Neuronal Activity in the Subthalamic Cerebrovasodilator Area under Partial-Gravity Conditions in Rats

The reduced-gravity environment in space is known to cause an upward shift in body fluids and thus require cardiovascular adaptations in astronauts. In this study, we recorded in rats the neuronal activity in the subthalamic cerebrovasodilator area (SVA), a key area that controls cerebral blood flow (CBF), in response to partial gravity. -Partial gravity{norm of matrix} is the term that defines the reduced-gravity levels between 1 g (the unit gravity acceleration on Earth) and 0 g (complete weightlessness in space). Neuronal activity was recorded telemetrically through chronically implanted microelectrodes in freely moving rats. Graded levels of partial gravity from 0.4 g to 0.01 g were generated by customized parabolic-flight maneuvers. Electrophysiological signals in each partial-gravity phase were compared to those of the preceding 1 g level-flight. As a result, SVA neuronal activity was significantly inhibited by the partial-gravity levels of 0.15 g and lower, but not by 0.2 g and higher. Gravity levels between 0.2-0.15 g could represent a critical threshold for the inhibition of neurons in the rat SVA. The lunar gravity (0.16 g) might thus trigger neurogenic mechanisms of CBF control. This is the first study to examine brain electrophysiology with partial gravity as an experimental parameter

Hypergravity Conditioning on Ileal Movements in Rats

Introduction: Stress is a common trigger for various physiological disturbances, including feeding disorders. One of the possible mechanisms for feeding disorders may be linked to changes in intestinal movement caused by stress. Therefore, here we investigated in vitro stress-induced changes in ileal movement. Methods: Rats (female Wistar, SPF) were divided into Control (1 G) and hypergravity (hyperG) groups. HyperG stress was applied daily for 10 min by a centrifugal apparatus for 1 to 30 d. Under barbiturate anesthesia, a 1-cm long section of the ileum was isolated and fixed in a Magnus-type chamber filled with tyrode solution. Intestinal movement was evoked by applying acetylcholine (Ach, 10? 7?10? 5 g ・ ml? 1). Antagonistic effects of adrenalin (Adr, 10? 4 g ・ ml? 1) on the Ach-evoked movements were also observed. Results: Clear ileum movements were observed after Ach application. The movement pattern was phasic (early) and tonic (late). Peak amplitude of the phasic wave was dose-dependent on the Ach concentration. No significant differences in the averaged peak amplitude between control and hyperG groups were observed. The peak amplitude was decreased by Adr application in both the control and hyperG groups; however, the degree of the decrement was higher in hyperG than in control at 1 d after stress loading. Discussion: The present study indicates that gravity stress modified ileal movement. Although basic ileum movements evoked by Ach were not influenced by stress, they were modified by Adr at a quite early stage after stress loading, suggesting an increase in the sensitivity of Adr receptors, but not of Ach receptors in the ileum

Age Differences in Naloxone Reversibility of Electroacupuncture on the Jaw Opening Reflex in Rats

Background: Electroacupuncture is one of the most popular physical treatments for clinical pain, but the potential influence of a patient’s age on the effectiveness of electroacupuncture treatment has not been clearly established. Objectives: The present study aimed to detect a potential difference in electroacupuncture- induced analgesia between juvenile and adult rats.Methods: In this study, we investigated the effects of electroacupuncture treatment on the nociceptive jaw-opening reflex evoked by tooth-pulp stimulation in juvenile and adult rats.Results: Our results showed there were age differences in electroacupuncture-induced analgesic effects in rats, especially with naloxone antagonization. The ratio of naloxonereversibility against electroacupuncture analgesia was greater in adult rats than in juvenile rats.Conclusion: These results suggest that electroacupuncture analgesia is produced mainly by the non-opioid system in juvenile rats and by the opioid system in adult rats

ラット前帯状回侵害受容性ニューロンのストレスによる応答変化

In the limbic system, the anterior cingulate cortex (ACCX) is one of the key areas involved in the close association between pain and emotion. However, neuronal changes in ACCX nociceptive responses after stress conditioning have not yet been quantitatively investigated. We investigated the modulation of nociceptive responses in the ACCX neurons following restraint stress in rats. The present study demonstrated that stress-conditioning enhanced excitatory nociceptive responses in the ACCX following tail stimuli in the mid-term (7 days). Short-term (3 days) and long-term (21 days) of stress conditioning did not affect these responses significantly. Nociceptive responses evoked by other sites of the body (nose, back and four paws) stimulation were not changed by stress-conditioning, indicating that neural information from the tail is important for emotional system modulation. It is suggested that the emotional/affective part of the pain sensation is strongly modified by stress through neuroplasticity in the ACCX.長崎大学学位論文 学位記番号:博(医歯薬)甲第640号 学位授与年月日:平成25年12月4日Author: Hiromi Yamashita, Jorge L. Zeredo, Kei Kaida, Mari Kimoto, Izumi Asahina, Kazuo TodaCitation: Journal of Integrative Neuroscience, 12(2), pp.235-246; 2013Nagasaki University (長崎大学)課程博

Métodos para indução de estresse experimental em adultos jovens

Introdução: O estresse produz mudanças emocionais e fisiológicas que podem ser avaliadas de diferentes formas e estressadas via laboratório.  Uma medida importante e popular para a avaliação psicofisiológica da resposta ao estresse agudo é a atividade eletrodérmica da pele. Objetivo: Este estudo visa revisar sistematicamente estudos que exploraram as alterações na atividade eletrodérmica da pele em situação de estresse agudo induzido na população de 18 a 30 anos. Métodos: A busca de literatura foi realizada nas seguintes bases de periódicos científicos: Scielo, Pubmed e BVS. Resultados: Inicialmente foram encontrados 326 artigos, dentre os quais, após as etapas da revisão, 6 foram incluídos nos resultados. Conclusão: Este artigo evidenciou grande importância de métodos estressantes que podem ser avaliativos e mensuráveis. Com o auxílio de um marcador fisiológico que é a condutância da Pele

Disinhibitory involvement of the anterior cingulate cortex in the descending antinociceptive effect induced by electroacupuncture simulation in rats

The present study was conducted to clarify the role of the anterior cingulate cortex(ACCX) in acupuncture analgesia. Experiments were performed on 35 female Wistar albino rats weighing about 300 g. Single unit recordings were made from ACCXneurons with a tungsten microelectrode. Descending ACCX neurons were identified byantidromic activation from electrical shocks applied to the ventral part of the ipsilateral PAG through a concentric needle electrode. Cathodal electroacupuncture stimulation of Ho-Ku (0.1 ms in duration, 45 Hz) for 15 min was done by inserting stainless steel needles bilaterally. An anodal silver-plate electrode (30 mm x 30 mm) was placed on the center of the abdomen. Naloxone (1.0 mg/kg, i.v.) was used to test whether changes of ACCX activities were induced by the endogenous opioid system or not. Data were collected from a total of 73 ACCX neurons. Forty-seven neurons had descending projection to the PAG, and 26 had no projections to the PAG. A majority of descending ACCX neurons were inhibited by electroacupuncture stimulation. By contrast, non-projection ACCX neurons were mainly unaffected by electroacupuncture. Naloxone did not reverse acupuncture effects on the changes of ACCX neuronal activities. Acupuncture stimulation had predominantly inhibitory effects on the activities of descending ACCX neurons. Since the functional connection between ACCX and 3/21 PAG is inhibitory, electroacupuncture caused disinhibition of PAG neurons, whose activity is closely related to descending antinociception to the spinal cord. Thisdisinhibitory effect elicited by acupuncture stimulation is thought to play a significant role in acupuncture analgesia

Associação entre a dor cervical e no ombro em relação ao estresse emocional em universitários dos cursos de saúde – FCE / Association between neck and shoulder pain in relation to emotional stress in university students of health courses - FCE

O estresse é um estado causado por estímulos que provocam excitação física e emocional, que ao perturbarem o equilíbrio do organismo podem gerar dores musculares na região cervical e dos ombros. A rotina acadêmica em geral é muito estressante principalmente por conta das atividades exigidas no decorrer do período letivo como provas, trabalhos, projetos, seminários, etc. Este estudo investigou as dores relacionadas ao estresse emocional e muscular na região cervical e dos ombros em estudantes dos cursos de saúde da Universidade de Brasília da Faculdade de Ceilândia. Trata-se de um estudo observacional e longitudinal, onde participaram 75 estudantes com idades entre 18 e 25 anos, no qual foram acompanhados e avaliados no início e no final do período letivo, onde supostamente os níveis de estresse estarão mais elevados. Foram utilizados os questionários semi-estruturados, o Inventário de Sintomas de Stress para Adultos de Lipp – ISSL para avaliação dos sintomas de estresse e o Diagrama de Dor Corlett e Manenica para avaliar as dores na região cervical e dos ombros. A análise estatística foi realizada através do Wilcoxon Test para comparar as variáveis de estresse na fase inicial e final do semestre. Os resultados mostraram diferenças significativas entre a amostra no início e no final do período letivo (p < 0.05) e que os estudantes em sua maioria apresentam sintomas de estresse prolongado com risco de desenvolvimento a graves problemas em sua saúde, além de frequentes dores na região cervical. O estresse excessivo causado pela intensa rotina acadêmica pode ser um fator decisivo no surgimento de dores na região cervical, comprometendo as condições de saúde física e mental dos futuros profissionais da área da saúde. Há a necessidade de propor novas alternativas no sentido de prevenção e diminuir o nível de estresse dos estudantes na sua rotina acadêmica, melhorando a sua qualidade de vida e modificando o ambiente da universidade mais saudável

Response Properties of Nucleus Reticularis Lateralis Neurons After Electroacupuncture Stimulation in Rats

A descending inhibitory mechanism from the periaqueductal gray (PAG) to the spinal cord through the nucleus raphe magnus (NRM) is strongly involved in endogenous analgesic system produced by acupuncture stimulation. In addition to the PAG to NRM system which descends in the medial pathway of the brain stem, the nucleus reticularis lateralis (NRL) situated in the lateral part of the brain stem is reported to play an important role in modulating centrifugal antinociceptive action. In the present study, to clarify the role of NRL in acupuncture analgesia, we investigated the response properties of NRL neurons to acupuncture stimulation. The majority of NRM-projecting NRL neurons were inhibited by electroacupuncture stimulation. This effect was antagonized by ionophoretic application of naloxone, indicating that endogenous opioids act directly onto these NRL neurons. By contrast, about half of spinal projecting NRL neurons were excited by electroacupuncture stimulation, suggesting that part of the NRL neurons may modulate pain transmission directly at the spinal level

Age Differences in Naloxone Reversibility of Electroacupuncture on the Jaw Opening Reflex in Rats

Background : Electroacupuncture is one of the most popular physical treatments for clinical pain, but the potential influence of a patient’s age on the effectiveness of electroacupuncture treatment has not been clearly established. Objectives: The present study aimed to detect a potential difference in electroacupuncture- induced analgesia between juvenile and adult rats. Methods : In this study, we investigated the effects of electroacupuncture treatment on the nociceptive jaw-opening reflex evoked by tooth-pulp stimulation in juvenile and adult rats. Results : Our results showed there were age differences in electroacupuncture-induced analgesic effects in rats, especially with naloxone antagonization. The ratio of naloxonereversibility against electroacupuncture analgesia was greater in adult rats than in juvenile rats. Conclusion : These results suggest that electroacupuncture analgesia is produced mainly by the non-opioid system in juvenile rats and by the opioid system in adult rats