

The possible mechanism of action of these drugs is discussed.
EFFECTS OF PARATHYROIDECTOMY ON THE DEVELOPMENT OF NEPHROCALCINOSIS AND CALCIUM, PHOSPHORUS AND MAGNESIUM BALANCE IN RATS
Authors: GOULDING AILSA , MALTHUS R. S.
Published: December 2008

Rats of different strains raised on a semipurified casein—sugar diet, develop a nephrocalcinosis in which deposits composed principally of calcium and phosphorus accumulate at the corticomedullary junction of the kidney. To determine whether the development of this nephrocalcinosis was in any way related to the activity of the parathyroid glands, female weanling 21-day-old rats were parathyroidectomized (PTX) or sham-operated and fed the semipurified diet for 3 weeks. Absorption, retention and excretion of Ca, P and Mg were studied during a 14-day balance period. The effects of injecting PTX rats with a small amount of parathyroid extract (15 U.S.P. units Lilly Para-thor-mone, every 12 h for 1 week) were examined.

Compared with sham-operated animals PTX rats showed: lower serum Ca and higher P concentrations; a lower urinary excretion (% intake) of Ca, P and Mg; a higher retention (% intake) of P and Mg; a higher concentration of Mg in bone (% femur ash). Administration of parathyroid extract (PTE) tended to reverse changes induced by parathyroidectomy but PTE-treated animals remained slightly hypocalcaemic. Sham-operated and PTE-treated PTX rats developed nephrocalcinosis but untreated PTX rats did not do so.

The results indicate that nephrocalcinosis did not develop in rats fed the semipurified diet in the absence of parathyroid hormone. It is postulated that although some activity of the parathyroid glands is needed for mineral deposition in the renal tubules, excessive activity is not necessarily a prerequisite to the development of this type of renal calcification.
THE METABOLISM OF STEROIDS IN THE CANINE PROSTATE AND TESTIS
Authors: HARPER M. E. , PIERREPOINT C. G. , FAHMY A. R. , GRIFFITHS K.
Published: December 2008

Prostatic tissue from young mature dogs was incubated in vitro with [4-14C]testosterone to assess androgen metabolism by this target organ. At the same time tissue from a dog previously treated with implants of oestradiol-17β and tissue from an older animal were also studied. Tissue from the oestrogen-treated dog showed considerable qualitative and quantitative differences from the normal in regard to metabolic activity. Fractionation of prostatic tissue after incubation with labelled testosterone indicated the localization of certain enzymes and products in the nucleus, and 5α-androstane-3α,17α-diol formation appeared particularly interesting. The relative activities of testicular tissue from the dogs in regard to the formation in vitro of androstenedione and testosterone from various radioactive precursors were measured.
EFFECT OF CALCITONIN ON [3H]PROLINE INCORPORATION INTO BONE HYDROXYPROLINE IN THE RAT
Authors: KALU D. N. , FOSTER G. V.
Published: December 2008

The effect of calcitonin on the incorporation of [3H]proline into bone hydroxyproline was investigated in young growing rats. The action of the hormone was studied under the following conditions: (1) acutely, in both intact and thyroparathyroidectomized rats, (2) after 20 days of daily treatment in both intact and thyroparathyroidectomized animals, (3) in thyroparathyroidectomized animals treated with parathyroid extract for 20 days, and (4) in animals fed a low calcium diet for 25 days. Calcitonin had no effect when given either acutely or long-term to intact animals. [3H]Proline incorporation into bone hydroxyproline was increased in rats fed low calcium diet, in rats treated with parathyroid extract for 20 days, and in acutely thyroparathyroidectomized rats. In each instance, calcitonin prevented or reduced this increase. The results are interpreted as evidence that, with the doses used, hydroxyproline synthesis under normal conditions is unaffected by the hormone. However, where hydroxyproline formation was increased, calcitonin reduced this increase.
EFFECTS OF PROLACTIN AND LUTEINIZING HORMONE ON THE CHOLESTEROL STORES IN THE MOUSE TESTIS
Authors: BARTKE A.
Published: December 2008

In intact adult male mice three injections, 2 h apart, of 3 μg luteinizing hormone (LH), 15 μg LH or 100 μg follicle-stimulating hormone (FSH) decreased the concentration of esterified cholesterol in the testes. Treatment with 35 μg testosterone propionate (TP)/day or 4 mg aminoglutethimide/day increased the concentration of esterified cholesterol. Single heterotopic pituitary homografts increased the concentration of esterified cholesterol; injecting 7·5 i.u. prolactin twice daily had similar effect. The concentration of free cholesterol showed little individual variation and little or no response to any of the above treatments. The concentration of testicular total cholesterol was increased in hypophysectomized mice. Administration of 10 μg LH or 50 μg TP daily for 28 days reduced the concentration of both esterified and free cholesterol in these animals to approximately the levels found in intact adult males. Prolactin (12 i.u./day) given alone or with TP had no effect, but it increased the concentration of esterified cholesterol in LH-treated animals. It is concluded that in the mouse testis the concentration of esterified, but not free, cholesterol tends to fluctuate with the apparent changes in the rate of androgen synthesis and that prolactin promotes accumulation of cholesterol esters. This could explain the synergism between prolactin and LH in stimulating spermatogenesis and the growth of androgen dependent tissues.
THE CHAMELEONIC BEHAVIOUR OF GONADOTROPHINS: A REVIEW OF RECENT RESULTS ON THEIR PHYSICOCHEMICAL PROPERTIES AND MOLECULAR STRUCTURE
Authors: HELLEMA M. J. C.
Published: December 2008

Human gonadotrophin preparations are extensively used for clinical and experimental purposes. There is a plethora of reports on the chemistry of gonadotrophins. However, the complete purification, isolation and elucidation of the structures of the follicle-stimulating hormone (FSH), the luteinizing hormone (LH) and human chorionic gonadotrophin (HCG) have not been achieved. Hindering factors are the instability of these gonadotrophins, the similarity of some of their physicochemical and immunological properties and the possibility that these hormones exist as hormone complexes rather than as single entities. These complicating factors necessitate a wide variety of sophisticated approaches to the study of the gonadotrophins. Some of the methods used and some of the structural, physicochemical and immunological characteristics of the gonadotrophins are the subject of this survey.
DIURNAL VARIATIONS OF THE ACHILLES TENDON REFLEX-TIME
Authors: ZAMRAZIL V. , NEMEC J. , VÁŇA S.
Published: December 2008

In a group of 35 patients (10 euthyroid, 9 hypothyroid and 16 thyrotoxic subjects) the diurnal variability of the Achilles tendon reflex-time (ART) was investigated. The ART was recorded by the electromagnetic method at 08.00, 12.00, 16.00 and 20.00 h, and 08.00 h on the following morning, and the contraction-time and half relaxation-time were evaluated.

In the entire group significant changes — prolongation — were found in the course of the day with a return to the initial value after 24 h. When classifying the patients into groups according to thyroid function, the changes were most marked in hypothyroid subjects and those with thyrotoxicosis partially alleviated by treatment. No significant changes were found in euthyroid subjects and those with highly active thyrotoxicosis. The significance of these findings and their implications are discussed.
IMMUNORADIOMETRIC ASSAY OF PARATHYROID HORMONE
Authors: ADDISON G. M. , HALES C. N. , WOODHEAD J. S. , O'RIORDAN J. L. H.
Published: December 2008

An immunoradiometric assay for parathyroid hormone has been developed. Antisera to bovine parathyroid hormone (BPTH) were screened for their ability to bind BPTH and human parathyroid hormone (HPTH). A BPTH-immunoadsorbent was used to extract antibodies from an antiserum which did not discriminate between BPTH and HPTH in a standard radioimmunoassay. These antibodies were labelled with 125I for use in the immunoradiometric assay. With this system as little as 5 pg BPTH and 8 pg HPTH could be detected. The serum concentration of BPTH was shown to rise in a cow rendered hypocalcaemic by an infusion of EDTA. Sera from patients with hyperparathyroidism contained high concentrations of hormone. These sera were found to dilute-out parallel to calibration curves obtained using HPTH extracted from parathyroid adenomata. The advantages of this method over the standard radioimmunoassay are discussed.
THE DEVELOPMENT OF THYROID-STIMULATING HORMONE-RELEASING FACTOR ACTIVITY IN THE NEONATAL RABBIT
Authors: ŚLEBODZIŃSKI A. , MACH Z. , MALINOWSKA W.
Published: December 2008

Nine-day chick embryos received grafts of hypothalamus, adenohypophysis, thyroid, and fat (controls) from 0-, 7-, 14- and 21-day-old rabbits to the chorio-allantois. In addition, aqueous rabbit adenohypophysial and hypothalamic extracts were given to 1-day-old chicks. Animals injected with thyrotrophin and saline served as controls. On the 5th day of incubation of treated embryos, or 24 h after the administration of the extracts, the chicks were killed and their thyroids studied histologically.

The hypothalamic grafts or extracts activated the chick thyroid gland and a similar trend was found in adenohypophysial or thyroid-stimulating hormone-treated chicks. The degree of activation of the embryo chick thyroid gland was related to the age of the donor rabbit. In general, thyroidstimulating hormone-releasing factor activity in hypothalamic heterografts or extracts appeared first in 14-day-old rabbits and was correlated with increasing thyrotrophic potency of the rabbit adenohypophysis.
THE INFLUENCE OF METHALLIBURE (ICI 33,828) ON SERUM AND PITUITARY THYROID-STIMULATING HORMONE LEVELS IN THE RAT
Authors: BOURKE J. R. , MANLEY S. W. , HAWKER R. W.
Published: December 2008

The effect of methallibure (ICI 33,828), a non-steroidal pituitary inhibitor, on serum and pituitary thyroid-stimulating hormone (TSH) levels has been investigated.

A biphasic action of the drug on serum TSH levels was observed, the greatest falls occurring with the lowest doses (2mg/day). Increasing dose and period of administration induced progressive decreases in pituitary TSH content. These results are interpreted in terms of three actions on the thyroid—pituitary system: (1) inhibition of the release of TSH from the pituitary, (2) inhibition of TSH synthesis evident only at higher doses, and (3) a thyroid-blocking action, which is also only observed at the higher dose levels, with consequent pituitary stimulation via the thyroid—pituitary feedback mechanism. Effects upon body weight and weight of endocrine organs are reported, that upon the seminal vesicles being the most marked.
CELL PROLIFERATION IN THE PREPUBERTAL MALE RAT ADRENAL CORTEX: AN AUTORADIOGRAPHIC STUDY
Authors: WRIGHT N. A.
Published: December 2008

On the basis of labelling indices measured with tritiated thymidine at intervals throughout its thickness, the adrenal cortex of prepubertal male rats has been divided into four compartments. These are called the glomerular, proliferative, fascicular and reticular compartments, respectively. Labelling indices measured for each compartment showed highest values in the glomerular and proliferative compartments, with values of 6·73% and 7·09% respectively. The fascicular compartment showed a lower index of 3·16% while the reticular compartment gave the lowest value of 1·15%. These differences are further reflected in measurements of the mitotic indices for each compartment.

The phases of the cell cycle have been measured by pulse-chase analysis in each compartment, and all phases estimated showed an increase in duration as the inner compartments were approached. The duration of interphase DNA synthesis (ts) was found to be shortest in the glomerular and proliferative compartments, with values of 7·45 and 7·73 h, respectively. The fascicular compartment showed lengthening of ts to 8·56 h, and the reticular compartment gave the highest value of 9·21 h. Similarly, the values obtained for G2 (the post-DNA synthetic interval) and tm (the duration of mitosis), and a calculated value of the cell cycle time all showed a general increase in duration from the outer to the inner compartments. The relation of these results to theories of adrenocortical cytogenesis is discussed, and it is suggested that the differences in cell cycle components can best be explained by the inward migration of cortical cells from the outer compartments.
THE EFFECT OF NEONATAL ADMINISTRATION OF SEX HORMONES ON THE TURNOVER OF HEPATIC MICROSOMAL PHOSPHOLIPID IN MALE AND FEMALE RATS
Authors: TOH Y. C.
Published: December 2008

The effect of neonatal administration of testosterone propionate and oestradiol benzoate on the metabolism of microsomal phospholipid in the liver of male and female rats was studied. Males had a greater uptake of radioactive phosphorus than females. Gonadectomy at the age of 4 weeks reduced the incorporation of 32P into the microsomal phospholipid. Administration of testosterone significantly increased 32P uptake both in the intact and ovariectomized females as well as in the castrated males, whereas oestradiol produced no effect. A sex difference of total microsomal phospholipid phosphorus was also found in the gonadectomized rats. Oestrogen caused no change in the intact animals but restored the level of phospholipid in ovariectomized female rats. On the other hand, testosterone significantly increased the total content of the phospholipid in the liver microsomes of both intact and gonadectomized male and female rats.
PRE-OVULATORY PROGESTERONE, THE ADRENAL CORTEX AND THE 'CRITICAL PERIOD' FOR LUTEINIZING HORMONE RELEASE IN RATS
Authors: FEDER H. H. , BROWN-GRANT K. , CORKER C. S.
Published: December 2008

During the day of pro-oestrus in rats showing regular 4-day oestrous cycles, the concentration of progesterone in peripheral plasma increased slowly from 09.30 to 13.30 h and more rapidly during and after the 'critical period' for luteinizing hormone (LH) release to reach a level of 24·4 ng/ml at 21.00 h. Administration of sodium pentobarbitone at 07.00 or 13.30 h (but not at 16.30) on the day of pro-oestrus delayed ovulation and also prevented the rise in progesterone concentration at 21.00 h on that day. Levels were found to be high 24 h later on the evening of the day preceding the delayed ovulation. It is concluded that the major rise during and after the 'critical period' is the result of LH stimulation of ovarian progesterone secretion.

The possibility that the gradual increase in peripheral plasma progesterone concentration that occurred before the 'critical period' was due to adrenal secretion and played some role in facilitating the onset of the ovulatory surge of LH was examined. The rise in plasma corticosterone concentration roughly paralleled that of progesterone up to the 'critical period' but the curves for the two steroids later became divergent. Suppression of adrenal activity during pro-oestrus by the administration of dexamethasone phosphate resulted in a blockade of ovulation which could be reversed by the administration of either progesterone or corticotrophin (ACTH). Conversely, blockade of ovulation followed ACTH administration at metoestrus and approximately 50% of animals adrenalectomized or sham-adrenalectomized at metoestrus or dioestrus failed to ovulate at the expected time. In adrenalectomized rats tested 12–15 days after operation, the period of pro-oestrus during which sodium pentobarbitone administration could block ovulation was more prolonged than in intact rats. The possible roles of progesterone of adrenal origin in facilitating LH release and entraining the LH release mechanism to the light—dark rhythm and of progesterone of ovarian origin in ensuring full sexual receptivity are discussed.
INFLUENCE OF INSULIN INJECTED INTO THE LATERAL VENTRICLE ON PITUITARY GROWTH-HORMONE RELEASE IN THE RAT
Authors: PECILE A. , MÜLLER E. E. , FELICI M. , NETTI C. , COCCHI D.
Published: December 2008

Injections of insulin (0·2 or 0·01 i.u./20 μl) into the lateral ventricle of the rat brain, while not changing blood glucose levels or altering the pituitary content of growth hormone (GH), blocked the release of GH from the pituitary and the decrease of growth-hormone releasing activity (GHRF) of stalk median eminence (SME) extracts in the presence of the hypoglycaemic effect on insulin (2 i.u./kg) given intraperitoneally. Intraventricular administration of insulin also impaired the GH release elicited by cold exposure (4 °C, 1 h) but not the release induced by electric shock. The possibility that insulin injected into the brain acts on glucose-sensitive GH-regulating structures is suggested.
MEASUREMENT OF PLASMA CORTISOL LEVELS IN THE EEL ANGUILLA ANGUILLA IN RELATION TO OSMOTIC ADJUSTMENTS
Authors: BALL J. N. , JONES I. CHESTER , FORSTER M. E. , HARGREAVES G. , HAWKINS E. F. , MILNE K. P.
Published: December 2008

The competitive protein-binding radioassay (CPB method) of Murphy (1967) has been adapted to determine total cortisol levels in the plasma of the eel, Anguilla anguilla L. Validation of the method for this species depended in part on the development of a chromatographic—fluorimetric technique for eel cortisol, following classical procedures and using radioactive tracers; by this means, the specificity of the CPB method for cortisol in eel plasma was established. Accuracy, precision and sensitivity of the CPB method were also investigated and were shown to be satisfactory.

Plasma total cortisol levels were determined in eels during osmotic adjustments after transfers from fresh water (FW) to sea-water (SW) and vice versa, and from FW to distilled water. Plasma osmotic pressure and/or sodium levels were monitored simultaneously, to follow the progress of osmotic regulation. In only one of the transfer situations did the plasma cortisol level change significantly, showing a marked transitory increase during the first few days after transfer from FW to SW, corresponding to the development and correction of an 'osmotic crisis'. Plasma cortisol levels were the same in eels adapted for long periods to FW and to SW. Plasma cortisol fell to extremely low levels after hypophysectomy.

These results are discussed in the light of the literature on hormonal control of osmoregulatory mechanisms in the eel, with particular emphasis on the role of adrenocorticosteroids in ionic regulation of animals in SW.
DETERMINATION OF THE DETAILED HYPOTHALAMIC ROUTE OF THE MILK-EJECTION REFLEX IN THE GUINEA-PIG
Authors: TINDAL J. S. , KNAGGS G. S.
Published: December 2008

The effect of various types of surgical damage to the forebrain on the release of oxytocin in response to electrical stimulation of the discrete ascending milk-ejection reflex pathway in the mid-brain was investigated in 99 anaesthetized lactating guinea-pigs. Oxytocin release was measured by comparison of experimental milk-ejection responses with the response to i.v. injection of known amounts of synthetic oxytocin.

Removal of the entire telencephalon, including cerebral cortex, hippocampi, amygdalae and forebrain rostral to the hypothalamus, did not affect the subsequent release of oxytocin after electrical stimulation of the pathway in the mid-brain, from which it was concluded that the reflex pathway within the forebrain is entirely diencephalic. Transection of the hypothalamus immediately rostral to the paraventricular (PV) nuclei was without effect, while transection immediately caudal to the PV nuclei blocked the release of oxytocin. Destruction of the PV nuclei by a radiofrequency lesion which spared the supraoptic (SO) nuclei blocked the release of oxytocin. Undercutting both PV nuclei so as to isolate them from the ventral hypothalamus blocked the release of oxytocin. Undercutting the PV nucleus ipsilateral to the stimulated side of the mid-brain blocked the release of oxytocin, while undercutting the contralateral PV nucleus had no effect. The PV nuclei, therefore, lie on the ascending path of the milk-ejection reflex, the SO nuclei do not, and, from the mid-brain forwards, the ascending pathway remains uncrossed.

The course of the reflex pathway was traced rostrally from the mesodiencephalic junction by making narrow transverse knife-cuts and determining which cuts reduced or blocked the release of oxytocin after mid-brain stimulation. At this level, the pathway on each side of the brain is represented by separate dorsal and ventral paths and in the present study it was found that the ventral path is more important than the dorsal path in terms of oxytocin release. The ventral path passes forward in the medial forebrain bundle, in the far-lateral hypothalamus, while the dorsal path enters the posterior hypothalamus dorsally in the periventricular region at the top of the third ventricle and impinges on the thalamic reuniens nucleus. Shortly afterwards the dorsal path swings abruptly in the lateral direction to join the ventral path in the lateral hypothalamus. The reunited pathway then moves forward in this position until it is level with the PV nuclei, where it swings dorsomedially to relay with the lateral tip of the ipsilateral PV nucleus, and in doing so intermingles with the descending neurosecretory fibres from this nucleus.
PARAVENTRICULAR—HYPOPHYSIAL NEUROSECRETORY PATHWAYS IN THE GUINEA-PIG
Authors: KNAGGS G. S. , TINDAL J. S. , TURVEY A.
Published: December 2008

The neurosecretory pathways from the paraventricular (PV) nuclei have been identified in the guinea-pig and plotted according to stereotaxic coordinates for the guinea-pig brain. The magnocellular neurosecretory neurones are concentrated in the lateral tip of the PV nucleus approximately half-way between the third ventricle and the fornix. Some neurosecretory fibres pass between the cranio-ventral extension of the PV nucleus and the supraoptic (SO) nucleus. Neurosecretory fibres leave the rostral region of the main part of the PV nucleus and pass ventral to the fornix, those from the middle region pass both ventral and dorsal to the fornix and those from the caudal region pass mainly dorsal to the fornix. After passing around the fornix, these fibres merge to form a broad band, the paraventricular—hypophysial tract, which curves ventrolaterally and then ventromedially in a gentle arc around the lateral edge of the anterior hypothalamic area and the hypothalamic ventromedial nucleus before turning caudomedially to run over the dorsal surface of the optic chiasma towards the median eminence. Neurosecretory fibres were not observed in the anterior hypothalamic area or in the ventromedial nucleus. An accessory PV nucleus was found dorsolateral to the fornix. Neurosecretory fibres pass over the fornix in both directions between the PV and the accessory PV nuclei, also fibres leave the accessory PV nucleus and pass ventrally to merge with those of the main paraventricular—hypophysial tract.
OESTROGEN RECEPTORS IN HUMAN UTERINE TISSUE
Authors: EVANS L. H. , HÄHNEL R.
Published: December 2008

The uptake and retention of [3H]oestradiol-17β by human uterine and muscle tissue was studied in vitro by incubation of tissue slices. The binding characteristics of immature rat and adult human tissue were compared. Human endometrium had a greater affinity for tritiated oestradiol than human myometrium. Human uterine tissues bound less [3H]oestradiol-17β than rat uterine horns. The difference in retention between a target and non-target tissue in the human tissue was much smaller than in the rat, although still highly significant. Binding was inhibited by low concentrations of oestradiol-17β, U-11100A and hexoestrol, but was not inhibited by the same concentrations of oestrone, oestriol or oestradiol-17α. Freezing the uterine tissue resulted in a loss of specific binding activity. Binding was shown to vary with different uterine specimens. There was a significant difference in [3H]oestradiol-17β retention between the proliferative and secretory phases of the menstrual cycle. The highest endometrial retention was found in endometrial carcinoma.
INHIBITION BY MANGANESE OF THE ACTION OF ANTIDIURETIC HORMONE ON ADENYL CYCLASE IN TOAD BLADDER
Authors: HYNIE S. , SHARP G. W. G.
Published: December 2008

In view of the report that Mn2+ stimulates sodium transport in the toad bladder but inhibits the effect of vasopressin on both water flow and sodium transport, the effects of this ion on adenyl cyclase from mucosal epithelial cells of toad bladder were investigated. Mn2+ was found to inhibit activation of adenyl cyclase by arginine vasopressin in the presence of Mg2+ and had no effect on activation of the enzyme by sodium fluoride. This is in marked contrast to the effects of Mn2+ on hormonal activation of adenyl cyclase from other tissues in which no inhibitory effects are seen and in which Mn2+ can replace Mg2+ in the reaction mixture. It is concluded that stimulation of sodium transport by Mn2+ is unlikely to be explainable by adenyl cyclase activation and that Mn2+ is not useful in the differentiation of the two forms of adenyl cyclase which are thought to be required for mediation of water flow and sodium transport stimulation by vasopressin.
A STUDY ON THE EFFECT OF INSULIN ON DNA, RNA AND PROTEIN SYNTHESIS IN MOUSE MAMMARY GLAND TISSUE IN ORGAN CULTURE
Authors: WANG D. Y. , AMOR VICKY
Published: December 2008

The rates of synthesis of DNA, RNA and protein of mouse mammary gland explants in organ culture have been determined. Stimulation with insulin resulted in maximal rates of synthesis of these components, all occurring between 18 and 22 h of culture.

The use of metabolic inhibitors of DNA, RNA or protein synthesis showed that after insulin stimulation, inhibition of any one of these processes was associated with a reduction in the synthesis of the other two components. Also the maximal rate of protein synthesis is governed by the net amount of RNA formed throughout the period of culture.

Evidence is presented that the stimulation of DNA, RNA or protein synthesis by insulin is not due to increased transport of amino acids and that insulin appears to act rapidly on processes which subsequently lead to enhanced synthetic activity.
TRANSFORMATION IN VITRO OF [4-14C]DEHYDROEPIANDROSTERONE TO 7-OXYGENATED DERIVATIVES BY NORMAL EARLY HUMAN PLACENTAL TISSUE
Authors: MIRHOM Y. W. , SZONTÁGH F. E.
Published: December 2008

Samples from three early human placentae were incubated with [4-14C]-dehydroepiandrosterone (DHA). It was found that [4-14C]DHA was transformed into 7-oxygenated derivatives in yields decreasing in the order: 7-oxo-DHA > 7β-hydroxy-DHA > 7α-hydroxy-DHA. These products were only slowly transformed into other derivatives.
THE ROLE OF OESTROGENS IN SPONTANEOUS OVULATION: LOCATION OF SITE OF ACTION OF POSITIVE FEEDBACK OF OESTROGEN BY INTRACRANIAL IMPLANTATION OF THE ANTI-OESTROGEN I.C.I. 46474
Authors: BAINBRIDGE J. G. , LABHSETWAR A. P.
Published: December 2008

In an attempt to locate the site(s) of action of the positive feedback of oestrogen for ovulation, a potent anti-oestrogen, I.C.I. 46474, was stereotaxically implanted into various parts of the brain or into the anterior pituitary. A dose of 5 μg of the anti-oestrogen when implanted into the cerebral cortex or injected subcutaneously on the morning of the day before pro-oestrus in 4-day cyclic rats was only marginally active in interfering with ovulation. By contrast, when the same amount was implanted into the median eminence region or the anterior pituitary, ovulation failed to occur in 80–100% of the rats (P < 0·05). Implantation of the cocoa butter vehicle alone into these regions interfered with ovulation in less than 35% of animals. Introduction of the anti-oestrogen into the anterior hypothalamic or mammillary region gave equivocal results. The data suggest that both the median eminence and the anterior pituitary contain receptors which can be blocked by the anti-oestrogen with resultant inhibition of ovulation. It is concluded that the positive feedback of oestrogen for ovulation is exerted both at the pituitary and the hypothalamic levels.
REGULATION OF PRODUCTION IN VITRO OF 5α-ANDROSTANE-3α,17β-DIOL IN THE IMMATURE RAT OVARY
Authors: SPRINGER C. , ECKSTEIN B.
Published: December 2008

The pattern of steroid synthesis in vitro in ovarian homogenate of immature rats was investigated with [7α-3H]pregnenolone as radioactive precursor. The metabolites, progesterone, androstenedione, testosterone and 5α-androstane-3α,17β-diol were obtained in radiochemically pure form. The steroids were identified by fractionation, partition column and thin-layer chromatography, derivative formation and by crystallization to constant activity. The steroidogenic patterns at the ages of 21 and of 31 days were found to be similar, but different from the pattern reported for adult rat ovaries. At 34 days of age, 1 day before the onset of puberty, the percentage radioactivity converted to progesterone was about ten times higher than that at 31 days. The production in vitro of 5α-androstane-3α,17β-diol by ovarian homogenates of 34-day-old rats was shown to depend on the concentration of pregnenolone in the incubation mixture. These findings are discussed in relation to the mechanism of the onset of puberty in the female mammal.
THE INFLUENCE OF OVARIAN HORMONES ON THE DECIDUAL ALKALINE PHOSPHATASE REACTION IN ADRENALECTOMIZED PSEUDOPREGNANT RATS
Authors: MANNING J. P.
Published: December 2008

The influence of oestradiol-17β and/or progesterone on decidual alkaline phosphatase was studied in adrenalectomized (day 1) and ovariectomized (day 1) rats after uterine traumatization on day 4 of pseudopregnancy. Enzyme activity was 10–15 times greater on day 8 of pseudopregnancy in untreated adrenalectomized and intact animals than in non-decidualized uteri. Treatment of ovariectomized and/or adrenalectomized rats with seven daily injections of 5 mg progesterone alone or combined with oestradiol-17β (0·1 μg on days 1–3, and 1·0 μg on days 4–7), did not alter the enzyme reaction. If 1·0 μg of the oestrogen was administered with 5 mg progesterone from days 1–7, no deciduoma response was observed. The results substantiate the hypothesis that progesterone is the only ovarian and adrenal hormone necessary for decidualization of traumatized uteri in pseudopregnant rats.
THE EFFECT OF SURGICAL ISOLATION OF THE HYPOTHALAMUS UPON REPRODUCTIVE FUNCTION IN THE FEMALE GUINEA-PIG
Authors: BUTLER JEAN E. M. , DONOVAN B. T.
Published: December 2008

Under stereotaxic guidance, the connexions between the hypothalamus and the rest of the brain were severed surgically in mature female guinea-pigs, and reproductive function was assessed by following the vaginal cycle and by histological study of the ovaries. Animals in which the hypothalamic island incorporated the suprachiasmatic nuclei, or in which the anterior connexions to the hypothalamus were severed by a cut placed just anterior to the suprachiasmatic nuclei, developed persistent vaginal oestrus. Such an anterior cut in the hypothalamus did not influence luteal function in hysterectomized animals. When the anterior border of a hypothalamic island, or an anterior cut through the hypothalamus, was caudal to the suprachiasmatic nuclei, oestrous cycles continued although they were slightly irregular. The ovaries contained corpora lutea. Severance of the posterior connexions to the hypothalamus did not alter the oestrous cycle. The role of the suprachiasmatic area in the generation of persistent vaginal oestrus is discussed.
STEROID CONTENT OF THE EQUINE OVARY DURING THE REPRODUCTIVE CYCLE
Authors: YOUNGLAI E. V.
Published: December 2008

Follicular fluid from individual follicles was collected from nine mares in oestrus and the concentration of the following steroids determined by gas—liquid chromatography: progesterone, 17α-hydroxyprogesterone, androstenedione, 19-norandrostenedione, epitestosterone, oestrone and oestradiol. The most vascular follicles, which were probably those destined to ovulate, tended to have the highest steroid concentrations. In these vascular follicles oestradiol was the main steroid found with an average concentration of 151 μg/100 ml.

In two out of three samples of follicular fluid taken from the mares with recent ovulations, oestradiol was present in large quantities. The corpora lutea from these mares contained the following steroids: progesterone (average: 1973 μg/100 g), 17α-hydroxyprogesterone (average: 65 μg/100 g), 20α-dihydroprogesterone (average: 249 μg/100g), pregnenolone (average: 33 μg/100 g). Pregnenolone was not detected in any of the samples of follicular fluid examined.

A pool of eight mid-cycle corpora lutea contained the same four steroids as those in newly formed corpora lutea but, in addition, oestradiol was detected in the order of 4 μg/100 g.
THE ROLE OF PROLACTIN IN THE REGULATION OF TESTICULAR FUNCTION: THE EFFECT OF PROLACTIN AND LUTEINIZING HORMONE ON 3β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN THE TESTES OF MICE AND RATS
Authors: HAFIEZ A. A. , PHILPOTT J. E: , BARTKE A.
Published: December 2008

Administration of 100 μg prolactin twice daily for 3 days increased 3β-hydroxysteroid dehydrogenase (3β-HSD) activity in the testes of dwarf mice compared with that found in the normal mouse. In hypophysectomized rats, prolactin (200 μg, same regimen) was without effect when given alone, whereas 5 μg luteinizing hormone (LH) alone injected twice daily, increased 3β-HSD activity to above normal. When prolactin and LH were administered in combination, 3β-HSD activity was raised to normal levels only.
EFFECT OF OESTROGEN ON OESTROUS BEHAVIOUR AND ITS VARIATION WITH SEASON IN THE EWE
Authors: FLETCHER I. C. , LINDSAY D. R.
Published: December 2008

The effects of dose of oestrogen and season on the expression of oestrous behaviour was studied in 60 spayed and 16 intact ewes.

In progesterone-primed spayed ewes the incidence and duration of oestrous behaviour increased and the interval between injection of oestrogen, and onset of oestrous behaviour decreased as the dose of oestrogen was increased. The linear regression of duration of oestrus on log dose of injected oestrogen provided the most precise measure of the effect of changing dose level of oestrogen on oestrous behaviour.

The sensitivity of spayed ewes to constant levels of oestrogen increased to a maximum near the middle of the breeding season and then declined to a minimum during the non-breeding season. In progesterone-synchronized intact ewes the interval between the end of progesterone treatment and onset of oestrus was at a minimum, and duration of oestrus at a maximum, near the middle of the breeding season. By bioassay it was estimated that endogenous oestrogen production was greater near the middle of the breeding season than at either the beginning or end.

It is concluded that seasonal variation in the expression of oestrous behaviour in intact ewes is controlled by changes in both the production of endogenous oestrogen and the sensitivity of ewes to it.
FEEDBACK EFFECTS OF THYROXINE ON THE HYPOTHALAMUS AND PITUITARY OF GOLDFISH, CARASSIUS AURATUS
Authors: PETER R. E.
Published: December 2008

The effect on thyroid activity of a systemically ineffective dose of thyroxine (T4) implanted in the hypothalamus or pituitary of goldfish was tested. Thyroid activity was decreased by T4 implantation in either location, indicating that T4 has a negative feedback effect on the pituitary causing a decrease in thyrotrophin secretion, and a positive feedback effect on the hypothalamus stimulating the secretion of thyrotrophin inhibitory factor (TIF). Fish with a T4 or blank-control implant in the pituitary that had a damaged pituitary stalk, as a result of the operative procedures, were hyperthyroid, suggesting either that TIF is more effective in suppressing thyrotroph activity than T4 and that the effect of T4 was masked by the absence of TIF, or, less likely, that T4 negative feedback in the pituitary is not effective independent of TIF. The results were compared with the information about T4 feedback in mammals.
RENIN LEVELS IN THE KANGAROO, THE WOMBAT AND OTHER MARSUPIAL SPECIES
Authors: SIMPSON PAMELA A. , BLAIR-WEST J. R.
Published: December 2008

A renin—angiotensin system was shown to be present in several marsupial species in plasma and homogenates of the renal cortex. Species studied were: Eastern Grey kangaroo (Macropus giganteus), Red kangaroo (Megaleia rufa), common wombat (Vombatus hirsutus), pademelon (Thylogale billardierii), Bennett's wallaby (Wallabia rufogrisea frutica), a quokka (Setonix brachyurus) and a tiger cat (Dasyurus maculatus). Renin-substrate was found in the plasma of the Eastern Grey kangaroo, the Red kangaroo and the wombat. Renin was shown to be present in the plasma of all species by incubation alone or with heterologous marsupial renin-substrate. Plasma renin concentration and renal renin content were estimated by an established method using standard sheep renin-substrate. Plasma renin concentration was high, suggesting that marsupial renins have a high affinity for sheep substrate; renal renin estimates were low relative to eutherian species, suggesting that renal storage may be small. Plasma renin concentration and renal renin levels were proportionately related. Renin levels were consistently lowest in the wombat. Bilateral nephrectomy of an Eastern Grey kangaroo reduced plasma renin concentration to zero and increased renin-substrate concentration eightfold. The angiotensin-like incubation product from Eastern Grey kangaroo renin-substrate did not cross react with antibodies to [5-Ile]-angiotensin I, suggesting that the product has a different sequence of amino acids.