bluuebunny/crossref_metadata_2025 huggingface dataset:
THE MILK-EJECTION REFLEX OF THE RAT: AN INTERMITTENT FUNCTION NOT ABOLISHED BY SURGICAL LEVELS OF ANAESTHESIA
Authors: LINCOLN D. W. , HILL ALISON , WAKERLEY J. B.
Published: December 2008

Milk ejection (ME) was studied in the lactating rat by the measurement of intramammary pressure, milk yield and behaviour. An intermittent pattern of ME was observed, both in conscious rats and in rats anaesthetized with tribromoethanol, pentobarbitone sodium and ethyl carbamate. Milk ejection was never seen as a reflex response with the onset of the suckling stimulus; the latency to the first ME varied from 10 min in the conscious rat to > 60 min during deep anaesthesia. Thereafter, ME occurred at regular intervals ranging from 3 to 5 min under optimal conditions to > 15 min during less favourable circumstances, though the young were content to suckle continuously for several hours irrespective of whether they obtained milk.

Each ME was associated with an abrupt and uniform rise in intramammary pressure and simulation of the individual ME was obtained by a rapid i.v. injection of 1 mu. oxytocin. The pups reacted immediately to the rise in pressure with a synchronized extensor reaction and a vigorous increase in suckling which lasted for about 10 s. There was, however, no apparent change in the suckling stimulus to account for the release of endogenous oxytocin some 10–20 s prior to these events. Milk ejection was a reflex phenomenon, nonetheless, for the removal of the pups abolished the intermittent release of oxytocin.

The rise in intramammary pressure was associated directly with the ejection of the milk and the pups abruptly increased in weight. Yields of 10–12 g were obtained from both conscious and anaesthetized rats after 18 h of separation from their young. Most of this milk was expressed in the first ten milk ejections.

Mammary distension and the size of the litter were important parameters determining the pattern of ME. The incidence of ME was appreciably lower in unseparated rats whether anaesthetized or not and in separated rats after prolonged suckling or artificial removal of the milk. A similar reduction was encountered when the number of suckling pups was changed from ten to five.

The physiological principles of the ME reflex in the rat are discussed and a theoretical model is presented.
THE EFFECT OF LOW DOSES OF HUMAN CHORIONIC GONADOTROPHIN ON THE FERTILIZING ABILITY OF HAMSTER EPIDIDYMAL SPERMATOZOA
Authors: LUBICZ-NAWROCKI C. M.
Published: December 2008

The fertilizing ability of spermatozoa in ligated caudae epididymides of golden hamsters was reduced to approximately 25% of the control level after 12 daily s.c. injections of 10 i.u. human chorionic gonadotrophin (HCG), but spermatozoa retained normal fertilizing ability after treatment with higher doses of HCG (30 and 40 i.u./day). This antifertility effect of HCG was mediated through the testes since removal of one testis reduced the adverse effect of 10 i.u. HCG/day by approximately 75% while spermatozoa retained normal fertilizing ability in animals bilaterally castrated and treated with testosterone. Additional experiments revealed that 12 daily injections of 250 μg testosterone significantly reduce fertilizing ability although treatment with 500 μg testosterone daily for the same period had no effect. It was found, also, that the antifertility effect produced by treatment with 10 i.u. HCG daily for 12 days was similar to that after 12 daily injections of 3·5 μg oestradiol benzoate (OB). While 250 μg testosterone/day in combination with OB (3·5 μg/day) augmented the antifertility effect of this hormone, 500 μg testosterone daily prevented to a small but significant extent, the antifertility effects of HCG and OB at these doses. By contrast to their effects on fertilizing ability, testosterone, HCG and OB had no significant effect on seminal vesicular fructose concentration which remained high in each experimental group. It is suggested that the antifertility effect of low doses of HCG results from stimulation of testicular secretion of testosterone and subsequent conversion of limited but significant amounts of testosterone into oestrogens, either in the testis or peripherally, which then antagonize the effects of testosterone in the cauda epididymidis.
EARLY EFFECTS OF STILBOESTROL ON GROWTH HORMONE AND PROLACTIN SECRETION AND ON PITUITARY MITOTIC ACTIVITY IN THE MALE RAT
Authors: LLOYD H. M. , MEARES J. D. , JACOBI JOAN
Published: December 2008

The effects of a single injection of 1 mg diethylstilboestrol dipropionate on pituitary mitotic activity and on secretion of growth hormone and prolactin were investigated in male rats on each of the first 15 days following the single dose and then at intervals for a total period of 63 days. Mitotic activity increased to a maximum on day 4 and then gradually diminished. Serum growth hormone was moderately increased during the 2nd week and serum prolactin showed a gradual rise with a return to normal on day 63. In the pituitary gland, growth hormone concentration diminished until day 28, whereas prolactin rose quickly at first, maintained a raised level and increased further on day 43. During the first 12 days, pituitary weight was significantly correlated with serum growth hormone and prolactin concentration. During days 13–28, serum prolactin, but not growth hormone, was significantly correlated with the pituitary mitotic index.
UPTAKE IN VITRO OF [3H]OXYTOCIN BY THE MAMMARY GLAND AND OTHER TISSUES OF THE RAT
Authors: EGAN SANDRA M. , LIVINGSTON A.
Published: December 2008

In the presence of 62 μu. or more of [3H]oxytocin/ml there was specific uptake of oxytocin by lactating rat mammary glands in vitro within 400 s under conditions similar to those used in the biossay of oxytocin with rat mammary strips in vitro. This uptake was blocked by pre-incubation with non-radioactive oxytocin. A similar, rapid, specific uptake of oxytocin by uterine tissue in vitro was observed. There was no specific uptake of oxytocin by non-target tissues such as heart and skeletal muscle. Measurements of inulin and water spaces of the tissues showed that, over these short periods of time, diffusion into mammary tissue was much less than into the other tissues. The ratios of uptake of [3H]oxytocin: [3H]inulin and [3H]oxytocin: [3H]water were much higher for mammary tissue than those for other tissues used, indicating a preferential (tissue-specific) uptake. Uterine tissue from stilboestrol-primed rats also showed a preferential uptake of oxytocin, though not as great as that for mammary tissue. It is suggested that the specific uptake of oxytocin by mammary and uterine tissue is due to binding to specific receptors.

There was a variation in the specific uptake of oxytocin with the day of lactation of the mammary tissue, and specific uptake was only observed after the 8th day. This could indicate synthesis of receptors during lactation. In a similar way, synthesis of receptors may occur in the non-pregnant uterus due to the influence of exogenous oestrogens, leading to the increase in specific uptake by non-pregnant uterine tissue for oestrogen-primed rats. There is some evidence of more than one type of binding site for oxytocin. Biological action may only be associated with one of these sites.
CHANGES IN THE LUTEINIZING HORMONE RELEASING ACTIVITY OF THE HYPOTHALAMUS, AND IN PITUITARY GLAND AND PLASMA LUTEINIZING HORMONE DURING THE OESTROUS CYCLE OF THE SHEEP
Authors: CRIGHTON D. B. , HARTLEY BARBARA M. , LAMMING G. E.
Published: December 2008

Thirty ewes with regular oestrous cycles were divided into six groups for slaughter relative to the time of first acceptance of the ram. The slaughter times were: 0 h (in practice within 40 min of onset of oestrus), 6, 12 and 36 h after onset and days 10 and 16 of the cycle. The hypothalamus was removed and the luteinizing hormone (LH) releasing factor activity extracted with 0·1 m-HCl. The extracts were tested for LH releasing activity by adding them to the medium in which anterior pituitary tissue from castrated male sheep was incubated. The LH content of the medium was measured by the ovarian ascorbic acid depletion method (Parlow, 1958).

The activity of the extract from the group slaughtered on day 16 of the cycle was high (minimal effective dose (MED) = 0·00625 hypothalamic equivalents (HE)). The potency declined with the onset of oestrus and remained low at 6 and 36 h after onset (MED in each case 0·025 HE) with intermediate potencies at 12 h and 10 days after onset (MED in each case 0·0125 HE). These changes are compared with changes in the LH content of the pituitary gland (bioassay) and of the plasma (radioimmunoassay) and with parameters of the ovarian activity of the animals.
UPTAKE AND METABOLISM OF [1,2-3H]PROGESTERONE INJECTED INTRALUMINALLY INTO THE UTERI OF SPAYED MICE
Authors: CLARK B. F.
Published: December 2008

[1,2-3H]Progesterone (5–50 pg) injected intraluminally into the uterus of spayed mice was retained only to a small extent; producing a 'half-life' of about 30 min compared with > 240 min for [6,7-3H]oestradiol-17β (50 pg). Retention of progesterone by the uterus was not significantly different from that by the plantaris muscle, a non-target tissue. Paper chromatography of extracts indicated that metabolism of [1,2-3H]progesterone occurred in both the uterus and the vagina within 5 min of local injection. There was more metabolism in the vagina and it was qualitatively different. No selective retention of progesterone or its metabolites occurred in either organ. The proportion of the radioactivity present as progesterone over 120 min after injection remained constant.
CORTICOSTERONE METABOLISM BY RAT ADRENOCORTICAL CELL SUSPENSIONS AND MONOLAYER CULTURES: THE EFFECT OF DAMAGE ON 11-DEHYDROGENASE ACTIVITY
Authors: O'HARE M. J.
Published: December 2008

The metabolism of [3H]corticosterone by freshly disaggregated suspensions and deliberately damaged monolayer cultures of rat adrenocortical cells has been examined. In both cases, increased yields of 11-dehydrocorticosterone were obtained compared with intact, undamaged monolayer cultures, in which effective 11-dehydrogenase activity was extremely low. It was concluded that the greater part of the effective 11-dehydrogenase activity of the freshly prepared adrenal cell suspension was due to cells damaged by the disaggregation procedure. The maximum rate at which corticosterone was converted to 11-dehydrocorticosterone by the suspensions was equivalent to at least 50 ng/million cells/h. Undamaged monolayer cultures did not metabolize more than 0·2 ng of corticosterone/million cells/h to 11-dehydrocorticosterone.
SERUM AND PITUITARY LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE AND PROLACTIN LEVELS IN GONADECTOMIZED MALE, FEMALE AND ANDROGENIZED FEMALE RATS TREATED WITH OESTRADIOL BENZOATE
Authors: MALLAMPATI R. S. , JOHNSON D. C.
Published: December 2008

Changes in serum concentrations and pituitary content of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin, determined by radioimmunoassay, were studied after oestradiol benzoate (OEB) administration to gonadectomized male and female rats and to gonadectomized females androgenized with 50 μg testosterone propionate on the 5th day post-partum. Oestradiol benzoate (0·05–50 μg) was given once a day for 7 days beginning 3 weeks after removal of the gonads. A rise in serum LH concentration was produced by 0·05 μg OEB in all animals, but a reduction was found with the larger doses. Serum FSH increased in females injected with 0·05 μg OEB, but males and androgenized females had decreased FSH levels with all doses. The prolactin concentrations increased in the sera of all animals treated with 0·05 μg or 0·5 μg oestrogen. Males showed no further increases with larger doses. A very large increase was found in females given 5 μg but 50 μg did not have this stimulatory effect. Dose-dependent increases in serum prolactin were noted in androgenized females. Pituitary prolactin content increased in females and androgenized females treated with oestrogen; a slight, but significant, increase was found only in the males given 50 μg. Pituitary LH was increased only in the animals receiving a large amount of oestrogen (5 or 50 μg). Glandular FSH increased in the males and androgenized females given 0·5 μg OEB, but in all animals a reduction in this gonadotrophin was found after giving 50 μg of the oestrogen. The results indicate that androgenization alters the normal female hypothalamo-hypophysial response to oestrogen but it does not induce the response pattern of the male.
PROGESTERONE AND OESTROGEN AND THE INITIATION OF LACTATION IN EWES
Authors: HARTMANN P. E. , TREVETHAN P. , SHELTON J. N.
Published: December 2008

The concentrations of lactose and progesterone were determined in mammary secretion and blood plasma, respectively, collected from ten ewes at daily intervals from 30 days before to 10 days after parturition. An initial increase in the concentration of lactose in the mammary secretion occurred as early as 30 days before parturition and was not related to changes in the concentration of progesterone in the peripheral plasma. On the other hand, there was a rapid fall in the concentration of progesterone in the peripheral plasma from 1 to 4 days before parturition and this fall was closely related to a second rapid increase in the concentration of lactose in the mammary secretion. The foetuses were removed from an additional 12 ewes by Caesarean section at 144 days of gestation; three ewes received no hormone therapy; three ewes received 62·5 mg progesterone/12 h for 5 days; three ewes received 2·0 mg oestradiol at 12, 24 and 36 h respectively after surgery; three ewes received both progesterone and oestrogen therapy. Whereas progesterone inhibited the increase in milk yield and lactose concentration after Caesarean section, progesterone and oestrogen in combination inhibited only the increase in milk yield. These results suggest that progesterone withdrawal initiates lactogenesis in the ewe.
ISOLATION AND CHARACTERIZATION OF A PITUITARY PEPTIDASE SPECIFICALLY RELEASING, FROM GROWTH HORMONE, A PEPTIDE (SOMANTIN) WITH ANTAGONISTIC ACTIVITY TO INSULIN IN VITRO
Authors: DRIVER C. J. , ARMSTRONG J. McD. , BORNSTEIN J. , NG F. M.
Published: December 2008

A peptidase has been isolated from ovine pituitary glands and has been purified. It specifically hydrolyses ovine growth hormone, releasing a peptide with somantin activity. It is proposed to call this peptidase somantin-releasing enzyme (SRE). It is a di-isopropylphosphorofluoridate-sensitive peptidase with a molecular weight of 23000 Daltons. It is optimally active near pH 8·0. It is of quite limited specificity, as it hydrolysed growth hormone to a limited extent only and did not hydrolyse most of the other proteins tested as substrates.
EFFECTS OF INTERMITTENT GLUCOSE INFUSIONS IN PREGNANT RATS ON THE FUNCTIONAL DEVELOPMENT OF THE FOETAL PANCREATIC B-CELLS
Authors: ASPLUND KJELL
Published: December 2008

During the last 5 days of gestation, pregnant rats were infused intravenously with a glucose solution daily for 2 h. The total amount of glucose administered per day was 3–4 g/kg body weight. This dose significantly raised the maternal serum glucose levels by 56 ± 17 mg/100 ml on day 17 of gestation and by 39 ± 15 mg/100 ml on day 21. Saline infusions into pregnant rats caused no significant alterations of the blood glucose concentrations. On day 21 of gestation, foetuses were delivered by Caesarean section and the insulin release was determined in vitro by incubating pieces of foetal pancreas first at a low glucose concentration (0·4 mg/ml) for 30 min and then at a high glucose concentration (3·0 mg/ml) for a subsequent 30-min period.

It was found that the foetal body weights were significantly lower in the glucose-infused group when compared with the foetal body weights from an untreated control group. The pancreatic insulin content and serum glucose levels of the foetuses when killed did not show any significant difference between the glucose-infused and control groups. In agreement with previous observations a high concentration of glucose failed to affect the insulin secretion in vitro from the pancreases of foetuses of untreated or saline-infused mothers in the control groups. By contrast, in the offspring of glucose-infused mothers, the pancreatic glands responded to the high glucose concentration in vitro with a significantly enhanced rate of insulin release.

These findings suggest that the development of the B-cell function before birth may be influenced even by minor, short-term increases in the maternal blood glucose levels. The pregnant rat, intermittently infused with glucose, may serve as a useful model for further studies on the effects of maternal carbohydrate disturbances on B-cell development in the offspring.
PLASMA OESTRADIOL-17β AND ITS RELATIONSHIP TO SERUM FOLLICLE-STIMULATING HORMONE IN IMMATURE FEMALE RATS
Authors: MEIJS-ROELOFS H. M. A. , UILENBROEK J. Th. J. , JONG F. H. de , WELSCHEN R.
Published: December 2008

Oestradiol-17β (E2) was measured by radioimmunoassay in the plasma of immature female rats. Maximal E2 levels of 55–60 pg/ml were found at 10–15 days of age; from day 25 to day 35 E2 levels were low to undetectable. The E2 measured appeared to be of ovarian origin: ovariectomy performed on day 13 resulted in a decreased E2 level 2 days later (13 pg/ml) as compared with the value from the control litter mates (46 pg/ml); after adrenalectomy the level of circulating E2 remained normal (54 pg/ml). The effects of ovariectomy and adrenalectomy on uterine weights followed a similar pattern: ovariectomy resulted in a decrease and adrenalectomy in no change in uterine weight.

In the strain of rat used, levels of follicle-stimulating hormone (FSH) in the serum (measured by radioimmunoassay) were high from day 10 to day 20 and showed a steep decrease on day 21. After ovariectomy on day 15 this decrease in serum FSH was not observed.

The influence of circulating E2 on serum levels of FSH was studied after ovariectomy followed by treatment with varying doses of oestradiol benzoate. Ovariectomy on day 13 resulted in a significantly increased FSH level 2 days later (1770 ng NIAMD-rat-FSH RP-1/ml) as compared with the value obtained from control animals (1033 ng/ml). This increase was not observed after daily injections of 0·1 μg oestradiol benzoate/100 g body weight.

The results indicate that E2 and FSH concentrations show a similar pattern between 5 and 35 days of age. Furthermore, an inhibitory feedback mechanism between oestrogens and FSH concentrations was found to be operative. The implications of these findings are discussed.
BREAKDOWN OF [3H]OXYTOCIN BY RAT TISSUES IN VITRO
Authors: EGAN SANDRA M. , LIVINGSTON A.
Published: December 2008

Tissue uptake of oxytocin by rat mammary gland, uterus, heart and skeletal muscle was demonstrated by incubation of these tissues with 3H-labelled oxytocin. Chromatography of tissue extracts showed that some breakdown of oxytocin had occurred after only 30 s. However, in all cases there was no breakdown of oxytocin in the corresponding incubation medium. This indicated that the breakdown of oxytocin occurred within the tissues.
AN ATTEMPT TO DEMONSTRATE CELL MIGRATION FROM THE ZONA GLOMERULOSA IN THE PREPUBERTAL MALE RAT ADRENAL CORTEX
Authors: WRIGHT N. A. , VONCINA D. , MORLEY A. R.
Published: December 2008

Recently, cell loss by necrosis has been demonstrated in the zona reticularis of the adrenal cortex; such loss is a prerequisite of the centripetal migration theory of adrenocortical cell renewal. Consequently a method has been evolved for the estimation of the rate of cell loss from the z. glomerulosa in prepubertal male rats aged 14 days.

The method depends upon measurement of the doubling time for the z. glomerulosa by weighing and serially sectioning adrenal glands at ages from 3 to 120 days, combined with point-counting. The doubling time for the z. glomerulosa at 14 days of age was 120 h.

A continuous labelling technique was used to estimate the growth fraction and the cell cycle time. In the z. glomerulosa these were 0·80 and 87 h respectively. These values gave an estimate of the cell production or birth rate of 0·00676 cells/cell/h, or 0·676 cells/100 cells/h, and consequently the potential doubling time (assuming no cell loss) was 102 h. Since the actual doubling time exceeds the potential doubling time, cells must be lost from the z. glomerulosa. This cell loss was found to be taking place at a rate of 0·0010 cells/cell/h, or 0·10 cells/100 cells/h, and the cell loss factor (ϕ) was 0·15.

Since necrosis has only been demonstrated in the z. reticularis, and evidently does not occur in the z. glomerulosa, this cell loss rate can be considered to represent the rate at which cells migrate from the z. glomerulosa. It is proposed, therefore, that in the prepubertal animal at least, centripetal cell migration does occur.
METABOLISM OF ANDROGENS IN VITRO BY HUMAN FACIAL AND AXILLARY SKIN
Authors: HAY J. B. , HODGINS M. B.
Published: December 2008

Human skin from forehead, cheek and axilla was incubated in vitro with [7α-3H]dehydroepiandrosterone (DHA), [7α-3H]DHA sulphate, [7α-3H]-androstenedione and [7α-3H]testosterone. The following enzyme activities were detected: 3β-hydroxysteroid dehydrogenase Δ4-5 isomerase, 17β-hydroxysteroid dehydrogenase, 3β-hydroxysteroid dehydrogenase, 3α-hydroxysteroid dehydrogenase, 5α-reductase, 5β-reductase, sulphotransferase, sulphatase, steroid hydroxylase. 5α-Reduced steroids were the major metabolites. All four substrates were converted to 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol. In axillary skin, conversion of 17-oxosteroids to 17β-hydroxysteroids was favoured, 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol being major metabolites. In facial skin, formation of 17-oxosteroids predominated with little accumulation of 5α-dihydrotestosterone or 5α-androstane-3α,17β-diol. 5α-Androstane-3β,17β-diol was a metabolite of DHA, androstenedione and testosterone but was found in lower amounts than 5α-androstane-3α,17β-diol. Similarly conversions to epiandrosterone were much lower than to androsterone in all the skin specimens.

It was concluded that the differences in accumulation of 5α-dihydrotestosterone were determined by the differences in 17β-oxidoreduction rather than differences in 5α-reductase, the activity of which was high in all skin specimens.
INFLUENCE OF TESTOSTERONE AND CYPROTERONE ACETATE ON THE RATE OF MITOSIS IN SEMINAL VESICLES OF RATS
Authors: DAHNKE H.-G. , SCHEUER A. , MOSEBACH K.-O.
Published: December 2008

From day 25 of life juvenile Wistar rats were injected with either testosterone (100 μg), cyproterone acetate (3 mg) or a combination of both substances. The rate of mitosis in the epithelium of seminal vesicles was determined 9, 24, 72 and 120 h after the initial injection. The rate of mitosis after testosterone application was found to have already increased by 120% within 24 h; after this no further increase could be detected.

Cyproterone acetate decreased the rate of mitosis by 50%, with the maximal effect after 72 h. Combined application of testosterone and cyproterone acetate augmented the rate of mitosis by 80% after 24 h; the rate decreased to control values after 72 h and remained constant for the rest of the observation time. The results are discussed on the basis of a receptor model.
LOCALIZATION OF NORETHISTERONE IN THE REPRODUCTIVE TRACT OF WOMEN
Authors: REED M. J. , FOTHERBY K. , PECK J. E. , GORDON Y.
Published: December 2008

[3H]Norethisterone was administered to women 1, 3 and 24 h before hysterectomy, when samples of blood, adipose tissue and tissues from the reproductive tract were obtained. At 1 h the highest concentrations of radioactivity were found in endometrium and stroma (0·77 and 0·78% respectively of the dose per 100 g tissue), the values in other tissues varying from 0·13 to 0·39%. By 3 h there was a decrease in the concentration in all tissues except adipose tissue and plasma and at this time the range of concentrations in all tissues, apart from plasma (0·40%), were similar (0·08 to 0·19%). There was a further decrease by 24 h. Mean values for the amount of radioactivity present in the tissues at 1 h were: uterus, 0·55%; adipose tissue, 21·6%; blood, 10·1%. By 24 h these values had decreased to 0·1, 7·0 and 6·6% respectively. In adipose tissue most of the radioactivity was present in the freely extractable state at all times studied, whereas in myometrium and cervix the amount of radioactivity freely extractable at 1 h (77%) had decreased by 24 h (39·0%). In plasma the amount of conjugated radioactivity increased from 54% at 1 h to 88% by 24 h. Whereas at 1 h most metabolites in plasma were conjugated as sulphates, by 24 h glucuronide conjugates were also important. In myometrial tissue 17·5 to 47·8% of the radioactivity was associated with the nuclear fraction.
COMPARATIVE STUDIES ON THE REDUCTION OF THE RESPONSE TO THE LONG-ACTING THYROID STIMULATOR BY SOLUBLE FRACTIONS FROM HUMAN, OVINE, BOVINE AND PORCINE THYROIDS
Authors: DIRMIKIS SUSAN , MUNRO D. S.
Published: December 2008

The response to the long-acting thyroid stimulator (LATS) but not to bovine thyroid-stimulating hormone (TSH) was reduced by soluble fractions from human, ovine, bovine and porcine thyroids. A significant increase in the capacities of human, ovine and bovine thyroidal soluble fractions to reduce the response to LATS occurred upon freezing and thawing of thyroidal homogenates. In human thyroids this change took place predominantly in the 4 S peak, which was the most active of the soluble fractions from frozen human thyroid tissue. However, in ovine and bovine thyroids, the change could be accounted for mainly by components of the 19 S peak, this being also the most active of the soluble fractions of frozen animal thyroids in reducing the response to LATS.

Whereas human LATS-binding activity (LAA) was destroyed by heating at 56 °C for 1 h the capacities of ovine, bovine and porcine thyroidal soluble fractions (or their 19 S components) to reduce the response to LATS were not affected by this treatment.

The interaction between human LAA and LATS can be reversed by 2 m-NaSCN, which also destroys LAA. However, NaSCN had no detectable effect on the capacities of soluble fractions (or their 19 S components) from ovine, bovine and porcine thyroids to reduce the response to LATS. The reduction of the response to LATS by very high concentrations of 4 S components, from frozen ovine thyroidal homogenate, was partially reversed by 2 m-NaSCN. Thus ovine thyroids may be a source of a substance with the properties of human LAA, but with a yield of approximately 10% of that obtained from human thyroid tissue.

It was concluded that ovine, bovine and porcine thyroidal soluble fractions reduced the response to LATS mainly by mechanisms other than binding to LAA.
PLASMA GROWTH HORMONE AND SERUM PHOSPHORUS CONCENTRATIONS IN RELATION TO THE MENOPAUSE AND TO OESTROGEN THERAPY
Authors: AITKEN J. M. , GALLAGHER M. J. D. , HART D. M. , NEWTON D. A. G. , CRAIG A.
Published: December 2008

Plasma human growth hormone (HGH) and serum phosphorus concentrations were measured during the fasting ambulatory state in middleaged men, pre- and postmenopausal women and postmenopausal women who had been taking 20–40 μg mestranol daily for 1–3 years.

The mean plasma HGH concentrations were consistently higher in the women than they were in the men, there was little difference between the mean values for pre- and postmenopausal women, and the mestranoltreated women had significantly higher mean values than the untreated postmenopausal women.

The mean serum phosphorus concentration was significantly higher after menopause and was significantly lower in those women on long-term lowdose mestranol therapy. A significant direct correlation was found between serum phosphorus and plasma HGH concentrations in untreated postmenopausal women.

It is suggested that the postmenopausal relative hyperphosphataemia is consistent with increased HGH activity.
EFFECTS OF ADENOHYPOPHYSECTOMY AND AMINOGLUTETHIMIDE ON WATER AND ELECTROLYTE COMPOSITION OF XENOPUS LAEVIS DAUDIN
Authors: EDWARDS B. R. , CHAN S. T. H.
Published: December 2008

Keeping Xenopus laevis Daudin in sodium-rich or sodium-free media leads to hypernatraemia or hyponatraemia respectively. Approximately 3 weeks after adenohypophysectomy, sodium and chloride concentrations in plasma and tissue water were reduced; there was also a net loss of the ions from the muscle. Potassium was not significantly affected. Aminoglutethimide, a proven inhibitor of corticosteroidogenesis in mammals, produced similar though more pronounced changes. In the adenohypophysectomized animal, this drug also produced a net increase in muscle potassium. The role of the urinary bladder in reabsorbing sodium has been demonstrated in Xenopus by an in-vivo technique. While the rate of urine flow was reduced in adenohypophysectomized toads, the rate of sodium excretion was essentially unchanged.
EFFECTS OF ANDROGEN ON THE AVERSIVE PROPERTIES OF MALE MOUSE URINE
Authors: JONES R. B. , NOWELL N. W.
Published: December 2008

The aversive properties of urine of castrated male mice receiving varying doses of testosterone phenylpropionate was assayed using males housed in groups of six as subjects. The aversive efficacy of the urine was found to rise with an increase in androgen levels. There was a delay of 5 days before the exogenous androgen exerted any effect on the aversive properties of the urine. This delay indicated that the aversive factor might be a pheromonal substance released from an androgen-dependent tissue, rather than being an excreted androgen metabolite.

The results are discussed in terms of androgen levels and possible territorial functions.
THE 11-OXYGENATION INDEX IN PREGNANCY: TENTATIVE EVIDENCE FOR DECREASED FOETAL ADRENOCORTICAL ENZYME ACTIVITY AT PARTURITION
Authors: MAKIN H. L. J. , TRAFFORD D. J. H. , WARD PATRICIA R. , LANE J.
Published: December 2008

The urinary 11-oxygenation index has been measured throughout pregnancy in 25 women. The index rose steadily throughout pregnancy. At about 35 weeks gestation it rose rapidly, reached a peak just before parturition and rapidly fell to normal thereafter. Statistical analysis indicated that there might be differences in the index levels between women who delivered spontaneously and women in whom induction was necessary. It is suggested that this rise in the index reflects a foetal adrenocortical enzyme inactivity, leading to an increased secretion of cortisol precursors into the maternal circulation at term, which may be involved in the processes of parturition.
SINGLE UNIT ACTIVITY IN THE HYPOTHALAMO-NEUROHYPOPHYSIAL SYSTEM OF BRATTLEBORO RATS
Authors: DYBALL R. E. J.
Published: December 2008

Unit activity was recorded in the supraoptic (SO) and paraventricular (PV) nuclei in Brattleboro (DI) rats both homozygous and heterozygous for the factor causing diabetes insipidus, and from normal Long-Evans rats from which the Brattleboro strain is derived. In these nuclei the distance between cells which could be antidromically excited by stimulation of the neural lobe did not differ between the three groups of animals. The electrical properties of the antidromically excited neurones, as judged by the latency of the antidromic spike, the maintenance of the amplitude of the spikes after short trains of stimuli, the existence of phasically firing units and antidromic inhibition, did not seem impaired in DI rats. The spontaneous discharge rates of antidromically identified neurones in the SO nuclei of both homozygous and heterozygous DI rats, but not of other hypothalamic units, were significantly faster than those in normal animals. Plasma sodium concentration and osmolality are known to be higher than normal in homozygous but not in heterozygous DI rats. These are therefore unlikely to be the only factors responsible for the increased firing rates in the SO nucleus of DI rats. The results are consistent with the suggestion that the primary lesion in DI rats is an impairment of vasopressin biosynthesis which does not involve the electrical properties of the neurones.
RELATIONSHIP OF VISCERAL BLOOD FLOW TO CORTISOL METABOLISM IN COLD-STRESSED SHEEP
Authors: PANARETTO B. A.
Published: December 2008

Whole body metabolic clearance rates (MCR) and splanchnic, hepatic and renal clearance rates of cortisol were estimated in six shorn sheep under control conditions. The measurements were repeated in the same animals when they were exposed to a cold, wet environment while they were maintaining a normal rectal temperature and again when they became hypothermic, their mean final rectal temperature ( ~ 36 °C) having been reduced approximately 2–3 °C below the control range. The quantitative changes in MCR that occurred during cold stress were found to be associated with corresponding changes in splanchnic and renal clearance rates. Increases in plasma cortisol concentrations up to 50 μg/1 were accompanied by proportional increases in rates of splanchnic blood flow and cortisol clearance. When cortisol concentrations rose above 50 μg/1 in hypothermic animals the MCR values tended to fall because of reductions in hepatic and renal blood flow; very large increases in plasma cortisol concentrations then resulted from comparatively small increases in production rate.
CHANGES IN PLASMA LEVELS OF OESTRADIOL, PROGESTERONE AND LUTEINIZING HORMONE IN IMMATURE RATS TREATED WITH PREGNANT MARE SERUM GONADOTROPHIN
Authors: WILSON CATHERINE A. , HORTH C. E. , ENDERSBY C. A. , McDONALD P. G.
Published: December 2008

The pattern of hormonal changes just before ovulation was investigated in immature rats induced to ovulate with pregnant mare serum gonadotrophin (PMSG). Oestradiol levels in the blood reached a maximum 42–52 h after PMSG treatment and then decreased dramatically. Pituitary luteinizing hormone (LH) levels remained constant until the time of the critical period (50–52 h) and then fell significantly. Plasma LH levels started to rise at 52 h, reached a peak at 54 h and fell to undetectable levels by 58 h. Plasma progesterone also reached a peak at 54 h and then fell slowly over the following dark period. The timing and pattern of changes in plasma and pituitary hormone levels were very similar to those seen in adult rats before ovulation. There was a positive correlation between the dose of PMSG, the peak concentration of plasma oestradiol and the average number of ova shed.
BLOOD AND URINE CLEARANCE OF LUTEINIZING HORMONE RELEASING HORMONE IN MAN MEASURED BY RADIOIMMUNOASSAY
Authors: JEFFCOATE S. L. , GREENWOOD R. H. , HOLLAND D. T.
Published: December 2008

The clearance of synthetic luteinizing hormone releasing hormone (LH-RH) after intravenous injection has been investigated in man. Thirteen tests were performed in ten subjects, four of whom were normal, the other six had proven disease of the hypothalamo-pituitary region. The rate of disappearance of LH-RH from the circulation could be represented as a double exponential with half-times of the two components of 5·3 and 27·4 min respectively. The initial volume of distribution was 11·1 ± 1·6 (s.d.) 1 and the metabolic clearance rate 1480 ± 170 (s.d.) 1/day. There was no difference in any of these parameters between normal and abnormal subjects. Between 0·75 and 2·8% of the injected dose was excreted in the urine within 8 h, of which 48% was excreted in the first hour. The daily production rates of LH-RH were calculated from the urinary excretion rates; these gave higher results than production rates calculated from the blood metabolic clearance rate. Possible reasons for this are discussed.
FAMILIAL GOITRE WITH ABSENCE OF THYROGLOBULIN AND SYNTHESIS OF THYROID HORMONES FROM THYROIDAL ALBUMIN
Authors: DESAI K. B. , MEHTA M. N. , PATEL M. C. , SHARMA S. M. , RAMANNA L. , GANATRA R. D.
Published: December 2008

Two siblings, a brother (H. B.) and a sister (R. B.) with long standing goitres were investigated. Radioactive iodine uptake by the thyroid was increased and a significant portion of the plasma radioactive iodine was not extractable with butanol. Chromatography of butanol extracts of serum after radioactive iodine administration showed distinct peaks of triiodothyronine and thyroxine. Microscopic examination of the surgical specimens of the goitres showed Hürthle cell carcinoma with follicles devoid of colloid in both specimens. Sucrose density gradient centrifugation, gel filtration on Sephadex G-200, salting out procedures, starch gel electrophoresis and immunological tests of the supernatant soluble fraction of thyroid homogenates showed a lack of thyroglobulin. Further fractionation of the soluble proteins showed that albumin was apparently involved in the synthesis of thyroid hormones in the absence of thyroglobulin.
FACTORS INFLUENCING THE UPTAKE OF [α-14C]AMINOISOBUTYRIC ACID BY RAT TESTES
Authors: IRUSTA O. , WASSERMANN G. F.
Published: December 2008

The action of various agents on the distribution ratio of [α-14C]aminoisobutyric acid ([14C]AIB) in the testes of adult and growing rats was studied. A decrease in the distribution ratio of [14C]AIB was observed in the testes during maturation. Follicle-stimulating hormone (FSH) administered in vivo to 22-day-old rats or to mature hypophysectomized animals increased the distribution ratio of [14C]AIB in testicular cells. Dibutyryl adenosine 3′: 5′-cyclic phosphate augmented the [14C]AIB uptake into testes of intact or hypophysectomized mature animals. This nucleotide was ineffective in rats under 32 days of age. Testes from mature and immature rats preincubated in vitro with cycloheximide for 1 h showed a decrease in the distribution ratio of [14C]AIB. Cycloheximide also blocked the action of FSH on [14C]AIB uptake in the testes of 22-day-old rats.
THE EFFECTS OF CALCITONIN AND PARATHORMONE ON PLASMA MAGNESIUM LEVELS BEFORE AND AFTER BIRTH IN THE RAT
Authors: GAREL J. M. , BARLET J. P.
Published: December 2008

Plasma magnesium levels measured in rats from 16·5 to 21·5 days of gestation and during the first week after birth proved to be invariably higher in the foetus than in the mother. The highest level observed was in the 16·5-day-old foetus. A small decrease occurred between 16·5 and 17·5 days of gestation; thereafter the plasma magnesium level did not change until 19·5 days and then decreased between 19·5 and 21·5 days. After birth an increase in plasma magnesium occurred with suckling but then remained constant during the first week of life.

Parathyroid hormone (0·25 USP unit/g) injected into 21·5-day-old foetuses had no effect on plasma magnesium levels from 0·5 to 24 h after injection. This dose was found to be very potent in raising plasma calcium values 4 h after injection. In the 3-day-old newborn rat this dose was similarly ineffective. Removal of the foetal parathyroid glands by decapitation at 17·5 days of gestation was followed by a decrease in plasma magnesium at 21·5 days of gestation. Parathyroid hormone (0·25 USP unit/g) injected into decapitated foetuses did not change the level of magnesium in the plasma.

Salmon calcitonin (S-CT) at two doses (0·4 and 4 ng/g) produced no effect on plasma magnesium concentrations in 3-day-old newborn rats 3 h after injection; whereas at both doses, marked diminutions in plasma calcium and phosphate concentrations were observed. After injection of 40 ng S-CT/g, plasma magnesium decreased in 3-day-old newborn rats 3 h after injection. This dose was found to decrease plasma magnesium in the 19·5-day-old foetus and in the 20·5-day-old foetus. Before 19·5 days of gestation no effect was observed.
BINDING OF LUTEINIZING HORMONE AND HUMAN CHORIONIC GONADOTROPHIN TO OVARIAN CELLS AND ACTIVATION OF ADENYLATE CYCLASE
Authors: KOCH Y. , ZOR U. , CHOBSIENG PRAKONG , LAMPRECHT S. A. , POMERANTZ S. , LINDNER H. R.
Published: December 2008

The binding of 125I-labelled ovine luteinizing hormone (OLH) and human chorionic gonadotrophin (HCG) to unbroken cells or homogenates from rat and bovine ovaries was studied in relation to the hormonal activation of adenylate cyclase. Both hormones are preferentially bound to ovarian tissue (luteal as well as follicular), while adrenal, kidney and liver showed no specific binding. The bound HCG was associated chiefly with the fraction of the homogenate sedimenting at 1000 g. Addition of excess unlabelled hormone (HCG, OLH) together with the corresponding or heterologous 125I-labelled hormone reduced the radioactivity bound to the tissue by 70–90%; rat LH also competed with OLH and HCG for binding sites, but follicle-stimulating hormone, prolactin, growth hormone, adrenocorticotrophin or glucagon were without effect. Binding could be dissociated from activation of adenylate cyclase by a two-stage incubation: at 4 °C rat ovarian slices bound the labelled hormones, though binding efficiency was reduced to about 20%, but no stimulation of the enzyme was observed. Reincubation of these slices, after washing, at 37 °C in hormone-free medium resulted in maximal activation of adenylate cyclase. Addition of homologous antibodies before the second incubation step abolished the effect of OLH but not that of HCG on the activation of the enzyme. Similarly, addition of homologous antibodies or of excess unlabelled hormone caused dissociation of bound 125I-labelled OLH but not of 125I-labelled HCG from receptor sites. It is concluded that (i) HCG, OLH and rat LH are bound to the same receptor on ovarian cells, but binding of OLH to the receptor is more labile than that of HCG; (ii) the receptor appears to be located on the plasma membrane, since it was largely associated with the 1000 g pellet and since bound OLH remained accessible to antibody; (iii) activation of adenylate cyclase requires the continued occupation of the binding site by the hormone, but occupation of only a fraction of the receptor sites by hormone is adequate to induce maximal production of cyclic AMP by the target tissue.
EFFECT OF SUCKLING AND ASSOCIATED FACTORS ON OVARIAN COMPENSATORY HYPERTROPHY DURING LACTATION IN THE RAT
Authors: MENA F. , AGUAYO D. , REYES G. , BEYER C.
Published: December 2008

The mechanism by which suckling affects the hypothalamo-pituitary-ovarian system was studied in lactating Wistar rats. Unilateral ovariectomy was carried out on day 4 post partum and the subsequent ovarian compensatory hypertrophy (OCH) was assessed on day 14 post partum. The weight of the corpora lutea (CL) of lactation, the CL of pregnancy and of the remainder of the ovary, here termed interstitial tissue, was determined for both ovaries. A clear OCH, mainly due to an increase in interstitial tissue, occurred in rats whose pups were removed on day 4 post partum. Suckling by two pups inhibited OCH, whereas suckling by six or ten pups produced significant ovarian atrophy, these effects being due to a decrease in weight of both interstitial tissue and CL of pregnancy which overcame an increase in weight of the CL of lactation. Inhibition of OCH occurred in spinal-cord transected rats suckling six pups. Suckling was suspended in unilaterally ovariectomized rats nursing ten pups on day 14 post partum, and the weight of the remaining ovary was determined 16, 32, 64 and 96 h later in four groups of rats. The weight of the remaining ovary returned to that of the control ovary 64 h after withdrawal of suckling. This effect was due to an increase in weight of interstitial tissue and of the CL of lactation. Maintenance of suckling for 64 h in rats with the galactophores ligated to prevent milk removal, inhibited OCH. By contrast, both oxytocin injections and exteroceptive stimulation provided by litters failed to block ovarian growth after suckling withdrawal. The results suggest that suckling itself is an important influence in the inhibition of OCH, but that other factors may contribute to the ovarian changes observed during lactation in the rat.
THE THYROTROPHIN RECEPTOR IN GUINEA-PIG THYROID HOMOGENATE: INTERACTION WITH THE LONG-ACTING THYROID STIMULATOR
Authors: MANLEY S. W. , BOURKE J. R. , HAWKER R. W.
Published: December 2008

Immunoglobulin G (IgG) prepared from sera containing the long-acting thyroid stimulator (LATS) inhibited the receptor binding of 125I-labelled thyrotrophin (TSH) in a particulate fraction of guinea-pig thyroid homogenate. This inhibition was shown to involve a binding interaction between IgG containing LATS and the receptor with a diminution in the number, but not affinity, of sites available for binding of TSH. Studies of dissociation kinetics and gel filtration of receptor—TSH complexes indicated that IgG containing LATS did not combine with receptors occupied by TSH. The data provide evidence that LATS and TSH bind to the same receptor site.
THE OVARIAN FOLLICLE OF THE SHEEPINHIBITION OF OESTROGEN SECRETION BY LUTEINIZING HORMONE
Authors: MOOR R. M.
Published: December 2008

The object of this study was to test the hypothesis that levels of luteinizing hormone (LH), comparable to those circulating at oestrus, inhibit oestrogen secretion from Graafian follicles of sheep. Three experimental approaches were used.

Follicles maintained in organ culture secreted high levels of oestrogen into the medium throughout a 7-day culture period; almost no progesterone was secreted under such conditions. By contrast, oestrogen secretion declined precipitously and progesterone secretion increased rapidly after the addition of LH (0·25 μg–10 μg NIH-LH-S 17/ml) to the culture medium.

In experiments combining in-vivo and in-vitro techniques, follicles were obtained from sheep from which the corpora lutea had been removed 24 h previously. The large follicles explanted from these sheep secreted high levels of oestrogen throughout the 7 days in culture. Insignificant amounts of oestrogen were, however, secreted in culture by large follicles that had been explanted from sheep in which 1 mg LH had been infused between 18 and 24 h after removal of the corpus luteum.

Experiments carried out entirely in vivo showed that intravenous infusion of 1 mg LH into sheep from which the corpora lutea had been removed 18 h previously prevented the ovaries from secreting, during the ensuing 22 h, the large amounts of oestrogen they would otherwise have produced.

The results demonstrate that oestrogen secretion by large Graafian follicles is terminated both in vitro and in vivo by an amount of LH corresponding to that released at oestrus.
THE INFLUENCE OF MATERNAL NUTRITION ON PLASMA HORMONE AND METABOLITE CONCENTRATIONS OF FOETAL LAMBS
Authors: BASSETT J. M. , MADILL DENISE
Published: December 2008

Merino ewes whose foetuses had surgically-implanted, indwelling vascular cannulae were used to determine the influence of maternal nutritional status on foetal plasma hormone levels during the last month of gestation. Observations were made during feeding of the ewes on a lucerne chaff diet ad libitum, during restricted feeding on the same diet and during fasting. Foetuses survived for an average of 31 days after the operation and seven out of the ten ewes lambed normally. In both ewes and foetuses, plasma concentrations of insulin were significantly higher 3–12 h after feeding than in prefeeding samples. Similar changes were seen with restricted and ad-libitum feeding. Fasting for 48 h caused significant decreases in insulin levels of both ewes and foetuses, but the decrease in foetal plasma insulin concentration was less than that in ewes. In agreement with earlier studies, foetal and maternal glucose concentrations were closely correlated and foetal fructose concentrations were closely related to foetal glucose concentrations. Foetal plasma insulin concentrations were closely correlated with glucose and fructose concentrations. Plasma growth hormone (GH) levels increased significantly in both ewes and foetuses during fasting. There were also significant increases during fasting in the plasma corticosteroid levels of the ewes, but not in those of their foetuses. Feeding did not cause significant changes in foetal plasma GH or corticosteroid concentrations although maternal GH concentrations were significantly increased and corticosteroid concentrations decreased 3–12 h after feeding on the restricted diet.

The results suggest that alterations in foetal plasma hormone concentrations could play an important role in foetal adaptation to fluctuations in maternal nutrient supply during the last month of gestation.