bluuebunny/crossref_metadata_2025_split huggingface dataset:
A DECREASED RESPONSE TO PARATHYROID HORMONE IN MAGNESIUM DEFICIENCY
Authors: MacMANUS J. , HEATON F. W. , LUCAS P. W. 
Published: December 2008

SUMMARY
The effect of magnesium deficiency on the response to parathyroid hormone has been investigated in vitro and in vivo. Parathyroid hormone increased the release of calcium, inorganic phosphate and hydroxyproline from rat femora into the incubation medium, but had a lesser effect on bones from magnesium-deficient animals than on femora from control rats. Similarly, injection of the hormone into thyro-parathyroidectomized rats produced smaller rises in plasma calcium and magnesium concentrations in magnesium-deficient rats than in control animals. It is concluded that magnesium deficiency inhibits the action of parathyroid hormone on its target organs.
HISTOCHEMICAL STUDIES OF BOVINE SEMINAL VESICLES DURING POSTNATAL DEVELOPMENT
Authors: RAMA F. , CASTELLANO M. A. , GERMINO N. I. , MICUCCI M. 
Published: December 2008

SUMMARY
The location of aldose and ketose reductases and of isocitric, succinic, malic and α-ketoglutaric dehydrogenases was studied by histochemical methods in the seminal vesicles of the bull, bull calf and castrated bulls.
The appearance of aldose and ketose reductase activity coincides with that of significant quantities of fructose collected from the accessory glands of calves of 5·5 months of age.
The enzymes of the Krebs' cycle, isocitric, succinic, malic and α-ketoglutaric dehydrogenases, could not be histochemically demonstrated in the seminal vesicles of bulls, bull calves and castrated young bulls.
The factors determining the high citric acid concentrations in bull seminal vesicles are discussed.
GONADOTROPHIC HORMONE SECRETION IN THE FEMALE RING DOVE IN RESPONSE TO VISUAL AND AUDITORY STIMULATION BY THE MALE
Authors: BARFIELD R. J. 
Published: December 2008

SUMMARY
Female ring doves secrete gonadotrophic hormone in response to courtship behaviour of the male. This investigation was concerned with the quantitative relationship between the courtship stimulation presented to females and the responses of their reproductive systems. In a first experiment the degree of female reproductive tract development was found to be correlated with the length of time of daily exposure to a courting male. In a second experiment exposure time was held constant and the amount of courtship presented to females was varied by using different programmes of stimulation by males. Here too, the degree of female reproductive tract development was correlated with the amount of daily courtship behaviour presented. It therefore appears that in the female ring dove secretion of gonadotrophin is graded in accordance with the amount of courtship behaviour perceived by her.
EFFECTS OF PROLACTIN ON SPERMATOGENESIS IN HYPOPHYSECTOMIZED MICE
Authors: BARTKE A. 
Published: December 2008

SUMMARY
Hypophysectomized mice were treated daily for 28 days with 12 i.u. prolactin, 10 μg luteinizing hormone (LH), 10 μg LH plus 12 i.u. prolactin, 50 μg testosterone propionate (TP), or 50 μg TP plus 12 i.u. prolactin. The yield of spermatogenesis was studied quantitatively from the counts of spermatogonia, preleptotene and pachytene spermatocytes and spermatids in the seminiferous tubules at stage VII of spermatogenesis. Prolactin administered alone caused a small, but significant, increase in the yield of spermatogenesis. Treatment with a mixture of LH, follicle-stimulating hormone and growth hormone in amounts 1·5 times higher than those reported as contaminants of prolactin had similar effects. Injections of LH or TP caused partial restoration of spermatogenesis. The yield of spermatogenesis was significantly higher in animals given LH plus prolactin than in the animals given LH alone. Prolactin, however, did not augment the effects of TP on spermatogenesis. It is concluded that prolactin acts on the Leydig cells of the testis to increase their responsiveness to LH. More androgen appears to be produced under the influence of LH when prolactin is also present.
THE EFFECT OF HYPOPHYSECTOMY ON THE RESPONSE OF THE SEBACEOUS GLAND TO TESTOSTERONE PROPIONATE
Authors: THODY A. J. , SHUSTER S. 
Published: December 2008

SUMMARY
The effect of varying doses of testosterone propionate (TP) on the sebum secretion and preputial gland weight of castrated and hypophysectomized—castrated rats was studied. The changes in preputial gland weight closely paralleled those of sebum secretion. Small doses of TP (0·05 mg) stimulated sebum secretion in hypophysectomized-castrated rats, but not in the castrated rats. Higher doses of TP increased sebum secretion in both the hypophysectomized—castrates and the castrated rats.
While 0·5 mg TP completely restored sebum secretion to normal levels in castrated rats but not in the hypophysectomized—castrated rats, the actual increase in sebum secretion produced by this dose of TP was similar in both groups. It is concluded that at physiological doses the action of TP on the sebaceous glands is independent of the pituitary. However, the presence of the pituitary is required for normal sebaceous gland activity.
REGULATION OF PITUITARY OVULATING HORMONE CONCENTRATION IN THE IMMATURE RAT TREATED WITH PREGNANT MARE SERUM
Authors: ZARROW M. X. , DINIUS JANET 
Published: December 2008

SUMMARY
The concentration of luteinizing hormone (LH) in the pituitary gland of the 28-day-old female rat increased from a value of 8·0 μequiv./mg fresh anterior pituitary at zero time to 20·1 μg at 51 h after treatment with 30 i.u. pregnant mare serum (PMS). The level then fell to 8·1 μg at 56 h. PMS had no effect on pituitary LH levels in the ovariectomized rat. Three daily injections of 5·0 μg of oestradiol benzoate caused an increase in pituitary LH levels to 16·1 μg at 51 h after the onset of the oestrogen treatment. This value is not significantly different from the level (20·1 μg/mg fresh weight) found in the intact, PMS-treated, immature rat. Uterine weights were also comparable for the two groups. Treatment with lower doses of oestradiol benzoate had no effect on pituitary LH levels and also failed to increase the uterine weight to values comparable with those obtained after PMS treatment. Treatment of 28-day-old, intact, female rats with 2 mg of progesterone at 24 h after the PMS injection resulted in a significant drop in pituitary LH levels.
THE EFFECT OF OVARIAN STEROIDS ON HYPOTHALAMIC THRESHOLDS FOR OVULATION IN THE FEMALE RAT
Authors: McDONALD P. G. , GILMORE D. P. 
Published: December 2008

SUMMARY
Electrochemical stimulation of the basal and preoptic hypothalamus, under sodium pentobarbitone anaesthesia, was carried out on the day of pro-oestrus in normal cycling and in ovarian hormone-treated female rats. Control rats ovulated in response to 25, 50 and 100 μA for 60 s in the median eminence and to 10 μA for 60 s in the preoptic area. Oestradiol (1 μg) given 24 h before median eminence stimulation significantly increased the number of rats ovulating. An injection of progesterone (1 mg) 24 h before median eminence stimulation did not affect the number of animals ovulating or the number of ova shed. In contrast, there was a significant reduction in the number of animals ovulating after preoptic stimulation. Stimulation of the median eminence 2–4 h after progesterone administration increased the number of animals ovulating. The results suggest that both oestradiol and progesterone exert a positive feedback effect at or below the level of the median eminence and that the negative feedback effect of progesterone is exerted on the preoptic area.
EFFECTS OF INTRADUCTAL PROLACTIN ON SOME ASPECTS OF THE ULTRA-STRUCTURE AND BIOCHEMISTRY OF MAMMARY TISSUE IN THE PSEUDOPREGNANT RABBIT
Authors: FIDDLER T. J. , BIRKINSHAW MARGARET , FALCONER I. R. 
Published: December 2008

SUMMARY
A study of the ultrastructure of the secretory epithelial cells of the mammary gland was carried out in virgin oestrous rabbits, pseudopregnant rabbits and pseudopregnant rabbits injected with prolactin to induce lactogenesis. Ultrastructural modifications of the mammary epithelial cells, from inactivity to active secretion after an intraductal injection of prolactin, are described. The changes produced after prolactin injection were characterized by a progressive increase in endoplasmic reticulum and in ribosomes in the cytoplasm. This was evident after 12–24 h. By the 2nd or 3rd day after hormone administration the cells had differentiated into active secretory epithelium. These cells were characterized by large numbers of ribosomes in the cytoplasm; an extensive development of rough endoplasmic reticulum; development of cisternae from the enlarging rough endoplasmic reticulum; hypertrophy of the Golgi apparatus and smooth endoplasmic reticulum; and the presence of protein granules in the vacuoles which were particularly abundant in the cytoplasm near the duct lumen. The presence of lipid droplets in the cells was less indicative of an active secretory state since they were also observed in mammary tissue from pseudopregnant rabbits. Biochemical investigation of the response of pseudopregnant mammary tissue to intraductal prolactin showed no significant rapid effects on either casein-like protein or lactose biosynthesis, but increases in both substances were observed on the 3rd day after hormone administration.
REDUCED THYROID ACTIVITY IN JAMAICANS
Authors: HARLAND W. A. , RICHARDS R. , GOLDBERG I. J. L. 
Published: December 2008

SUMMARY
The results presented demonstrate reduced thyroid activity in euthyroid Jamaicans. In 15 subjects, thyroid clearance of 131I was 13·0 ± 8·8 (s.d.) ml/min, and renal clearance was 20·6 ± 9·7 ml/min. In 205 healthy volunteers the 24 h 131I thyroid uptake averaged 13·8% and in 60·9% the uptake was less than 10% of the dose. Urinary excretion of 131I was correspondingly high. However, excretion of stable iodine in urine averaged only 62·0 μg/day. Thyroid secretion rate (TSR) calculated in a group of subjects with complete collection of urine was 12·0 μg I/day in women and 11·4 μg I/day in men. Protein-bound iodine (PBI) values in 50 subjects were 5·9 ± 1·3 μg/100 ml. Uptake of tri-iodothyronine by red blood cells also gave low values. The apparent discrepancy between low TSR and normal PBI is discussed. These findings, together with other reported values, indicate reduced thyroid activity in the tropics. It is argued that reduced metabolism is probably secondary to lower thyroid activity.
THE EFFECT OF PROLACTIN ON THE SLOUGHING CYCLE IN THE HYPOPHYSECTOMIZED—THYROIDECTOMIZED LIZARD, GEKKO GECKO L.
Authors: CHIU K. W. , PHILLIPS J. G. 
Published: December 2008

SUMMARY
Hypophysectomized—thyroidectomized geckos failed to slough during the experimental period of about 120 days. The resting phase of the sloughing cycle persisted so that the outer epidermal generation remained incomplete. These results indicate that one important endocrine component of the sloughing cycle is the normal functioning of the pituitary—thyroid system.
Prolactin administration at 0·4 i.u./g body wt on alternate days restored sloughing by reducing the length of the resting phase; the outer generation was completed and was shed after the appearance of a new inner unit.
DISTRIBUTION OF [131I]α1–24ADRENOCORTICOTROPHIN IN THE INTACT GUINEA-PIG
Authors: GOLDER MERIEL P. , BOYNS A. R. 
Published: December 2008

SUMMARY
Intact, unanaesthetized guinea-pigs were injected intravenously with [131I]α1–24adrenocorticotrophin (ACTH) (50–70 ng). The concentrations of radioactivity found in the kidney were considerably higher than in other tissues. There was no evidence for preferential accumulation in the adrenal gland as a whole when compared with 125I-labelled bovine albumin ([125I]BSA), [125I]poly-l-tyrosine and [125I]iodide. The intra-adrenal distribution of 131I radioactivity showed one peak at the border between the zona glomerulosa and the z. fasciculata and another in the z. reticulosa. The intra-adrenal distribution of [125I]BSA and [125I]iodide differed from that of [131I]α1–24ACTH.
ANALYSIS OF RIBOSOMES AND POLYSOMES DERIVED FROM RABBIT MAMMARY GLANDS DURING PREGNANCY AND LACTATION
Authors: HERRIMAN I. D. , BAIRD G. D. , BRUCE JUDY M. 
Published: December 2008

SUMMARY
Whole-ribosome and polysome-enriched fractions were prepared from the mammary glands of rabbits during late pregnancy and lactation. The composition of the fractions was determined by sucrose density gradient analysis and electron microscopy. The range of size of polysomal aggregates was similar in the late-pregnant and lactating gland, with aggregates containing five to nine ribosomal units predominating. However, the amount of polysomes relative to monosomes was invariably found to increase after parturition. The greater portion of this increase was accounted for by the increased abundance of aggregates containing five to nine units.
THE INFLUENCE OF LESIONS IN THE POSTEROVENTRAL GREY MATTER OF THE MID-BRAINS OF RATS ON SALT EXCRETION
Authors: GWYNNE H. L. , LOCKETT MARY F. , MARWOOD J. F. 
Published: December 2008

SUMMARY
Lesions in the posteroventral grey matter of the mid-brain reduced the ability of rats to excrete single oral saline loads and to adapt at normal speed to salt loading. Rats with these lesions had normal adrenal and thyroid function but stores of growth hormone in the adenohypophysis were reduced. Typical behavioural changes were induced: these included hyperactivity, almost frenzied blind running when disturbed which converted to perimeter running when obstructed by any object; hyperphagia and obesity. Effects on ability to handle salt loads are attributed to section of fibres ascending to the diencephalic centre in the posterior nuclei of the hypothalamus which influences salt balance.
EXTRATHYROIDAL EFFECT OF THIOCYANATE AND PROPYLTHIOURACIL: THE DEPRESSION OF THE PROTEIN-BOUND IODINE LEVEL IN INTACT AND THYROIDECTOMIZED RATS
Authors: LANGER P. 
Published: December 2008

SUMMARY
In rats to which 125I was administered for 28 days, the level of protein-bound 125I (PB125I) (estimated by trichloroacetic acid precipitation or filtration on a Sephadex G-25 column) was measured. In intact animals, after a single dose of 16 mg thiocyanate ion, a significant decrease of PB125I was found, which was inversely related to the level of thiocyanate in plasma. The decrease was much faster than that in rats after thyroidectomy. From these findings an extrathyroidal effect of thiocyanate was postulated and tested in rats fed 125I− for 28 days and then thyroidectomized immediately before the administration of a single dose of 16 mg thiocyanate ion or 15 mg propylthiouracil. The level of PB125I in most of the latter animals 4, 8, 18 and 24 h after the administration of the drugs was significantly lower than that in thyroidectomized controls.
INCREASE IN THYROTROPHIN SECRETION BY RAT PITUITARY AUTOGRAFTS AFTER INFUSION OF HYPOTHALAMIC EXTRACTS
Authors: EVANS J. S. , AVERILL R. L. W. 
Published: December 2008

SUMMARY
Thyroidal uptake and release of 131I were used to study the effects of prolonged infusion of porcine hypothalamic extract on the ability of rat pituitary autografts to secrete thyrotrophin (TSH). The extract used contained insufficient TSH to induce release of thyroidal 131I in hypophysectomized rats.
After infusion for 10 days, the time of maximal uptake of 131I and onset of 131I release was significantly shortened by infusion of hypothalamic, but not cerebral cortical extract, when compared with non-infused autografted controls. The rate of release of thyroidal 131I was significantly increased by the infusion of hypothalamic extract so that by 96–120 h after the administration of 131I the rate of release was not significantly different from that in intact controls.
Accelerated thyroidal release of 131I began 42–48 h after the application of hypothalamic extracts to pituitary autografts and fell rapidly after withdrawal of the extract. At the end of 14–17 days of infusion sections of the autografts contained aldehyde-fuchsin positive staining basophils.
THE SECRETION OF CORTISOL AND ITS MAMMARY UPTAKE IN THE GOAT
Authors: PATERSON J. Y. F. , LINZELL J. L. 
Published: December 2008

SUMMARY
In pregnant and in lactating goats the rate of cortisol secretion was measured by continuous intravenous infusion of tritium-labelled cortisol. Uptake of cortisol by the mammary gland was measured by simultaneous sampling of blood from the carotid artery and superficial epigastric vein, and measurement of mammary blood flow. In pregnant goats the rate of cortisol secretion was 9 μg/min but in preparturient and in lactating goats the rate was about 32 μg/min. There was a small but significant difference in cortisol concentration between the carotid artery and mammary vein. In pregnant goats the mammary uptake of cortisol was about 0·2 μg/min; this was increased to about 1·3 μg/min in preparturient and in lactating animals. Negligible quantities of cortisol were secreted in the milk.
Cortisol was administered by continuous infusion for 4 h into two lactating goats. Although there was some stimulation of milk secretion it seems likely that it resulted from a systemic rather than local action of cortisol.
LABOUR IN THE RABBIT: EFFECT OF ELECTRICAL STIMULATION APPLIED TO THE INFUNDIBULUM AND MEDIAN EMINENCE
Authors: LINCOLN D. W. 
Published: December 2008

SUMMARY
Labour was induced by electrical stimulation of the infundibulum and median eminence in the conscious prepartum rabbit. The stimulus was applied for 20 s through a chronically implanted platinum—rhodium electrode and consisted of 1 mA biphasic pulses at 50/s.
The first visible signs of labour occurred 1·5–3·0 min after stimulation and activity usually ceased within 25 min. This was sometimes sufficient for the delivery of the entire litter. The litters ranged from 5 to 11 pups. Frequently, labour ceased before all the young were expelled, but labour was easily restarted by a further period of stimulation. There were cases in which labour was restarted on more than four occasions before parturition reached completion. Parturition was sometimes left in a suspended state for more than 24 h. The viability of the pups was not adversely influenced by the protracted nature of such parturitions. Stimulation was most effective at inducing labour when applied close to the predicted time of parturition and the treatment was almost totally ineffective when applied more than 48 h before the predicted time. Nest-building was not precipitated by the premature birth of the young and sometimes occurred a day or more after parturition.
The stimulation parameters used for the induction of labour caused large milk-ejection responses when applied to the same animals during lactation. Some of these milk-ejection responses were equal to the release of more than 100 mu. oxytocin.
These results suggest that the rapid expulsion of the pups during natural labour in the rabbit could be the result of a sudden and very large release of oxytocin.
THE EFFECT OF HYPOPHYSIAL STALK-SECTION ON THE CORPUS LUTEUM OF THE GUINEA-PIG
Authors: ILLINGWORTH DOREEN V. , PERRY J. S. 
Published: December 2008

SUMMARY
The effects of hypophysial stalk-section on the growth and function of the corpus luteum of the non-pregnant guinea-pig have been compared with the effects of hypophysectomy (as previously described) and with the effects of prolactin administered to hypophysectomized animals. Stalk-section soon after ovulation did not impair the growth of the corpora lutea nor their ability to secrete progesterone. Stalk-section before day 9 of the oestrous cycle prevented the normal regression of the corpora lutea; they continued to grow and 3 weeks after ovulation were as large as those of pregnant animals, or of non-pregnant hysterectomized guinea-pigs. The corpora lutea regressed irregularly during the following 2 weeks. When performed on, or later than day 9, stalk-section did not prevent luteal regression at the normal time.
Administration of prolactin (10 i.u./day) to hypophysectomized guinea-pigs restored the growth-rate of the corpora lutea, which reached sizes comparable to those of the normal cycle, and those of stalk-sectioned animals, by 10 days after ovulation.
Our results indicate that prolactin can have substantial luteotrophic activity in the guinea-pig.
PROLACTIN PRODUCTION BY THE HUMAN ANTERIOR PITUITARY CULTURED IN VITRO
Authors: GALA R. R. 
Published: December 2008

SUMMARY
A pituitary was obtained from a patient with metastatic breast cancer and cultured for 81 days in Medium 199. The medium was changed every 3 days. The prolactin activity of the medium, as estimated by the local crop gland proliferation assay, was significantly lower in the first 3-day culture period than in subsequent periods. Prolactin activity was similar between days 6 and 21 of culture, decreasing to the limits of the bioassay system on the 27th day of culture. Analytical disc electrophoresis of the medium revealed the presence of a protein component which migrated behind human growth hormone (HGH). A densitometric analysis of the bands in disc electrophoresis showed that the protein concentration of the component migrating behind HGH correlated with the prolactin activity of the medium for later periods of culture. A calculation of the specific activity of this component gave a value of 125 i.u. prolactin/mg protein.
THE EFFECT OF INTRAVENOUS ALDOSTERONE ON ARTERIAL PRESSURE IN THE RABBIT AND ITS MODIFICATION BY VARIATIONS IN DIET
Authors: BURSTYN P. G. , HORROBIN D. F. , LLOYD I. J. 
Published: December 2008

SUMMARY
Thirty-nine decerebrate rabbits, curarized and maintained by artificial ventilation, were used in the experiments. In a control group which received only saline intravenous infusions, arterial pressure remained virtually unchanged for 6 h after decerebration. Three other groups were used, all of which received intravenous infusions of aldosterone starting 1 h after decerebration and continuing for 5 h: in these groups the pressure 1 h after decerebration was taken as 100%. In a group of animals which received a normal diet before the acute experiment, the mean percentage pressure rise at the end of 5 h of aldosterone infusion was 20·0 ± 2·3 (s.e.m.)%. In a group whose drinking water had been replaced with 1% NaCl solution, the mean percentage pressure rise after 5 h was 29·6 ± 3·2. In a group pretreated with a low salt intake, the mean percentage pressure rise after 5 h was 10·3 ± 2·8%. These results show that intravenous infusions of aldosterone at the rate of 6 μg/kg/h can raise arterial pressure in acute experiments, and that varying the sodium intake can alter the responsiveness of the cardiovascular system to the hypertensive action of aldosterone.
THE UPTAKE OF TRITIATED LYSINE VASOPRESSIN BY RAT AND PIG PITUITARY NEURAL LOBES IN VITRO
Authors: EDWARDS B. A. 
Published: December 2008

SUMMARY
Uptake of tritiated lysine vasopressin ([3H]LVP) was studied in halved neural lobes of rats (which had been given either tap water (control group) or 2% (w/v) NaCl solution as drinking water for 4 days) as well as in slices of pig neural lobe. Uptake of radioactivity into the neural lobes was shown but analysis of the extracts of incubated lobes of both species by ion exchange chromatography showed that very little of it remained in the tissue as hormone. In addition, some radioactivity was associated with trichloroacetic acid-insoluble proteins.
After 90 min of incubation, and after correction for the breakdown, the uptake of unchanged [3H]LVP, expressed as a tissue: medium ratio, was 0·14 ± 0·04 and 0·09 ± 0·03 (mean ± s.e.m.) for the saline-treated and control rats respectively, while the tissue: medium ratios for the breakdown product(s) were 6·47 ± 0·45 and 5·50 ± 0·36. The results suggest uptake of [3H]LVP into the cell with almost complete intracellular breakdown of the hormone.