bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of Corticotropin Releasing Factor (CRF), Urocortin and CRF Type 1 Receptors in Hypothalamic‐Hypophyseal Systems Under Osmotic Stimulation
Authors: Imaki T. , Katsumata H. , Miyata M. , Naruse M. , Imaki J. , Minami S. 
Published: March 2003

AbstractThe expression of corticotropin releasing factor (CRF) and urocortin in hypothalamic magnocellular neurones increases in response to osmotic challenge. To gain a better understanding of the physiological roles of CRF and urocortin in fluid homeostasis, CRF, urocortin and CRF type 1 receptor (CRFR‐1) gene expression was examined in the hypothalamic‐hypophyseal system usingin situ and double‐label in situ hybridization following chronic salt loading. CRFR‐1 expression was further examined by immunohistochemistry and receptor binding. Ingestion of hypertonic saline by Sprague‐Dawley rats for 7 days induced CRF mRNA exclusively in the oxytocin neurones of the magnocellular paraventricular nucleus (PVN) and the supraoptic nucleus (SON), but induced CRFR‐1 mRNA in both oxytocin and vasopressin‐containing magnocellular neurones. Hypertonic saline treatment also increased urocortin mRNA expression in the PVN and the SON. In the SON, urocortin was localized to vasopressin and oxytocin neurones but was rarely seen in CRF‐positive cells. Changes in CRFR‐1 mRNA expression in magnocellular neurones by hypertonic saline treatment were accompanied by changes in CRFR‐1 protein levels and receptor binding. Hypertonic saline treatment increased CRFR‐1‐like immunoreactivity in the magnocellular PVN and SON, and decreased it in the parvocellular PVN. CRF receptor binding in the PVN and SON was also increased in response to osmotic stimulation. Finally, hypertonic saline treatment increased CRFR‐1 mRNA, CRFR‐1‐like immunoreactivity and CRF receptor binding in the intermediate pituitary. These results demonstrate that the increase in the expression of CRF and urocortin message in magnocellular neurones induced by salt loading is accompanied by an increase in CRF receptor levels and binding in the hypothalamus and intermediate pituitary. Thus, CRF and urocortin may exert modulatory effects locally within magnocellular neurones as well as at the pituitary gland in response to osmotic stimulation.
Purinergic Regulation of Intracellular Ca2+ Concentration of Rat Pituitary Folliculo‐Stellate Cells in Primary Culture
Authors: Uchiyama M. , Nakajima Y. , Sakuma Y. , Kato M. 
Published: March 2003

AbstractPituitary folliculo‐stellate cells (FSCs) are glia‐like cells in the anterior pituitary and are believed to modulate the activity of the pituitary endocrine cells. However, little is known what regulates the activity of FSCs. We hypothesized that ATP could act on FSCs, because ATP is coreleased with pituitary hormones from endocrine cells. To test this possibility, we examined the effect of ATP by measuring intracellular Ca2+ concentration [Ca2+]i of FSCs in primary culture. Both ATP and UTP increased the [Ca2+]i in a concentration‐dependent manner in a range between 0.1 µM and 10 µM. The response was completely suppressed by thapsigargin, an inhibitior of endoplasmic reticulum Ca2+‐ATPase, and was significantly suppressed by U‐73122, an inhibitor of phospholipase C. The response was also suppressed by caffeine, a blocker of IP3 receptor, whereas that was not suppressed by ryanodine, an antagonist of ryanodine receptor. These results indicate that ATP increases [Ca2+]i of FSCs by activating phospholipase C via P2Y purinergic receptor and suggest that ATP would be one of paracrine factors to FSCs in the anterior pituitary.
Serine/Threonine Phosphatase Inhibitors Decrease Adrenergic Arylalkylamine N‐Acetyltransferase Induction in the Rat Pineal Gland
Authors: Spessert R. , Rapp M. , Vollrath L. 
Published: March 2003

AbstractAdrenergic regulation of the pineal enzyme serotonin N‐acetyltransferase [arylalkylamine N‐acetyltransferase (AA‐NAT); EC 2.3.1.87] accounts for the circadian rhythm in melatonin formation. In the present study, the role of protein phosphatases in the adrenergic regulation of rat pineal AA‐NAT was investigated using specific inhibitors. In cultured pineals, the serine/threonine phosphatase type 1 and type 2A inhibitors okadaic acid and calyculin A significantly decreased adrenergically or cAMP‐induced AA‐NAT activity, whereas the serine/threonine phosphatase type 2B inhibitor cypermethrin and tyrosine phosphatase inhibitor dephostatin were ineffective. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) data indicate that okadaic acid exerts its effect on cAMP‐dependent AA‐NAT induction by downregulating the amount of AA‐NAT transcript. The ‘third’ messengers, inducible cAMP early repressor (ICER) and Fos‐related antigene‐2 (Fra‐2), are believed to play a negative role in pineal AA‐NAT transcription. Okadaic acid increased the cAMP responsiveness of neither ICER mRNA nor Fra‐2 mRNA. Therefore, the regulatory role of pineal serine/threonine phosphatases in adrenergically stimulated AA‐NAT expression probably does not depend on ICER or Fra‐2.
GABA Mediates Steroid‐Induced Astrocyte Differentiation in the Neonatal Rat Hypothalamus
Authors: Mong J. A. , Nuñez J. L. , McCarthy M. M. 
Published: March 2003

AbstractOur previous work has demonstrated that astrocytes in the developing arcuate nucleus of the rat hypothalamus are sexually dimorphic as a result of differential exposure to oestradiol. Moreover, our experiments in neonatal rats suggest an absence of oestrogen receptors (ER) in arcuate nucleus astrocytes in vivo. This, along with the conspicuous lack of evidence in the literature confirming the presence of ER in arcuate nucleus astrocytes of the neonatal rat brain, led us to question the mechanism by which oestrogen induces changes in arcuate nucleus astrocyte morphology. Based on our previous findings that oestradiol increases γ‐aminobutyric acid (GABA) levels in the neonatal rat arcuate, we hypothesize that GABA is released from neighbouring oestrogen‐sensitive neurones and alters arcuate nucleus astrocyte morphology. Here, we report that in vivo reduction of GABA synthesis in the neonatal rat brain by antisense oligodeoxynucleotides to glutamic acid decarboxylase prevented gonadal steroid‐induced astrocyte differentiation in males and testosterone‐treated females. Conversely, activation of GABAA receptors with the agonist muscimol increased astrocyte differentiation in females in the absence of gonadal steroids. Given that GABA is made only in neurones and that its synthesis is increased by oestradiol, we conclude that it acts as a diffusible factor inducing the differentiation of neighbouring astrocytes.
Photoperiodic Control of Oestrous Cycles in Syrian Hamsters: Mediation by the Mediobasal Hypothalamus
Authors: Lewis D. , Freeman D. A. , Dark J. , Wynne‐Edwards K. E. , Zucker I. 
Published: March 2003

AbstractTo assess whether the mediobasal hypothalamus (MBH) is necessary for photoperiodic control of oestrous cycles and prolactin secretion, we tested intact female Syrian hamsters (controls) and those that had sustained unilateral or bilateral lesions of the MBH. All hamsters displayed 4‐day oestrous cycles postoperatively in the long‐day photoperiod (14 h light/day); control females and those with unilateral MBH damage ceased to undergo oestrous cycles approximately 8 weeks after transfer to a short‐day photocycle (10 h light/day), whereas 12 of 15 females with bilateral MBH lesions continued to generate 4‐day oestrous cycles throughout 22 weeks in short days. Serum prolactin concentrations were either undetectable or low in all hamsters 8 or 14 weeks after the transfer to short‐day lengths, but increased above long‐day baseline values by week 22. We conclude that melatonin‐binding sites in the MBH mediate suppression of oestrous cycles but not prolactin secretion by short‐day lengths; recovery of prolactin secretion in females during prolonged exposure to short‐day lengths reflects development of refractoriness to melatonin in a substrate distinct from the MBH. These findings suggest that separate neural pathways mediate photoperiodic control of gonadotropin and prolactin secretion in female hamsters.
Habituation and Cross‐Sensitization of Stress‐Induced Hypothalamic‐Pituitary‐Adrenal Activity: Effect of Lesions in the Paraventricular Nucleus of the Thalamus or Bed Nuclei of the Stria Terminalis
Authors: Fernandes G. A. , Perks P. , Cox N. K. M. , Lightman S. L. , Ingram C. D. , Shanks N. 
Published: March 2003

AbstractHabituation of the hypothalamic‐pituitary‐adrenal (HPA) response to chronic intermittent restraint stress (30 min/day for 15 days) and the cross‐sensitization to a heterotypic stress [i.p. lipopolysaccharide (LPS)] were investigated in intact male Sprague Dawley rats, and in rats bearing quinolinic acid lesions to the medial anterior bed nuclei of the stria terminalis (BST) or anterior region of the paraventricular nucleus of the thalamus (PVT). In intact animals, a single period of restraint increased plasma corticosterone levels at 30 min and led to an increase in corticotropin‐releasing hormone (CRH) mRNA levels in the PVN at 3 h. LPS had a smaller effect on corticosterone and more variable effect on CRH mRNA. Chronic intermittent restraint stress caused a decrease in body weight and increase in adrenal weights, with concomitant increase in basal corticosterone levels. These animals also displayed marked habituation of the corticosterone and CRH mRNA responses to the homotypic stress of restraint, but no loss of the corticosterone response to the heterotypic stress of LPS and a cross‐sensitization of the CRH mRNA response. This pattern of stress responses in control and chronically stressed animals was not significantly affected by lesions to the PVT or BST, two areas which have been implicated in the coping response to stress. Thus, these data provide evidence for independent adaptive mechanisms regulating HPA responses to psychological and immune stressors, but suggest that neither the medial anterior BST nor the anterior PVT participate in the mechanisms of habituation or cross‐sensitization.
Cocaine and Amphetamine‐Regulated Transcript mRNA Regulation in the Hypothalamus in Lean and Obese Rodents
Authors: Robson A. J. , Rousseau K. , Loudon A. S. I. , Ebling F. J. P. 
Published: March 2003

AbstractCocaine and amphetamine‐regulated transcript (CART) mRNA and immunoreactivity are expressed abundantly in the hypothalamus. Central administration of various fragments of this neuropeptide decreases food intake in rodents. To find out whether CART might play a role in the physiological regulation of energy balance, we used in situ hybridization to investigate whether CART mRNA abundance changed in two chronic obese/fat versus lean states and after acute dietary restriction. In the first study, mice were treated with goldthioglucose to destroy glucose‐responsive neurones in the ventromedial hypothalamus. This produced hyperphagia and obesity: 7 weeks after treatment, those receiving goldthioglucose weighed 70% more than the controls. CART mRNA abundance in the arcuate nucleus of goldthioglucose‐treated mice was decreased by 71% compared to levels in the control mice, but CART expression was unaffected in the dorsolateral hypothalamus. In the second study, male Siberian hamsters were exposed to short days to induce a physiological winter response in which body weight decreases as fat reserves are catabolized, and food intake correspondingly declines. After 8 weeks in short days, body weight had declined by 18% relative to controls maintained in long days in a summer fat state. CART mRNA levels did not differ significantly between the two groups in any hypothalamic areas. In the third study, male Siberian hamsters, either in long days or after 12 weeks exposure to short days to induce weight loss, were subject to a 48‐h period of fasting. Although photoperiod per se did not affect CART expression, fasting produced a significant decrease in CART mRNA in the arcuate nucleus of hamsters in both the long‐ and short‐day state. We conclude that CART‐producing cells are involved in energy homeostasis: the marked decrease in CART expression in the arcuate nucleus in goldthioglucose‐lesioned mice may contribute to the development of obesity, and the decrease following acute dietary restriction in hamsters may reflect a compensatory mechanism to reduce caloric expenditure, but our results do not indicate that CART is involved in long‐term seasonal regulation of body weight.
Gender Specific Effect of Neonatal Handling on Stress Reactivity of Adolescent Rats
Authors: Park M. K. , Hoang T. A. , Belluzzi J. D. , Leslie F. M. 
Published: March 2003

AbstractEarly neonatal handling of rat pups produces dampened hypothalamic‐pituitary‐adrenal axis reactivity to stress in adult male offspring. However, less is known about whether there is a similar effect for females. Although, most studies of neonatal handling have examined subsequent effects during adulthood, adolescence is an important developmental stage for stress responsivity. To address these issues, the effect of neonatal handling on the endocrine stress response and brain activity of male and female rats was determined in response to acute restraint stress during adolescence. Consistent with previous findings in adult males, neonatal handling reduced restraint stress‐induced hormone levels in adolescent males. However, in contrast, we found elevated plasma hormone concentrations in handled females. A gender‐specific handling effect on brain activity was also evident, with significantly increased stress‐induced activation of the posterior cingulate cortex of handled females, as measured by c‐fos mRNA expression. The striking gender difference in the effect of early neonatal handling provides evidence that this must be considered as an important variable in subsequent stress responsivity induced by early manipulations.
A study of incidents of violence towards staff by patients in an NHS Trust hospital
Authors: Vanderslott  
Published: March 2003

The aim of the study was to survey the degree and the extent of violence towards nursing staff by patients within a hospital environment. The information gathered will form a basis for future reference once the care packages are developed in the community. The study investigated the number of recorded incidents of aggression towards nursing staff by patients (n= 164) in an NHS Trust hospital for one year (October 1993–September 1994). The degree of recorded incidents of aggression was analysed using the Overt Aggression Scale. The results showed that the degree of aggression was mostly moderate to mild and occurred mostly in the Learning Disability Unit. Male staff were more involved in actual recorded incidents than expected in the given population. Health care assistants were more likely to be involved in aggressive incidents than any other grade of staff. There were significant findings in the time and location of the recorded aggressive incidents.The study, therefore, highlights the need to report and record incidents, the need for ongoing training, skilful management of resources and the recognition of environmental factors that can lead to patients' violence and aggression towards nursing staff.
Heart period and heart period variability during sleep on the MIR space station
Authors: GUNDEL ALEXANDER , DRESCHER JÜRGEN , SPATENKO YURI A. , POLYAKOV VALERY V. 
Published: March 2003

SummaryThe long‐term acclimation of cardiac rhythms to microgravity was studied in four astronauts aboard the Russian space station MIR during wakefulness and sleep. Sleep polygraphies were obtained between the third and the 30th day in space and, in addition, prior to mission on the ground. From each of the sleep polygraphies, beat‐to‐beat intervals of cardiac rhythms were determined. The response of heart period and heart period variability to the stimulus microgravity was tested during sleep across sleep stages and during waking. A lengthening of heart period by about 100 ms was found in space compared to measurements on the ground. The slowing of heart rate was more pronounced for non‐REM sleep than for REM sleep. A systematic change in heart period in relation to the duration of the stay in space could not be detected. An analysis of heart period variability in the high frequency (respiratory sinus arrhythmia) band supports the hypothesis that the decrease of heart rate under microgravity is produced by an increase in parasympathetic activity. Testing the response of cardiac rhythms to microgravity across distinct behavioural states seems to be a powerful tool to investigate the cardiovascular system.
Sleep paralysis in the elderly
Authors: Wing Yun‐Kwok , Chiu Helen , Leung Tony , Ng Jana 
Published: March 2003

SummaryIsolated sleep paralysis (SP) is a common sleep phenomenon that is highly colored by indigenous beliefs. In Hong Kong Chinese, the ‘ghost oppression phenomenon’ (GO) has been shown to be descriptively identical to SP. The prevailing concept is that the majority of cases with SP have their onset during adolescence, but the lack of any systematic study on an older population means that late‐onset cases can not be excluded. In a study investigating the prevalence of mental disorders in Chinese elderly aged above 70 y in Hong Kong, we employed the revised GO questionnaire to study the prevalence of SP in this group of elderly as well. One hundred and fifty‐eight subjects were finally analyzed for the study. Almost 18% (95% C.I. 11.77%, 23.68%) of the subjects reported experiences of GO. Their description of the features of GO showed striking similarity to those of SP. There was a clear bimodal distribution of onset of GO with peaks during adolescence and after age 60 y. At least one‐third of the cases were late onset. In concordance with the rapid eye movement (REM)/wakefulness dissociation hypothesis of SP, those elderly with GO+ experiences also had more frequent nocturnal sleep disturbances. A family history was reported in 10% of subjects.
The recuperative value of brief and ultra‐brief naps on alertness and cognitive performance
Authors: Tietzel Amber J. , Lack Leon C. 
Published: March 2003

SummaryThe aim of the study was to investigate the recuperative value of brief and ultra‐brief naps following nocturnal sleep restriction. Sixteen young adult healthy sleepers participated in a repeated measures design comprising four experimental conditions: no nap, 30‐s nap, 90‐s nap and 10‐min nap. On the evening preceding each laboratory session, participants limited their nocturnal sleep to between 24:00 and 05:00 h. Measures of subjective alertness, objective alertness, fatigue, vigour and cognitive performance were taken before the nap and at several intervals postnap. Consistent with our previous study (Tietzel and Lack 2001), the 10‐min nap resulted in significantly improved alertness and cognitive performance relative to a no‐nap control. There were no measurable improvements for the 30‐ and 90‐s nap conditions relative to no nap, which suggests that the mechanism underlying the benefits of brief naps does not appear to be the onset of stage 1 sleep. Further research is required to investigate whether the benefits of brief naps are because of the onset of stage 2 or delta wave sleep, or a specific duration of sleep between 90 s and 10 min.
Measures of cognitive function in persons with varying degrees of sleep‐disordered breathing: the Sleep Heart Health Study
Authors: Boland Lori L. , Shahar Eyal , Iber Conrad , Knopman David S. , Kuo Tracy F. , Nieto F. Javier ,   For the Sleep Heart Health Study (SHHS) Investigators
Published: March 2003

SummaryEpidemiologic literature suggests that persons with clinically diagnosed sleep apnoea frequently have impaired cognitive function, but whether milder degrees of sleep‐disordered breathing (SDB) are associated with cognitive dysfunction in the general population is largely unknown. Approximately 1700 subjects free of clinically diagnosed SDB underwent at‐home polysomnography (PSG) as part of the Sleep Heart Health Study (SHHS) and completed three cognitive function tests within 1–2 years of their PSG: the Delayed Word Recall Test (DWR), the WAIS‐R Digit Symbol Subtest (DSS), and the Word Fluency test (WF). A respiratory disturbance index (RDI) was calculated as the number of apnoeas and hypopnoeas per hour of sleep. After adjustment for age, education, occupation, field centre, diabetes, hypertension, body‐mass index, use of CNS medications, and alcohol drinking status, there was no consistent association between the RDI and any of the three cognitive function measures. There was no evidence of a dose–response relation between the RDI and cognitive function scores and the adjusted mean scores by quartiles of RDI never differed from one another by more than 5% for any of the tests. In this sample of free‐living individuals with mostly mild to moderate levels of SDB, the degree of SDB appeared to be unrelated to three measures of cognitive performance.
Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG
Authors: Huber R. , Treyer V. , Borbély A. A. , Schuderer J. , Gottselig J. M. , Landolt H.‐P. , Werth E. , Berthold T. , Kuster N. , Buck A. , Achermann P. 
Published: March 2003

SUMMARYUsage of mobile phones is rapidly increasing, but there is limited data on the possible effects of electromagnetic field (EMF) exposure on brain physiology. We investigated the effect of EMF vs. sham control exposure on waking regional cerebral blood flow (rCBF) and on waking and sleep electroencephalogram (EEG) in humans. In Experiment 1, positron emission tomography (PET) scans were taken after unilateral head exposure to 30‐min pulse‐modulated 900 MHz electromagnetic field (pm‐EMF). In Experiment 2, night‐time sleep was polysomnographically recorded after EMF exposure. Pulse‐modulated EMF exposure increased relative rCBF in the dorsolateral prefrontal cortex ipsilateral to exposure. Also, pm‐EMF exposure enhanced EEG power in the alpha frequency range prior to sleep onset and in the spindle frequency range during stage 2 sleep. Exposure to EMF without pulse modulation did not enhance power in the waking or sleep EEG. We previously observed EMF effects on the sleep EEG (A. A. Borbély, R. Huber, T. Graf, B. Fuchs, E. Gallmann and P. Achermann. Neurosci. Lett., 1999, 275: 207–210; R. Huber, T. Graf, K. A. Cote, L. Wittmann, E. Gallmann, D. Matter, J. Schuderer, N. Kuster, A. A. Borbély, and P. Achermann. Neuroreport, 2000, 11: 3321–3325), but the basis for these effects was unknown. The present results show for the first time that (1) pm‐EMF alters waking rCBF and (2) pulse modulation of EMF is necessary to induce waking and sleep EEG changes. Pulse‐modulated EMF exposure may provide a new, non‐invasive method for modifying brain function for experimental, diagnostic and therapeutic purposes.