bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in epidermal growth factor concentrations of submandibular gland, plasma and urine of normal and sialoadenectomized female mice during various reproductive stages
Authors: Kurachi H. , Oka T. 
Published: December 2008

ABSTRACT
The concentrations of epidermal growth factor (EGF) were measured by radioimmunoassay in the submandibular gland, plasma and urine of adult female C3H/HeN mice whilst virgin and during pregnancy, lactation and after lactation. During gestation there was a significant increase in the submandibular EGF concentration which was five to seven times higher than that found in virgin mice. The level of EGF in the gland remained high during the period of lactation and even several weeks after lactation. Plasma EGF levels were also increased during the periods of pregnancy, lactation and after lactation when compared with those of virgin mice. These increases were, however, apparent only between 24.00 and 08.00 h, because of circadian variations in circulating EGF. The level of plasma EGF was significantly (P<0·05) higher during the 24.00–08.00 h period than during the 12.00–20.00 h period in all stages examined. Concentrations of EGF in the urine of virgin, pregnant, lactating and primiparous mice remained relatively constant, and the levels were much higher than those in the plasma. Similar studies using sialoadenectomized pregnant and lactating mice indicated that the plasma levels of EGF were below the level of sensitivity of the assay (<16·5 pmol/l (<0·1 ng/ml)) even during the 24.00–08.00 h period, whereas urinary EGF remained at high levels which were similar to those of normal pregnant and lactating mice. These results suggest that submandibular EGF contributes to the increase in plasma EGF which occurs after gestation, but is not the major source of the urinary EGF.
J. Endocr. (1985) 106, 197–202
The role of microfilaments in the priming effect of LH-releasing hormone: an ultrastructural study using cytochalasin B
Authors: Lewis C. E. , Morris J. F. , Fink G. 
Published: December 2008

ABSTRACT
We have investigated the possibility that microfilaments are involved in the priming effect of LH-releasing hormone (LHRH) by ultrastructural morphometry of hemipituitary glands from adult female mice. Glands incubated for 2 consecutive hours with 8·5 nmol LHRH/1 responded with a marked increase in the amount of LH released into the medium during the second hour compared with the first hour of incubation. This priming effect of LHRH on LH secretion was accompanied by a significant margination of secretory granules and a drop in the total granule content of the gonadotrophs. Although the number of microfilaments remained the same, there was an increase in their length and a change in orientation so that the angle between the microfilaments and the plasmalemma was significantly reduced after both the first and second hour of exposure of LHRH. The addition of 14·3 μmol cytochalasin B/l to the incubation medium significantly increased the amount of LH released in the first hour of incubation when compared with the amount of LH released by LHRH alone, but completely abolished the priming effect of LHRH. Cytochalasin B also prevented the LHRH-induced increase in the length and the change in orientation of the microfilaments. These results indicate that LHRH priming involves an increase in length of microfilaments and a change in their orientation relative to the plasmalemma.
J. Endocr. (1985) 106, 211–218
Endocrine control of uterine oxytocin receptors in the ewe
Authors: Sheldrick E. L. , Flint A. P. F. 
Published: December 2008

ABSTRACT
Specific binding of [3H]oxytocin to high affinity sites (hormone receptors) in membrane preparations from uterine tissues of the ewe has been determined at varying stages of the oestrous cycle and in pregnancy. Mean receptor concentrations in caruncular and inter-caruncular endometrium and in myometrium were 14·2, 1·9 and 13·0 fmol/mg protein respectively between days 10 and 13 of the cycle. By the day of oestrus these values had increased to 749, 1085 and 179 fmol/mg protein. These increases in receptor concentrations coincided with luteolysis and falling plasma progesterone levels and followed the preovulatory decline in peripheral oxytocin and rise in ovarian venous oestradiol-17β. Receptor concentrations were low in all uterine tissues from pregnant animals between days 14 and 19 after oestrus. Analysis of binding parameters by Scatchard plot suggested a single population of receptor molecules in each of the tissues studied with apparent dissociation constants in the range 1·9–2·2 nmol/l. A number of naturally occurring neurohypophysial peptides inhibited binding of [3H]oxytocin to the receptor from ewes at oestrus; the cross-reactions of arginine vasopressin and vasotocin exceeded that of oxytocin.
Use of a receptor binding assay to measure oxytocin in extracts of corpora lutea on days 4 and 10 after oestrus gave values similar to those obtained by radioimmunoassay, suggesting the absence of other receptor-active peptides in the corpus luteum.
It is concluded that the oxytocin receptor is present in both components of the endometrium, as well as in the myometrium and that changes in uterine receptor concentrations before oestrus are consistent with receptor activation by steroid hormones.
J. Endocr. (1985) 106, 249–258
Vasoactive intestinal peptide in rat hypophysial portal blood: effects of electrical stimulation of various brain areas, the oestrous cycle and anaesthetics
Authors: Brar A. K. , Fink G. , Maletti M. , Rostene W. 
Published: December 2008

ABSTRACT
Vasoactive intestinal peptide (VIP) was measured by radioimmunoassay in hypophysial portal and peripheral blood from adult male and female Wistar rats. The results confirmed that the concentration of VIP in hypophysial portal blood was significantly greater than in peripheral blood and showed that VIP release into portal blood was not affected by removal of the gut, the largest peripheral source of VIP. Electrical stimulation of the median eminence, several hypothalamic nuclei, the amygdala or hippocampus had no significant effect on the release of VIP into portal blood, possibly because under the conditions of the experiment the spontaneous release of VIP is already at a maximum. In female rats, the VIP released into portal blood collected between 13.00 and 18.30 h of each day of the 4-day oestrous cycle varied under different anaesthetics, and there was no consistent increase in VIP release on pro-oestrus suggesting that VIP is not involved in the pro-oestrous surge of prolactin.
J. Endocr. (1985) 106, 275–280
Growth hormone responses to multiple injections of a fragment of human growth hormone-releasing factor in conscious male and female rats
Authors: Clark R. G. , Robinson I. C. A. F. 
Published: December 2008

ABSTRACT
The GH responses to single i.v. injections of GH-releasing factor (GRF) in conscious male rats are highly variable. Although normal male rats show a pulsatile secretory pattern of GH with pulses occurring at intervals of 3–3·5 h, the peaks occur at different times in individual animals. We have compared the GH responses of young conscious male and female rats to multiple i.v. injections of 1 μg human (h) GRF1-29NH2. The peak GH responses occurred 3–5 min after hGRF1-29NH2 injection and were lower in female than in male rats. Both males and females responded uniformly to hGRF1-29NH2 injections given 180 min apart and the GH responses became entrained with no endogenous GH pulsing. Female rats produced consistent GH peaks in response to hGRF1-29NH2 injections at 90-min intervals, whereas male rats responded only to alternate injections, so that GH peaks occurred only every 180 min despite giving GRF every 90 min. When the frequency of hGRF1-29NH2 administration was increased to once every 40 min female rats again responded consistently to each injection. Male rats responded intermittently, being able to respond to two injections 40 min apart, after which they became refractory to hGRF1-29NH2. This cycle of varying sensitivity to GRF in male rats probably underlies their 3-hourly endogenous GH secretory rhythm. Female rats can respond uniformly to repeated GRF injections, consistent with their more continuous pattern of endogenous GH secretion. Introducing a pulse of 10 μg rat GH into a series of hGRF1-29NH2 injections did not induce refractoriness to hGRF1-29NH2, suggesting that GH does not itself desensitize the pituitary to GRF. Whether the different patterns of GH secretion in males and females result from different patterns of GRF and/or somatostatin secretion remains to be determined.
J. Endocr. (1985) 106, 281–289
Effects of flavonoids on insulin secretion and 45Ca2+ handling in rat islets of Langerhans
Authors: Hii C.S.T. , Howell S.L. 
Published: December 2008

ABSTRACT
The effects of some flavonoids, a group of naturally occurring pigments one of which has been claimed to possess antidiabetic activities, on insulin release and 45Ca2+ handling have been studied in isolated rat islets of Langerhans. Insulin release was enhanced by approximately 44–70% when islets were exposed to either (−)epicatechin (0·8 mmol/l) or quercetin (0·01–0·1 mmol/l); others such as naringenin (0·1 mmol/l) and chrysin (0·08 mmol/l) inhibited hormone release by approximately 40–60%. These effects were observed only in the presence of 20 mmol glucose/l. Quercetin (0·01 mmol/l) and (−)epicatechin (0·8 mmol/l) both inhibited 45Ca2+ efflux in the presence and absence of extracellular Ca2+. In the presence of 20 mmol glucose/l both the short-term (5 min) and steady-state (30 min) uptake of 45Ca2+ were significantly increased by either quercetin or (−)epicatechin. These results suggest that the stimulatory compounds such as quercetin and (−)epicatechin may, at least in part, exert their effects on insulin release via changes in Ca2+ metabolism.
J. Endocr. (1985) 107, 1–8
Pituitary receptors for LH-releasing hormone (LHRH) and responsiveness to LHRH in adult female rats after neonatal monosodium l-glutamate treatment
Authors: Inkster S. E. , Clayton R. N. , Whitehead S. A. 
Published: December 2008

ABSTRACT
The effects of neonatal monosodium l-glutamate (MSG) treatment on pituitary responsiveness to LH-releasing hormone (LHRH) and on pituitary LHRH receptors have been investigated in the intact adult female rat. Three- to four-month-old rats treated with MSG (4 mg/g body wt) on days 2, 4, 6, 8 and 10 after birth had significantly reduced ovarian and pituitary weights, showed an absence or disruption of ovarian cyclicity after puberty, and had significantly higher concentrations of serum prolactin despite normal levels of LH. In-vitro pituitary LH responses to LHRH were in the normal range for one group of treated animals whilst in a second group the LH responses were markedly enhanced. In contrast, the total number of pituitary LHRH receptors were significantly reduced in all MSG-treated animals showing that the increased pituitary responsiveness of MSG-treated animals is not attributable to an increase in pituitary LHRH receptors.
J. Endocr. (1985) 107, 9–13
Ornithine decarboxylase activity and polyamines in the anterior pituitary gland during the rat oestrous cycle
Authors: Persson L. , Nilsson M. , Rosengren E. 
Published: December 2008

ABSTRACT
The biosynthesis of polyamines, an ubiquitous group of amines shown to be essential for normal cellular growth and differentiation, was studied in the rat anterior pituitary gland during the different stages of the oestrous cycle. The activity of ornithine decarboxylase (ODC), which catalyses the rate-limiting step in the biosynthesis of polyamines, was low during oestrus, metoestrus and dioestrus. However, a marked transitory rise in ODC activity was found in the pituitary gland on the evening of pro-oestrus. The rise in ODC activity was accompanied by an increase in the pituitary content of the polyamines putrescine and spermidine.
Ovariectomy did not significantly change the basal ODC activity in the pituitary gland. Oestrogen treatment of ovariectomized rats resulted in a marked stimulation of pituitary polyamine biosynthesis. The largest effects were observed when oestrogen was given as two injections 72 h apart, which gave rise to levels of ODC activity comparable to those observed on the evening of pro-oestrus.
The increase in polyamine synthesis in the anterior pituitary gland during pro-oestrus appeared not to be related to the preovulatory secretion of LH or prolactin, since neither LH-releasing hormone nor thyrotrophin-releasing hormone (which induces a secretion of prolactin) affected pituitary ODC activity. The observed biosynthesis of polyamines may be associated with the cellular proliferation which occurs in the anterior pituitary gland at oestrus.
J. Endocr. (1985) 107, 83–87
Recurrent mammary gland contractions induced by a low tonic release of oxytocin in rats
Authors: Poulain D. A. , Tasker J. G. 
Published: December 2008

ABSTRACT
In urethane-anaesthetized lactating rats, intramammary pressure occasionally displayed recurrent variations or oscillations having a slow rise time, low amplitude, long duration and a periodicity of 1–4 min. These oscillations differed from changes in intramammary pressure characteristic of reflex milk ejections induced by suckling, and were also observed in unsuckled rats. They were suppressed by lesions of the pituitary stalk or by stimulating the septum, a structure that inhibits the activity of the magnocellular system. They could be induced by long-term low frequency stimulation of the pituitary stalk, lesions of the septum or long-term infusions of oxytocin at a low rate of 0·05–0·3 mu./min. We suggest that the recurrent oscillations in intramammary pressure constitute a particular mode of response of the mammary gland to a tonic release of oxytocin resulting from a moderate but sustained increase in the basal level of electrical activity of the oxytocin-secreting neurones.
J. Endocr. (1985) 107, 89–96
Oxytocin and sexual behaviour in the male rat and rabbit
Authors: Stoneham M. D. , Everitt B. J. , Hansen S. , Lightman S. L. , Todd K. 
Published: December 2008

ABSTRACT
In male New Zealand white rabbits, it was shown that oxytocin but not vasopressin concentrations in plasma were markedly raised after ejaculation. In male Wistar rats, oxytocin infused into the internal carotid artery reduced the number of intromissions made before ejaculation but had no other significant effect. Infusion of oxytocin into the third ventricle increased the latencies to the first mount and intromission and lengthened post-ejaculatory refractory periods. It is suggested that oxytocin released into the periphery during coitus, while not essentially involved in ejaculation, may exert effects on the genital periphery. Behavioural effects of centrally administered oxytocin suggest that it may play a role in the neural mechanisms underlying post-ejaculatory refractoriness.
J. Endocr. (1985) 107, 97–106
Differential effects of melatonin on the stimulated release of LH from dispersed pituitary cells of the prepubertal female rat
Authors: Symons A. M. , Arendt J. , Pryde S. J. 
Published: December 2008

ABSTRACT
The effect of melatonin on the stimulated release of LH from prepubertal female rat pituitary cells in vitro was investigated. Significant inhibition of LH-releasing hormone and calcium ionophore-induced LH release was seen but not of potassium-induced release. These results suggest a specific interaction between melatonin and the endogenous events leading to LH release, and may implicate melatonin as an important neuroendocrine component of pubertal development in this species.
J. Endocr. (1985) 107, 107–112
Endogenous opioids and related peptides: from molecular biology to clinical medicine The Sir Henry Dale Lecture for 1985
Authors: Imura H. , Kato Y. , Nakai Y. , Nakao K. , Tanaka I. , Jingami H. , Koh T. , Yoshimasa T. , Tsukada T. , Suda M. , Sakamoto M. , Morii N. , Takahashi H. , Tojo K. , Sugawara A. 
Published: December 2008

ABSTRACT
Advances in techniques in molecular biology have facilitated the research into endogenous opioids and related peptides in several ways. The organization and expression of genes and the primary structure of three precursor proteins of opioid peptides have been elucidated. These studies predicted the presence of potentially bioactive peptides, which has been confirmed by later studies. Advances in techniques in protein chemistry have helped to elucidate the distribution and molecular forms of endogenous opioids and related peptides in the body, and the processing of precursor proteins. Studies on the function of these peptides have shown a broad spectrum of actions. Leumorphin, a newly identified peptide, has been shown to exhibit unique biological activities. In spite of extensive studies, the physiological and pathophysiological significance of opioid peptide systems are not yet completely understood. This is mainly due to the paucity of our knowledge about opioid receptors. Further studies on the subtypes of opioid receptors will help to elucidate all aspects of the function of endogenous opioids and related peptides.
J. Endocr. (1985) 107, 147–157
Dissociation between emotional and endocrine responses preceding an academic examination in male medical students
Authors: Allen P. I. M. , Batty K. A. , Dodd C. A. S. , Herbert J. , Hugh C. J. , Moore G. F. , Seymour M. J. , Shiers H. M. , Stacey P. M. , Young S. K. 
Published: December 2008

ABSTRACT
A study was made in 2 consecutive years of the emotional states and morning and afternoon serum levels of prolactin, cortisol and testosterone of male medical students during a 4- to 5-week period preceding a major university examination. 'Distress', 'anxiety' and, to a lesser degree, 'depression' increased during the 2 weeks immediately preceding the examination and were positively correlated with personality anxiety or neuroticism traits. Group means for hormones showed no consistent change over the same period. Neither was there evidence for a correlation between endocrine and emotional changes within individual students during the pre-examination period. A restricted study showed that there were significant increments in cortisol in samples taken during the examination itself.
Changes in emotional state before an examination occurred in the absence of equally dramatic changes in levels of the three hormones studied, though this relationship may have altered during the examination itself. This suggests that the factors controlling the two categories of response may relate differently, in some way, to the imminence of this stressful event.
J. Endocr. (1985) 107, 163–170
Measurement of phospholipase A2 activity in human endometrium during the menstrual cycle
Authors: Bonney R. C. 
Published: December 2008

ABSTRACT
Phospholipase A2 activity was measured in human endometrium throughout the menstrual cycle using an assay based on the liberation of oleic acid from 1-palmitoyl-2-[14C]oleoyl phosphatidylcholine. The enzyme was shown to be calcium dependent, to have an optimum pH of 8–9 and an apparent Michaelis constant of 110 μmol/l. Enzyme activity was low in early proliferative-phase tissue (6·08 ±1·42 (s.e.m.) pmol oleic acid released/mg protein per min) but rose significantly (P < 0·01) during the late proliferative phase (10·86 ±2·79 pmol/mg per min). There was a tenfold increase in activity 2–4 days after ovulation (45·6 ± 13·6 pmol/mg per min) which thereafter declined to reach values which at menstruation were not significantly different from those of the proliferative phase (4·5 ± 1·76 pmol/mg per min). The results indicate that phospholipase A2 activity in human endometrium is related to the stage of the menstrual cycle and suggest that arachidonic acid release may be influenced by oestradiol and progesterone.
J. Endocr. (1985) 107, 183–189
Amplitude of episodic release of LH as a measure of pituitary function analysed from the time-course of hormone levels in the blood: comparison of four menstrual cycles in an individual
Authors: McIntosh R. P. , McIntosh J. E. A. 
Published: December 2008

ABSTRACT
Pulse amplitude and frequency are often used to describe measurements of LH in blood. Such analyses are compatible with models of LH being released from the pituitary in episodes that are controlled by pulses of hypothalamic gonadotrophin-releasing hormone. The amplitudes of these secretory episodes as seen in blood are usually defined as the net heights of peaks above a baseline. As a measure of each pituitary secretory episode, this is valid only if peaks are regularly and widely spaced, making overlap negligible. When episodes are erratic and frequent so that only fractions of peaks have been cleared from the circulation before others follow, nadirs between peaks include output from previous episodes and do not define a physiologically meaningful baseline. Applied to overlapping peaks, such measures of amplitude usually underestimate pituitary secretory episodes and imply a tonic mode of LH secretion in addition to pulsatile release.
Using the additional information of fitted LH clearance coefficients to define the shapes of LH peaks, a simple method based on an episodic mode of release alone is described, for estimating more accurately the relative sizes of secretory episodes as observed in blood, free of the effects of overlapping peaks. Using this analysis we have described the variation in amplitude, interval and clearance rates of LH secretory episodes within and between four normal menstrual cycles of a single individual. Thirteen, 3–6 h blood sampling sessions were performed during early follicular growth at the transition from luteal to follicular phases when the frequencies of LH peaks, LH/FSH ratios and progesterone concentrations were changing markedly.
Our secretory episode model described all data well without the need to introduce a tonic mode of release. When frequent pulses overlapped we found that amplitudes of episodes were usually higher than peaks estimated by conventional methods, but a decrease in both amplitude and pulse interval occurred after the start of menstruation. Highly variable patterns of LH release were demonstrated in the late luteal phase of this normal individual while FSH levels rose consistently.
J. Endocr. (1985) 107, 231–239
Central nervous system-mediated growth inhibition of a rat prostate carcinoma by an opioid
Authors: Reubi J. C. 
Published: December 2008

ABSTRACT
Long-term treatment for more than 3 months with a central nervous system (CNS)-active drug, the opioid agonist bremazocine, at a dose of 1 mg/kg per day elicited an 80% inhibition of the volume of the subcutaneously transplanted rat prostate adenocarcinoma Dunning R3327H. Whereas, under this therapy, prostate tumour and prostatic weights were decreased, testes and pituitary weights remained normal. Bremazocine inhibited not only the growth of freshly transplanted tumours but also that of well-grown Dunning prostate carcinomas since, after 41 days of treatment, such tumours showed a volume inhibition of 52%. In these experiments bremazocine decreased LH and testosterone plasma levels significantly. Bremazocine, therefore, probably acts mainly through suprapituitary CNS-opiate receptor sites, which indirectly, rather than locally, mediate LH inhibition. Indeed, no specific receptors for bremazocine could be found in the Dunning tumour, which makes a local action of bremazocine in this tissue unlikely. The efficient tumour growth inhibition through the supra-pituitary action of bremazocine makes such opiate drugs, which lack respiratory and side effects due to improper use, of potential interest for treatment of prostatic tumours.
J. Endocr. (1985) 107, 247–250