bluuebunny/crossref_metadata_2025_split huggingface dataset:
IDENTIFICATION OF HUMAN LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE β-SUBUNIT AND GONADOTROPHIN α-SUBUNIT IN FOETAL AND ADULT PITUITARY GLANDS
Authors: HAGEN C. , McNEILLY A. S. 
Published: December 2008

SUMMARY
Specific radioimmunoassays were used to assess the content of LH, FSH, the gonadotrophin α-subunit and the LH β-subunit in four adult, 19 normal foetal pituitary glands (9·5–32 weeks of gestation) and a pituitary extract from an anencephalic foetus (36 weeks). The hormones and subunits were further identified by column chromatography on Sephadex G-100. All pituitary glands contained free α-subunit and intact LH but the α-subunit:LH ratio was significantly higher in the early foetal pituitaries (9·5–16 weeks) than in the four adult pituitaries. Only small or undetectable amounts of LH β-subunit and 'undetectable' FSH were found in these early foetal pituitaries (9·5–11·5 weeks). The concentration of intact hormones or subunits in the pituitaries showed no significant sex difference in any of the groups. In contrast to these results, only α-subunit was detectable in the pituitary of the anencephalic foetus.
For 14 early foetuses (age of gestation 10–16 weeks) the serum levels of LH–HCG, FSH, and α-subunit in the circulation were significantly higher than in 26 foetuses at term (37–41 weeks). On the basis of these results a theory for the development of the gonadotrophin secretion from the foetal pituitary gland is outlined.
PLASMA PROGESTERONE LEVELS IN GUINEA-PIGS ACTIVELY IMMUNIZED AGAINST PROSTAGLANDIN F2α, HYSTERECTOMIZED OR TREATED WITH INTRA-UTERINE INDOMETHACIN
Authors: POYSER N. L. , HORTON E. W. 
Published: December 2008

SUMMARY
Five guinea-pigs actively immunized against a prostaglandin F2α(PGF2α)–bovine serum albumin conjugate showed elongated oestrous cycles. During these, corpora lutea were maintained in a functional secretory state as indicated by plasma progesterone levels. The results are compatible with the view that the PGF2α antibodies neutralized the PGF2α released from the uterus and thus prevented its normal luteolytic effect. Similar patterns of progesterone secretion were observed in two hysterectomized animals and in two animals with intra-uterine implants of indomethacin.
EFFECT OF MAGNESIUM DEFICIENCY AND PARATHYROID HORMONE ON CYCLIC AMP METABOLISM IN RAT RENAL CORTEX
Authors: ASHBY J. P. , HEATON F. W. 
Published: December 2008

SUMMARY
The influence of magnesium deficiency on cyclic AMP metabolism was investigated in rats on diets of normal and low calcium content. Magnesium deficiency itself did not significantly affect either the basal concentration or the parathyroid hormone-stimulated formation of cyclic AMP in the renal cortex.
Magnesium-deficient rats with hypercalcaemia excreted more cyclic AMP in the urine, but similar rats that developed hypocalcaemia on low calcium intake excreted less than their respective controls. The former type of animals also tended to accumulate more cyclic AMP in the renal cortex in response to the injection of a standard dose of parathyroid hormone, whereas rats of the latter type accumulated less. The activity of parathyroid hormone-stimulated renal cortical adenylate cyclase in vitro was increased by magnesium and reduced by calcium under most conditions, but with low concentrations of magnesium small amounts of calcium had a stimulatory effect. These observations suggest that cyclic AMP metabolism is influenced by metabolic disorders developing secondary to magnesium deficiency.
ELECTRICAL STIMULATION OF THE HYPOTHALAMUS AND LUTEINIZING HORMONE SECRETION IN JAPANESE QUAIL
Authors: DAVIES D. T. , FOLLETT B. K. 
Published: December 2008

SUMMARY
Experiments were undertaken to localize those hypothalamic areas in the male quail (Coturnix coturnix japonica) where electrical stimulation would increase LH secretion. The posterior basal hypothalamus was stimulated with rectangular pulses (height 500 μA) through a bipolar electrode for 6 min, blood samples being taken for LH assay 20 min before, and 2, 10, 20 and 30 min after stimulation. The highest plasma concentration was observed in the 2 min sample. Over the next 30 min the LH level decreased to the resting concentration. The relative increase in LH level was greatest in sexually immature quail and least in photostimulated castrated birds, although the highest absolute levels were seen in the castrated quail. There were no statistical differences between the magnitude of the LH increases in sexually immature, mature and castrated quail.
Various hypothalamic regions were then stimulated with a smaller current (200 μA) applied for only 2 min. A highly significant rise in LH followed stimulation of either the tuberal hypothalamus (postero-dorsal part of the infundibular nuclear complex, PD-INC), or the preoptic region (POR) while stimulation 0·5–1·5 mm away from these regions did not change LH secretion. Stimulation of the anterior basal hypothalamus, or of the suprachiasmatic area, caused a significant rise in LH concentration although this was less than that seen after stimulation of the POR. Stimulation in the POR or the PD-INC was ineffective if the tuberal hypothalamus had been deafferentated surgically some days previously. The data complement the studies in which destruction of the PD-INC or the POR by electrolytic lesions has been shown to block photoperiodically induced testicular growth and LH secretion.
POTENTIATION BY URETHANE AND INHIBITION BY PENTOBARBITONE OF OXYTOCIN RELEASE IN VITRO
Authors: DYBALL R. E. J. 
Published: December 2008

SUMMARY
Isolated rat neural lobes were incubated in vitro in Locke's solution containing anaesthetic quantities of urethane, pentobarbitone or tribromoethanol. The oxytocin content of the incubation medium was estimated before, during and after stimulation of the tissue by raising the potassium chloride concentration from 5·6 to 56 mmol/l. Urethane (25 mmol/l) significantly potentiated oxytocin release (P < 0·01) whereas tribromoethanol (0·5 mmol/l) had no obvious effect and pentobarbitone (0·4 mmol/l) significantly (P < 0·01) inhibited its release. Reduction of the sodium chloride concentration in the medium potentiated the release of oxytocin in each case but did not alter its pattern. Urethane which increased secretion of oxytocin also increased calcium ion uptake by the neural lobes and pentobarbitone which decreased oxytocin release decreased calcium ion uptake. The results may explain why the blood concentration of the neurohypophysial hormones tends to be higher in rats anaesthetized with urethane than with tribromoethanol. Inhibition of hormone release by pentobarbitone suggests that this anaesthetic is unsuitable for use in studies of neurohypophysial hormone release. A partial explanation of the anaesthetic properties of urethane and pentobarbitone may also have been found if the release of neurotransmitter substances is influenced in a similar manner.
STIMULATION OF CARP INTERRENAL FUNCTION BY ADRENOCORTICOTROPHIN
Authors: ILAN Z. , YARON Z. 
Published: December 2008

SUMMARY
The effect of ACTH on cortisol concentration in the plasma of the carp has been studied; cortisol was determined using a competitive protein-binding radioassay. Blood was sampled at 12.00 h (the diurnal minimum) by cardiac puncture. The plasma cortisol level of undisturbed carp (blood obtained 1–3 min after netting) was 46 ± 14 (s.e.m.) ng/ml.
One hour after injection of ACTH (1·0 i.u./100 g body wt., i.m.) the level of cortisol increased to 415 ± 62 ng/ml and reached a maximum of 656 ± 62 ng/ml after 2 h. The level of cortisol in saline-injected control carp after 2 h was 72 ± 33 ng/ml. A transient rise of cortisol was noted in both groups 30 min after injection (315 ± 51, 315 ± 62 ng/ml). This was attributed to a surge of endogenous ACTH, presumably due to handling.
Carp head kidneys were superfused in vitro. They released cortisol spontaneously, but the releasing rate declined exponentially and reached a minimum after 135 min. Addition of ACTH to the medium was followed by a prompt increase in cortisol release. The rate of cortisol release was maximal 30–45 min after addition of ACTH and was identical to the rate at the beginning of the superfusion.
INABILITY OF ACTINOMYCIN D TO ACT UPON THE UTERINE REFRACTORY STATE RESULTING FROM NIDATORY OESTROGEN ACTION IN RATS
Authors: LEROY F. , VAN HOECK J. , BOGAERT C. 
Published: December 2008

SUMMARY
After priming with oestradiol, ovariectomized rats were given 6 days of progesterone treatment in which two doses of 50 ng oestradiol were superimposed on days 3 and 6. This basic regimen allows the oestradiol-induced (1st injection) inhibition of uterine sensitivity to decidual stimuli to appear. Actinomycin D given instead of, or together with, the first dose of oestradiol could not mimic, or prevent oestrogen action in the occurrence of the uterine refractory state. This drug was unable to interfere with the minimal 48 h progesterone treatment which is requisite to uterine sensitization. Our results together with other data from the literature, suggest that luteal hormones do not need to act at the transcriptional level to sensitize and desensitize the uterus to implantation.
PLACENTAL LACTOGEN IN THE COW
Authors: BUTTLE H. L. , FORSYTH ISABEL A. 
Published: December 2008

SUMMARY
Placental lactogen secretion has been demonstrated in cows on days 36, 178, 182 and 270 of pregnancy by co-culture of cotyledonary tissue with mouse mammary gland explants. Bovine placental lactogen probably originated from the foetal cotyledon and showed no detectable cross-reaction in immunoassays for bovine prolactin or growth hormone. Peripheral plasma samples collected from seven primiparous heifers at 2-week intervals throughout pregnancy showed a seasonal rhythm in prolactin concentration, measured by radioimmunoassay, with high levels in the summer. Monthly samples were bioassayed for total lactogenic activity by a rabbit mammary gland organ culture method. Positive responses were obtained only when prolactin levels were high ( > 70 ng/ml), indicating that levels of placental lactogen in the circulation are much lower in the cow than in sheep, goats or women.
THE INFLUENCE OF OESTRADIOL-17β AND PROGESTERONE ON THE CONTRACTILITY OF THE OVIDUCT OF THE TURTLE, CHRYSEMYS PICTA, IN VITRO
Authors: CALLARD I. P. , HIRSCH MADELYN 
Published: December 2008

SUMMARY
The contractility of the oviduct of Chrysemys picta (the fresh-water turtle) was studied in vitro. Significant regional differences in contractile activity were observed. Contractions increased in amplitude and duration and decreased in frequency from the proximal to the distal end of the oviduct. Injections of oestradiol-17β in vivo increased the amplitude of contractions and decreased the duration of the rest period in segments taken from the distal end of the oviduct. In contrast, progesterone injections significantly reduced the duration of both contractile and resting periods.
EFFECT OF UNILATERAL AND BILATERAL CASTRATION AND CRYPTORCHIDISM ON SERUM GONADOTROPHINS IN THE RAT
Authors: GOMES W. R. , JAIN S. K. 
Published: December 2008

SUMMARY
The effects of unilateral and bilateral cryptorchidism and castration on serum concentrations of testosterone, FSH and LH in adult male rats were examined. The results provide no evidence for compensatory growth or development of the remaining scrotal testes up to 32 days after unilateral castration, although the scrotal testis of unilaterally cryptorchid rats showed enlargement when compared with those of control rats (P < 0·05) at 32 days. Unilateral treatments had few significant effects on serum hormones, but testosterone was increased on day 4 (P < 0·05) in unilaterally cryptorchid rats and on day 32 (P < 0·05) in unilaterally castrated rats, compared with controls, and FSH levels were higher in unilaterally castrated rats on day 16 (P < 0·05). Bilateral cryptorchidism caused an increase in serum FSH within 4 days (P < 0·05) and in serum LH by 8 days (P < 0·05) after surgery, with both hormones reaching levels double those found in control rats (P < 0·01) by day 16, while testosterone levels were maintained at or above control values. Bilateral castration resulted in a marked decrease in testosterone levels (P < 0·01) and a sharp increase in serum gonadotrophins. FSH had nearly doubled (P < 0·01) and LH had increased fourfold (P < 0·01) 4 days after castration, their levels reaching 773% (LH) and 287% (FSH) of control values by 32 days (P < 0·01). The observations support the hypothesis of a separate, testosterone-independent feedback system of the testis on the hypophysis.
HORMONE STORAGE IN INDIVIDUAL NEUROSECRETORY GRANULES OF THE PITUITARY GLAND: A QUANTITATIVE ULTRASTRUCTURAL APPROACH TO HORMONE STORAGE IN THE NEURAL LOBE
Authors: MORRIS J. F. 
Published: December 2008

SUMMARY
A quantitative ultrastructural study of the neurosecretory granules in the neural lobe of the rat was performed in order to calculate the number of such granules in the neural lobe and thus, provided all hormone is intragranular, to derive the hormone content of individual granules. The results suggest that the gland contains 1·44 × 1010 granules and that an individual granule (mean diameter 160 nm) contains about 84000 hormone molecules. The errors involved in the many measurements made are analysed, and the calculated value for the amount of space available for each hormone molecule within the granule is shown to agree well with independently reported data for the expected size of a molecule of protein–hormone complex, and for the size of subunits visualized in freeze-etched material.
These results are compatible with exclusive intragranular hormone storage as a 'solid' core, and the physical form that this core might take is discussed. The data are used to express what is known of hormone turnover and release in terms of the numbers of granules involved. Comparison of different parts of the neural lobe suggests that, apart from the most anterior part of the gland, there is little regional variation in quantitative aspects of granule storage in the neural lobe.
RELATION BETWEEN PROLACTIN AND GONADOTROPHIN SECRETION IN POST-PARTUM LACTATING RATS
Authors: LU K. H. , CHEN H. T. , HUANG H. H. , GRANDISON L. , MARSHALL S. , MEITES J. 
Published: December 2008

SUMMARY
In post-partum lactating rats, sucking by the young was associated with high prolactin release and maintenance of lactation but severe inhibition of LH and FSH release and suspension of oestrous cycles. Shortly after the pups were removed on day 22 post partum, LH and FSH release returned to normal and oestrous cycles resumed. Twice-daily injections of ergocornine methanesulphonate (ERG) into mothers beginning at 5 or 7 days post partum, resulted in sustained inhibition of prolactin release and diminished milk secretion. By frequent exchange of pups between control and ERG-treated mothers, it was possible to maintain vigorous sucking and almost normal pup growth despite low serum prolactin levels and diminished lactation. In these rats, serum levels of LH remained low during 11 or more days of treatment with ERG, but serum FSH was consistently higher than in untreated control mothers. After 11 or more days of ERG treatment, most rats showed a return to normal LH and FSH release and resumption of oestrous cycles. These results suggest (a) that the sucking stimulus rather than high prolactin levels in the circulation is mainly responsible for inhibition of LH and FSH release during the first 11 days post partum, (b) that the sucking stimulus acts to increase prolactin and inhibit LH release by separate hypothalamic mechanisms, and (c) that administration of ERG results in diminished prolactin release and lactation, and in increased release of FSH and subsequently of LH with earlier resumption of oestrous cycles.
DEVELOPMENTAL, DIURNAL AND OESTROUS CYCLE-DEPENDENT CHANGES IN THE ACTIVITY OF LIVER ENZYMES
Authors: STENBERG ÅKE 
Published: December 2008

SUMMARY
The metabolism of [4-14C]4-androstene-3,17-dione was studied in the 105000 g microsomal and supernatant fractions of liver from developing rats of both sexes. The following enzyme activities were measured: 5β-reductase (supernatant fraction) and 5α-reductase, 17α- and 17β-hydroxysteroid reductases, 6β-, 7α- and 16α-hydroxylases (microsomal fraction). The activities of the 3α- and 3β-hydroxysteroid reductases were estimated by calculating the ratios of 3α-:5α- and 3β-: 5α-reduced metabolites formed, respectively.
Most enzyme activities present at birth (i.e. 5β-reductase, 5α-reductase, 17β-hydroxysteroid reductase, 6β- and 7α-hydroxylase) increased until 20 days of age in both male and female rats. Between 20 and 30 days of age a number of masculine metabolic characteristics appeared in both sexes, i.e. the 16α-hydroxylase and the 17α-hydroxysteroid reductase were induced, the 5β-reductase activity rapidly increased and the 5α-reductase activity slightly decreased. During a third period beginning 30 days after birth the adult male enzyme activity pattern was completed by the induction of 3β-hydroxysteroid reductase and a further increase in the activity of 16α-hydroxylase. After 30 days of age a feminine type of liver metabolism also rapidly developed in female rats; the 16α-hydroxylase and the 17α-hydroxysteroid reductase activities disappeared, the 6β-hydroxylase and the 5β-reductase activities decreased and the 5α-reductase activity increased six times.
The developmental patterns of enzyme activities in the rat liver are consistent with a first developmental phase (0–30 days of age) independent of hypophysial control and probably determined primarily by the genome of the liver cell and a second phase (from 30 days onwards) with increasing sexual differentiation under hypophysial control. This control is mediated by some kind of feminizing factor in female rats and possibly by some kind of androgen-elicited secretion of masculinizing factor(s) in male rats.
The metabolism of [4-14C]4-androstene-3,17-dione was also studied during different times of the day and during different phases of the oestrous cycle. The 16α-hydroxylase activity showed a diurnal variation with higher values at noon than at midnight. The 5β-reductase activity reached a maximal activity during metoestrus.
INHIBITION OF HUMAN CHORIONIC GONADOTROPHIN-INDUCED HYPERTROPHY OF THE OVARIES AND UTERUS IN IMMATURE MICE BY SOME PINEAL INDOLES, 6-HYDROXYMELATONIN AND ARGININE VASOTOCIN
Authors: VAUGHAN MARY K. , VAUGHAN G. M. , REITER R. J. 
Published: December 2008

SUMMARY
Administration of the indoles 5-methoxytryptophol, 6-hydroxymelatonin, melatonin, N-acetylserotonin or 5-methoxyindole-3-acetic acid (six 100-μg injections given at intervals of 12 h) inhibited both the absolute and relative ovarian and uterine weights of immature female mice pre-treated with HCG. Administration of 5-hydroxytryptophol or 5-methoxytryptamine at the same dosage inhibited ovarian but not uterine hypertrophy in mice pre-treated with HCG.
EFFECTS OF SODIUM PENTOBARBITONE ADMINISTRATION ON GONADOTROPHIN RELEASE, FIRST OVULATION AND OVARIAN MORPHOLOGY IN PUBERTAL RATS
Authors: OSMAN P. , MEIJS-ROELOFS H. M. A. 
Published: December 2008

SUMMARY
Pubertal female rats received sodium pentobarbitone (PB; 45 mg/kg body wt) at various hours on the day of first pro-oestrus. Maximal blockade of ovulation, in about 60% of the rats, occurred after PB treatment at 12.00, 13.00 and 14.00 h. The number of small antral follicles (100–499 × 105 μm3) was reduced 1 day after PB treatment in both blocked and ovulating rats. In the ovaries of non-ovulating rats signs of stimulation by LH such as dispersion of cumulus cells, oocyte maturation and early luteinization were sometimes present; in ovulating rats cystic corpora lutea with entrapped ova were found in addition to normal corpora lutea. Gonadotrophin measurements after PB treatment (14.00 h) in pubertal and adult rats showed (at 17.00 h) reduced levels of both LH and FSH, these levels being lower in the adults. Gonadotrophin levels of blocked and ovulating pubertal rats overlapped.
In PB-treated, pubertal rats in which ovulation was postponed by 1 day, vaginal oestrus was prolonged by 1 day and the subsequent dioestrus by 2 days.
The pubertal rat is thus less sensitive to PB treatment than the adult. PB treatment of the younger animal influences not only the ovulatory process but also follicular growth and, presumably, the length of the approaching cycle.
EFFECT OF VARIOUS PUTATIVE NEUROTRANSMITTERS ON THE SECRETION OF CORTICOTROPHIN-RELEASING HORMONE FROM THE RAT HYPOTHALAMUS IN VITRO – A MODEL OF THE NEUROTRANSMITTERS INVOLVED
Authors: JONES M. T. , HILLHOUSE E. W. , BURDEN JANET 
Published: December 2008

SUMMARY
The effect of incubating the hypothalamus of adult male rats with various neurotransmitters upon the release of corticotrophin-releasing hormone (CRH) was studied. The CRH activity in the incubation medium was assayed in 48 h median eminence-lesioned rats and the corticosteroidogenesis of excised adrenals in vitro was used as the end-point. 5-Hydroxytryptamine (100 pg/ml–10 ng/ml) caused a dose-dependent release of CRH which was antagonized by methysergide (30–100 ng/ml). The response to 5-hydroxytryptamine was also inhibited by hexamethonium and atropine which indicated that it was acting through a cholinergic interneurone. Melatonin (10 ng) did not alter the basal release of CRH but inhibited the action of both 5-hydroxytryptamine (10 ng) and acetylcholine (3 pg). Thus it appears that both 5-hydroxytryptamine and melatonin play a role in the control of CRH release. Noradrenaline blocked the release of CRH induced by both acetylcholine and 5-hydroxytryptamine and presumably this inhibition was caused by direct action on the CRH neurone. γ-Aminobutyric acid (GABA) also inhibited the release of CRH and may also be involved in the regulation of CRH secretion. The inhibitory neurotransmitters, noradrenaline, GABA and melatonin, act via independent receptor mechanisms. A model based on the above data is presented.
EFFECT OF IONIC ENVIRONMENT ON THE RELEASE OF HUMAN PLACENTAL LACTOGEN IN VITRO
Authors: CHOY V. J. , WATKINS W. B. 
Published: December 2008

SUMMARY
Short-term incubation of human placental tissue in Krebs–Ringer bicarbonate buffered media with various concentrations of K+ and Ca2+ showed a graded response in human placental lactogen (HPL) release at different Ca2+ concentrations, but no effect at increased K+ concentration. Media with high Ca2+ caused an inhibition of release, while Ca2+-free media caused a stimulation in HPL release. High concentrations of Mg2+ inhibited release minimally, while Ba2+ had no effect. There was no change in HPL release when Na+ concentration was increased. La3+-Locke's solution markedly inhibited release of HPL but the significance of this effect is unknown. These results suggest that Ca2+ is not required for HPL secretion from placental tissue. It seems that HPL secretion in vitro does not follow the usual pattern where a physiological stimulus or high K+ concentration causes inward movement of calcium which couples stimulation to secretion.