bluuebunny/crossref_metadata_2025 huggingface dataset:
A PRIMING EFFECT OF LUTEINIZING HORMONE RELEASING FACTOR ON THE ANTERIOR PITUITARY GLAND IN THE FEMALE RAT
Authors: AIYER M. S. , CHIAPPA SHARON A. , FINK G.
Published: December 2008

The possibility that luteinizing hormone releasing factor (LH-RF) not only stimulates the secretion of luteinizing hormone (LH) but also has the ability to prime the anterior pituitary gland so that further exposure to LH-RF enhances the responsiveness of the gonadotrophs has been investigated. The effect of two successive i.v. injections of the same dose of LH-RF (50 ng/100 g body weight) on the concentration of LH in plasma was determined in rats anaesthetized with sodium pentobarbitone. Blood samples were collected from the external jugular vein immediately before and at frequent intervals after the injections of LH-RF, and plasma concentrations of LH and, in some samples, follicle-stimulating hormone (FSH) were measured by radioimmunoassay.

In rats anaesthetized with sodium pentobarbitone at 13.30 h of pro-oestrus and injected i.v. with two successive doses of LH-RF, separated by an interval of 30, 60, 120 or 240 min, the LH response to the second injection was significantly greater than that to the first. The LH response was greatest when the two doses were separated by an interval of 60 min. The FSH response to the second injection of LH-RF given 60 min after the first was not significantly different from that to the first injection.

Compared with pro-oestrus, the priming effect of LH-RF was much less at metoestrus and dioestrus, and could not be demonstrated at oestrus. Ovariectomy on the morning of dioestrus reduced the LH responses to the first and second injections of LH-RF given 60 min apart on the afternoon of pro-oestrus, an effect which was partially reversed by administration of oestradiol benzoate shortly after ovariectomy. These findings together with the fact that administration of oestradiol benzoate at metoestrus increased the magnitude of the priming effect of LH-RF at dioestrus suggest that the response at pro-oestrus is dependent upon the rise in plasma oestradiol-17β which reaches a peak on the morning of pro-oestrus.

Although oestrogen plays an important role in determining the magnitude of the priming effect of LH-RF, it appears that none of the steroids secreted by either the ovaries or the adrenal glands mediates this effect since the profile and magnitude of the LH responses to the two doses of LH-RF injected at pro-oestrus into rats adrenalectomized and ovariectomized before the first injection of LH-RF were comparable to those in control animals.

The possible role which the priming effect of LH-RF may play in the development of the preovulatory surge of LH in the rat and man is discussed.
GONADOTROPHIN SECRETION AFTER ELECTRICAL STIMULATION OF THE PREOPTIC AREA DURING THE OESTROUS CYCLE OF THE RAT
Authors: FINK G. , AIYER M. S.
Published: December 2008

The responsiveness of the hypothalamo-hypophysial axis to electrical stimulation of the medial preoptic area was tested at various times during the oestrous cycle of the rat. Animals were anaesthetized with sodium pentobarbitone, and glass-insulated bipolar platinum electrodes were stereotaxically implanted in the medial preoptic area. The stimulus consisted of accurately balanced biphasic rectangular pulses, height 500 μA, duration 2 ms and frequency 60 Hz, applied in trains of 30 s intervals. The concentration of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in blood samples withdrawn from the external jugular vein immediately before and at frequent intervals up to 1 h after application of the stimulus was determined by radioimmunoassay. In all animals the stimulus was applied for a period of 15 min, for it was found that under these conditions the profiles of LH and FSH produced in individual animals were similar to those which followed the i.v. injection of 50 ng synthetic luteinizing hormone releasing factor (LH-RF)/100 g body wt, the minimal ovulatory dose of LH-RF in our laboratory.

Both for LH and FSH, the profiles of responsiveness of the hypothalamo-hypophysial axis to electrical stimulation through the oestrous cycle resembled closely the profile of responsiveness of the anterior pituitary gland to LH-RF administered intravenously. There was a relatively gradual increase in pituitary sensitivity, in terms of the mean maximal increments, between the early afternoon of dioestrus and pro-oestrus, followed by an abrupt and marked rise which reached a peak at 18.00 and 21.00 h of pro-oestrus for LH and FSH, respectively. Sensitivity of the hypothalamo-hypophysial axis declined through oestrus and metoestrus reaching a nadir at 13.30 h of dioestrus. While these results do not exclude a change in sensitivity of the neural component of the hypothalamo-hypophysial axis during the oestrus cycle, they do indicate that the timing and magnitude of changes in sensitivity of the anterior pituitary gland to both endogenous and exogenous LH-RF are similar. This raises the possibility that a marked increase in the secretion of LH-RF during the afternoon of pro-oestrus may not be necessary for the occurrence of the surge of LH and FSH, for conceivably the latter could depend on a change in sensitivity of pituitary gonadotrophs to constant or only slightly increased levels of LH-RF in hypophysial portal blood.

Our findings are compared with those of workers who have employed electrochemical stimulation of the preoptic area.
RADIOIMMUNOASSAY OF SYNTHETIC PROGESTOGENS, NORETHISTERONE AND NORGESTREL
Authors: WARREN R. J. , FOTHERBY K.
Published: December 2008

Antibodies to norethisterone and norgestrel were raised in rabbits by injecting the steroid 3-carboxymethyloxime coupled to bovine serum albumin. Within 6 months of the first injection, antisera were obtained which gave 50% binding of the labelled steroid at dilutions of 1:100000; after treatment with Rivanol the antisera had titres of 1:20000 to 1:30000. Labelled ligands were prepared by iodination of the tyrosine methyl esters of the steroid oximes; minimum specific activities of 100 to 150 Ci/mmol were obtained. Dextran-charcoal suspension was used for the separation of bound and free labelled steroid. The effect of changes in the incubation conditions on the sensitivity of the assay were investigated. The reliability criteria for the assays were satisfactory, blank values were low and the mean recoveries were greater than 90%. The sensitivity of the method corresponded to a concentration of the steroids in plasma of 30 pg/ml. The coefficient of variation for replicate analyses on the same sample varied from 13·5 to 16%. Apart from the parent steroid, the 3-oxime and the tyrosine methyl ester of the oxime, significant cross-reaction with the antiserum was also obtained with the dihydro and tetrahydro metabolites of the progestogens. After administration orally of 1 mg norgestrel or 1 mg norethisterone to human subjects, peak levels of the steroids in plasma were obtained within 1 to 2 h. Norgestrel was metabolized more slowly than norethisterone. For the periods 2–8 h and 8–24 h after administration of norethisterone the half-lives were approximately 3 h and 5 h respectively; for norgestrel the half-lives were 2·8 h and 10 h. Twenty-four hours after administration, the mean levels of norgestrel and norethisterone in plasma were 1·5 and 0·2 ng/ml respectively corresponding approximately to 0·4% and 0·05% of the dose in the total plasma volume.
INFLUENCE OF THE TROPHOBLAST UPON DIFFERENTIATION OF THE UTERINE EPITHELIUM DURING IMPLANTATION IN THE MOUSE
Authors: POLLARD R. M. , FINN C. A.
Published: December 2008

During the preparation of the uterus for implantation of blastocysts the luminal surface of the epithelial cells undergoes a characteristic differentiation. In non-pregnant animals this can be induced by progesterone and oestrogen, but in pregnant animals the basic hormonal control is augmented by a local effect of the blastocyst. This has been demonstrated by examining the uteri of animals made unilaterally pregnant. The differentiation of the luminal epithelial surface of the fertile horn was in advance of that in the sterile horn. The injection of oil into one horn of the uterus of pseudopregnant animals also accelerated the change in the luminal surface of the injected horn.

It is suggested that contact with the cell membrane of the trophoblast influences differentiation of the uterine epithelium and that oil is able to mimic this contact reaction.
SERIAL ASSAYS OF PLASMA GROWTH HORMONE IN TREATED AND UNTREATED ACROMEGALY
Authors: HUNTER W. M. , GILLINGHAM F. J. , HARRIS P. , KANIS J. A. , McGURK F. M. , McLELLAND J. , STRONG J. A.
Published: December 2008

Assays for human growth hormone (HGH) were carried out on 89 acromegalic patients, 81 of whom were studied before any treatment had been given. Serial studies were undertaken, generally at 6-monthly intervals, with the same test procedure, using a 50 g oral glucose tolerance test (GTT) and identical assay conditions over a period of 8 years. Twenty-three patients were assessed at intervals during periods of up to 4 years whilst they remained untreated. The general picture was one of unchanging HGH levels.

Ten patients were studied before and after external irradiation. HGH levels showed a slow continuing fall for as long as 4 years and thereafter they stabilized at one-third of pretreatment values. HGH levels in 12 patients treated with radioactive implants showed an immediate fall to one-third, and thereafter a further slow decline to one-tenth of pretreatment levels. The response in eight patients treated by surgical removal of pituitary tissue and subsequent radiotherapy varied considerably.

No patient, treated or untreated, showed evidence of partial suppression of HGH secretion during the GTT although three patients consistently responded to glucose with paradoxical hypersecretion.
EFFECT OF ERGOCORNINE ON PERPHENAZINE-AND OESTROGEN-INDUCED PROLACTIN RELEASE
Authors: KULKARNI P. N. , SIMPSON A. A.
Published: December 2008

Both oestradiol and perphenazine induced a significant increase in prolactin release by ovariectomized rats. Ergocornine completely inhibited the initial perphenazine-induced prolactin release which normally reaches a maximum during the first 2·5 h. However, ergocornine did not prevent a significant increase in prolactin release after daily administration of perphenazine. It inhibited oestrogen-induced prolactin release. The results support earlier suggestions that prolactin release is controlled by two mechanisms. Only one of the mechanisms can be blocked by ergocornine.
EFFECTS OF CORTISOL ON THE PRESERVATION OF RAT SKIN AT −3 °C
Authors: DE LOECKER W. , DOMS D. , STAS M. L.
Published: December 2008

Although cortisol slightly inhibited the incorporation of 2-14C]glycine into the proteins of rat skin samples incubated in vitro, addition of the hormone to the storage medium had a marked protective effect on protein and DNA metabolism. The incorporation of [2-14C]glycine into the proteins, and to a lesser degree that of [6-3H]thymidine into DNA, were stimulated when the incubated skin had been exposed to cortisol during storage. The skin samples stored in buffer containing cortisol transported α-aminoisobutyric acid more effectively; this was concluded to be due to a stabilizing effect of cortisol on the cell membrane. During storage protein catabolism and possibly protein turnover were stimulated by cortisol.
HORMONAL CONTROL OF PROLIFERATION IN THE GUINEA-PIG UTERUS
Authors: MARCUS G. J.
Published: December 2008

In the normal non-pregnant guinea-pig uterus, proliferation of the surface epithelium occurred principally on day 3 after oestrus (vaginal opening). Intense mitotic activity occurred on the following day in the lower regions of the glands. Mitotic activity was pronounced in the endometrial stroma on the succeeding 2 days.

In the ovariectomized guinea-pig, oestrogen stimulated cell devision only in the surface and superficial glandular epithelia, but conditioned the endometrium to respond to progesterone so that at least 2 successive days of progesterone treatment after oestrogen priming elicited both intense glandular proliferation and extensive stromal cell division, while progesterone alone induced uterine closure.

The proliferative responses of the guinea-pig endometrium thus resembled the responses of the rabbit endometrium rather than the rat or mouse endometrial reaction to hormonal stimulation.
METABOLIC EFFECTS OF CORTISOL AND CORTICOTROPHINS IN THE AUSTRALIAN BRUSH-TAILED OPOSSUM, TRICHOSURUS VULPECULA (KERR)
Authors: THAN KHIN AYE , McDONALD I. R.
Published: December 2008

The effect of cortisol and adrenocorticotrophic hormone (ACTH) administration on indices of carbohydrate, fat and protein metabolism was investigated in the conscious marsupial brush-tailed opossum Trichosurus vulpecula (Kerr).

Short-term (1 h) i.v. infusions of cortisol at 0·02, 0·20 and 1·0 mg/kg/h caused plasma glucose concentration to rise rapidly from the normal range of 106–119 mg/100 ml to 145–163 mg/100 ml at the end of the infusion period without consistent changes in plasma urea, amino acid or free fatty acid (FFA) concentration. Similar infusions of porcine or synthetic ACTH at 0·45 i.u./kg/h increased plasma glucose concentration to similar levels without significant change in plasma urea or amino acid concentration, but with a marked increase in plasma FFA concentration.

Daily injections of 1 mg cortisol acetate/kg for 8 days caused a moderate loss of weight, increased urinary nitrogen excretion and glycosuria in all animals. In one animal it was possible to associate these changes with an increase in plasma cortisol concentration to 8·6 μg/100 ml, and an increase in plasma glucose and urea concentrations to 172 and 52 mg/100 ml, respectively.

Liver glycogen concentrations in normal and 24 h-fasted animals were 5·53 ± 0·73 and 0·20 ± 0·14 g/100 g respectively, and daily i.m. injections of 1 mg cortisol acetate/kg increased the liver glycogen concentration to 3·38 ± 0·63 g/100 g in 24 h-fasted animals.

The erythrocytes contained only small amounts of glucose which increased during cortisol-induced hyperglycaemia.

It is concluded that Trichosurus is highly sensitive to the metabolic effects of glucocorticoids, which resemble those found in eutherian mammals, particularly the rabbit.
NUCLEAR AND CYTOPLASMIC OESTROGEN RECEPTORS IN VAGINAL AND UTERINE TISSUE OF MICE TREATED NEONATALLY WITH STEROIDS AND PROLACTIN
Authors: SHYAMALA G. , MORI T. , BERN H. A.
Published: December 2008

Neonatal treatment of female mice with oestrogen or androgen induces persistent vaginal cornification, which may be dependent or independent of ovarian hormones according to the amount administered. The concentration of oestrogen-binding protein in the cytoplasm and in the nuclear fraction was measured in the uterus and vagina of mice treated neonatally with either steroid alone or in combination with prolactin. Vaginal oestrogen responsiveness (dependence) of mice treated with low and high doses of steroids was correlated with oestrogen receptor content. Neonatal treatment with prolactin in combination with the low dosage steroid treatments favoured development of ovary-independent cornification and a concomitant decrease in oestrogen receptors in about 50% of the mice studied.
RELEASE OF 131I FROM THE OVARY OF THE LAYING JAPANESE QUAIL AFTER INJECTION OF PERCHLORATE, THIOCYANATE OR IODIDE
Authors: McLAUGHLIN PAMELA A. , NIRMALAN G. P. , TAM K. H. , ROBINSON G. A.
Published: December 2008

Intramuscular injection of KSCN, KClO4 or KI into laying Japanese quail resulted in the discharge of 12·6 to 34·0% of the ovarian 131I within a 1-h measurement period for birds studied 1 to 6 h after labelling. Potassium thiocyanate was as effective as an equimolar quantity of KClO4 in causing this discharge. For birds studied 18 h after labelling, no consistent effect of KClO4, KSCN or KI on ovarian 131I levels was found. Gel, thin-layer and paper chromatography of labelled oocytes determined that > 92% of the 131I was present as inorganic iodide.
CHICK KIDNEY ADENYLATE CYCLASE: SENSITIVITY TO PARATHYROID HORMONE AND SYNTHETIC HUMAN AND BOVINE PEPTIDES
Authors: MARTIN T. J. , VAKAKIS N. , EISMAN J. A. , LIVESEY S. J. , TREGEAR G. W.
Published: December 2008

Adenylate cyclase activity of crude plasma membranes from chick kidney was stimulated by low doses of parathyroid hormone (PTH). Sensitivity to PTH was ten to twenty times greater than that of a similar preparation from rat kidney cortex. Synthetic peptides consisting of the NH2-terminal 34 amino acids of bovine PTH (BPTH) and of human PTH (HPTH) were assayed, as were several analogues of these peptides. Bovine PTH (1–34) and HPTH (1–34) were equivalent in their action on chick kidney but the human peptide had only 20% of the activity of the bovine peptide on rat kidney cortex adenylate cyclase. Bovine proPTH ( −6→ + 34) and (Tyr1)-BPTH (1–34) had less activity than BPTH (1–34). Bovine PTH (2–34) inhibited the response to BPTH (1–34). Neither salmon calcitonin nor vasopressin stimulated adenylate cyclase activity.
EFFECT OF CORTISOL ON INSULIN SENSITIVITY OF THE MARSUPIAL BRUSH-TAILED OPOSSUM, TRICHOSURUS VULPECULA (KERR)
Authors: THAN KHIN AYE , McDONALD I. R.
Published: December 2008

An investigation was made of the interactions between insulin and cortisol on carbohydrate, fat and protein metabolism in the marsupial brush-tailed opossum Trichosurus vulpecula (Kerr).

Intravenous injection of 0·15 i.u. regular insulin/kg caused a prompt fall in plasma glucose concentration to 33–54% of the control value, in the first 30 min, with complete recovery within 4 h. This was associated with a slow fall in plasma amino acid concentration and a moderate rise in plasma free fatty acid (FFA) concentration. Plasma cortisol concentration was increased 1·5 h after insulin injection to maximum values of 1·24–4·44 μg/100 ml, which were approximately proportional to the degree of hypoglycaemia.

Pretreatment with five daily i.m. injections of 1 mg cortisol acetate/kg caused a marked reduction in insulin sensitivity of three out of four opossums, and increasing the dose to 5 mg/kg caused a similar reduction in insulin sensitivity of the remaining opossum. Cortisol pretreatment raised the control plasma amino acid and FFA concentrations and enhanced the effect of insulin injection on these variables. There was a linear relationship between the control plasma cortisol concentration, within the physiological range, and sensitivity to insulin.

It is concluded that, in contrast to the red kangaroo, the interactions between insulin and glucocorticoids in Trichosurus resemble those reported for eutherian mammals. However, the unusual increase in plasma FFA after insulin injection is unexplained.
EFFECTS OF PREMATURE WEANING ON ADRENAL FUNCTION IN INTACT AND GONADECTOMIZED RATS
Authors: OGLE T. F. , KITAY J. I.
Published: December 2008

Premature weaning of intact or gonadectomized male and female rat pups did not alter adrenal function at day 49 provided the level of nutrition was sufficient to prevent loss of body weight. However, when nutrition was limited during the early weaning period (day 16–21) both intact male and female rats exhibited decreased production of corticosterone in vitro. Mechanisms mediating this decreased capacity may differ according to sex. In the male rat, production of total steroids in vitro was decreased as were resting plasma levels of corticosterone, suggesting that the set-point for regulation of corticosterone is altered by diminished adrenocorticotrophic hormone secretion. On the other hand, early weaning of the female did not affect plasma levels of corticosterone or total steroid production in vitro; however, the proportionate production of corticosterone compared with total steroid output in vitro was lowered. This effect could be mediated by depressed plasma levels of luteinizing hormone which obtained in prematurely weaned females whereby a paucity of oestrogen could alter the balance between corticosterone and total steroid production.
NEONATAL ANDROGEN ADMINISTRATION AND AGGRESSION IN THE FEMALE GOLDEN HAMSTER DURING INTERACTIONS WITH MALES
Authors: PAYNE A. P.
Published: December 2008

Female golden hamsters received either 300 μg testosterone propionate in oil, or oil alone, on day 1 of life. As adults they were observed in interactions with intact males when (i) intact, (ii) after ovariectomy and (iii) after ovariectomy and treatment with 1 mg testosterone propionate/day. Intact control female hamsters showed normal behaviour for this species by exhibiting more aggression than their male partners. After ovariectomy and subsequent treatment with testosterone propionate the levels of aggression shown by the two sexes became equal. Whilst neonatally androgen-treated females were also more aggressive than the males with which they interacted, they differed from the control females in that their aggressiveness was significantly reduced by ovariectomy and then enhanced by subsequent androgen therapy. When intact and when receiving exogenous androgens, the neonatally androgenized females showed significantly more aggression than the control females.
DAILY CONCENTRATIONS OF GONADOTROPHINS AND PROLACTIN IN THE SERUM OF PREGNANT OR LACTATING HAMSTERS
Authors: BAST J. D. , GREENWALD G. S.
Published: December 2008

The concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin in serum at 09.00 h on each day of pregnancy and 9 selected days of lactation in the hamster were determined by radioimmunoassays.

The concentration of FSH on day 1 of the 16-day pregnancy was approximately fivefold greater than the levels on subsequent days. Concentrations of LH decreased on each of the first 3 days of gestation, rose slightly during mid-pregnancy, and then tended to decline during the last trimester. The concentration of prolactin increased approximately twofold from day 1 to day 3, remained elevated until day 8, and then gradually returned during the last half of gestation to the level on day 1. The concentrations of the three hormones on the first 4 days of pregnancy differed markedly from the concentrations during the oestrous cycle.

Parturition had occurred and lactation begun by 09.00 h on day 16 of pregnancy (day 1 of lactation) and the levels of hormone on this day were unchanged from the levels on day 15 of pregnancy. Thereafter, the concentration of FSH increased two- to fourfold while the levels of LH increased until day 3 but then returned to the levels found at day 1. Concentrations of prolactin remained unchanged after day 1 of lactation, except for a decrease on day 2.
EFFECT OF SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE ON PLASMA LUTEINIZING HORMONE IN THE FEMALE DOMESTIC FOWL, GALLUS DOMESTICUS
Authors: BONNEY ROSEMARY C. , CUNNINGHAM F. J. , FURR B. J. A.
Published: December 2008

A dose of 20 μg luteinizing hormone releasing hormone (LH-RH) was injected i.v. into laying hens at different times in relation to ovulation and into immature hens of different ages. In laying hens a small but significant increase in plasma LH was consistently observed similar in height but shorter in duration than the natural pre-ovulatory surge of LH. The response was markedly less than that seen in cockerels injected with LH-RH. The time of injection of LH-RH in relation to ovulation did not affect the response unless it was administered immediately after the pre-ovulatory LH peak, when no release of LH occurred. The release of LH which normally occurs 4–7 h before ovulation was, however, unaffected by a rise in plasma LH stimulated by injection of LH-RH a short time previously. The lack of response to LH-RH in the 3 h before ovulation may be due to a depletion of the pituitary reserve of available LH since the normal pre-ovulatory peak of LH is more prolonged than that induced by LH-RH. In no case was premature ovulation seen after i.v. administration of LH-RH.

After LH-RH injection a striking increase in plasma LH, similar in magnitude to that in the cockerel, was observed in immature hens aged 11 weeks, but the response decreased with age until at 21 weeks, when basal levels of LH had increased, no response occurred. This would appear to be an important modification of the pituitary response to releasing hormone which coincides with the maturation of the hypothalamic-pituitary-gonadal system at the onset of sexual maturity.
PARTURITION IN THE GUINEA-PIG; PLASMA LEVELS OF STEROID HORMONES, STEROID-BINDING PROTEINS, AND OXYTOCIN, AND THE EFFECT OF CORTICOSTEROIDS, PROSTAGLANDINS AND ADRENOCORTICOTROPHIN
Authors: ILLINGWORTH D. V. , CHALLIS J. R. G. , ACKLAND N. , BURTON A. M. , HEAP R. B. , PERRY J. S.
Published: December 2008

Parturition in the guinea-pig is not preceded by any consistent change in the maternal plasma concentrations of progesterone, total unconjugated oestrogens or corticosteroids, or by a significant change in the concentration of progesterone-binding globulin (PBG). The onset of parturition was delayed by high doses of oestrogens (stilboestrol and oestradiol), but was not affected by oestriol or an antiserum raised against oestradiol. Premature parturition was achieved by the intra-carotid infusion of adrenocorticotrophin or prostaglandins (PGF2α, PGE2, I.C.I. 80,996) in conscious animals with indwelling catheters. I.C.I. 80,996, a potent analogue of PGF2α, induced parturition in all seven guinea-pigs treated; delivery occurred within 6 h of starting the infusion in six animals, and within 48 h in the seventh. The undesirable side-effects that accompanied treatment with PGF2α or PGE2 were not encountered with I.C.I. 80,996. Parturition induced experimentally resembled normal delivery but was not preceded by any significant change in the maternal levels of progesterone, total unconjugated oestrogens, corticosteroids, PBG or CBG in the circulation. Oxytocin was not detected until the delivery of the first foetus.

Parturition was not induced by maternal or foetal injections of corticosteroids or dexamethasone. Earlier findings are confirmed that the foetal adrenal grows steadily throughout late pregnancy and, unlike the foetal lamb adrenal, undergoes no rapid phase of growth immediately before term. Foetal adrenal weight decreased relative to foetal body weight.

The trigger for parturition in this species remains unidentified.
RELATIONSHIP OF THE SEX OF THE FOETUS TO THE AMOUNT OF HUMAN CHORIONIC GONADOTROPHIN IN PLACENTAE; SINGLE AND DIZYGOTIC TWIN PLACENTAE COMPARED
Authors: HOBSON BRUCE , WIDE LEIF
Published: December 2008

Human chorionic gonadotrophin (HCG) was assayed by biological and radioimmunological methods in placentae from 16 women with a normal twin pregnancy. When the concentration and total amount of HCG in placentae was related to the sex of the twin foetus, no significant difference between 'male' and 'female' placentae was found. This is contrary to findings that there is a significant (P < 0·005) difference in the concentration of HCG per g and per placenta of singletons at term. A comparison between the grouped geometric mean data from bioassays shows that the amount of HCG per g and per placenta falls between the geometric mean values for 'male' and 'female' singleton placentae.
CLEARANCE AND METABOLISM OF NEUROPHYSINS BY RAT KIDNEY
Authors: MORRIS B. J. , HUTCHINSON J. S. , JOHNSTON C. I.
Published: December 2008

The half-life in the circulation of 125I-labelled porcine neurophysins, injected intravenously into rats, was determined. The radioactivity in blood collected at intervals after injection was characterized as neurophysin by polyacrylamide gel electrophoresis. The half-life of neurophysin I was 1·5 ± 0·1 (s.e.m.) min and that of neurophysin II was 1·7 ± 0·1 min. The metabolic clearance rate of neurophysin I and neurophysin II was 1·9 ± 0·1 and 1·3 ± 0·2 ml/min/200 g respectively. Clearance from the circulation was due to both equilibration with the extravascular space and rapid specific accumulation by the kidney. The neurophysins were filtered at the glomerulus. Most of the neurophysin taken up by the kidney was incorporated into lysosomes, probably in the proximal tubule and degraded to lowmolecular-weight metabolites which appeared in urine and which represented the principal mode of excretion of neurophysins.
DISTRIBUTION OF RADIOACTIVITY IN THE ORGANS OF THE RAT AND MOUSE AFTER INJECTION OF [125I]α-MELANOCYTE-STIMULATING HORMONE
Authors: DUPONT A. , KASTIN A. J. , LABRIE F. , PELLETIER G. , PUVIANI R. , SCHALLY A. V.
Published: December 2008

The distribution of radioactivity after intrajugular injection of 125Ilabelled α-melanocyte-stimulating hormone (α-MSH) was studied by whole-body autoradiography of the mouse and by direct measurement of radioactivity in individual organs of the rat. Very high uptake of radioactivity in the pineal gland was measured 5 min after the injection of [125I]α-MSH. Lower levels of accumulation of radioactivity were found in the kidney and in the posterior (including intermediate) lobe of the pituitary. High uptake was also found in the thyroid, stomach, and oesophagus. The specificity of uptake of [125I] α-MSH into the pineal and pituitary is suggested by the very low uptake of Na125I into those tissues.
DISTRIBUTION OF RADIOACTIVITY IN THE ORGANS OF THE RAT AND MOUSE AFTER INJECTION OF l-[3H]PROLYL-l-LEUCYL-GLYCINAMIDE
Authors: DUPONT A. , LABRIE F. , PELLETIER G. , PUVIANI R. , COY D. H. , SCHALLY A. V. , KASTIN A. J.
Published: December 2008

The distribution of radioactivity after intrajugular injection of l-[3H]prolyl-l-leucyl-glycinamide has been studied by whole-body autoradiography in the mouse and by direct measurement of radioactivity in individual organs of the rat. There is good agreement between results obtained with the two techniques and animal species. High levels of radioactivity were found in the pineal gland, anterior pituitary, posterior (including intermediate) lobe of the pituitary, and epididymal and brown fat. Lower uptake of radioactivity occurred in the submaxillary gland, kidney, and adrenal gland. The preferential uptake of radioactivity by the pineal gland after injection of the labelled tripeptide suggests a role for this hypothalamic hormone in the control of pineal activity.
A COMPARISON OF THE CHARACTERISTICS OF PARTURITION INDUCED BY PROSTAGLANDIN F2α, INFUSED INTRA-AORTICALLY, WITH THOSE FOLLOWING OVARIECTOMY IN THE RAT
Authors: BUCKLE J. W. , NATHANIELSZ P. W.
Published: December 2008

Prostaglandin F2α (PGF2α) was infused intra-aortically at different rates into rats for 11·5 h from day 18 of gestation. At doses in excess of 5 μg/h premature delivery invariably occurred 40–41 h later. At lower doses an all-or-none effect was observed, some animals delivering prematurely and others continuing to term. Parturition could not be induced earlier than 40 h after the start of the treatment even by a continuous infusion of PGF2α, suggesting that the luteolytic role of PGF2α is more important than its oxytocic action in this case.

The rate of fall in plasma progesterone was greater in the rats delivering prematurely than those delivering at term, although the final concentrations of between 15 and 30 ng/ml at delivery were the same.

Labour appeared more normal in the animals receiving PGF2α than in those which had been bilaterally ovariectomized. The possible significance of this in relation to an effect of PGF2α on oestrogen secretion is discussed.
THE INFLUENCE OF SERUM ON THE UPTAKE, CONVERSION AND ACTION OF DIHYDROTESTOSTERONE IN RAT PROSTATE GLANDS IN ORGAN CULTURE
Authors: LASNITZKI ILSE , FRANKLIN HILARY R.
Published: December 2008

The influence of serum on the uptake, conversion and action of dihydrotestosterone in relation to the sex steroid binding protein, TeBG, has been investigated in rat ventral prostates in organ culture.

The organs were incubated with [1,2-3H]dihydrotestosterone in: (1) serum-free medium, (2) horse serum, foetal and newborn bovine serum or (3) human male and human pregnancy serum.

With all sera the uptake of dihydrotestosterone fell with rising serum concentration, at first steeply and then more gradually. At the same concentration, the uptake was significantly lower in explants incubated with human pregnancy serum than in those kept with human male serum. The conversion of dihydrotestosterone to androstanediol followed the same pattern and less androstanediol was formed in the presence of pregnancy serum. Since pregnancy serum contains higher amounts of TeBG than male serum, the lowered uptake suggests that only the free hormone was available to the target organ.

Addition of unlabelled dihydrotestosterone resulted in a higher uptake than that measured in explants incubated with the labelled steroid only.

The effect of the human sera on uptake and conversion was correlated with the androgenic activity of dihydrotestosterone applied at physiological concentrations and expressed as the percentage of secretory columnar cells present. The degree of maintenance closely corresponded to the uptake of the hormone. In serum-free medium, the number of columnar cells approached the values found in vivo, with male serum their number, though reduced, was still substantial, with pregnancy serum it was extremely low.

It is concluded that the amounts of TeBG present in serum regulate the supply of the hormone to the target tissue and thus control its biological action.
CONCENTRATIONS OF PROLACTIN IN SERIAL BLOOD SAMPLES FROM GOATS BEFORE, DURING AND AFTER MILKING THROUGHOUT LACTATION
Authors: HART I. C.
Published: December 2008

Two experiments are described in which prolactin was measured in (a) serial blood samples taken at monthly intervals (April–November) from six lactating goats before, during and after milking and (b) in similar blood samples taken on days 2, 7 and 12 after parturition. The quantity of prolactin released at milking (April–August) varied both between goats and within the individual goat. No correlation was found between the duration of milking and the quantity of prolactin released into the circulation (r = − 0·24, P > 0·1) or the average concentration of prolactin found at milking (April-August) and the average daily milk yield of the individual goat (r = −0·57, P > 0·1). No evidence was found for a release of prolactin conditioned by events normally preceding milking. The results showed a correlation between the average concentration of prolactin released at milking each month and the average milk yield of the six goats (r = 0·67, P < 0·05). The physiological significance of this correlation is discussed. No correlation was found between the average concentration of prolactin released during early lactation and the average milk yield of the goats (r = 0·36, P > 0·1).
COMPARATIVE EFFECT OF INSULIN ON EXPLANTED ADRENAL MEDULLARY TISSUE AND RAT ADRENAL MEDULLA IN SITU
Authors: PIEZZI R. S. , POHORECKY L. A. , CAVICCHIA J. C. , GALLEANO J. P.
Published: December 2008

The adrenal medulla and explanted medullary cells in the anterior chamber of the eye were examined 3 h after the administration of insulin to rats. No alterations were seen in the explanted cells. In the adrenal medulla, light and electron microscopy indicated depletion of adrenaline cells; noradrenaline cells were not affected. Levels of catecholamines were three times higher in the explanted tissue after insulin treatment; in the medulla in situ they declined by 70%. These results confirm that insulin has no direct releasing effect on chromaffin cells.
RESPONSE OF MOUSE GRAAFIAN FOLLICLES IN ORGAN CULTURE TO VARYING DOSES OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE
Authors: NEAL P. , BAKER T. G.
Published: December 2008

The response of mouse ovaries maintained in organ culture to follicle-stimulating hormone (FSH), luteinizing hormone (LH) and human chorionic gonadotrophin (HCG) was assessed using quantitative histological and radioimmunoassay techniques.

In terms of the induction of preovulatory maturation in follicular oocytes, 1 μg FSH/ml medium was as effective as 10 μg LH/ml. The lowest doses of HCG and LH used (0·2 i.u./ml and 1 μg/ml respectively) had no effect on oocyte maturation, whereas the response to FSH was virtually unchanged irrespective of dose (1–10 μg/ml). When the level of progesterone in the medium at the end of organ culture was used as an index of ovarian response, LH was more effective than FSH and HCG, although all the hormones induced a significant increase, irrespective of dose.

These results are discussed in terms of the mode of action of gonadotrophins in the processes culminating in ovulation.
EFFECT OF PROSTAGLANDIN E2 AND A2 ON STEROID SYNTHESIS BY THE RAT ADRENAL GLAND
Authors: SPÄT A. , JÓZAN SARA
Published: December 2008

Prostaglandin E2 increased aldosterone output by superfused capsular adrenal glands obtained from sodium-repleted, hypophysectomized rats but corticosterone did not show a statistically significant increase. Prostaglandin A2 increased corticosterone but not aldosterone production by incubated capsular glands obtained from sodium-repleted, hypophysectomized rats. Both aldosterone and corticosterone production rates were increased by PGA2 after previous sodium restriction. Corticosterone production rate of the decapsulated adrenal gland was not significantly modified by prostaglandin A2 in a concentration effective on the capsular adrenal gland. A possible role of prostaglandins in the regulation of aldosterone secretion is discussed.
STUDIES ON THE NATURE OF MAMMALIAN HYPOTHALAMIC THYROTROPHIN RELEASING HORMONE USING IMMUNOCHEMICAL, CHROMATOGRAPHIC AND ENZYMIC TECHNIQUES
Authors: JEFFCOATE S. L. , WHITE N.
Published: December 2008

Hypothalamic extracts from three mammalian species (rat, rabbit and sheep) were found to contain several ng of immunoreactive thyrotrophin releasing hormone (TRH)-like activity. This substance chromatographed on ion exchange chromatography (carboxymethyl cellulose) as a single peak that was indistinguishable from synthetic TRH. Hypothalamic TRH was also inactivated by normal human plasma at a rate (1·21–1·46%/μl plasma/h and 1·59–1·77%/50 μl plasma/min) similar to that of synthetic TRH (1·42%/μl plasma/h and 1·73%/50 μl plasma/min). This combination of chromatographic and enzymic techniques can be applied to the identification of immunoreactive TRH in body fluids.
AROMATIZING ACTIVITY OF PLACENTAL MICROSOMAL FRACTIONS FROM EWES IN LATE GESTATION
Authors: MANN M. R. , CURET L. B. , COLAS A. E.
Published: December 2008

Placental microsomes from eight domestic sheep at 136–146 days of gestation were incubated with radioactive androstenedione, testosterone and dehydroepiandrosterone. Aromatizing activity was examined in the presence and absence of cortisol and the rates of both oestrone and oestradiol synthesis were measured. Oestrone predominated in preference to oestradiol in most of the incubations, a result opposite to that found with human placentae. The sharp increase in the rate of oestradiol production found in the 144- to 146-day-old placentae incubated with testosterone may indicate a more rapid increase of aromatizing than of 17β-hydroxysteroid dehydrogenase activity. The presence of cortisol in the mixtures did not significantly affect the placental aromatizing activity, indicating that there is no direct effect of cortisol on the enzyme system as measured in vitro.

The dramatic rise of overall mean aromatizing activity from 4·86 ± 0·22 (s.e.m.) at 138–141 days of gestation to 12·96 ± 0·38 pmol/mg protein/min at 144–146 days (with a greater relative increase in the rate of oestradiol formation), suggests that changes in placental aromatizing activity may play an important role in maternal and foetal plasma oestrogen surges before ovine parturition.
RAPID PURIFICATION OF TRI-IODOTHYRONINE AND THYROXINE PROTEIN CONJUGATES FOR ANTIBODY PRODUCTION
Authors: BURKE C. W. , SHAKESPEAR R. A.
Published: December 2008

Thyroxine (T4) and tri-iodothyronine (T3) were coupled to human serum albumin (HSA) with carbodi-imide. By adsorption chromatography on Sephadex G-25, fractions containing purified conjugate, but not reversibly-bound T3 or T4, were obtained, and this procedure took 5 h; considerably less than the conventional dialysis technique. Highly specific high-titre antisera were produced in rabbits and guinea-pigs by injection of these fractions in Freund's adjuvant.
SUPPRESSION OF PROGESTERONE SECRETION IN LACTATING RATS BY ADMINISTRATION OF ERGOCORNINE AND THE EFFECT OF PROLACTIN REPLACEMENT
Authors: TOMOGANE H. , ÔTA K. , YOKOYAMA A.
Published: December 2008

In order to assess the stimulatory effect of prolactin on the secretion of progesterone from corpora lutea in lactating rats, ergocornine maleate (ECO; 1 mg/day), an inhibitor of prolactin secretion, was administered subcutaneously on days 6 and 7 of lactation in primiparous rats. By day 8 of lactation, the concentration of progesterone in ovarian venous blood fell to an undetectable level in the ECO-treated animals, while the concentration in the control animals was very high at this stage of lactation. The level of 20α-hydroxypregn-4-en3-one was significantly higher on day 8 of lactation in ECO-treated than in control rats. Lactational dioestrus was interrupted by treatment with ECO and vaginal oestrus appeared 3–4 days after the start of treatment. Administration of ECO caused deleterious depression of milk production and of food intake of mother rats. In the pair-fed control animals, lactation continued almost normally throughout the experimental period. Prolactin (1 mg/day) administered simultaneously with ECO increased progesterone to levels even higher than those in control rats and restored 20α-hydroxypregn-4-en-3-one levels to those of the controls. The effect of the drug on milk production was alleviated.

The results strongly suggest that prolactin is the most important factor in maintaining the function of corpora lutea in the lactating rat.
DYNAMICS OF INSULIN RELEASE BY PERFUSED HAMSTER (MESOCRICETUS AURATUS) PANCREASES: EFFECTS OF HYPOPHYSECTOMY, BOVINE AND HUMAN GROWTH HORMONE, AND PROLACTIN
Authors: CURRYt DONALD L. , BENNETT LESLIE L. , LI CHOH HAO
Published: December 2008

The hamster exhibits a biphasic pattern of insulin secretion; however, the dynamic response differs qualitatively from that of the rat in that there is a steady-state second release phase. A marked attenuation of insulin secretion as a result of hypophysectomy was observed after 3 weeks, but not after 2 weeks. This depression of insulin secretion was restored to near or above normal levels by bovine growth hormone, human growth hormone, and prolactin.
THE THYROXINE-BINDING PROPERTIES OF SERUM PROTEINS. A COMPETITIVE BINDING TECHNIQUE EMPLOYING SEPHADEX G-25
Authors: SUTHERLAND R. L. , SIMPSON-MORGAN M. W.
Published: December 2008

A competitive binding technique is described for the estimation of the thyroxine (T4)-binding properties of serum proteins in dilute blood serum and lymph. When used in conjunction with an assay for total T4 the following parameters can be estimated: the number of functionally different T4 binding proteins, their individual association constants and binding capacities for T4, the amount of T4 which is bound to each binding species, and the concentration of unbound (free) T4.

Both human and sheep serum have three functionally different T4-binding proteins. The association constants for the three human proteins were 9·5 × 109, 1·6 × 108 and 3·1 × 105 1/mol for T4-binding globulin (TBG), T4-binding prealbumin (TBPA) and serum albumin, respectively. The corresponding sheep proteins, TBG, TBP-2 and albumin, had association constants of 8·9 × 109, 1·4 × 108 and 3·5 × 1051/mol. Human TBG had a mean binding capacity of 21·3 μg/100 ml and that of ovine TBG was 12·8 μg/100 ml. The other specific binding proteins (TBPA in man and TBP-2 in sheep) had mean binding capacities of 307 and 359 μg/100 ml respectively.

Two functionally different T4-binding proteins were identified in rat serum.
EFFECTS OF ANTIBODY TO OESTROGEN OR OF OVARIECTOMY ON THE INCORPORATION OF [35S]METHIONINE INTO BRAIN PROTEIN AND ON GONADOTROPHIN LEVELS DURING THE OESTROUS CYCLE IN THE RAT
Authors: TER HAAR M. B. , MACKINNON P. C. B.
Published: December 2008

The incorporation of [35S]methionine into protein of the anterior pituitary and discrete brain areas was measured following the administration of antibodies to oestrogen, ovariectomy, or adrenalectomy on the afternoon of dioestrus. The antibody to oestrogen deleted the circadian rhythms of methionine incorporation normally observed in the various brain areas together with the peaks of incorporation normally observed in the median eminence area and anterior pituitary on the evening of pro-oestrus. The peaks of incorporative activity normally observed in the preoptic area and amygdala (relative to the putamen) at 03.00 h on the day of pro-oestrus were also deleted. Administration of the antiserum on the morning of pro-oestrus failed to alter the pattern of methionine incorporation normally observed on the evening of pro-oestrus.

Ovariectomy performed at 16.00 h of dioestrus blocked the preovulatory rise of luteinizing hormone (LH) (as did the antibody to oestrogen) and inhibited the peak of methionine incorporation normally observed in the anterior pituitary on the evening of pro-oestrus. However, for the peak in the median eminence to be inhibited, ovariectomy had to be performed on the morning of the preceding oestrus. Adrenalectomy alone, or adrenalectomy with ovariectomy, performed on the afternoon of dioestrus did not affect the levels of methionine incorporation in the brain or anterior pituitary at 18.00 h on the day of prooestrus.

Animals which had been ovariectomized and injected with 2·5 μg oestradiol benzoate on the morning of oestrus showed significantly increased levels of methionine incorporation in all the brain areas and the anterior pituitary at 18.00 h of expected pro-oestrus. The administration of antibody to oestrogen to a similar group of animals on the afternoon of expected dioestrus inhibited the rise at 18.00 h of expected pro-oestrus. The apparent discrepancy between the results obtained with ovariectomy and the antiserum appeared to be due to the ability of the antiserum to neutralize the activity of oestrogens retained by the tissues.

The present results suggest that the changes in incorporation of methionine into protein in the brain and anterior pituitary are brought about by the action of endogenous oestrogen: there appears to be a steady summative effect on the median eminence throughout the oestrous cycle together with a short-lived effect occurring during pro-oestrus and affecting the anterior pituitary.
THE RESPONSIVENESS OF THE ANTERIOR PITUITARY GLAND TO LUTEINIZING HORMONE RELEASING FACTOR IN RATS EXPOSED TO CONSTANT LIGHT
Authors: FINK G.
Published: December 2008

The responsiveness of the anterior pituitary gland to synthetic luteinizing hormone releasing factor (LH-RF) was tested in rats exposed to constant light. At a dosage of 50 ng LH-RF/ 100 g body wt the mean maximal increments in plasma LH and FSH were similar to those at 10.00 h of pro-oestrus. The increments in the plasma gonadotrophins at dosages of 500 and 1000 ng LH-RF/100 g body wt did not differ significantly from those at 250 ng LH-RF/ 100 g body wt. These findings suggest that, in contrast to rats which exhibit regular oestrous cycles, the preovulatory (post-coital) release of LH in rats exposed to constant light may depend almost entirely on the release of a relatively large amount of LH-RF into hypophysial portal vessel blood. Whereas in pro-oestrous animals a relatively small fraction of the readily releasable pool of LH is released during the spontaneous preovulatory surge, in rats exposed to constant light most releasable LH appears to be discharged during the reflex preovulatory surge of this hormone. The concentrations of radioimmunoassayable FSH in blood samples withdrawn before the injection of LH-RF support the view that FSH secretion in the rat is increased by constant exposure to light.