bluuebunny/crossref_metadata_2025_split huggingface dataset:
Food Restriction Affects the Gonadotropin Releasing Hormone Neuronal System of Male Prairie Voles (Microtus ochrogaster)
Authors: Kriegsfeld L. J. , Ranalli N. J. , Trasy A. G. , Nelson R. J. 
Published: March 2003

AbstractIndividuals of species inhabiting temperate and boreal latitudes optimize the timing of energetically costly processes by curtailing nonessential energetically demanding processes when environmental conditions are not favourable. One proximate environmental variable used to fine‐tune moment‐to‐moment changes in reproductive physiology and behaviour is food intake. The neuroendocrine mechanisms by which food restriction leads to the cessation of reproduction in seasonally breeding rodent species remain largely unspecified. The present study sought to determine the effects of extended food restriction on the gonadotropin releasing hormone (GnRH) neuronal system. Male prairie voles (Microtus ochrogaster) were either fed ad libitum or were exposed to either 1, 2 or 3 weeks of moderate (70% of daily mean) food restriction. In accordance with previous studies of food restriction, gross reproductive organ masses and body mass were unaffected by food deprivation. Although 1 week of food restriction did not result in alterations in the GnRH neuronal system, food restriction for 2 weeks was associated with increased GnRH‐immunoreactive (GnRH‐ir) neurone soma size. Three weeks of food restriction resulted in a pronounced increase in GnRH‐ir neurone numbers, as well as an increase in fibre intensity in the main fibre pathway to the median eminence. Taken together, these findings suggest that extended food restriction leads to modifications in the GnRH neuronal system, providing a means for temporary cessation of reproduction without gross alterations in reproductive physiology. This transient change in the hypothalmo‐pituitary‐gonadal axis, without pronounced changes in reproductive organ morphology, likely provides a mechanism for the rapid reinitiation of breeding in nature when local conditions provide adequate food availability.
Increased Corticosterone Pulse Frequency During Adjuvant‐Induced Arthritis and its Relationship to Alterations in Stress Responsiveness
Authors: Windle R. J. , Wood S. A. , Kershaw Y. M. , Lightman S. L. , Ingram C. D. , Harbuz M. S. 
Published: March 2003

AbstractFrequent blood sampling from males rats was used to study hypothalamic‐pituitary‐adrenal (HPA) axis activation during arthritis and its association with diminished responses to acute psychological stress. In control rats, corticosterone release occurred in a series of 13 ± 1 pulses per 24 h. Induction of arthritis by Mycobacterium‐adjuvant injection initially increased the rate of hormone release within each pulse and, by day 14 postinjection, when hind‐paw inflammation was established, caused a marked increase in pulse frequency to 22 ± 1 per 24 h leading directly to elevated circulating corticosterone levels. In both control and adjuvant‐treated rats, there was a marked response to a 10‐min noise stress when the stimulus coincided with a rising or interpulse phase of the endogenous corticosterone rhythm. However, when the noise stress coincided with a falling phase of this rhythm, the response was greatly diminished. Since corticosterone pulse frequency was markedly increased and hence interpulse interval decreased by day 14, there was an increased probability of the noise stress occurring during the nonstress responsive falling phase of the corticosterone secretory cycle. As a result, the group mean response to noise stress was significantly smaller in the arthritic than the controls (70.2 ± 9.2 versus 107.8 ± 13.0 ng/ml, respectively). In contrast to the differential response to noise stress, all rats showed similar responses to the acute immunological challenge with i.v. lipopolysaccharide. Thus, altered basal pulse frequency is a major factor influencing HPA activation during acute psychological stress.
Involvement of Postsynaptic EP4 and Presynaptic EP3 Receptors in Actions of Prostaglandin E2 in Rat Supraoptic Neurones
Authors: Shibuya I. , Setiadji S. V. , Ibrahim N. , Harayama N. , Maruyama T. , Ueta Y. , Yamashita H. 
Published: March 2003

AbstractWe have reported that supraoptic nucleus (SON) neurones are excited by prostaglandin E2 (PGE2) presumably via dual postsynaptic PG receptors, FP receptors and unidentified EP receptors, and that presynaptic EP receptors may also be involved in the excitation. In the present study, to clarify the receptor mechanism of the PGE2‐mediated actions on SON neurones, we studied the pre‐ and postsynaptic effects of four newly developed EP agonists that are selective for each of the four EP receptors, EP1−4, on rat SON neurones using extracellular recording and whole‐cell patch‐clamp techniques. The EP4 agonist ONO‐AE1‐329 mimicked the excitatory effects of PGE2, whereas the EP1 agonist ONO‐DI‐004, the EP2 agonist ONO‐AE1‐257 and the EP3 agonist ONO‐AE‐248 had little or no effect. The effects of ONO‐AE1‐329 were unaffected by the EP1/FP/TP antagonist, ONO‐NT‐012, which potently suppressed the excitation caused by the FP agonist fluprostenol and PGE2. ONO‐AE1‐329 caused marked excitation when responses to fluprostenol were desensitized by repeated applications of fluprostenol. Patch‐clamp analysis in SON neurones showed that ONO‐AE1‐329 induced inward currents at a holding potential of −70 mV and the reversal potential of the currents was −35.1 ± 2.3 mV. On the other hand, the frequency of spontaneous inhibitory postsynaptic currents recorded from SON slice preparations was suppressed by ONO‐AE‐248, but unaffected by the other three EP agonists. These results suggest that SON neurones possess postsynaptic EP4 receptors and that γ‐aminobutyric acid neurones innervating SON neurones possess presynaptic EP3 receptors in their terminals. Activation of the two EP receptors may be involved in the excitatory regulation of SON neurones by PGE2.
Ghrelin Stimulates Insulin Secretion from the Pancreas of Normal and Diabetic Rats
Authors: Adeghate E. , Ponery A. S. 
Published: March 2003

AbstractGhrelin is a novel 28‐amino acid gut–brain peptide, which was first isolated in the rat stomach. This study examined the effect of ghrelin on insulin secretion from the isolated pancreas of normal and diabetic rats. Diabetes was induced by a single dose of streptozotocin. Four weeks after the induction of diabetes, pancreatic tissue fragments of normal and diabetic rats were treated with different concentrations (10−12, 10−9 and 10−6 M) of ghrelin. Ghrelin evoked large and significant increases in insulin secretion from the pancreas of both normal and diabetic rats. In the pancreas of normal rats, diltiazem (calcium channel antagonist) or a combination of atropine (muscarinic cholinergic receptor antagonist), propranolol (β‐adrenergic receptor antagonist) and yohimbine (α2‐adrenergic receptor antagonist) significantly reduced the stimulatory effect of ghrelin on insulin secretion. Diltiazem and yohimbine failed to inhibit ghrelin‐evoked insulin release in diabetic rat pancreas. Ghrelin‐immunoreactivity cells was observed in 2.6% and 3.8% of the total cell population in the islet of Langerhans of normal and diabetic rats, respectively.
Regulation of Sex Differences in Progesterone Receptor Expression in the Medial Preoptic Nucleus of Postnatal Rats
Authors: Quadros P. S. , Goldstein A. Y. N. , De Vries G. J. , Wagner C. K. 
Published: March 2003

AbstractThe medial preoptic nucleus (MPN) of the rat, an excellent model for understanding the mechanisms involved in sexual differentiation, is highly sensitive to gonadal hormones during both pre‐ and post‐natal life. Progesterone receptor (PR) expression is sexually dimorphic in the prenatal MPN. Males have significantly higher levels of PR‐immunoreactivity (PRir) than females from approximately embryonic day 19 through at least the day of birth, suggesting that PR may play a role in sexual differentiation. Because the MPN is still sensitive to steroid hormones postnatally, the present study investigated PR expression in the MPN of males and females after birth using immunocytochemistry. Results indicate that a sex difference in PR expression persists until at least postnatal day (P) 28. However, females begin to express PR around P10. Because oestradiol regulates PR expression in the adult brain, this study also examined the influence of gonadal hormones on PR expression in the neonatal male and female MPN. Castration on the day of birth significantly reduced levels of PRir in the MPN by 24 h following surgery. Ovariectomy on P4, before the onset of ovarian steroidogenesis, prevented the induction of PR expression in the female MPN, observed in controls by P13. In both sexes, the presence of PRir in the MPN is dependent on gonadal hormone exposure. These findings suggest that differences in steroid secretion by the neonatal male and female gonads are responsible for producing sex differences in the level of PR expression in the postnatal MPN.
Sauvagine Regulates Ca2+ Oscillations and Electrical Membrane Activity of Melanotrope Cells of Xenopus laevis
Authors: Cornelisse L. N. , Deumens R. , Coenen J. J. A. , Roubos E. W. , Gielen C. C. A. M. , Ypey D. L. , Jenks B. G. , Scheenen W. J. J. M. 
Published: March 2003

AbstractCa2+ oscillations regulate secretion of the hormone alpha‐melanphore‐stimulating hormone (α‐MSH) by the neuroendocrine pituitary melanotrope cells of the amphibian Xenopus laevis. These Ca2+ oscillations are built up by discrete increments in the intracellular Ca2+ concentration, the Ca2+ steps, which are generated by electrical membrane bursting firing activity. It has been demonstrated that the patterns of Ca2+ oscillations and kinetics of the Ca2+ steps can be modulated by changing the degree of intracellular Ca2+ buffering. We hypothesized that neurotransmitters known to regulate α‐MSH secretion also modulate the pattern of Ca2+ oscillations and related electrical membrane activity. In this study, we tested this hypothesis for the secretagogue sauvagine. Using high temporal‐resolution Ca2+ imaging, we show that sauvagine modulated the pattern of Ca2+ signalling by increasing the frequency of Ca2+ oscillations and inducing a broadening of the oscillations through its effect on various Ca2+ step parameters. Second, we demonstrate that sauvagine caused a small but significant decrease in K+ currents measured in the whole‐cell voltage‐clamp, whereas Ca2+ currents remained unchanged. Third, in the cell‐attached patch‐clamp mode, a stimulatory effect of sauvagine on action current firing was observed. Moreover, sauvagine changed the shape of individual action currents. These results support the hypothesis that the secretagogue sauvagine stimulates the frequency of Ca2+ oscillations in Xenopus melanotropes by altering Ca2+ step parameters, an action that likely is evoked by an inhibition of K+ currents.
Centrally Administered Galanin‐Like Peptide Modifies Food Intake in the Rat: A Comparison with Galanin
Authors: Lawrence C. B. , Baudoin F. M.‐H. , Luckman S. M. 
Published: March 2003

AbstractGalanin‐like peptide (GALP) is a recently identified neuropeptide that shares sequence homology with the orexigenic neuropeptide, galanin. In contrast to galanin, GALP is reported to bind preferentially to the galanin receptor 2 subtype (GalR2) compared to GalR1. The aim of this study was to determine the effect of GALP on feeding, body weight and core body temperature after central administration in rats compared to the effects of galanin. Intracerebroventricular (i.c.v.) injection of GALP (1 µg−10 µg) significantly stimulated feeding at 1 h in both satiated and fasted Sprague‐Dawley rats. However, 24 h after GALP injection, body weight gain was significantly reduced and food intake was also usually decreased. In addition, i.c.v. GALP caused a dose‐related increase in core body temperature, which lasted until 6–8 h after injection, and was reduced by peripheral administration of the cyclooxygenase inhibitor, flurbiprofen (1 mg/kg). Similar to GALP, i.c.v. injection of galanin (5 µg) significantly increased feeding at 1 h in satiated rats. However, there was no difference in food intake and body weight at 24 h, and galanin only caused a transient rise in body temperature. Thus, similar to galanin, GALP has an acute orexigenic effect on feeding. However, GALP also has an anorectic action, which is apparent at a later time. Therefore, GALP has complex opposing actions on energy homeostasis.
Oestrogens, Via Transforming Growth Factor α, Modulate Basic Fibroblast Growth Factor Synthesis in Hypothalamic Astrocytes: In Vitro observations
Authors: Galbiati M. , Martini L. , Melcangi R. C. 
Published: March 2003

AbstractThe data presented here show that, in cultures of type 1 astrocytes obtained from the hypothalamus of neonatal female rat, 17β‐oestradiol is able to increase both the mRNA and the protein levels of basic fibroblast growth factor (bFGF). In particular, after 24 h of exposure to 17β‐oestradiol (10−9 and 10−10 m), an increase of messenger levels of bFGF appears in hypothalamic type 1 astrocytes. Similarly, an induction of bFGF protein is also evident at this time of exposure. The effect on the mRNA and protein levels of bFGF is blocked by the presence in the medium of an antibody raised against the transforming growth factor α (TGFα) receptor. This observation indicates that, TGFα, whose synthesis is modulated by oestrogens in hypothalamic astrocytes and which is able to increase, both the mRNA and the protein levels of bFGF in our experimental model, may act as the mediator of the oestrogenic induction of bFGF. Hypothalamic astrocytes, together with hypothalamic neurones synthesizing and secreting luteinizing hormone‐releasing hormone (LHRH), form the LHRH network in conjunction with other neuronal systems. Gonadal steroids in general, and oestrogens in particular, play an important role in the control of the activity of this network. In addition, bFGF and TGFα, two growth factors released from astrocytes, are able to influence the activity of LHRH neurones. The present observations suggest that oestrogens may also act on LHRH neurones in an indirect fashion (i.e. by modulating the expression of bFGF and TGFα in glial cells).
Interleukin‐1β Depolarizes Paraventricular Nucleus Parvocellular Neurones
Authors: Ferri C. C. , Ferguson A. V. 
Published: March 2003

AbstractInterleukin‐1β (IL‐1β) is involved in hypothalamic regulation of corticotropin releasing hormone (CRH) secretion and consequent downstream modulation of the neuroimmune response. In this study, whole‐cell patch clamp recordings of rat parvocellular neurones in a slice preparation of the paraventricular nucleus (PVN) of the hypothalamus were performed to examine the cellular effects of IL‐1β. In response to 1 nm IL‐1β, 65% of parvocellular neurones tested exhibited a clear depolarization, which was abolished in the presence of tetrodotoxin (TTX). This depolarization was partially dependent on nitric oxide formation, as demonstrated by attenuation of the response in the presence of N‐ω‐nitro‐l‐arginine methylester, a nitric oxide synthase inhibitor. The effects of IL‐1β on responsive parvocellular neurones were associated with a decrease in the frequency of inhibitory post synaptic potentials (IPSPs). Bicuculline administration blocked the effects of IL‐1β, suggesting that this cytokine modulates GABA‐ergic output, resulting in a decrease in inhibitory input (IPSPs) and consequent depolarization. These data support the conclusion that IL‐1β influences the excitability of parvocellular neurones in the PVN, as a secondary consequence of nitric oxide generation and modulation of GABAergic inhibitory input to these cells. They elucidate cellular correlates underlying the well‐established neuroimmune roles of IL‐1β in the paraventricular nucleus of the hypothalamus.
Displacement of a mobile tooth during impression procedure: effect of impression tray design
Authors: Nishi Y. , Hamano T. , Kawahata N. , Nagaoka E. 
Published: March 2003

When fabricating prostheses in a partially edentulous arch with some mobile teeth, it is important to minimize tooth displacement during the impression procedure. The present study examined the effect of custom tray designs on the displacement of a mobile central incisor in a mandibular simulation model with six anterior teeth. Twelve custom trays were designed according to the different spaces and perforated holes in the region of the remaining teeth. As a result, the degree of displacement of the mobile tooth could be reduced according to the size of spaces and the location of perforated holes in the custom tray. Introduction
Structure–property relationship of cast Ti–Nb alloys
Authors: Lee C. M. , Ju C. P. , Chern Lin J. H. 
Published: March 2003

The present work is a study of the microstructure, mechanical properties and corrosion behaviour of a series of binary Ti–Nb alloys with Nb contents up to 35 wt%, with emphasis placed on the structure–property relationship of the alloys. The results indicate that crystal structure and morphology of the Ti–Nb alloys are sensitive to the Nb content. The cast c.p. Ti has a hexagonal α phase with a lath type morphology. The alloys containing 15 wt% or less Nb are dominated by a hexagonal α′ phase with an acicular, martensitic structure. When containing 17·5–25 wt% Nb, the alloys are primarily comprised of an orthorhombic α′′ phase. With 27·5 wt% Nb, metastable β phase starts to be retained. With Nb contents higher than 30 wt%, the equi‐axed β phase is almost entirely retained. Small amounts of ω phase are detected in alloys containing 27·5 and 30 wt% Nb. Among all present alloys, Ti–10Nb and Ti–27·5Nb exhibit the highest strengths, while the α′′‐dominated (17·5 and 20Nb) and β‐dominated (> 30Nb) alloys have the lowest moduli. All Ti–Nb alloys show excellent corrosion resistance in Hank's solution at 37 °C. From the present data, the microhardness, bending strength and modulus of the various phases in Ti–Nb alloys are compared and tentatively summarized as follows:Microhardness: ω > α′ > α′′ > β > α (c.p. Ti)Bending strength: ω > α′ > α′′ > β > α (c.p. Ti)Bending modulus: ω > α (c.p. Ti) > α′ > α′′ > β
Behavioural treatment for sleep problems in children with severe learning disabilities and challenging daytime behaviour: Effect on sleep patterns of mother and child
Authors: WIGGS LUCI , STORES GREGORY 
Published: March 2003

Children with sleep problems present serious management problems to their parents. Such children are also more likely to have additional problems, behavioural disturbance being particularly common. This randomized controlled trial of behavioural interventions for the children's sleep problems was conducted to explore the efficacy and mechanisms of treatment in children with the most extreme forms of problems: severe learning disabilities, severe sleep problems and severe daytime challenging behaviour.Fifteen index families received behavioural advice for the child's sleep problem and were compared with 15 matched controls who received no such advice. Repeat assessments of the children's and mothers’ sleep were made by parental report as well as actometry. Objective changes in the children's sleep quality and quantity were not seen after treatment. However, mothers in the treatment group reported improvements in the children's sleep problems and had an increased sleeping time themselves following treatment.The results indicate that sleep problems can be successfully treated in this group of children, although the mechanisms of treatment may not be as direct as supposed. This has implications for understanding of sleep problems in children with learning disabilities and also for clinical practice, when considering ways of offering help to these highly ‘challenged’ families.
Cognitive function and treatment of obstructive sleep apnea syndrome
Authors: LOJANDER J. , KAJASTE S. , MAASILTA P. , PARTINEN M 
Published: March 2003

SummaryAmong patients with obstructive sleep apnea syndrome (OSAS), impairment of cognitive function, i.e. deficits in memory, attention, and visuconstructive abilities are common. We applied different forms of treatment for patients with newly diagnosed OSAS in a randomized study with a one‐year follow‐up. Patients with BMI > 40 kg/m4 and the Bourdon‐Wiersma (r=0.36). Success in treatment of OSAS did not affect neuropsychological outcome. We concluded that the standard cognitive test battery is insufficiently sensitive to identify positive changes in patients with OSAS, especially among those with a high level of overall mental functioning.
Effects of light exposure and sleep displacement on dim light melatonin onset
Authors: Gordijn M. C. M. , Beersma D. G. M. , Korte H. J. , VAN DEN Hoofdakker R. H. 
Published: March 2003

SummaryThe purpose of the study was to induce in two different ways, a phase‐angle difference between the circadian pacemaker and the imposed sleep–wake cycle in humans, we intended to: (i) shift the circadian pacemaker by exposure to bright light and keep the timing of the sleep–wake cycle fixed; and (ii) keep the timing of the circadian pacemaker fixed by a constant light–dark cycle and displace sleep. We monitored dim light melatonin onset (DLMO), core body temperature and sleep. DLMO was delayed significantly after 3 days of a 3‐h delayed sleep‐phase when compared with 3 days of sleep at a normal or 3‐h advanced sleep‐phase. The shifts in DLMO were not accompanied by shifts in body temperature, changes in waking‐up time or by a change in the duration of the first rapid eye movement (REM) sleep episode. Three days of light exposure in the morning or evening resulted in shifts in DLMO of similar magnitude, but this was accompanied by shifts in the rhythm of body temperature, changes in waking‐up time and in the duration of the first REM sleep episode. We conclude that the changes observed after light exposure reflect shifts in the circadian pacemaker. In contrast, we propose that the changes observed in DLMO after sleep displacement are not mediated by the circadian pacemaker. These results raise some doubts about the reliability of DLMO as a marker of circadian phase in cases of sleep disturbances. Finally, we initiate a search for changes in sleep that might be responsible for the unexpected effects on DLMO.
Circadian preference, sleep and daytime behaviour in adolescence
Authors: Giannotti Flavia , Cortesi Flavia , Sebastiani Teresa , Ottaviano Salvatore 
Published: March 2003

SummaryThe aim of this study was to determine the relationship between circadian preferences, regularity of sleep patterns, sleep problems, daytime sleepiness and daytime behaviour. As a part of an epidemiological survey on sleep in a representative sample of Italian high‐school students, a total of 6631 adolescents, aged 14.1–18.6 years, completed the School Sleep Habits Survey, a comprehensive questionnaire including items regarding sleep, sleepiness, substance use, anxiety and depressed mood, use of sleeping pills, school attendance and a morningness/eveningness scale. The sample consisted of 742 evening‐types (315 males and 427 females; mean age 17.1 years) and 1005 morning‐types (451 males and 554 females; mean age 16.8 years). No significant sex differences were found for morningness/eveningness score. Eveningness was associated with later bedtime and wake‐up time, especially on weekends, shorter time in bed during the week, longer weekend time in bed, irregular sleep–wake schedule, subjective poor sleep. Moreover, evening types used to nap more frequently during school days, complained of daytime sleepiness, referred more attention problems, poor school achievement, more injuries and were more emotionally upset than the other chronotype. They referred also greater caffeine‐containing beverages and substances to promote sleep consumption. Our results suggest that circadian preference might be related not only to sleep pattern, but also to other adolescent behaviours.