bluuebunny/crossref_metadata_2025_split huggingface dataset:
CONCENTRATIONS OF CYCLIC AMP IN RABBIT OVARIAN TISSUE DURING THE PREOVULATORY PERIOD AND PSEUDOPREGNANCY AFTER INDUCTION OF OVULATION BY ADMINISTRATION OF HUMAN CHORIONIC GONADOTROPHIN
Authors: GOFF A. K. , MAJOR PATRICIA W. 
Published: December 2008

SUMMARY
Concentrations of cyclic AMP were measured in rabbit ovaries at various times after injection of an ovulatory dose of human chorionic gonadotrophin (HCG). A biphasic increase in cyclic AMP concentration occurred during the preovulatory period, with peaks 30 min and 3–4 h after HCG injection. Concentrations of cyclic AMP had returned to those observed in ovaries of control oestrous animals before the onset of ovulation 10–12 h after administration of HCG, and remained low throughout the period of pseudopregnancy. Concentrations of cyclic AMP in the newly formed and developing corpora lutea were similar to the concentrations observed in the remainder of the tissue during this period. No significant increase in cyclic AMP concentration was observed 7–9 days after initiation of ovulation. Concentrations of ATP were also investigated during the preovulatory period. The dose– response relationship of HCG to cyclic AMP production in oestrous rabbit ovaries was investigated.
SEX-DEPENDENT PREPUBERTAL GONADOTROPHIN SURGES IN THE RAT
Authors: ENEROTH PETER , GUSTAFSSON JAN-ÅKE , SKETT PAUL , STENBERG ÅKE 
Published: December 2008

SUMMARY
The concentrations of LH and FSH were measured by radioimmunoassay in sera from immature male and female rats of various ages. Fairly high levels of FSH were found in both sexes at birth but LH was not detected. FSH peaks appeared in the male at 13 and 19 days of age and in the female at 13 and 17–19 days of age. LH was undetectable in the male before 12 days of age, rose to a peak (440 ± 60 (s.d.) ng/ml) at 13 days of age and fell below the detection level again between 15 and 25 days of age. A further increase then occurred which almost reached adult levels. LH was first detectable in the female rat at 11 days of age with a peak value of 130 ± 35 ng/ml at 12 days. The hormone was undetectable on days 14 and 15, rose to a second peak on day 18 (148 ± 56 ng/ml), and was again absent between 19 and 25 days of age. The concentration rose, as in the male, between days 25 and 28 to a level similar to that of the adult. The results show sexual differences in prepubertal gonadotrophin surges.
The LH peak at 12–13 days in both sexes appears to be light-dependent. The FSH peak at this time was affected by light but was not strictly light-dependent.
INFLUENCE OF THE PITUITARY GLAND ON INSULIN SECRETION IN THE GENETICALLY OBESE (ob/ob) MOUSE
Authors: BELOFF-CHAIN ANNE , EDWARDSON J. A. , HAWTHORN JANET 
Published: December 2008

SUMMARY
The influence of the pituitary gland of lean and genetically obese (ob/ob) mice on insulin secretion from microdissected pancreatic islets of lean and ob/ob mice has been studied by perifusing the pituitaries of these animals in series with the isolated islets and measuring insulin secretion at 5-min intervals over a period of 60 min.
It has been shown that the pituitary perifusate of both lean and obese mice stimulate insulin secretion from lean mouse islets but not from obese mouse islets. The maximum stimulation occurs in the first 10 min and with the lean mouse pituitaries returns to the basal level in about 20 min, whereas with the obese mouse pituitaries insulin secretion is about double that from the control islets even after 40 min.
A concentration of pure porcine ACTH equivalent to about three times the amount released from the pituitary gland under the experimental conditions used, caused only a small stimulation of insulin release. Possible interpretations of these findings and further lines of investigation are discussed.
EFFECTS OF ELECTRICAL STIMULATION OF THE NEUROHYPOPHYSIS ON LABOUR IN THE RAT
Authors: BOER K. , LINCOLN D. W. , SWAAB D. F. 
Published: December 2008

SUMMARY
Labour was studied in 69 primiparous and multiparous rats by continuous observation and by the recording of intra-uterine activity. The effect of electrical stimulation of the neurohypophysis with stimulation parameters selected to create a pulsatile release of oxytocin was investigated. Stimulation was applied to the neurohypophysis through chronically implanted electrodes every 5 min, in 45 min sessions, from noon on Day 21 of gestation and at 3 h intervals thereafter.
Electrical stimulation successfully promoted (or induced) the onset and facilitated the course of labour. Stimulation at 12.00 h on Day 21, or at a subsequent stimulation session 3, 6, 9 or more hours later, promoted an immediate increase in the frequency and amplitude of uterine contractions. Overt signs of abdominal straining followed within 5–30 min and the first pup was delivered shortly thereafter. These 'induced' deliveries were almost identical to those displayed by control rats; labour continued to completion despite the termination of the stimulation session after 45 min. By contrast, one third of the stimulated animals displayed an interrupted pattern of labour in which events virtually ceased for 30–60 min when stimulation was terminated. Stimulation, however, only advanced labour by 1–2 h in relation to control animals; this was not statistically significant.
Stimulation accelerated the delivery of the first 5 pups in each litter. In both stimulated and control animals, the birth intervals declined over these first few deliveries to reach the lowest values of 5–6 min throughout the remainder of labour. The most common litter size was 12 pups.
The distribution of labour on Day 21 and 22 was bimodal. Seventy per cent of the animals gave birth between 12.00 and 18.00 h on Day 21, a few gave birth during the following night and the remainder formed a second peak on Day 22. All litters of less than 6 pups were born during this later period.
The implications of these results in the context of spontaneous labour are discussed. We conclude that endogenous oxytocin (with perhaps other neurohypophysial hormones) released in pulses of 1–3 mu. every 5 min can promote a pattern of labour on Day 21 of gestation that is almost indistinguishable from that which occurs naturally.
MODIFICATION OF RAT UTERINE MONOAMINE OXIDASE ACTIVITY BY STEROID HORMONES
Authors: GROSSO D. S. , GAWIENOWSKI A. M. 
Published: December 2008

SUMMARY
The monoamine oxidase (MAO) activity in the ovariectomized rat uterus was significantly increased above control levels in animals given testosterone: 33% (P < 0·01) with tryptamine or 34% (P < 0·05) with tyramine as substrate. Activity was also higher in hydrocortisone-treated animals: 30% (P < 0·05) with tyramine or 25% (P < 0·05) with tryptamine as substrate. Progesterone injection increased MAO activity toward tyramine by 20% but towards tryptamine by only 8%. The differences are not statistically significant but are believed to be real since they were reproducible. MAO activity in oestradiol-treated animals was 11% less than in the controls for both substrates. Although they are not significant differences, they were reproducible. No change in MAO activity was observed in the cerebellum, hypothalamus or anterior pituitary of ovariectomized rats after steroid treatment. At oestrus the enzyme activity in the uterus was lower than at dioestrus or prooestrus when β-phenylethylamine was the substrate. When 5-hydroxytryptamine was used to measure enzyme activity, the same values were found at oestrus, dioestrus and prooestrus. Ovariectomy did not cause any changes in MAO activity in any of the tissues. Effects of the steroids in vivo were probably not due to a direct action on the enzyme since only at high concentrations did they have any effect on the mitochondrial enzyme activity of the uterus in vitro.
RESPONSIVENESS OF THE OVARY TO GONADOTROPHINS IN PRE- AND PERINATAL LIFE: OESTROGEN SECRETION IN TISSUE AND ORGAN CULTURES
Authors: LEVINA S. E. , GYÉVAI A. , HORVÁTH E. 
Published: December 2008

SUMMARY
Secretion of oestrogen by the ovaries of foetal (15–19 days of gestation) and newborn rats in organ and tissue culture was not detectable by fluorometry when the ovary was taken from foetuses before folliculogenesis had occurred. In organ cultures of ovaries, the time of folliculogenesis corresponded with the normal timing of folliculogenesis in vivo. In tissue cultures the process of formation of follicles was delayed.
Oestrogens were present in the medium when folliculogenesis was fully established in the cultured foetal ovaries. Secretion began spontaneously and did not depend on the addition of gonadotrophins to the medium. The addition of gonadotrophins to the culture medium did not affect the level of oestrogen secreted by the foetal and newborn rat ovaries during the period of incubation (2–3 weeks).
SYNTHESIS AND SECRETION OF A LARGE GLYCOPROTEIN IN THE PARS INTERMEDIA
Authors: HOPKINS C. R. 
Published: December 2008

SUMMARY
The biosynthesis, intracellular transport and release of [3H]leucine-containing secretory product has been followed in the pars intermedia of Xenopus laevis and, in particular, the synthesis and secretion of a large molecular weight glycoprotein secretory product was demonstrated. However, if Xenopus adrenocorticotrophin does contain a leucine residue the results obtained provided no support for the view that it serves as a precursor for melanocyte-stimulating hormone in this species.
ASPECTS OF ADRENAL FUNCTION IN THE DOMESTIC FOWL
Authors: CULBERT J. , WELLS J. W. 
Published: December 2008

SUMMARY
Chromatographic purification of extracts of hen peripheral plasma on Florisil columns before measurement by spectrofluorometry showed a basal level for corticosterone of 1–3 μg/100 ml, which is much lower than concentrations previously reported using acid fluorescence. Neither handling, restraint nor repeated bleeding affected the concentration of this hormone or of glucose.
Adrenal function tests with two preparations of synthetic corticotrophin showed that they caused a rapid rise in blood corticosterone and eventually of glucose. Results of studies using insulin or tolbutamide i.v. suggest that there is a threshold concentration of plasma glucose (about 70 mg/100 ml) below which hypoglycaemia stimulates the hypothalamic-pituitary-adrenal system in fowls.
Prolonged treatment of laying hens with protamine zinc insulin led to aphagia and cessation of egg-laying; increased concentrations of corticosterone were observed 2 days after the administration of insulin ceased, coinciding with the return to normal plasma levels of glucose.
'Chemical adrenalectomy' with metyrapone showed that the restoration of plasma glucose to a normal concentration after insulin treatment is dependent upon fully functional adrenal cortical tissue. It appears likely that the adrenal medulla is a target for corticosterone which probably regulates the tissue levels of phenylethanolamine-N-methyltransferase, one of the enzymes necessary for the biosynthesis of adrenaline.
SYNTHESIS OF DEHYDROEPIANDROSTERONE AND DEHYDROEPIANDROSTERONE SULPHATE BY THE HUMAN ADRENAL
Authors: DOOUSS T. W. , SKINNER S. J. M. , COUCH R. A. F. 
Published: December 2008

SUMMARY
The role of pregnenolone sulphate in adrenal steroid biosynthesis and the ability of the human adrenal gland to synthesize and secrete dehydroepiandrosterone (DHA) and dehydroepiandrosterone sulphate (DHA sulphate) was investigated. The presence of pregnenolone sulphate and DHA sulphate was demonstrated by measuring their concentrations in human adrenal tissue. Pregnenolone sulphate was metabolized in vitro mainly to free steroids, including DHA and cortisol, as well as directly to DHA sulphate in some cases. Similar results were obtained upon perfusion of the adrenal gland in situ with [14C]pregnenolone and [3H]pregnenolone sulphate as the substrates and isolating the metabolites from the adrenal venous blood. Dehydroepiandrosterone sulphate was derived mainly from the sulphation of free DHA. The hydrolysis of DHA sulphate did not appear to make a significant contribution to the amounts of DHA synthesized under these conditions.
The adrenal secretion of DHA and DHA sulphate by eight patients undergoing adrenalectomy was determined by measuring the concentrations of these compounds in samples of adrenal and peripheral venous blood taken simultaneously. In one patient secretion of DHA and DHA sulphate was equivalent whilst in the remainder there was much greater secretion of DHA.
SERUM LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE CONCENTRATIONS IN IMMATURE FEMALE RATS TREATED WITH MULTIPLE INJECTIONS AND VARIOUS AMOUNTS OF LUTEINIZING HORMONE RELEASING HORMONE
Authors: JOHNSON D. C. , MALLAMPATI R. S. 
Published: December 2008

SUMMARY
Release of immunoreactive LH and FSH was induced in immature intact female rats by repeated injections of synthetic luteinizing hormone releasing hormone (LH-RH). Altering the dose of LH-RH (5, 10, 20, 50 ng) and the frequency of administration (every 10, 20, 30 or 60 min) over a period of 2 h produced a variety of serum LH and FSH concentrations and ratios. When the dose was a constant 20 ng but the frequency of injections was either 20 or 30 min, a steady state in serum gonadotrophin concentrations was reached within 1 h and the level remained the same during the second hour. When given every 10 min, 20 ng LH-RH produced a much higher concentration of both LH and FSH during the second hour of stimulation. Examination of the gonadotrophin levels after each injection of LH-RH showed that the pituitary response was variable in spite of a constant stimulus.
EFFECT OF THYROIDECTOMY ON THE ACTIVITY OF α-GLUCOSIDASES AND ACID HYDROLASES IN THE SMALL INTESTINE OF RATS DURING WEANING
Authors: KOLDOVSKÝ OTAKAR , JUMAWAN JOCELYN , PALMIERI MICHAEL 
Published: December 2008

SUMMARY
Adrenalectomy performed on 14-day-old rats delayed the usual increase of sucrase and maltase activity as well as the decrease of acid β-galactosidase, β-glucuronidase and N-acetyl-β-glucosaminidase activity during the third postnatal week. Since these changes were only delayed, the role of the thyroid was explored. Thyroidectomy performed simultaneously with adrenalectomy on 14-day-old rats did not influence the increase in body weight and growth of the small intestine (already slowed down by adrenalectomy), but caused a further substantial delay in the maturation of the enzyme profile of the small intestine. Our results indicate that the thyroid is involved in regulation of the hydrolases studied.
EFFECTS OF CASTRATION AND GONADAL STEROIDS ON SERUM LUTEINIZING HORMONE AND PROLACTIN IN OLD AND YOUNG RATS
Authors: SHAAR C. J. , EUKER J. S. , RIEGLE G. D. , MEITES J. 
Published: December 2008

SUMMARY
Changes in serum LH and prolactin concentrations in response to bilateral gonadectomy and gonadal steroid replacement were measured in mature young (4–6 months) and old (23–30 months) female and male Long–Evans rats. On day 13 after gonadectomy, female rats were injected with oestradiol benzoate (OB) and male rats with testosterone propionate (TP) for a period of 12 days. They were then permitted a recovery period of 6 weeks. Serum prolactin and LH concentrations were measured by radioimmunoassay in single blood samples taken at various intervals before and after gonadectomy and during and after steroid treatment.
Serum LH levels were about the same in intact young and old female rats, but after ovariectomy LH rose several fold higher in young than in old female rats. In male rats, serum LH values were about four times greater in intact young than in intact old rats, and after orchidectomy the increase in serum LH was greater in young than in old rats. Oestradiol benzoate and TP injections into female and male young and old rats produced variable effects on LH release. Serum prolactin concentrations were approximately six times higher in old intact than in young intact female rats, and after ovariectomy showed a much greater percentage reduction in old than in young female rats. Administration of OB produced a greater absolute increase in serum prolactin in old than in young female rats. Serum prolactin values were about the same in old and young male rats, and the effects of castration and TP administration on serum prolactin were not markedly different in the two age groups. These results indicate that old female and male rats are less capable of releasing LH than young rats of both sexes, but old females release more prolactin than young females.
RESPONSE OF ISOLATED RABBIT ARTICULAR AND EPIPHYSEAL CHONDROCYTES TO RAT LIVER SOMATOMEDIN
Authors: ASH PATRICIA , FRANCIS M. J. O. 
Published: December 2008

SUMMARY
Isolated rat liver, when perfused with medium containing bovine growth homone produced somatomedin-like activity (liver somatomedin).
Liver somatomedin is useful in studies of the hormonal control of the cartilage plate in vitro, since unlike serum it is not contaminated with other hormones or growth factors (apart from growth hormone). Chondrocytes isolated from various regions of the growth cartilage responded differently to liver somatomedin; proliferative chondrocytes, like those isolated from the articular cartilage, showed increased [3H]thymidine uptake in response to liver somatomedin, whereas hypertrophic chondrocytes did not respond. It is suggested that there is a reduction in the response to somatomedin by growth plate chondrocytes as they pass from the proliferative to the hypertrophic state.
Thyroxine, thought to be involved in the processes of hypertrophy and new bone formation, did not directly affect [3H]thymidine uptake by proliferative chondrocytes, but inhibited stimulation of their activity by liver somatomedin.
Measurement of [3H]thymidine uptake by isolated articular chondrocytes may provide a useful assay for both liver and serum somatomedin. The graded response of chondrocytes to increasing concentrations of liver somatomedin paralleled the response to increasing levels of serum somatomedin.
EFFECTS OF STEROID HORMONES ON DEVELOPING MOUSE SKIN IN VITRO
Authors: SINGH AMREEK , HARDY MARGARET H. 
Published: December 2008

SUMMARY
Pieces of skin from 13·5- to 15-day-old foetal mice were grown in organ culture in a biological medium with or without the addition of hormonal steroids. Cortisol (7·5 μg/ml) caused thinning of the non-cornified epidermis and flattening of the stratum granulosum after 3 days. By 6 days the epidermis was thinner and hair follicles were regressing, and these changes continued up to 12 days. Administration of corticosterone (5 μg/ml) also produced thinning of the epidermis and regression of the follicles after 6 days.
Good differentiation of epidermis and hair follicles was obtained when testosterone (100 μg/ml) was added to the medium. The non-cornified epidermal layers were similar to those of control cultures at 3 days but less than half as thick at 6 days. Hair follicles differentiated as rapidly in medium containing testosterone as in normal medium, but, unlike in the latter medium, also developed sebaceous gland anlagen at 6 days. Some explants in testosterone medium showed signs of sebaceous cell differentiation at 9 days.
CALCITONIN, PARATHYROIDECTOMY AND MODELLING OF BONES IN THE GROWING RAT
Authors: WHALEN J. P. , KROOK L. , MACINTYRE I. , NUNEZ E. A. 
Published: December 2008

SUMMARY
After calcitonin injection, parathyroidectomy, or both, in young growing rats, broadening of the proximal femoral metaphysis with lack of normal concavity of the medial and lateral contours was observed radiographically. Histologically, this abnormal modelling was associated with retarded osteocytic osteolysis. Further manifestations of decelerated resorption included retention and extension of the chondroid core in the secondary spongiosa, retention of cartilage in the cortex and a large increase in the number of cementing lines.
EFFECTS OF CADMIUM ON THE HYDRO-OSMOTIC AND NATRIFERIC RESPONSES OF THE TOAD BLADDER TO VASOPRESSIN
Authors: BENTLEY P. J. , YORIO T. , FLEISHER L. 
Published: December 2008

SUMMARY
Cadmium, 10−3 mol/l on the mucosal or 10−5 mol/l on the serosal side of the toad urinary bladder, inhibits the hydro-osmotic effect of vasopressin. This inhibition is irreversible.
The osmotic transfer of water in the absence of vasopressin was unaffected by the presence of the Cd2+.
The hydro-osmotic response to cyclic AMP was also reduced by the Cd2+, but the response due to hypertonicity of the serosal bathing solution was unaffected.
The short-circuit current (reflecting active transmural Na+ transport) was inhibited by 10−3 mol Cd2+/1 on the serosa, but was increased by 10−3 mol/l at the mucosa or 10−4 mol/l at the serosa.
The natriferic response of the bladder to vasopressin was unaffected when Cd2+ was present under conditions that inhibited the hydro-osmotic response, further emphasizing that separate effector mechanisms may be involved for each effect.
STIMULATORY EFFECT OF PROSTAGLANDIN F2α ON THE PLASMA CONCENTRATION OF TESTOSTERONE IN BULLS
Authors: HAYNES N. B. , HAFS H. D. , WATERS R. J. , MANNS J. G. , RILEY A. 
Published: December 2008

SUMMARY
The concentrations of peripheral plasma testosterone were measured by radioimmunoassay in samples collected from five bulls, each given i.m. injections of 0, 5, 15, 30 and 60 mg prostaglandin F2α (PGF2α). Synchronized peaks in testosterone concentration occurred with maximum values 1–2 h after treatment. These increases of testosterone persisted significantly longer than those observed to occur as natural episodic peaks during two 24 h periods in the same bulls. The mean peak testosterone concentration after PGF2α injection was related to the dose of PGF2α, values after 60 and 30 mg doses being significantly greater than after 15 mg. The response produced by a 5 mg dose was not significant. The results indicate that intramuscular injection of PGF2α acutely stimulates synthesis and release of testosterone in bulls.
MODIFICATION OF MYOMETRIAL ACTIVITY IN VIVO BY ADMINISTRATION OF CYCLIC NUCLEOTIDES AND THEOPHYLLINE TO THE PREGNANT RAT
Authors: BUCKLE J. W. , NATHANIELSZ P. W. 
Published: December 2008

SUMMARY
Myometrial activity was recorded in vivo in unrestrained pregnant rats from day 19 of gestation using radiotelemetry. The effects of short-term infusions of theophylline, dibutyryl cyclic AMP and 8-bromo-cyclic GMP were investigated. All three compounds caused a decrease in oxytocin-induced, prostaglandin F2α-induced and spontaneous uterine activity. After cessation of the infusion of these compounds uterine activity returned to near pre-infusion levels within approximately 15 min in most animals. The possible roles of cyclic nucleotides in the control of myometrial contraction are discussed in the light of these observations.
THE SYNERGISTIC ACTION OF α-MELANOCYTE-STIMULATING HORMONE AND TESTOSTERONE ON THE SEBACEOUS, PROSTATE, PREPUTIAL, HARDERIAN AND LACHRYMAL GLANDS, SEMINAL VESICLES AND BROWN ADIPOSE TISSUE IN THE HYPOPHYSECTOMIZED-CASTRATED RAT
Authors: EBLING F. J. , EBLING ERIKA , RANDALL VALERIE , SKINNER J. 
Published: December 2008

SUMMARY
α-Melanocyte-stimulating hormone was shown to act synergistically with testosterone to stimulate the sebaceous, prostate and preputial glands and the seminal vesicles in hypophysectomized-castrated rats. The sebaceous glands differed from the other three organs in that α-MSH not only acted synergistically, but also had a significant effect which was independent of the presence of exogenous testosterone. The response of the brown adipose tissue to testosterone, considerably reduced by hypophysectomy, was not restored by α-MSH. The Harderian and lachrymal glands were also pituitary-dependent and their weights in hypophysectomized-castrated rats were not restored by α-MSH.