bluuebunny/crossref_metadata_2025 huggingface dataset:
A STUDY OF THE RELATIONSHIP BETWEEN THE THYROID GLAND AND SEBUM SECRETION IN THE RAT
Authors: THODY A. J. , SHUSTER S.
Published: December 2008

Thyroidectomy of intact and castrated rats produced significant reductions in their rates of sebum secretion. Replacement therapy with thyroxine (T4) increased the rate of sebum secretion of the castrated-thyroidectomized rats. Treatment with testosterone propionate also stimulated sebum secretion in castrated-thyroidectomized rats. When given together these two hormones had an additive effect on the rate of sebum secretion.

Thyrotrophic hormone (TSH) stimulated sebum secretion in castrated-hypophysectomized, but not in thyroidectomized rats.

It is concluded that TSH affects sebum secretion through its action on the thyroid, presumably by stimulation of T4 secretion.
EFFECTS OF PINEALECTOMY AND CONSTANT LIGHT AND DARKNESS ON PROLACTIN LEVELS IN THE PITUITARY AND PLASMA AND ON PITUITARY ULTRASTRUCTURE OF THE RAT
Authors: RELKIN R. , ADACHI M. , KAHAN S. A.
Published: December 2008

The effects of constant light, constant darkness and diurnal lighting, in combination with pinealectomy or sham-pinealectomy, on pituitary and plasma concentrations of radioimmunoassayable prolactin were investigated in 8-week-old male and virgin female rats. Two to three days after operation random groups of pinealectomized and sham-pinealectomized animals of the same sex were placed together in either continous light, continuous darkness or diurnal light, and killed 21 days later. Compared with sham-operated diurnally-illuminated controls, constant darkness caused a decrease in pituitary prolactin content and a rise in plasma prolactin levels. Pinealectomy or constant illumination reversed the effect of constant darkness, resulting in an increase in pituitary prolactin content and a fall in plasma prolactin levels when compared with sham-operated diurnally-illuminated controls. Electron microscopy of lactotrophic cells of the sham-pinealectomized animals exposed to constant darkness revealed few cytoplasmic granules, whereas these cells in the sham-pinealectomized animals exposed to constant light contained abundant granules; compared with the former groups, lactotrophic cells of sham-pinealectomized rats exposed to diurnal lighting revealed an intermediate degree of granulation.
ROLE OF MONOAMINES IN OVULATION: EVIDENCE FOR A SEROTONINERGIC PATHWAY FOR INHIBITION OF SPONTANEOUS OVULATION
Authors: LABHSETWAR A. P.
Published: December 2008

The effect of a monoamine oxidase inhibitor (MAOI) (mebanazine) given alone or in combination with 5-hydroxy-dl-tryptophan (5-HTP) or dihydroxyphenylalanine (l-DOPA) on spontaneous ovulation was tested in 4-day cyclic rats. Injections of the MAOI or 5-HTP alone, which cause a selective rise in the hypothalamic serotonin level, blocked spontaneous ovulation in 32% and 0% of rats, respectively, and in 73% of rats when given together. By contrast, a combination of MAOI and l-DOPA, which causes a selective rise in the hypothalamic catecholamines, did not block ovulation. A single injection of α-methyl-p-tyrosine, but not of α-methyl-m-tyrosine, blocked ovulation in 100% of rats. These results provide experimental support for the existence of a serotoninergic component in the control of ovulation.
MAINTENANCE OF PREGNANCY BY SYNTHETIC PROGESTAGENS IN GUINEA-PIGS OVARIECTOMIZED BEFORE IMPLANTATION; PROGESTERONE-BINDING PROTEIN AND PLACENTAL PROGESTERONE SECRETION
Authors: ILLINGWORTH DOREEN V. , DEANESLY RUTH
Published: December 2008

In guinea-pigs ovariectomized before implantation, pregnancy can be maintained during the first 3 or 4 weeks, a critical period of early growth, by synthetic progestagens that do not metabolize to progesterone (norgestrel, medroxyprogesterone acetate and melengestrol acetate). It follows that peripheral plasma progesterone levels are related to placental progesterone secretion. There were indications that progesterone secretion by the placenta begins as early as day 16–18 of pregnancy. In the experimental animals the plasma progesterone levels, measured by a competitive protein-binding technique, were 9·4 ± 2·07 ng/ml (mean ± s.e.m.; n = 18) by days 20–22 of pregnancy; they continued to rise and reached 26·4 ± 3·88 ng/ml (n = 8) by days 27 to 29.

The metabolic clearance rate of progesterone measured in four pregnant ovariectomized animals with progesterone or progestagen implants, was < 10 l/day as in normal pregnant animals. The calculated production rates of progesterone in the experimental animals (0·1 to 0·35 mg/day) reflect the placental production rate of progesterone. A simple 'assay' is described for the high affinity progesterone-binding protein of pregnancy (progesteronebinding globulin).
ANDROGEN-INDUCED CELL PROLIFERATION AND DIFFERENTIATION IN THE SEMINAL VESICLE AND COAGULATING GLAND OF THE CASTRATED MOUSE
Authors: MORLEY A. R. , WRIGHT N. A.
Published: December 2008

Castrated male mice were injected with 250 μg testosterone propionate on 3 consecutive days. With the third injection, 1 μCi tritiated thymidine/g body weight was given intraperitoneally. A pulse-chase analysis in the seminal vesicle and coagulating gland was performed during the next 50 h and labelling and mitotic indices were obtained.

One hour after the injection of tritiated thymidine the labelling index was 19% in the seminal vesicle and 13% in the coagulating gland. The mitotic index was 1·7% in the seminal vesicle and 1·4% in the coagulating gland.

The observed cell cycle (Tc) duration in the seminal vesicle was 25 h, and the duration of DNA synthesis (ts) was 9 h. The calculated duration of mitosis (tm) was 0·6 h, the presynthetic duration (tG1) was 14·2 h, and the postsynthetic duration (tG2) 1·2 h. Forty-eight hours after testosterone propionate the growth fraction was 0·62 and a decycling ratio of 0·8 was calculated. In the coagulating gland Tc was 52·0 h, ts 9·0 h, tm 1·0 h, tg1 41·0 h and tG2 1·0 h.
SOME LIGHT- AND ELECTRON-MICROSCOPICAL OBSERVATIONS ON THE PARS TUBERALIS OF THE PITUITARY GLAND OF THE RABBIT
Authors: CAMERON E. , FOSTER C. L.
Published: December 2008

The cytological appearance of the pars tuberalis both at the light- and the electron-microscopical levels is described. Two main types of cell, one, which is designated the tuberalis cell, having a rounded contour, pale cytoplasm with a few small secretory granules of about 100 nm in diameter, many polyribosomes and a relatively large ovoid nucleus; and the other, the interstitial cell, with long processes often encircling tuberalis cells, an irregular nucleus and cytoplasm with abundant microfilaments about 10 nm in diameter were seen. Beaded nerve fibres and neurosecretory material were demonstrated in the pars tuberalis with chrome alum—haematoxylin, a finding confirmed at the electron-microscopical level where nerve fibres which appeared to be making contact with tuberalis cells and containing numerous microvesicles of about 50 nm in diameter were observed.
OSTEOPOROSIS AFTER OOPHORECTOMY IN THE MATURE FEMALE RAT AND THE EFFECT OF OESTROGEN AND/OR PROGESTOGEN REPLACEMENT THERAPY IN ITS PREVENTION
Authors: AITKEN J. M. , ARMSTRONG E. , ANDERSON J. B.
Published: December 2008

Fifty-two mature female rats on a controlled diet were studied to compare the effects of oophorectomy, and hormone replacement therapy after oophorectomy, on femoral morphology and mineral content. Oophorectomy was followed by the development of osteoporosis after 11 months of observation. This was characterized by a reduction in ash per unit length of bone and a diminution of mid-shaft femoral cortical width. The administration of a progestogen (9 μg ethynodiol diacetate/rat/day) for 10 months after oophorectomy prevented the reduction in ash per unit length from occurring, whereas an oestrogen (0·9 μg mestranol/rat/day) had no significant effect on either parameter of osteoporosis. The progestogen appeared to produce this effect by a relative increase in periosteal new bone formation at the expense of increased loss of bone from the endosteal surface.
PROGESTATIONAL STEROIDS DURING PSEUDOPREGNANCY IN THE RABBIT
Authors: HORRELL ELISABETH , MAJOR PATRICIA W. , KILPATRICK R. , SMITH BRENDA M.
Published: December 2008

The secretion of progestational steroids by the rabbit ovary was examined during pseudopregnancy. Progesterone secretion rose up to the mid-period but exceeded secretion of 20α-dihydroprogesterone only on days 7 and 9. The development of the corpus luteum and interstitial tissue and their content of progestational steroids were also examined during this period. The progesterone content of corpus luteum tissue fell towards the end of pseudopregnancy, while the corpora lutea remained large. Levels of 20α-dihydroprogesterone were generally higher in the interstitial tissue after the first few days. A significant alteration in the pattern of steroid synthesis and secretion occurred at a time corresponding to the period of implantation in the pregnant rabbit.
SELECTIVE BREEDING FOR VARIATIONS IN THYROIDAL IODINE RELEASE RATE IN MICE
Authors: CHAI C. K. , MELLOH ANN
Published: December 2008

Mice were selectively bred for high and low thyroidal 131I release rates. Two lines with sharp contrast in the selection criterion were produced, and an estimate of heritability was made. There were correlated differences in thyroid histology, protein-bound 131I, cholesterol level, haematocrit, adrenal and testicular weights, and some behavioural characteristics. It was concluded that multiple genetic factors affect the rate of thyroidal iodine release, and that the high release strain had greater thyroid activity than the low release strain. Some genetic aspects of thyroid function are discussed.
INFLUENCE OF PHOTOPERIOD ON OESTROGENIC INDUCTION OF NEST-BUILDING IN CANARIES
Authors: STEEL ELIZABETH , HINDE R. A.
Published: December 2008

A 20h light:4h darkness lighting schedule induced a high level of gathering behaviour in intact canary hens in autumn and winter. The same schedule was relatively ineffective in ovariectomized birds, indicating that the ovary is normally a mediator in the photostimulation of nest-building behaviour. However, exogenous oestrogen given to ovariectomized birds on normal winter daylengths resulted in only a slight increase in gathering behaviour, while in similar birds previously exposed for 5 weeks to a 20h light: 4h darkness schedule a rapid increase in gathering occurred to a level approaching that of intact birds on long photoperiods. A similar difference in response to hormone injection with and without exposure to long photoperiods was also seen with testosterone and with oestrogen and testosterone in combination.

Nest-building was not completely eliminated in ovariectomized birds. Ovariectomized birds on 20h light:4h darkness per day gathered more than those on normal daylengths. This is unlikely to be a consequence of the longer time available for building activity as it can be suppressed in the long-photoperiod birds by methallibure, a gonadotrophin inhibitor. The possibility that a non-ovarian mechanism is involved in building behaviour is discussed.

The results suggest that although the effect of long photoperiods on nest-building is mediated largely by oestrogen there is a second factor operating without which oestrogen is relatively ineffective. Possible mechanisms for this effect are discussed.
A COMPARISON BETWEEN CHORIONIC GONADOTROPHINS EXTRACTED FROM HUMAN, RHESUS MONKEY AND MARMOSET PLACENTAE
Authors: HOBSON BRUCE , WIDE LEIF
Published: December 2008

Evidence is provided to show that chorionic gonadotrophins extracted from the human, rhesus monkey and marmoset placentae have antigenic determinants in common. Similar slopes were obtained for these gonadotrophins in a radioimmunoassay for human chorionic gonadotrophin (HCG). The biological activity of the monkey gonadotrophins was neutralized by anti-HCG serum. When the gonadotrophic activity of the monkey placental extracts was assayed biologically and immunologically, using HCG as a standard, similar results were obtained. Higher values were obtained by the immunoassay than by the bioassay when extracts of human placenta were assayed using the same HCG standard.
NEONATAL ADRENOCORTICAL FUNCTION AND ITS POSSIBLE RELATION TO THE UPTAKE OF MACROMOLECULES BY THE SMALL INTESTINE OF THE GUINEA-PIG AND RABBIT
Authors: MALINOWSKA K. W. , HARDY R. N. , NATHANIELSZ P. W.
Published: December 2008

Plasma cortisol and corticosterone were separated by Sephadex LH-20 chromatography. The high concentration of plasma cortisol immediately after birth in the guinea-pig coincided with the decline in 125I-labelled polyvinyl pyrrolidone (PVP) uptake (closure) between 48 and 72 h. Similarly, in the rabbit, plasma cortisol concentration was increasing at the time of closure, 18–21 days after birth. These results suggest that there is a correlation between the time when the concentration of the main plasma adrenocortical steroid rises and the time when the neonatal small intestine ceases to take up PVP.
GENETIC ANALYSIS OF PLASMA CORTICOSTERONE LEVELS IN TWO INBRED STRAINS OF MICE
Authors: ELEFTHERIOU B. E. , BAILEY D. W.
Published: December 2008

Plasma corticosterone levels were determined fluorometrically in mice of two unrelated highly inbred strains, C57BL/6By and BALB/cBy, and in seven of their derived recombinant-inbred strains as well as their F1 hybrid and backcross generations necessary to arrive at a genetic model for plasma corticosterone levels. It was concluded that the simplest genetic model, and one which fits the experimental results, was one which assumed that plasma corticosterone levels are controlled genetically by two loci with the epistatic interaction indicating dependency of pathways of action for the two genes.
PROLONGATION OF PSEUDOPREGNANCY IN THE RAT BY SLITTING THE UTERUS
Authors: PAKURAR ALICE SWOPE , ROTHCHILD I.
Published: December 2008

On day 9 of dioestrus the uteri of pseudopregnant rats bearing deciduomata were either slit lengthwise to curette out the decidual tissue or were removed in toto to determine if the prolonging effect of decidualization on pseudopregnancy could be eliminated. Both operations significantly reduced the length of the pseudopregnancy dioestrus (combined mean of 19·3 ± 0·56 days v. 22·2 ± 0·77 days for rats with intact deciduomata; P < 0·01). Conversely, the control experiment of slitting the non-decidualized uterus on day 9 significantly prolonged pseudopregnancy in comparison with control groups (19·2 ± 0·92 days v. 13·5 ± 0·37 days for pseudopregnant controls which were not subjected to operation, or had a laparotomy or uterine traumatization performed on day 9; P < 0·001). The effect of slitting the uterus on other days of pseudopregnancy was investigated. The mechanism through which slitting prolongs pseudopregnancy is unknown.
CHARACTERISTICS OF FAST FEEDBACK CONTROL OF CORTICOTROPHIN RELEASE BY CORTICOSTEROIDS
Authors: JONES M. T. , BRUSH F. R. , NEAME R. L. B.
Published: December 2008

Corticosterone was administered intraperitoneally to rats, and the consequent changes in plasma corticosterone concentration traced. Stress (sham bilateral adrenalectomy) was applied at various times when the plasma corticosterone concentration was changing at different rates, and it was shown that there was a critical rate of rise of plasma corticosterone concentration of about 1·3 μg/100 ml plasma/min in excess of which the stress response was inhibited. Rates of rise less than this did not affect the stress response. A state of ' saturation' of the control system was also demonstrated to result from high plasma corticosterone concentrations when the response to stress was not inhibited as above. A model of the system is suggested to explain these and other data.
REGULATION OF INSULIN SECRETION IN THE OVINE FOETUS IN UTERO. EFFECTS OF SODIUM VALERATE ON SECRETION AND OF ADRENOCORTICOTROPHIN-INDUCED PREMATURE PARTURITION ON THE INSULIN SECRETORY RESPONSE TO GLUCOSE
Authors: BASSETT J. M. , THORBURN G. D. , NICOL DIANNE H.
Published: December 2008

Intravenous infusions of glucose into lambs in utero (130–150 days) and after birth, confirmed the marked post-natal increase in the magnitude of the response of plasma insulin to glucose. These studies also suggest that insulin secretion in foetal lambs is stimulated by glucose at lower plasma concentrations than in lambs after birth. The short-chain fatty acid, valeric acid, given as the sodium salt, caused a very rapid increase in the plasma insulin level of foetal lambs, when given either by intravenous injection or infusion. When birth was induced after only 135 days of gestation by i.v. infusion of a synthetic adrenocorticotrophin preparation (Synacthen) into foetal lambs there was also a prematurely induced maturation of the insulin secretory response to glucose. In these prematurely born lambs the insulin secretory response to i.v. glucose infusion was similar to that of normal lambs after birth and differed greatly from that of normal foetuses of similar age.

The results indicate that maturation of the insulin secretory mechanism in the lamb is associated with parturition and suggest that these changes may be consequences of the increasing corticosteroid secretion in the foetus during the last few days of gestation.
THE EFFECT OF THYROTROPHIC RELEASING FACTOR ON DIFFERENT HYPOTHALAMIC AREAS AND THE ANTERIOR PITUITARY GLAND: A BIOCHEMICAL AND ULTRASTRUCTURAL STUDY
Authors: MOGUILEVSKY A. , CUERDO-ROCHA SILVIA , CHRISTOT JANINE , ZAMBRANO D.
Published: December 2008

A study on the effect of synthetic thyrotrophic releasing factor (TRF) on different areas of the central nervous system and on the anterior pituitary gland was performed in a system in vitro. These observations were combined with ultrastructural studies of the anterior pituitary gland after intracarotid TRF administration. TRF specifically decreased the incorporation in vitro of labelled amino acids into proteins of the medial hypothalamus, whereas the anterior pituitary gland showed enhanced protein synthesis. At the electron microscope level, only thyrotrophs showed enhanced signs of activation after 5, 15 and 30 min of TRF administration, which consisted in hypertrophy of the rough endoplasmic reticulum and Golgi complexes associated with a marked increase in the number of secretory granules undergoing extrusion into the perivascular and extracellular spaces. These observations indicate that the medial hypothalamus may be related to regulatory mechanism(s) of TRF secretion. They provide further morphological identification of the thyrotrophs and corroborate that TRF acts on these cells by promoting release and synthesis of thyrotrophin.
HYPERTROPHY AND HYPERPLASIA IN THE MOUSE UTERUS AFTER OESTROGEN TREATMENT: AN AUTORADIOGRAPHIC STUDY
Authors: MARTIN L. , FINN C. A. , TRINDER GAIL
Published: December 2008

The uteri of untreated ovariectomized mice consisted almost entirely of myometrium and connective tissue stroma. After oestrogenic stimulation these tissues underwent marked hypertrophy, but showed little proliferation.

The luminal epithelium underwent marked hyperplasia, with most cells dividing twice to quadruple cell numbers by 35–40 h, when they made up 10–12% of the uterine tissue volume and 20% of the total uterine cell population. The proliferative response was rapid, highly synchronized and short-lived. The number of cells incorporating [3H]thymidine first increased 8·5 h after oestradiol-17β and by 13–16 h 60–70% were engaged in DNA synthesis. Up to 21 h cell-death was minimal. From 21 h onwards the proliferation rate declined and the rate of cell death increased. A second injection of oestrogen prevented the rise in death rate and produced a second smaller burst of DNA synthesis. Cells in DNA synthesis or mitosis were insensitive to oestrogen.

A smaller proliferative response occurred in the glands: only 25% of cells entered DNA synthesis after the first injection of oestradiol and none after the second. Gland cells appeared to die in situ and there was no evidence that they migrated into the luminal epithelium.
OESTROGEN SYNTHESIS FROM [4-14C—1,2-3H]TESTOSTERONE BY A 160000 g SUPERNATANT FROM BABOON PLACENTA AND BY POSTMICROSOMAL FRACTIONS
Authors: MILEWICH L. , AXELROD L. R.
Published: December 2008

A baboon placental homogenate was centrifuged at 160000 g for 70 min to give a microsomal fraction and a supernatant, which on further centrifugation at 260000 g for 110 min gave a first postmicrosomal fraction and a second supernatant. This supernatant was centrifuged at 260000 g for 210 min to afford a second postmicrosomal fraction and a third supernatant.

The incubation of the first supernatant with [4-14C—1,2-3H]testosterone gave androstenedione, 19-hydroxytestosterone, 19-hydroxyandrostenedione, 17β-oestradiol and oestrone; incubation with the postmicrosomal supernatants yielded androstenedione only. When the two postmicrosomal fractions were incubated with the substrate, both 17β-oestradiol and androstenedione were obtained as metabolites. The losses of tritium from 17β-oestradiol and from oestrone metabolites were consistent with previous findings.
DISAPPEARANCE OF ENDOGENOUS RENIN FROM THE CIRCULATION AFTER NEPHRECTOMY IN PREVIOUSLY HEPATECTOMIZED OR COLONECTOMIZED DOGS
Authors: AMERY A. , EYSKENS E. , DELOOZ H. , FAGARD R.
Published: December 2008

The changes in plasma renin concentration (PRC) were studied in dogs after hepatectomy and bilateral nephrectomy, and after colonectomy and bilateral nephrectomy in a control group of animals. In the colonectomized dogs the PRC averaged 9·4 ± 4·2 units/l at the moment of the removal of the second kidney (time zero) and decreased to 44% of this value in the sample withdrawn 15 min later, and to 20·6% after 1 h. In the hepatectomized dogs the PRC averaged 44·3 ± 29·2 units/l at time zero and decreased to 70·6% of this value within 15 min, and to 30·3% after 1 h.

The results showed that the dogs without a liver were still able to remove renin from the circulation, suggesting that other mechanisms of renin clearance were operative.
THE EFFECT OF METHYLCHOLANTHRENE ON BILIARY THYROXINE EXCRETION IN NORMAL AND GUNN RATS
Authors: BASTOMSKY C. H. , PAPAPETROU P. D.
Published: December 2008

Biliary fistulae were produced in rats given [125I]thyroxine (T4) 18 h previously. Treatment of normal animals with 3-methylcholanthrene (MCA) raised the bile: plasma 125I ratio (B: P ratio) and biliary clearance of plasma 125I three times. All of the increase could be explained by enhanced excretion of T4-glucuronide.

In Gunn rats the B: P ratio and biliary clearance of plasma 125I was one quarter of normal and only a small fraction of biliary 125I was present as T4-glucuronide. In these animals MCA slightly, but significantly, enhanced the B: P ratio and biliary clearance of plasma radioactivity. The mechanism was not clear; it was not due to increased glucuronide formation and did not appear to be due to effects on the binding of T4 to plasma proteins.

MCA, in all the normal rats studied, lowered the serum protein-bound iodine (PBI), but in female Gunn rats it had no effect. Enhanced biliary excretion of T4 seemed to be responsible for the low serum PBI in MCA-treated normal rats. In normal male rats MCA increased thyroid 131I uptake, but had no effect in normal or Gunn female rats.

Injection of female mice with MCA reduced the half-life of circulating T4.
THE RELATIONSHIP OF THE SPLANCHNIC, HEPATIC AND RENAL CLEARANCE RATES TO THE METABOLIC CLEARANCE RATE OF CORTISOL IN CONSCIOUS SHEEP
Authors: PANARETTO B. A. , PATERSON J. Y. F. , HILLS F.
Published: December 2008

The uptake of cortisol by organs in the splanchnic area of conscious, undisturbed sheep was estimated before and during the administration of adrenocorticotrophic hormone (ACTH) by measuring cortisol concentration differences in portal and hepatic venous plasma and estimating hepatic plasma flow rates. Metabolic clearance rates (MCR) of plasma cortisol were measured simultaneously. The total splanchnic clearance of cortisol was 61% of MCR in the animal, 48% being accounted for by the liver. When ACTH was given there were increases in MCR and these were accompanied by proportional increases in hepatic plasma flow rates. When ACTH was infused the total splanchnic clearance rate was 65% of MCR, 52–59% being accounted for by the liver.

In other experiments the renal clearance rate of cortisol was studied. Under control conditions, and when ACTH was given, the renal clearance was 11% of MCR.

The relationship of the sum of individual clearances to MCR is compared and discussed.
DNA SYNTHESIS IN THE ENDOMETRIUM OF PROGESTERONE-TREATED MICE
Authors: MARTIN L. , FINN C. A. , TRINDER GAIL
Published: December 2008

[3H]Thymidine autoradiography was used to study DNA synthesis in the uteri of spayed mice treated with progesterone and oestradiol. Progesterone suppressed DNA synthesis in the glandular epithelium whether oestrogen was given or not. It also suppressed DNA synthesis in the luminal epithelium. Here oestradiol produced morphological changes and eventual re-entry of some cells into DNA synthesis.

Progesterone altered the nuclear morphology of the stromal cells and increased the number synthesizing DNA. In these conditions a single injection of oestrogen was followed 10–15 h later by the synchronized entry into DNA synthesis of 30–40% of stromal cells. However, a second injection produced no further response.

It was concluded that progesterone stimulated stromal cells in the resting phase to enter the cell cycle and that oestrogen then accelerated their passage through a single round of replication and division by shortening the interval between mitosis and DNA synthesis, following which the cells withdrew from the cell cycle.
HORMONE-INDUCED ACTIVATION OF TARGET-SPECIFIC LYSOSOMES: ACUTE TRANSLOCATION TO THE NUCLEUS AFTER ADMINISTRATION OF GONADAL HORMONES IN VIVO
Authors: SZEGO CLARA M. , SEELER BARBARA J.
Published: December 2008

Recent evidence from these laboratories has implicated the primary lysosomal population of specific target cells in the selective reception of steroid hormones at the cell periphery. This phenomenon was shown to be associated with covert labilization of the lysosomal bounding membrane. It has now been demonstrated that this interaction with trophic hormones results in rapid migration of lysosomes to a perinuclear position. Suspensions of nuclei were isolated from preputial glands of ovariectomized rats within short intervals after administration of gonadal hormone in vivo. Identification of cellular organelles by ultraviolet fluorescence microscopy was carried out on preparations subjected to intravital staining in vitro with acridine orange. Lysosomes were present in high concentrations in nuclear fractions of preputial glands from animals pretreated with oestradiol-17β, diethylstilboestrol, or testosterone, and essentially absent in preparations obtained from animals injected with oestradiol-17α or control solution. The response could be detected within 1 min of hormone administration, was obtained with as little as 0·1 μg hormone/100 g body wt, and was not observed in preparations from lung tissue. In the early stages of hormonal activation, lysosomes in preputial gland preparations formed adherent perinuclear clusters and appeared relatively intact. However, lysosome fragmentation and dissolution rapidly ensued and was accompanied by the appearance of polynuclear—multilysosomal aggregates. Concomitantly, isolated lysosome preparations subjected to enzymatic analyses revealed increased release from the particle-bound form of hydrolytic enzymes characteristic of these organelles. Progressive nuclear metachromasy was also observed after administration of the active hormones, suggesting the breakdown of macromolecules which yield products with enhanced capacity for binding acridine orange. These results suggested that modification of the nuclear surface and of intranuclear constituents, leading to altered adhesiveness and dye binding, respectively, may reflect the activity of structurally latent hydrolases released in situ from lysosomal membranes labilized by exposure to hormone. The present results support the concept that lysosomal function may be involved in the coupling of initial steroid—receptor interaction at the cell membrane with hormone-dependent events in specific target cells.
HUMAN FOETAL ADRENAL 4-ENE-3-OXOSTEROID SYNTHESIS: AN INVESTIGATION OF [4-14C]PREGNENOLONE AND [4-14C]-DEHYDROEPIANDROSTERONE METABOLISM USING NEW TECHNIQUES
Authors: TAYLOR T. , HAMILTON W.
Published: December 2008

Human foetal adrenal slices were incubated with [4-14C]pregnenolone (20 foetuses) and [4-14C]dehydroepiandrosterone (18 foetuses). Product 4-ene-3-oxosteroids were isolated as a group and measured in toto by a double isotope dilution procedure. Production of compounds of the 4-ene-3-oxosteroid fraction was estimated over several time-intervals and relative to the protein content of the incubated tissue.

No conversion of [4-14C]pregnenolone by foetal adrenal tissue to 4-ene-3-oxosteroids was detectable although metabolism of the substrate to other compounds was indicated. Conversion of [4-14C]dehydroepiandrosterone to 4-ene-3-oxosteroids, principally androstenedione, occurred in incubations of tissue from 7 of the 10 male foetuses studied with this substrate, and from 2 of undetermined sex, but not from 6 female foetuses so studied. Testosterone formation from [4-14C]dehydroepiandrosterone was not detectable. There was no apparent variation in 4-ene-3-oxosteroid formation relative to foetal age in the range investigated (approximately 6–20 foetal weeks).

These results are interpreted, in the light of previous studies, as giving credence to the concept of substrate specificity in human foetal adrenal 4-ene-3-oxosteroid formation. The evidence that foetal adrenal androstenedione formation may be sex-dependent is considered, and the implications discussed.
THE EFFECT OF HYPOCALCAEMIA ON THE SECRETION OF CALCITONIN
Authors: WEST T. E. T. , O'RIORDAN J. L. H. , COPP D. H. , BATES R. F. L. , CARE A. D.
Published: December 2008

Hypocalcaemia was produced by i.v. infusion of EDTA into pigs from which the thyroid venous effluent could be quantitatively collected. Calcitonin in the effluent was measured by radioimmunoassay. Reduction of plasma calcium concentration rapidly suppressed the secretion of calcitonin. In contrast, as plasma calcium was raised slowly from hypocalcaemic levels by infusion of CaCl2, calcitonin secretion quickly returned and increased rapidly. The secretion rate observed when the plasma calcium concentration had been raised from hypocalcaemia to the initial normocalcaemic level was 3½–10 times greater than that observed during the normocalcaemia which pertained at the start of each experiment. A previous period of hypocalcaemia also produced an exaggerated response to a subsequent hypercalcaemic stimulus. It is suggested that the preconditioned response of calcitonin secretion increases the efficiency of the role of calcitonin in calcium homeostasis.
DISTRIBUTION OF ADRENOCORTICOTROPHIC HORMONE-STIMULATED ADENYLATE CYCLASE IN THE ADRENAL CORTEX
Authors: GOLDER MERIEL P. , BOYNS A. R.
Published: December 2008

The intra-adrenal distribution of adenylate cyclase was measured in microsections of guinea-pig and rat adrenals. Addition of α-adrenocorticotrophin-(1–24)-tetracosapeptide (α1–24ACTH) in vitro to sections of normal guinea-pig adrenals stimulated enzyme activity in glomerular—fascicular border zone tissue and reticular tissue. The intravenous injection of α1–24ACTH increased adenylate cyclase activity in sections of adrenal cortex from dexamethasone-treated guinea-pigs. Enzyme activity was enhanced in glomerular—fascicular border zone tissue, reticular and fascicular—reticular border zone tissue. In the rat, hypophysectomy reduced adrenal adenylate cyclase activity to undetectable levels within 48 h. Addition of α1–24ACTH to tissue sections in vitro augmented enzyme activity.

Adenylate cyclase activity was also measured in homogenates of whole guinea-pig adrenal tissue. α1–24ACTH (10, 100 and 1000 ng/ml) stimulated basal enzyme activity, whereas porcine insulin (400 pg/ml and 4 ng/ml) was without effect. Insulin inhibited the stimulation of adenylate cyclase activity by α1–24ACTH at concentrations of 10 ng/ml and 100 ng/ml. At higher concentrations of α1–24ACTH, insulin was without effect.
MORPHOLOGICAL RESPONSES TO CORTICOTROPHIN AND CYCLIC AMP BY ADULT RAT ADRENOCORTICAL CELLS IN MONOLAYER CULTURE
Authors: O'HARE M. J. , NEVILLE A. MUNRO
Published: December 2008

Confluent monolayer cultures of cells from the zona fasciculata and zona reticularis of the normal adult rat adrenal cortex were maintained with or without corticotrophin (ACTH) for up to 4 months, without proliferation of adrenal cells. Proliferating fibroblast-like cells, however, eventually overgrew the adrenal monolayer in cultures both with and without ACTH. Adrenocortical cells in culture, maintained without ACTH, spread rapidly to form a confluent monolayer, whereas cell spreading was markedly inhibited in the presence of ACTH. Exposure of previously unstimulated cells to ACTH or cyclic AMP caused the adrenal cells to retract with loss of confluence, the process being reversed when ACTH or cyclic AMP was withdrawn. Ultrastructural features of cells cultured with ACTH were typical of normal adrenocortical cells; in cultures without ACTH they were similar to those of adrenocortical cells found in the hypophysectomized rat.
THE SECRETION OF DEHYDROEPIANDROSTERONE AND DEHYDROEPIANDROSTERONE SULPHATE IN MAN
Authors: NIESCHLAG E. , LORIAUX D. L. , RUDER H. J. , ZUCKER I. R. , KIRSCHNER M. A. , LIPSETT M. B.
Published: December 2008

The secretion of dehydroepiandrosterone (DHA) and its sulphate (DHAS) was examined by measuring their concentrations in adrenal venous, gonadal venous, and peripheral venous plasma. Both steroids were secreted by the adrenal cortex and the rate of DHA secretion was higher than that of DHAS in seven out of eight subjects. Adrenocorticotrophin (ACTH) caused an increase in DHA and DHAS secretion by 15–30 min after administration. When ACTH was infused for 8 h, peripheral DHA concentrations increased at 2 h and decreased subsequently in five out of eight subjects suggesting depletion of substrate or cofactors for this biosynthetic pathway.

Gonadal secretion of DHA was present in each subject (eight women and two men) but DHAS secretion could not be demonstrated. Exogenous human chorionic gonadotrophin (HCG) caused an increase in plasma DHA. Examination of the diurnal variation of plasma DHA concentrations revealed a 40% decrease from 08.00 to 20.00 h.
EFFECT OF GONADOTROPHINS ON THE SECRETION OF OESTRADIOL-17β AND TESTOSTERONE BY THE RAT TESTIS
Authors: DE JONG F. H. , HEY A. H. , van der MOLEN H. J.
Published: December 2008

Concentrations of oestradiol-17β and testosterone were estimated in peripheral venous plasma and testicular venous plasma of adult male rats before and after administration of human chorionic gonadotrophin (HCG) or follicle-stimulating hormone (FSH). The concentration of oestradiol-17β in peripheral plasma, as measured with a radioimmunological technique, was 2·0 ± 0·9 (s.d.) pg/ml (n = 12). Peripheral testosterone concentrations were 2·4 ± 1·8 (s.d.) ng/ml (n = 21). Concentrations of oestradiol-17β and testosterone in testicular venous plasma were significantly higher than those in peripheral plasma. After intravenous administration of HCG (100 i.u.), oestradiol-17β and testosterone concentrations in testicular venous plasma increased significantly. After prolonged s.c. administration of HCG (5 days) the concentration of oestradiol-17β in testicular venous plasma did not change significantly, although the concentration of testosterone increased more than ten times. Intravenous administration of HCG after 5 days of pretreatment with HCG caused a significant increase in oestradiol-17β concentrations in testicular venous plasma. The increase in testosterone concentration was not significant under these conditions.

Intravenous administration of FSH did not change oestradiol-17β or testosterone concentrations in testicular venous plasma.
THE EFFECT OF PREGNANCY ON THE COLLAGEN OF THE UTERINE CERVIX OF THE MOUSE
Authors: RIMMER DIANE M.
Published: December 2008

The collagen content of the cervix of the pregnant mouse was found to be least on day 10 of pregnancy and greatest just before parturition (day 19). Similarly, the weight of cervical tissue was least on day 9 and greatest at parturition (day 20). However, the collagen concentration in the tissue was maximal on day 9 (7·54% of wet weight) and minimal on day 20 (1·56% of wet weight) because the collagen content decreased more than the weight during the first half of pregnancy and the weight increased more than the collagen during the latter part of pregnancy. Fluctuations in the trend of results were recorded early in the second half of pregnancy and steady changes were only observed in the last few days before parturition. On the first day post partum, conditions had returned to the oestrous state. The results are discussed with regard to the endocrine state of the animal and comparisons are made with changes in the rat cervix during pregnancy.
EFFECT OF HUMAN CHORIONIC GONADOTROPHIN ON TESTICULAR 5α-ANDROSTANE-3β-HYDROXYSTEROID DEHYDROGENASE, 3β-HYDROXYDEHYDROEPIANDROSTERONE DEHYDROGENASE AND ALCOHOL DEHYDROGENASE OF IMMATURE RATS
Authors: FROWEIN JOACHIM
Published: December 2008

Testicular enzymes related to steroid conversion were studied in infantile rats during sexual maturation, and the effect of human chorionic gonadotrophin (HCG) on the specific activities of the enzymes was analysed.

Activity of 5α-androstane-3β-hydroxysteroid dehydrogenase, which increases between days 20 and 30, was markedly enhanced after administration of HCG. Alcohol dehydrogenase activity, which is related to 3β-hydroxysteroid dehydrogenase activity, also increased after HCG treatment. The other enzyme activities investigated, i.e. 3β-hydroxyde-hydroepiandrosterone dehydrogenase and testosterone-17β-dehydrogenase, did not respond to HCG administration. These results suggest that different enzymes are responsible for the conversion of 3β-hydroxylated androgenic steroids and that the testicular alcohol dehydrogenase is not identical to the 3β-hydroxysteroid dehydrogenase described here.

On the assumption that HCG enhances enzyme activities indirectly by stimulating the synthesis of androgens which in turn produce the observed effect, different androgenic steroids (epiandrosterone, 5α-androstane-3,17-dione, 5α-dihydrotestosterone, 5α-androstane-3β,17β-diol) were tested for their ability to increase enzyme activities. None of these metabolites had an effect similar to that of HCG. The antiandrogen cyproterone (1,2α-methyl-6-chloro Δ4,6-pregnadien-17β-ol-3,20-dione) acetate, which was administered simultaneously with HCG, did not prevent the effect of HCG. From these results and other published reports it is concluded that in the testis of the infantile rat the metabolism of 5α-hydrogenated androgenic metabolites is stimulated by HCG.
THE MILK-EJECTION REFLEX OF THE RAT: A 20- TO 40-FOLD ACCELERATION IN THE FIRING OF PARAVENTRICULAR NEURONES DURING OXYTOCIN RELEASE
Authors: WAKERLEY J. B. , LINCOLN D. W.
Published: December 2008

Antidromically-identified paraventricular (PV) neurones were studied in the anaesthetized rat during milk ejection (ME) evoked by the natural stimulus provided by the suckling young. An intermittent pattern of ME was observed, though the ME interval was slightly longer (10–20 min) in the doe during unit recording than in unoperated or conscious animals (5–15 min). PV neurones displayed a steady background of spike discharge in both the non-lactating rat and lactating rat during suckling. The firing rates ranged from 0 to 9·4 spikes/s and were exponentially distributed with 32% of the units firing at <1 spike/s. Phasic patterns of discharge were seen in 18% of the units.

Fifty-eight per cent of the PV units displayed a stereotyped and explosive acceleration in spike activity some 15–20 s before the rise in intramammary pressure at ME. The peak firing rate during this brief (2–4 s) response was in the range of 24–84 spikes/s. A prominent after-inhibition was then displayed by these responsive units, though this second component of the response was variable in duration (7–56 s). The electrical activity of the remaining units, including all the cells with phasic discharge, was not correlated with ME.

There was no apparent change in the intensity of the suckling stimulus at the time of PV activation, i.e. 15–20 s before ME. Secondly, the activity of the PV neurones was not influenced by the rise in the intramammary pressure and the increased sucking of the pups at the time of ME. Simulation of an individual ME was obtained with both 1 mu. exogenous oxytocin, i.v., and electrical stimulation of the neurohypophysis (50 pulses/s for 4 s). The latencies to ME ranged from 7–14 s and 11–23 s, respectively.

In conclusion, an explosive increase in the electrical activity of PV neurones precipitates the release of oxytocin at ME.
PROLACTIN CONTENT OF CANINE PITUITARY GLAND
Authors: SALUJA P. G. , HAMILTON J. M. , GRONOW M.
Published: December 2008

The prolactin concentration in the dog pituitary gland was determined by isoelectric focusing of adenohypophysial extract in polyacrylamide gels followed by densitometry of the isolated stained hormone band. Dogs of both sexes and various ages (excluding newborn pups and weanlings) were studied. The bitches comprised animals at different stages of the oestrous cycle and also included a small number of pregnant, lactating or ovariectomized animals.

Low pituitary prolactin concentrations were found in males, sexually immature females and dioestrous females. Concentrations about 1·5 times as high occurred in oestrous, metoestrous (luteal) and ovariectomized females. Post-partum lactating bitches had the highest pituitary prolactin concentrations, these being double those occurring at dioestrus. With the exception of relatively high concentrations in ovariectomized bitches, these results are in good agreement with findings in the rat, mouse and rabbit. The persistence of high pituitary prolactin levels throughout metoestrus was believed to be associated with differences between the canine and murine reproductive cycle. Age did not influence pituitary prolactin levels in either males or females.
ULTRASTRUCTURAL PRESERVATION OF THE DENSE CORE OF POSTERIOR PITUITARY NEUROSECRETORY GRANULES AND ITS IMPLICATIONS FOR HORMONE RELEASE
Authors: MORRIS J. F. , CANNATA M. A.
Published: December 2008

Neural lobe neurosecretory granules (NSG) have been studied after different fixation procedures. When the pH of prefixation in a triple-aldehyde solution was varied, the dense core of NSG's was best preserved at pH's 5·0 and 6·0 but at pH's 7·0 and 8·0 loss of density of the granule core occurred and was most marked at pH 8·0. Increased duration of prefixation resulted in progressive loss of density of the granule core at pH's 7·0, 7·3 and 8·0, but at pH's 5·0 and 6·0 granules remained dense-cored, even after 24 h prefixation. When osmium tetroxide was used alone as a fixative, dense cores were again best preserved at acidic pH. This finding was correlated with studies in vitro in which the fixative solutions were reacted with aqueous suspensions of known components of the NSG's.

The neural lobes of animals stimulated to release hormone by substitution of 2% NaCl solution for drinking water were also studied after fixation at different pH's. There was a significant decrease in the number of NSG's after treatment but no significant decrease in the proportion of NSG's which retained the dense-cored appearance at any pH. This suggests that hormone loss from the neural lobe is associated with loss of entire granules rather than with a reduction of density of the granule core and this finding is discussed in the light of theories on the mechanism of hormone release.
EFFECTS OF ADRENALECTOMY AND/OR DEFICIENCY OF PITUITARY PROLACTIN SECRETION ON INITIATION AND MAINTENANCE OF LACTATION IN MICE
Authors: NAGASAWA HIROSHI , YANAI REIKO
Published: December 2008

In order to examine the effects of deficiency of adrenal corticosteroids and/or prolactin on the initiation and maintenance of lactation in mice, C3H/He female mice were adrenalectomized and/or implanted during days 13–15 of pregnancy with a pellet of 2-bromo-α-ergocryptine (EC), a potent inhibitor of pituitary prolactin secretion. Average body weights of the young and mammary contents of DNA and RNA were determined on days 0 (day of parturition) and 10 of lactation. On day 0, no differences in these parameters were found among groups, and plenty of milk was present in the stomachs of the young. Furthermore, the treatments did not affect the duration of pregnancy, the number of still-born young or the maternal behaviour at parturition. All young in the group adrenalectomized and implanted with EC died by day 2. Adrenalectomy or implantation of EC retarded the growth of young after day 2 and decreased markedly the mammary nucleic acid content on day 10. These results strongly suggest that adrenal corticosteroids and prolactin play minor roles in the initiation of lactation at parturition, while they are indispensable for the maintenance of lactation in mice.
ADRENOCORTICAL FUNCTION IN THE AUSTRALIAN BRUSH-TAILED POSSUM TRICHOSURUS VULPECULA (KERR)
Authors: THAN KHIN AYE , McDONALD I. R.
Published: December 2008

The peripheral plasma concentration and secretion rate of cortisol in the conscious marsupial brush-tailed possum Trichosurus vulpecula (Kerr) was investigated under basal conditions and during maximal corticotrophin (ACTH) stimulation.

Cortisol concentration in peripheral plasma was 0·92 ± 0·48 (s.d.) μg/100 ml in males, and 1·01 ± 0·57 in females. It was lowest at 08.00 h, when the possums were asleep and not easily aroused. Although there was a high variance, a third degree polynomial fitted the data plotted against time over 24 h at the 95% level of confidence, indicating a diurnal periodicity.

Ether anaesthesia, porcine and synthetic (24 amino acids) ACTH caused plasma cortisol concentrations to rise to maxima of no more than 7 μg/100 ml. The dose-response curve to ACTH indicated a maximum response at 0·12 i.u./kg/h with a potency of approximately 1/6 that found in sheep and 1/20 that found in man.

Cortisol secretion rates in non-stimulated possums were 2·71 ± 1·01 μg/kg/h in males and 4·32 ± 1·74 in females. They increased during maximal ACTH stimulation to 6·24 ± 1·58 μg/kg/h in males, and 13·28 ± 7·82 in females. Metabolic clearance rates were lowest in animals not accustomed to repeated blood sampling and rose in subsequent experiments.

It is concluded that the adrenal cortex of Trichosurus, like that of eutherian mammals, responds to changes in activity, stressful stimuli and ACTH, but quantitatively, the responses to these stimuli are very much lower.