RESUMO
PURPOSE: To clarify the subjective and objective impacts of a change in a 12-h shift schedule, involving a reduction in the number of crews, on workers at an electronic parts production company. METHODS: Forty-two workers participated in this study. Subjective indicators (e.g. questionnaires) and objective indicators [e.g., psychomotor vigilance task (PVT)], as well as an activity monitor-based sleep assessment, were measured during a > 1-year period that encompassed the shift schedule change. The study outcome was a comparison of work-related injury rates measured 1 year before and after the change in shift schedule. RESULTS: After the shift schedule change, questionnaire scores regarding work-related burdens and PVT performance parameters, including mean response time and number of lapses, increased significantly. However, we also observed divergences in the trends of the subjective and objective measures 1 year after the change. Despite these variations in both types of measures, we observed no significant differences in work-related injury rates measured before and after the shift schedule change. CONCLUSION: This study revealed that a reduction in the number of crews in a 12-h shift schedule has a negative impact on the subjective and objective indicator after the change in shift schedule; only indicators of alertness did not recover at 1 year after the change. Assessments of the workers' performances and the regular implementation of health and safety programs for more than 1 year are needed to maintain workers' health after the change in shift schedule.
Assuntos
Jornada de Trabalho em Turnos/psicologia , Tolerância ao Trabalho Programado/psicologia , Adulto , Atenção , Eletrônica , Fadiga , Humanos , Japão , Masculino , Indústria Manufatureira , Pessoa de Meia-Idade , Traumatismos Ocupacionais/epidemiologia , Desempenho Psicomotor , Sono , Inquéritos e Questionários , Desempenho Profissional , Adulto JovemRESUMO
It is important for workers to maintain a high quality of sleep to obtain their best performance at the workplace and in daily life. Insufficient sleep and/or dyssynchrony between internal clock and external light/dark cycles cause daytime sleepiness, and could result in a reduction of the working efficiency. Sleepiness may sometimes cause enormous economic and social losses. A recent report also indicated that lack of sleep might be a risk factor for chronic health problems such as metabolic syndrome. Therefore, it is important for an occupational physician to investigate and understand the sleep problems in workers, both to prevent serious accidents or loss at the workplace and to keep workers in good health.Additionally, the proper treatment of workers with some common sleep disorders such as an obstructive sleep apnea syndrome, or a circadian rhythm sleep disorder, needs to be understood. Shift work type is important for both worker's health and work management.
Assuntos
Transtornos do Sono-Vigília , Humanos , Saúde Ocupacional , Médicos do TrabalhoRESUMO
BACKGROUND: Previous studies have not estimated vaccine effectiveness (VE) against influenza in the working-age Japanese population. In this study, we determined VE in adult workers at a Japanese company. METHODS: We estimated VE based on self-reported data regarding influenza infections and vaccinations in employees of an auto parts manufacturing company during three influenza seasons from 2017 to 2020. VE was estimated as 100% × [1 - odds ratio (the ratio of the odds of being diagnosed with influenza among enrollees with and without influenza vaccination)]. Odds ratios were estimated using logistic regression. RESULTS: We included 11,347 worker records [3,592 (2017-18), 3,663 (2018-19), and 4,092 (2019-20)] from employees who had worked with the company throughout each influenza season. The adjusted VE was moderate and significant in the 2019-20 season (VE = 53%; 95% confidence interval [CI] = 30% to 69%) but low or negative and non-significant during the 2017-18 (VE = 28%; 95% CI = -5% to 50%) and 2018-19 (VE = -11%; 95% CI = - 42% to 14%) seasons. CONCLUSIONS: Influenza vaccines were moderately effective during the 2019-20 season but showed low or negative effectiveness during the 2017-18 and 2018-19 seasons. Self-reports from worker records can successfully help determine VE against influenza.
Assuntos
Vírus da Influenza A Subtipo H1N1 , Vacinas contra Influenza , Influenza Humana , Adulto , Estudos de Casos e Controles , Humanos , Vírus da Influenza A Subtipo H3N2 , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Japão/epidemiologia , Estações do Ano , Vacinação , Eficácia de VacinasRESUMO
STUDY OBJECTIVE: Caffeine, an adenosine A1 and A2a receptor antagonist, is a widely consumed stimulant and also used for the treatment of hypersomnia; however, the wake-promoting potency of caffeine is often not strong enough, and high doses may induce side effects. Caffeine is metabolized to paraxanthine, theobromine, and theophylline. Paraxanthine is a central nervous stimulant and exhibits higher potency at A1 and A2 receptors, but has lower toxicity and lesser anxiogenic effects than caffeine. DESIGN: We evaluated the wake-promoting efficacy of paraxanthine, caffeine, and a reference wake-promoting compound, modafinil, in a mice model of narcolepsy, a prototypical disease model of hypersomnia. Orexin/ataxin-3 transgenic (TG) and wild-type (WT) mice were subjected to oral administration (at ZT 2 and ZT14) of 3 doses of paraxanthine, caffeine, modafinil, or vehicle. RESULTS: Paraxanthine, caffeine, and modafinil significantly promoted wakefulness in both WT and narcoleptic TG mice and proportionally reduced NREM and REM sleep in both genotypes. The wake-promoting potency of 100 mg/kg p.o. of paraxanthine during the light period administration roughly corresponds to that of 200 mg/kg p.o. of modafinil. The wake-promoting potency of paraxanthine is greater and longer lasting than that of the equimolar concentration of caffeine, when the drugs were administered during the light period. The wake-promotion by paraxanthine, caffeine, and modafinil are associated with an increase in locomotor activity and body temperature. However, the higher doses of caffeine and modafinil, but not paraxanthine, induced hypothermia and reduced locomotor activity, thereby confirming the lower toxicity of paraxanthine. Behavioral evaluations of anxiety levels in WT mice revealed that paraxanthine induced less anxiety than caffeine did. CONCLUSIONS: Because it is also reported to provide neuroprotection, paraxanthine may be a better wake-promoting agent for hypersomnia associated with neurodegenerative diseases.
Assuntos
Temperatura Corporal/efeitos dos fármacos , Cafeína/farmacologia , Estimulantes do Sistema Nervoso Central/farmacologia , Atividade Motora/efeitos dos fármacos , Narcolepsia/tratamento farmacológico , Sono/efeitos dos fármacos , Teofilina/farmacologia , Animais , Ataxina-3 , Compostos Benzidrílicos/farmacologia , Modelos Animais de Doenças , Feminino , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modafinila , Narcolepsia/genética , Neuropeptídeos , Proteínas Nucleares , Orexinas , Fatores de TranscriçãoRESUMO
Down syndrome is characterized by a host of behavioral abnormalities including sleep disturbances. Sleep and EEG was studied at the age of 3 months in two mouse models of the condition, Ts65Dn and Ts1Cje, carrying one extra copy of partially overlapping segments of the mmu chromosome 16 (equivalent to the human chromosome 21). We found that the Ts65Dn mice showed increased waking amounts at the expense of non-REM sleep, increased theta power during sleep and a delayed sleep rebound after sleep deprivation. In contrast, Ts1Cje had limited sleep and EEG abnormalities, showing only a delayed sleep rebound after sleep deprivation and no difference in theta power. We previously found that mice over-expressing the human APPwt transgene, a gene triplicated in Ts65Dn but not Ts1Cje, also show increased wake and theta power during sleep. These results demonstrate abnormalities in sleep and EEG in Ts65Dn mice and underscore a possible correlation between App overexpression and hippocampal theta oscillations.
Assuntos
Modelos Animais de Doenças , Síndrome de Down/genética , Síndrome de Down/fisiopatologia , Eletroencefalografia , Sono/fisiologia , Análise de Variância , Animais , Eletromiografia , Análise de Fourier , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Deleção de Sequência , Sono/genética , Privação do Sono/fisiopatologia , TrissomiaRESUMO
STUDY OBJECTIVE: To determine whether hypocretin receptor gene (hcrtR1 and hcrtR2) expression is affected after long-term hypocretin ligand loss in humans and animal models of narcolepsy. DESIGN: Animal and human study. We measured hcrtR1 and hcrtR2 expression in the frontal cortex and pons using the RT-PCR method in murine models (8-week-old and 27-week-old orexin/ataxin-3 transgenic (TG) hypocretin cell ablated mice and wild-type mice from the same litter, 10 mice for each group), in canine models (8 genetically narcoleptic Dobermans with null mutations in the hcrtR2, 9 control Dobermans, 3 sporadic ligand-deficient narcoleptics, and 4 small breed controls), and in humans (5 narcolepsy-cataplexy patients with hypocretin deficiency (average age 77.0 years) and 5 control subjects (72.6 years). MEASUREMENT AND RESULTS: 27-week-old (but not 8-week-old) TG mice showed significant decreases in hcrtR1 expression, suggesting the influence of the long-term ligand loss on the receptor expression. Both sporadic narcoleptic dogs and human narcolepsy-cataplexy subjects showed a significant decrease in hcrtR1 expression, while declines in hcrtR2 expression were not significant in these cases. HcrtR2-mutated narcoleptic Dobermans (with normal ligand production) showed no alteration in hcrtR1 expression. CONCLUSIONS: Moderate declines in hcrtR expressions, possibly due to long-term postnatal loss of ligand production, were observed in hypocretin-ligand deficient narcoleptic subjects. These declines are not likely to be progressive and complete. The relative preservation of hcrtR2 expression also suggests that hypocretin based therapies are likely to be a viable therapeutic options in human narcolepsy-cataplexy.
Assuntos
Encéfalo/metabolismo , Modelos Animais de Doenças , Narcolepsia/genética , Receptores Acoplados a Proteínas G/genética , Receptores de Neuropeptídeos/genética , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Alelos , Animais , Encéfalo/patologia , Cães , Feminino , Lobo Frontal/metabolismo , Lobo Frontal/patologia , Expressão Gênica/genética , Genótipo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/deficiência , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Transgênicos , Pessoa de Meia-Idade , Narcolepsia/patologia , Neuropeptídeos/deficiência , Receptores de Orexina , Orexinas , Ponte/metabolismo , Ponte/patologia , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Especificidade da EspécieRESUMO
Orexins/hypocretins are neuropeptides that have various physiological effects, including the regulation of both the feeding behavior neuroendocrine functions and sleep-wakefulness cycle. Recent studies have suggested that the orexin system may also be involved in neuronal damage in the clinical setting and animal experiments. The aim of this study was to examine the role of the hypothalamic orexin-A/hypocretin-1 system in patients with intracerebral hemorrhage (ICH). The CSF orexin-A/hypocretin-1 levels were measured in 11 ICH patients. CSF orexin-A/hypocretin-1 levels were low in ICH patients during the 13 days following the ICH event. The mean CSF orexin-A/hypocretin-1 levels were 61.1+/-22.3 (S.D.) pg/ml (range 27.5-106.9 pg/ml). The decreasing in the CSF orexin-A/hypocretin-1 levels was not related to the severity of ICH. The CSF orexin-A/hypocretin-1 levels were lower in the thalamic hemorrhage patients than those in other patients (48.5+/-23.3 pg/ml vs. 65.2+/-21.2 pg/ml; p=0.03.) These data indicate that orexin-A/hypocretin-1 may therefore play an important role in the various physiological responses including sleep, feeding, and the overall metabolism in ICH patients.
Assuntos
Hemorragia Cerebral/líquido cefalorraquidiano , Peptídeos e Proteínas de Sinalização Intracelular/líquido cefalorraquidiano , Neuropeptídeos/líquido cefalorraquidiano , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , OrexinasRESUMO
Reduced cerebrospinal fluid (CSF) histamine levels were found in human hypersomnia. To evaluate the functional significance of changes in CSF histamine levels, we measured the levels in rats across 24h, after the administration of wake-promoting compounds modafinil, amphetamine, and thioperamide, and after sleep deprivation and food deprivation. Thioperamide significantly increased CSF histamine levels with little effects on locomotor activation. Both modafinil and amphetamine markedly increased the locomotor activity, but had no effects on histamine. The levels are high during active period and are markedly elevated by sleep deprivation, but not by food deprivation. Our study suggests that CSF histamine levels in rats reflect the central histamine neurotransmission and vigilance state changes, providing deeper insight into the human data.
Assuntos
Encéfalo/metabolismo , Distúrbios do Sono por Sonolência Excessiva/líquido cefalorraquidiano , Histamina/líquido cefalorraquidiano , Sono/fisiologia , Transmissão Sináptica/fisiologia , Vigília/fisiologia , Anfetamina/farmacologia , Animais , Compostos Benzidrílicos/farmacologia , Encéfalo/efeitos dos fármacos , Estimulantes do Sistema Nervoso Central/farmacologia , Ritmo Circadiano/efeitos dos fármacos , Ritmo Circadiano/fisiologia , Distúrbios do Sono por Sonolência Excessiva/fisiopatologia , Privação de Alimentos/fisiologia , Masculino , Modafinila , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Piperidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Sono/efeitos dos fármacos , Privação do Sono/metabolismo , Privação do Sono/fisiopatologia , Vigília/efeitos dos fármacosRESUMO
To visualize oxytocin in the hypothalamo-neurohypophysial system, we generated a transgenic rat that expresses the oxytocin-monomeric red fluorescent protein 1 (mRFP1) fusion gene. In the present study, we examined the age-related changes of oxytocin-mRFP1 fluorescent intensity in the posterior pituitary (PP), the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) of transgenic rats. The mRFP1 fluorescent intensities were significantly increased in the PP, the SON and the PVN of 12-, 18- and 24-month-old transgenic rats in comparison with 3-month-old transgenic rats. Immunohistochemical staining for urocortin, which belongs to the family of corticotropin-releasing factor family, revealed that the numbers of urocortin-like immunoreactive (LI) cells in the SON and the PVN were significantly increased in 12-, 18- and 24-month-old transgenic rats in comparison with 3-month-old transgenic rats. Almost all of urocortin-LI cells co-exist mRFP1-expressing cells in the SON and the PVN of aged transgenic rats. These results suggest that oxytocin content of the hypothalamo-neurohypophysial system may be modulated by age-related regulation. The physiological role of the co-existence of oxytocin and urocortin in the SON and PVN of aged rats remains unclear.
Assuntos
Envelhecimento/fisiologia , Ocitocina/metabolismo , Núcleo Hipotalâmico Paraventricular/fisiopatologia , Urocortinas/metabolismo , Animais , Arginina Vasopressina/metabolismo , Hormônio Liberador da Corticotropina/metabolismo , Hormônio Liberador da Corticotropina/farmacologia , Proteínas de Fluorescência Verde/efeitos dos fármacos , Proteínas de Fluorescência Verde/genética , Proteínas Luminescentes/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Ratos Transgênicos , Núcleo Supraóptico/fisiopatologia , Sinapsinas/efeitos dos fármacos , Sinapsinas/metabolismo , Proteína Vermelha FluorescenteRESUMO
Recent studies in human and animal models of narcolepsy have suggested that obesity in narcolepsy may be due to deficiency of hypocretin signaling, and is also under the influence of environmental factors and the genetic background. In the current study, using two hypocretin/orexin deficient narcoleptic mouse models (i.e. preproorexin knockout (KO) and orexin/ataxin-3 transgenic (TG) mice) with cross-sectional assessments, we have further analyzed factors affecting obesity. We found that both KO and TG narcoleptic mice with mixed genetic backgrounds (N4-5, 93.75-96.88% genetic composition of C57BL/6) tended to be heavier than wild type (WT) mice of 100-200 days old. The body weight of heterozygous mice was intermediate between those of KO and WT mice. Obesity was more prominent in females in both KO and TG narcoleptic mice and was associated with higher serum leptin levels, suggesting a partial leptin resistance. Obesity is less prominent in the congenic TG narcoleptic mice, but is still evident in females. Our results confirmed that hypocretin/orexin ligand deficiency is one of the critical factors for the obese tendency in narcolepsy. However, multiple factors are also likely to affect this phenotype, and a sex difference specific alteration of leptin-hypocretin signaling may be involved.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/genética , Leptina/sangue , Neuropeptídeos/genética , Obesidade/etiologia , Aumento de Peso , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Modelos Animais , Narcolepsia/metabolismo , Obesidade/metabolismo , Orexinas , Fatores Sexuais , Transdução de Sinais/fisiologiaRESUMO
We previously reported that the intrathoracic pressure (ITP) decreases and the transmural pressure of the aortic wall (TMP) increases during 4.5 s of microgravity (muG) induced by free drop. To examine the ITP response to a longer period of muG in the absence of the respiratory rate (RR) decrease, i.e., bradypnea, which occurs at the onset of muG, we measured the aortic blood pressure at the diaphragma level (AP) and ITP. We then calculated the TMP at the aortic arch level during 20 s of muG induced by parabolic flight in anesthetized rats (n = 7) with either spontaneous ventilation (SPN-V) or controlled ventilation (CONT-V). In the SPN-V group, the bradypnea was observed in all rats after the onset of the muG (RR change -13.9 +/- 2.9/min). The ITP during muG (-9.3 +/- 0.9 mmHg) was significantly lower than that during 1 G (-7.7 +/- 0.9 mmHg), and the TMP was significantly increased during muG (112 +/- 6 mmHg) compared to 1 G (103 +/- 5 mmHg). Similar changes in ITP and TMP were observed in the CONT-V group: During muG and 1G, respectively, the ITP was -8.4 +/- 0.6 mmHg and -5.9 +/- 0.7 mmHg, and the TMP was 112 +/- 6 mmHg and 101 +/- 6 mmHg, whereas no change in RR was observed because of the controlled ventilation. These results show that the ITP decreases and the TMP increases during muG, and they are not affected by a disturbance of respiratory rhythm.
Assuntos
Mecânica Respiratória/fisiologia , Tórax/fisiologia , Ausência de Peso , Anestesia , Animais , Aorta Torácica/fisiologia , Pressão Sanguínea/fisiologia , Líquidos Corporais/fisiologia , Masculino , Pressão , Ratos , Ratos Sprague-DawleyRESUMO
STUDY OBJECTIVES: Using two different canine models of narcolepsy, we evaluated the therapeutic effects of hypocretin-1 on cataplexy and sleep. MEASUREMENTS AND RESULTS: Intracerebroventricular administration of hypocretin-1 (10 and 30 nmol per dog) but not intravenous administration (up to 6 microg/kg) induced significant wakefulness in control dogs. However, hypocretin-1 had no effect on cataplexy or wakefulness in hypocretin receptor-2 gene (Hcrtr2) mutated narcoleptic Dobermans. Only very high intravenously doses of hypocretin-1 (96-384 microg/kg) penetrated the brain, to produce a short-lasting anticataplectic effect in a hypocretin-ligand-deficient animal. CONCLUSIONS: Hypocretin-1 administration, by central and systemic routes, does not improve narcoleptic symptoms in Hcrtr2 mutated Dobermans. Systemic hypocretin-1 hardly crosses the blood-brain barrier to produce therapeutic effects. The development of more centrally penetrable and longer lasting hypocretin analogs will be needed to further explore this therapeutic pathway in humans.
Assuntos
Proteínas de Transporte , Peptídeos e Proteínas de Sinalização Intracelular , Narcolepsia , Neuropeptídeos , Mutação Puntual/genética , Receptores de Neuropeptídeos/genética , Receptores de Neuropeptídeos/metabolismo , Animais , Encéfalo/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/uso terapêutico , Cataplexia/tratamento farmacológico , Cataplexia/genética , Cataplexia/metabolismo , Cães , Eletroencefalografia , Eletromiografia , Eletroculografia , Injeções Intravenosas , Narcolepsia/tratamento farmacológico , Narcolepsia/genética , Narcolepsia/metabolismo , Neuropeptídeos/deficiência , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Neuropeptídeos/uso terapêutico , Receptores de Orexina , Orexinas , Receptores Acoplados a Proteínas GRESUMO
Different potencies for hypocretin-1 and -2 in sleep-wake regulation and feeding after intracerebroventricular (ICV) administration have been reported. These differences were often explained by the selectivity of the two hypocretins for hypocretin receptor-1 and -2, but little attention has been paid to kinetics of hypocretin peptides. We investigated the kinetics of the ICV hypocretin-1 and -2 in rats. ICV hypocretin-1 (10 nmol) increased hypocretin-1 peptide level in the CSF by 800-fold from baseline with the elevation lasting over 4 h. In contrast, after ICV hypocretin-2 (10 nmol), no significant rise in the CSF was found. CSF hypocretin levels were significantly correlated with the biological activities of CSF hypocretin-1 and -2 using the Ca(2+) mobilization assay. Difference in the kinetics of hypocretins should be considered for interpreting ICV effects of hypocretins.
Assuntos
Proteínas de Transporte/líquido cefalorraquidiano , Peptídeos e Proteínas de Sinalização Intracelular , Neuropeptídeos/líquido cefalorraquidiano , Neurotransmissores/líquido cefalorraquidiano , Animais , Proteínas de Transporte/administração & dosagem , Proteínas de Transporte/farmacocinética , Linhagem Celular , Humanos , Injeções Intraventriculares , Masculino , Neuropeptídeos/administração & dosagem , Neuropeptídeos/farmacocinética , Orexinas , Radioimunoensaio , Ratos , Ratos WistarRESUMO
To examine the usefulness of Mn(2+) contrasted magnetic resonance imaging (MRI) in hypothalamic imaging, images obtained using T(1)-weighted MRI were compared with Fos expression, which is known to increase after activation of voltage-dependent Ca(2+) channels. Intravenous infusion of MnCl(2) elicited a rapid increase in the T(1)-weighted MRI signal intensity in the vessels and ventricles, but not in the brain parenchyma, suggesting that Mn(2+) did not diffuse freely across the blood-brain barrier. When the blood-brain barrier was broken by right intracarotid arterial injection of 25% D-mannitol, an increased signal intensity was seen in the right brain. Intracarotid arterial injection of hypertonic NaCl elicited rapid and striking increases in signal intensity in the paraventricular hypothalamic nucleus, supraoptic nucleus, and preoptic area, which are thought to be involved in central osmotic regulation. These observations were consistent with the Fos expression results. These results indicate that Mn(2+) contrasted MRI is a useful technique for investigating the autonomic center in the hypothalamus.
Assuntos
Meios de Contraste , Hipotálamo/efeitos dos fármacos , Hipotálamo/fisiologia , Imageamento por Ressonância Magnética , Manganês , Animais , Barreira Hematoencefálica , Artérias Carótidas , Imuno-Histoquímica , Injeções Intra-Arteriais , Injeções Intravenosas , Íons , Cloreto de Magnésio/farmacologia , Masculino , Manganês/farmacocinética , Manitol/farmacologia , Núcleo Hipotalâmico Paraventricular/fisiologia , Área Pré-Óptica/fisiologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Wistar , Solução Salina Hipertônica/farmacologia , Núcleo Supraóptico/fisiologiaRESUMO
In order to define the sequence of forebrain activation involved in osmoregulation, central activation in response to intracerebroventricular injection of NaCl solution (10 microl of 0.15, 0.5, or 1.5 M) was detected using manganese-contrasted magnetic resonance imaging (MRI) in anesthetized rats. Changes in renal sympathetic nerve activity (RNA) were also measured, and the time courses of forebrain activation and RNA changes compared. NaCl injection resulted in rapid activation of the subfornical organ (SFO), organum vasculosum lamina terminalis (OVLT), and periventricular regions and the lateral hypothalamic area (LHA), then of the paraventricular hypothalamic nucleus (PVN) and supraoptic nucleus (SON). The delay in activation in the PVN and SON showed a wide variation from 0 to 5.78 min, and the average delay in the PVN (2.88+/-0.34 min) and SON (2.90+/-0.39 min) was significantly greater than that in the SFO (0.40+/-0.10 min) and OVLT (0.74+/-0.13 min). NaCl (1.5 M) injection elicited a rapid, large increase in RNA, which consisted of two components, an early rapid increase at 99 s after injection (160+/-27%) and a slower increase at 9 min after injection (209+/-34%). These results suggest that the PVN and SON are activated not only by the afferent input from the SFO and OVLT but also by diffusion of the hypertonic stimulus to these regions and probably by their intrinsic osmosensitivity. The PVN might be responsible for the second slower component of the RNA response, but cannot be responsible for the first component.
Assuntos
Imageamento por Ressonância Magnética/métodos , Prosencéfalo/efeitos dos fármacos , Prosencéfalo/metabolismo , Solução Salina Hipertônica/administração & dosagem , Animais , Injeções Intraventriculares , Masculino , Manganês/metabolismo , Ratos , Ratos Wistar , Fatores de TempoRESUMO
To evaluate changes in the cerebral circulation during acute microgravity (microG), we measured intracranial pressure (ICP), aortic pressure at the diaphragm level, and cerebral flow velocity (CFV) in anesthetized rats (n = 5) during 4.5 s of microG induced by free drop, then calculated arterial pressure at the eye level (AP(eye)) and cerebral perfusion pressure (CPP = AP(eye)-ICP), and estimated CPP-CFV relationship. The rats were placed in the flat and the 30 degrees head-up positions. In the head-up position, ICP, AP(eye), and CPP were significantly increased by 2.2 +/- 0.4, 12.3 +/- 2.0, and 10.1 +/- 1.7 mmHg respectively during microG, whereas the CFV did not change significantly. In the flat position, none of these variables were significantly affected by microG. The slope of the CPP-CFV relationship was decreased only in the head-up position, suggesting that the cerebrovascular resistance was increased by microG. These findings indicate that the change in gravitational (hydrostatic) pressure is a key factor in understanding the changes in cerebral circulation during acute microG.
Assuntos
Circulação Cerebrovascular , Ausência de Peso/efeitos adversos , Animais , Aorta/fisiologia , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea , Diafragma , Pressão Intracraniana , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
To test the hypothesis that the aortic wall is stretched without increasing aortic pressure (AP) during microgravity (microG), the AP, intrathoracic pressure (ITP), and aortic diameter (AD) were measured in anesthetized Sprague-Dawley rats during 4.5 s of microG produced by freefall. A smooth and immediate reduction in gravity (G) occurred during freefall, microG being achieved 100 ms after the start of the drop. Acute microG elicited an immediate increase in AD, which was not accompanied by an increase in AP. However, the ITP decreased during microG resulted in an increase in the calculated transmural pressure (TP = AP-ITP) of the aortic wall. A simple linear regression analysis showed that the slopes of the plot of AP vs. AD differed at 1 G and microG, whereas those for the plot of TP vs. AD did not. Thus, the increase in AD during microG was accounted for by the increase in TP. These results suggest that a decrease in ITP, resulting in an increase in TP of the aorta, is a key issue in understanding cardiovascular responses to microG.
Assuntos
Aorta/anatomia & histologia , Coração/fisiologia , Tórax/fisiologia , Simulação de Ausência de Peso , Anestesia , Animais , Aorta/fisiologia , Pressão Sanguínea/fisiologia , Processamento Eletrônico de Dados , Frequência Cardíaca/fisiologia , Modelos Lineares , Masculino , Pressão , Ratos , Ratos Sprague-Dawley , Telemetria/métodosRESUMO
As one of the causes of the space adaptation syndrome, an increased intracranial pressure due to the cephalad fluid shift is suggested. In the present study, we measured intracranial pressure (ICP), aortic pressure and cerebral flow velocity (CFV) in anesthetized rats (n=5) during 4.5 sec of microgravity induced by free drop. The rats were set at horizontal prone (Flat) and 30-degree head-up whole body tilting (HU) positions to examine the effect of gravitational pressure gradient. Then, arterial pressure at the eye level (APeye), cerebral perfusion pressure (CPP; CPP=APeye-ICP), and CPP-CFV relationship was calculated. In HU position, ICP, APeye, and CPP increased by 2.2 +/- 0.4, 12.3 +/- 2.0, and 10.1 +/- 1.7 mmHg respectively. However, CFV did not change significantly. In Flat position, none of these variables did not change significantly. In HU position the slope of CPP-CFV relationship decreased, suggesting the increased cerebral flow resistance. However, it did not change in Flat position. These results can be understood by the disappearance of gravitational pressure gradient by microgravity and the cerebral autoregulation.
Assuntos
Pressão Sanguínea/fisiologia , Circulação Cerebrovascular/fisiologia , Pressão Intracraniana/fisiologia , Postura/fisiologia , Ausência de Peso , Animais , Aorta/fisiologia , Velocidade do Fluxo Sanguíneo , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
OBJECTIVES: The aim of this study was to investigate whether the combination of extension of the encoding time and repetition of a test trial would improve the visual recognition memory performance in older adults. METHODS: We evaluated visual memory performance in young and older adults on a Yes-No recognition memory test under four different conditions. The conditions consisted of combinations of encoding times of two and four seconds (E2 and E4) and first and second retrieval practice test trials (T1 and T2): E2T1, E2T2, E4T1 and E4T2. Performance was evaluated by measuring hit rates, false alarm rates, discrimination ability and response bias. RESULTS: Older adults showed better improvement of hit rate and discrimination ability under the E4T2 conditions whereas young adults showed better memory performance under the E2T2 conditions. CONCLUSIONS: A longer encoding time and repetition of the test was effective in improving the visual memory performance in terms of the hit rates and discrimination ability of older adults. The results suggest that this strategy should be useful in providing a suitable work environment for older workers.