Raphe obscurus neurons participate in thermoregulation in rats.

In mammalian, several evidences suggest that central serotonin participates in thermoregulation. Nucleus raphe obscurus (NRO), a serotonergic nucleus, has been recognized to be the source of generation of various hemodynamic patterns in different behavioral conditions, but its involvement in thermoregulation is unclear. In the present study, extracellular action potentials of NRO neurons were recorded in anesthetized rats, which were submitted to cold and warm stimuli in the tail. The firing rate of the neurons was compared before and after each stimulation. It was found that 59% of the neurons submitted to a cold stimulus trial had a significant increase in their firing frequency, while 48% of the neurons submitted to warm stimulation trial were inhibited. The opposite responses in neuronal activity of NRO units to cooling or heating suggest that these cells are involved in producing the homoeothermic vascular adaptations secondary to changes in cutaneous temperature in the rat tail.

Raphe obscurus neurons participate in thermoregulation in rats / Neurônios do núcleo obscuro da rafe participam da termorregulação em ratos

In mammalian, several evidences suggest that central serotonin participates in thermoregulation. Nucleus raphe obscurus (NRO), a serotonergic nucleus, has been recognized to be the source of generation of various hemodynamic patterns in different behavioral conditions, but its involvement in thermoregulation is unclear. In the present study, extracellular action potentials of NRO neurons were recorded in anesthetized rats, which were submitted to cold and warm stimuli in the tail. The firing rate of the neurons was compared before and after each stimulation. It was found that 59% of the neurons submitted to a cold stimulus trial had a significant increase in their firing frequency, while 48% of the neurons submitted to warm stimulation trial were inhibited. The opposite responses in neuronal activity of NRO units to cooling or heating suggest that these cells are involved in producing the homoeothermic vascular adaptations secondary to changes in cutaneous temperature in the rat tail.

A termorregulação em mamíferos envolve a participação da serotonina. O núcleo obscuro da rafe (NRO), que é serotoninérgico, participa do controle autonômico, mas seu envolvimento na termorregulação é incerto. Neste estudo, registramos potenciais de ação extracelulares de neurônios do NRO em ratos anestesiados nos quais a cauda foi submetida a estímulos de calor ou frio. A frequência de disparo dos neurônios foi comparada antes e depois dos estímulos. O grupo controle não apresentou modificação da frequência de disparo, enquanto que 59% dos neurônios registrados em animais submetidos a estímulo de frio tiveram sua frequência aumentada. Por outro lado, 48% dos animais submetidos a estímulo de calor tiveram sua frequência de disparo diminuída. As respostas opostas da frequência de disparo em neurônios de animais submetidos à estimulação com frio e calor sugere que estes neurônios estejam envolvidos na geração de respostas hemodinâmicas, que são coerentes com a termorregulação nesta espécie.

The role of magnesium sulfate in prevention of seizures induced by pentylenetetrazole in rats.

Magnesium sulfate (MgSO4) has been used to prevent seizures in eclampsia. This study examined the central effects of MgSO4 on different types of pentylenetetrazole (PTZ)-induced seizures. Male Wistar rats were submitted to intracerebroventricular (ICV) administration of MgSO4 at different doses followed by intraperitoneal administration of PTZ. The latency to the onset of the first seizure induced by PTZ was significantly increased by ICV administration of MgSO4 at a dose of 100 µg compared to the control treatment. In addition, the total period during which animals presented with seizures was significantly reduced at this dose of MgSO4. Furthermore, the latency to the onset of the first partial complex seizure was significantly increased by the lowest dose of MgSO4. However, a high dose of MgSO4 had no effect or even potentiated the effect of PTZ. These results suggest that, depending on the dose, MgSO4 may be important in prevention of epileptic seizures.

Alongamento muscular na dor lombar crônica inespecífica: uma estratégia do método GDS / Stretching in nonspecific chronic low back pain: a strategy of the GDS method

O objetivo deste estudo foi verificar a eficácia do alongamento muscular, usando uma sequência proposta pelo Método Godelieve Denys-Struyf (GDS) na redução da dor, na incapacidade funcional, no aumento da flexibilidade global e na capacidade de contração do músculo transverso do abdome (TrA), em indivíduos com dor lombar crônica inespecífica. Participaram 55 pacientes, de 18 a 60 anos, divididos em dois grupos: Grupo Alongamento (n=30) submetido a exercícios de alongamento, duas vezes por semana, e Grupo Controle (n=25) que não realizou tratamento. A dor foi avaliada pela escala visual analógica; a incapacidade funcional, pelo Índice de Oswestry; a flexibilidade global, pelo terceiro dedo ao solo; e a capacidade de contração do TrA, pela unidade de biofeedback pressórico. Foram realizadas três avaliações, inicial, após 8 e 16 semanas da inicial. Foi considerado nível de significância de α<0,05. Os resultados mostram que o Grupo Alongamento apresentou diminuição na dor, incapacidade funcional e aumentou a flexibilidade global (p<0,001) após 8 e 16 semanas (p<0,05), porém não melhorou a capacidade de contração do TrA (p=0,13). A sequência de alongamentos usada no método GDS mostra-se eficaz na redução da dor, incapacidade funcional e melhora da flexibilidade global em pacientes com dor lombar crônica inespecífica.

The purpose of this study was to assess the effectiveness of stretching exercises of the Muscle and Joint Chains Godelieve Denys-Struyf (GDS) method in pain reduction, functional disability, increase global flexibility, and ability of the transversus abdominis muscle (TrA) contraction in individuals with nonspecific chronic low back pain. Fifty-five patients, from 18 to 60 years-old, participated in this study divided into two groups: the Stretching Group (n=30) underwent stretching exercises twice a week; the Control Group (n=25) was subjected only to evaluation. Pain was assessed by a visual analogue scale, functional disability by the Oswestry Questionnaire, global flexibility by third finger to the ground test and the ability of TrA contraction by a pressure biofeedback unit. Three evaluations were performed, starting after 8 and 16 weeks from the beginning. Significance level was α<0.05. Results show that the Stretching Group presented a decrease in pain, functional disability, and increased global flexibility (p<0.001) after 8 and 16 weeks (p<0.05). No improvement in the ability of TrA muscle contraction was demonstrated (p=0.13). The sequence of stretching exercises used in the GDS method is effective in reducing pain, functional disability, and improving global flexibility in patients with nonspecific chronic low back pain.

Acute cardiorespiratory effects of intracisternal injections of mercuric chloride.

The present studies were conducted to changes arising from mercury poisoning in the central nervous system (CNS), with a focus on determining the receptors and neurotransmitters involved. Currently, little is known regarding the neurological basis of the cardiopulmonary effects of mercury poisoning. We evaluated changes in systolic arterial pressure (SAP), diastolic arterial pressure (DAP), respiratory rate (RR) and heart rate (HR) following a 5 µl intracisternal (i.c) injection of mercuric chloride (HgCl(2)) and the participation of the autonomic nervous system in these responses. 58 animals were utilized and distributed randomly into 10 groups and administered a 5 µL intracisternal injection of 0.68 µg/kg HgCl(2) (n=7), 1.2 µg/kg HgCl(2) (n=7), 2.4 µg/kg HgCl(2) (n=7), 60 µg/kg HgCl(2) (n=7), 120 µg/kg HgCl(2) (n=3), saline (control) (n=7), 60 µg/kg HgCl(2) plus prazosin (n=6), saline plus prazosin (n=6), 60 µg/kg HgCl(2) plus metilatropina (n=4) or saline plus metilatropina (n=4)HgCl(2). Anesthesia was induced with halothane and maintained as needed with urethane (1.2 g/kg) administered intravenously (i.v.) through a cannula placed in the left femoral vein. The left femoral artery was also cannulated to record systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and heart rate (HR). A tracheotomy was performed to record respiratory rate. Animals were placed in a stereotaxic frame, and the cisterna magna was exposed. After a stabilization period, solutions (saline or HgCl(2)) were injected i.c., and cardiopulmonary responses were recorded for 50 min. Involvement of the autonomic nervous system was assessed through the i.v. injection of hexamethonium (20 mg/kg), prazosin (1 mg/kg) and methylatropine (1 mg/kg) 10 min before the i.c. injection of HgCl(2) or saline. Treatment with 0.68, 1.2, 2.4 µg/kg HgCl(2) or saline did not modify basal cardiorespiratory parameters, whereas the 120 µg/kg dose induced acute toxicity, provoking respiratory arrest and death. The administration of 60 µg/kg HgCl(2), however, induced significant increases (p<0.05) in SAP at the 30°, 40° and 50° min, timepoints and DAP at the 5°, 10°, 20°, 30°, 40° and 50° timepoints. RR was significantly decreased at the 5°, 10°, 20°, 40° and 50° min timepoints; however, there was no change in HR. Hexamethonium administration, which causes non-specific inhibition of the autonomic nervous system, abolished the observed cardiorespiratory effects. Similarly, prazosin, a α(1)-adrenoceptor blocker that specifically inhibits sympathetic nervous system function, abolished HgCl(2) induced increases in SAP and DAP without affecting HR and RR. Methylatropine (1 mg/Kg), a parasympathetic nervous system inhibitor, exacerbated the effects of HgCl(2) and caused slow-onset respiratory depression, culminating in respiratory arrest and death. Our results demonstrate that increases in SAP and DAP induced by the i.c. injection of mercuric chloride are mediated by activation of the sympathetic nervous system.

Processo de implantação de Programa de Saúde Auditiva em duas maternidades públicas / Implantation process of a Hearing Health Program in two public maternity hospitals

OBJETIVOS: Apresentar os resultados do processo de implantação de um programa de saúde auditiva neonatal em serviço público e revisar os aspectos determinantes no planejamento, efetividade, manutenção e aprimoramento. MÉTODOS: A fim de colaborar com a implantação de novos serviços, avaliamos os fatores: capacitação de equipe, ambiente de teste (ruído e indivíduo), falso-negativo, evasão e tempo de exame, em um estudo transversal, que incluiu a triagem auditiva de todos os recém-nascidos de duas maternidades públicas, por meio de Emissões Otoacústicas. RESULTADOS: Dos 4951 bebês recém-nascidos no período de 2002 a 2005, foram avaliados 3364 (67,9 por cento), sendo 425 (12,61 por cento) portadores de indicadores de risco para deficiência auditiva. Houve confirmação da perda auditiva em sete recém-nascidos (0,3 por cento) por meio do Potencial Evocado Auditivo do Tronco Encefálico. CONCLUSÕES: Verificou-se a necessidade de protocolos com critério "passa e falha" bem definidos para cada população alvo. A triagem auditiva pode ser realizada até 30 dias após o nascimento, e sua realização não deve se limitar às maternidades. Treinamento e supervisão da equipe são cruciais, além de um sistema de agendamento e acompanhamento dos casos em seguimento, para diminuição da evasão e localização das perdas auditivas de aparecimento tardio, associando os programas de triagem à responsabilidade da confirmação do diagnóstico e intervenção. Desta maneira, teremos condições de mensurar a deficiência auditiva no Brasil e compará-la com o perfil epidemiológico de países onde estes programas já delinearam a saúde auditiva de sua população.

PURPOSE: To present the results of an implantation process of a neonatal hearing health program in public services and to review determinant aspects on its planning, effectiveness, maintenance and improvement. METHODS: In order to aid the implementation of new services, factors such as team qualification, test environment (noise and subject), false-negative, evasion and evaluation time were assessed in a cross-sectional study which included the hearing screening of all newborns in two public maternity hospitals, through otoacoustic emissions. RESULTS: Out of 4951 newborns in the period from 2002 to 2005, 3364 (67.9 percent) were assessed; 425 (12.61 percent) had risk indicators for hearing impairment. Hearing loss was confirmed in seven newborns (0.3 percent) through the Brainstem Auditory Evoked Potential. CONCLUSIONS: The need for protocols with well defined "pass and fail" criterion for each target population was verified. Hearing screening should be carried out within 30 days following birth and should not be limited to maternity hospitals. Team training and supervision is crucial, as well as electronic appointment and monitoring system, in order to decrease evasion and to detect late hearing loss, associating screening programs with the responsibility of diagnostic confirmation and intervention. This way, one will be able to measure hearing deficiency in Brazil and compare it with epidemiological profiles of countries where such programs have already outlined the hearing health of their population.

A comparison of the effects of stimulation within the raphe nuclei on arterial blood pressure in the anaesthetized rabbit and rat

Blood pressure changes were evoked in the anaesthetized rabbit and rat by stimulating electrically within the caudal raphe nuclei. The responses evoked in the two species were very different, mainly pressor in the rat (85% pressor, 5% depressor) compared with approximately similar proportions of depressor and pressor in the rabbit (29% and 27%, respectively). The responses evoked from a particular site could not be reversed by changing the stimulus strength. It is proposed that the haemodynamic responses evoked in the rabbit and the rat, in response to stimulation within raphe, are related to differences in the central organization of these nuclei and/or their connexions. These results are then discussed in relation to the observation that the tonic phase of desynchronized sleep is accompanied by hypotension in the rabbit and hypertension in the rat. Finally, it is suggested that the haemodynamic differences observed during desynchronized sleep in these two species are caused by differences in central nervous regulation which involve the caudal raphe nuclei, magnus, pallidus and obscurus

A comparison of the effects of stimulation within the raphe nuclei on arterial blood pressure in the anaesthetized rabbit and rat

Blood pressure changes were evoked in the anaesthetized rabbit and rat by stimulating electrically within the caudal raphe nuclei. The responses evoked in the two species were very different, mainly pressor in the rat (85% pressor, 5% depressor) compared with approximately similar proportions of depressor and pressor in the rabbit (29% and 27%, respectively). The responses evoked from a particular site could not be reversed by changing the stimulus strength. It is proposed that the haemodynamic responses evoked in the rabbit and the rat, in response to stimulation within raphe, are related to differences in the central organization of these nuclei and/or their connexions. These results are then discussed in relation to the observation that the tonic phase of desynchronized sleep is accompanied by hypotension in the rabbit and hypertension in the rat. Finally, it is suggested that the haemodynamic differences observed during desynchronized sleep in these two species are caused by differences in central nervous regulation which involve the caudal raphe nuclei, magnus, pallidus and obscurus (AU)

Cardiovascular regulation in the acute decerebrate rat

Male Wistar rats were decerebrated at precollicular level, by aspiration under ether anaesthesia. The experiments employed rats instrumented for chronic electrocardiogram (ECG) recordings or mean blood pressure (MBP) and heart rate (Hr) determination. Immediately after surgery, decerebrate (D) and sham operated (SO) animals presented a small and ismilar increase in their HR. Three and a half hours after surgery, SO group presented a normal HR, whilst D animals continued to show an increas ein their HR up to 4.5 h, when it stabilized. Twenty four hours after surgery both groups presented similar MBP (D:110ñ6; SO:108ñ11; SO:335ñ5 beats/min). The blockade of parasympathetic tonus induced significant increases in the HR of both groups, withou major changes in their MBP. Beta-adrenergic blockade reduced HR of both groups, bringin HR of D almost to control level. Simultaneously there was a reduction in MBP of D but not of SO animals. When parasympathetic blockade was superimposed to beta-adrenergic blockade, there was a significant increase in HR of SO, but not of D or in MBP of both groups. Thus we conclude that the decerebrate rat presents normal MBP with simultaneous tachycardia mainly caused by increased sympathetic outflow to the heart

Cardiovascular regulation in the acute decerebrate rat

Male Wistar rats were decerebrated at precollicular level, by aspiration under ether anaesthesia. The experiments employed rats instrumented for chronic electrocardiogram (ECG) recordings or mean blood pressure (MBP) and heart rate (Hr) determination. Immediately after surgery, decerebrate (D) and sham operated (SO) animals presented a small and ismilar increase in their HR. Three and a half hours after surgery, SO group presented a normal HR, whilst D animals continued to show an increas ein their HR up to 4.5 h, when it stabilized. Twenty four hours after surgery both groups presented similar MBP (D:110ñ6; SO:108ñ11; SO:335ñ5 beats/min). The blockade of parasympathetic tonus induced significant increases in the HR of both groups, withou major changes in their MBP. Beta-adrenergic blockade reduced HR of both groups, bringin HR of D almost to control level. Simultaneously there was a reduction in MBP of D but not of SO animals. When parasympathetic blockade was superimposed to beta-adrenergic blockade, there was a significant increase in HR of SO, but not of D or in MBP of both groups. Thus we conclude that the decerebrate rat presents normal MBP with simultaneous tachycardia mainly caused by increased sympathetic outflow to the heart (AU)