The interaction between hippocampal cholinergic and nitrergic neurotransmission coordinates NMDA-dependent behavior and autonomic changes induced by contextual fear retrieval.

RATIONALE: Re-exposing an animal to an environment previously paired with an aversive stimulus evokes large alterations in behavioral and cardiovascular parameters. Dorsal hippocampus (dHC) receives important cholinergic inputs from the basal forebrain, and respective acetylcholine (ACh) levels are described to influence defensive behavior. Activation of muscarinic M1 and M3 receptors facilitates autonomic and behavioral responses along threats. Evidence show activation of cholinergic receptors promoting formation of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) in dHC. Altogether, the action of ACh and NO on conditioned responses appears to converge within dHC. OBJECTIVES: As answer about how ACh and NO interact to modulate defensive responses has so far been barely addressed, we aimed to shed additional light on this topic. METHODS: Male Wistar rats had guide cannula implanted into the dHC before being submitted to the contextual fear conditioning (3footshocks/085 mA/2 s). A catheter was implanted in the femoral artery the next day for cardiovascular recordings. Drugs were delivered into dHC 10 min before contextual re-exposure, which occurred 48 h after the conditioning procedure. RESULTS: Neostigmine (Neo) amplified the retrieval of conditioned responses. Neo effects (1 nmol) were prevented by the prior infusion of a M1-M3 antagonist (fumarate), a neuronal nitric oxide synthase inhibitor (NPLA), a NO scavenger (cPTIO), a guanylyl cyclase inhibitor (ODQ), and a NMDA antagonist (AP-7). Pretreatment with a selective M1 antagonist (pirenzepine) only prevented the increase in autonomic responses induced by Neo. CONCLUSION: The results show that modulation in the retrieval of contextual fear responses involves coordination of the dHC M1-M3/NO/cGMP/NMDA pathway.

In Situ Effects of Doxycycline on Neuromuscular Junction in Mice.

BACKGROUND: The antibacterial mechanism of doxycycline is known, but its effects on the nerve-muscle system are still not unclear. OBJECTIVE: The aim of the study was to combine molecular targets of the neuromuscular machinery using the in situ neuronal blocker effect of doxycycline, a semisynthetic second-generation tetracycline derivative, on mice neuromuscular preparations. METHODS: The effects of doxycycline were assessed on presynaptic, synaptic cleft, and postsynaptic neurotransmission, along with the muscle fiber, using the traditional myographic technique. Precisely, the effects of doxycycline were categorized into "all" or "nothing" effects depending on the concentration of doxycycline used; "all" was obtained with 4 µM doxycycline, and "nothing" was obtained with 1-3 µM doxycycline. The rationale of this study was to apply known pharmacological tools against the blocker effect of 4 µM doxycycline, such as F55-6 (Casearia sylvestris), CaCl2 (or Ca2+), atropine, neostigmine, polyethylene glycol (PEG 400), and d-Tubocurarine. The evaluation of cholinesterase enzyme activity and the diaphragm muscle histology were performed, and protocols on the neuromuscular preparation submitted to indirect or direct stimuli were complementary. RESULTS: Doxycycline does not affect cholinesterase activity nor causes damage to skeletal muscle diaphragm; it acts on ryanodine receptor, sarcolemmal membrane, and neuronal sodium channel with a postjunctional consequence due to the decreased availability of muscle nicotinic acetylcholine receptors. CONCLUSION: In conclusion, in addition to the neuronal blocker effect of doxycycline, we showed that doxycycline acts on multiple targets. It is antagonized by F55-6, a neuronal Na+-channel agonist, and Ca2+, but not by neostigmine.

Metformin Improves Autonomic Nervous System Imbalance and Metabolic Dysfunction in Monosodium L-Glutamate-Treated Rats.

Metformin is an antidiabetic drug used for the treatment of diabetes and metabolic diseases. Imbalance in the autonomic nervous system (ANS) is associated with metabolic diseases. This study aimed to test whether metformin could improve ANS function in obese rats. Obesity was induced by neonatal treatment with monosodium L-glutamate (MSG). During 21-100 days of age, MSG-rats were treated with metformin 250 mg/kg body weight/day or saline solution. Rats were euthanized to evaluate biometric and biochemical parameters. ANS electrical activity was recorded and analyzed. Metformin normalized the hypervagal response in MSG-rats. Glucose-stimulated insulin secretion in isolated pancreatic islets increased in MSG-rats, while the cholinergic response decreased. Metformin treatment normalized the cholinergic response, which involved mostly the M3 muscarinic acetylcholine receptor (M3 mAChR) in pancreatic beta-cells. Protein expression of M3 mAChRs increased in MSG-obesity rats, while metformin treatment decreased the protein expression by 25%. In conclusion, chronic metformin treatment was effective in normalizing ANS activity and alleviating obesity in MSG-rats.

Neostigmine treatment induces neuroprotection against oxidative stress in cerebral cortex of asthmatic mice.

During chronic inflammatory disease, such asthma, leukocytes can invade the central nervous system (CNS) and together with CNS-resident cells, generate excessive reactive oxygen species (ROS) production as well as disbalance in the antioxidant system, causing oxidative stress, which contributes a large part to neuroinflammation. In this sense, the aim of this study is to investigate the effects of treatment with neostigmine, known for the ability to control lung inflammation, on oxidative stress in the cerebral cortex of asthmatic mice. Female BALB/cJ mice were submitted to asthma model induced by ovalbumin (OVA). Control group received only Dulbecco's phosphate-buffered saline (DPBS). To evaluate neostigmine effects, mice received 80 µg/kg of neostigmine intraperitoneally 30 min after each OVA challenge. Our results revealed for the first time that treatment with neostigmine (an acetylcholinesterase inhibitor that no crosses the BBB) was able to revert ROS production and change anti-oxidant enzyme catalase in the cerebral cortex in asthmatic mice. These results support the communication between the peripheral immune system and the CNS and suggest that acetylcholinesterase inhibitors, such as neostigmine, should be further studied as possible therapeutic strategies for neuroprotection in asthma.

Cholinergic anti-inflammatory pathway confers airway protection against oxidative damage and attenuates inflammation in an allergic asthma model.

Asthma is characterized by the influx of inflammatory cells, especially of eosinophils as well as reactive oxygen species (ROS) production, driven by the release of the T helper 2 (Th2)-cell-associated cytokines. The cholinergic anti-inflammatory pathway (CAP) inhibit cytokines production and controls inflammation. Thus, we investigated the effects of pharmacological activation of CAP by neostigmine on oxidative stress and airway inflammation in an allergic asthma model. After the OVA challenge, mice were treated with neostigmine. We showed that CAP activation by neostigmine reduced the levels of pro-inflammatory cytokines (IL-4, IL-5, IL-13, IL-1ß, and TNF-α), which resulted in a decrease of eosinophils influx. Furthermore, neostigmine also conferred airway protection against oxidative stress, attenuating ROS production through the increase of antioxidant defense, evidenced by the catalase (CAT) activity. We propose, for the first time, that pharmacological activation of the CAP can lead to new possibilities in the therapeutic management of allergic asthma.

Tetanic Facilitation of Neuromuscular Transmission by Adenosine A2A and Muscarinic M1 Receptors is Dependent on the Uptake of Choline via High-Affinity Transporters.

BACKGROUND/AIMS: In this study, we evaluated the functional impact of facilitatory presynaptic adenosine A2A and muscarinic M1 receptors in the recovery of neuromuscular tetanic depression caused by the blockage of high-affinity choline transporter (HChT) by hemicholinium-3 (HC-3), a condition that mimics a myasthenia-like condition. METHODS: Rat diaphragm preparations were indirectly stimulated via the phrenic nerve trunk with 50-Hz frequency trains, each consisting of 500-750 supramaximal intensity pulses. The tension at the beginning (A) and at the end (B) of the tetanus was recorded and the ratio (R) B/A calculated. RESULTS: Activation of A2A and M1 receptors with CGS21680 (CGS; 2 nmol/L) and McN-A-343c (McN; 3 µmol/L) increased R values. Similar facilitatory effects were obtained with forskolin (FSK; 3 µmol/L) and phorbol 12-myristate 13-acetate (PMA; 10 µmol/L), which activate adenylate cyclase and protein kinase C respectively. HC-3 (4 µmol/L) decreased transmitter exocytosis measured by real-time videomicroscopy with the FM4-64 fluorescent dye and prevented the facilitation of neuromuscular transmission caused by CGS, McN, and FSK, with a minor effect on PMA. The acetylcholinesterase inhibitor, neostigmine (NEO; 0.5 µmol/L), also decreased transmitter exocytosis. The paradoxical neuromuscular tetanic fade caused by NEO (0.5 µmol/L) was also prevented by HC-3 (4 µmol/L) and might result from the rundown of the positive feedback mechanism operated by neuronal nicotinic receptors (blocked by hexamethonium, 120 µmol/L). CONCLUSION: Data suggest that the recovery of tetanic neuromuscular facilitation by adenosine A2A and M1 receptors is highly dependent on HChT activity and may be weakened in myasthenic patients when HChT is inoperative.

Functional respiratory imaging after neostigmine- or sugammadex-enhanced recovery from neuromuscular blockade in the anesthetised rat: a randomised controlled pilot study / Imagem funcional da respiração após aceleração da recuperação do bloqueio neuromuscular com neostigmina ou sugamadex em ratos anestesiados: estudo piloto controlado e randomizado

Abstract Objectives Reductions in diaphragm activity are associated with the postoperative development of atelectasis. Neostigmine reversal is also associated with increased atelectasis. We assessed the effects of neostigmine, sugammadex, and spontaneous reversal on regional lung ventilation and airway flow. Methods Six Sprague-Dawley rats were paralysed with rocuronium and mechanically ventilated until recovery of the train-of-four ratio to 0.5. We administered neostigmine (0.06 mg.kg-1), sugammadex (15 mg.kg-1), or saline (n = 2 per group). Computed tomography scans were obtained during the breathing cycle. Three-dimensional models of lung lobes were generated using functional respiratory imaging technology, and lobar volumes were calculated during the breathing cycle. The diaphragmatic surface was segmented for the end-expiratory and end-inspiratory scans. The total change in volume was reported by the lung volume change from the end-expiratory scan to the end-inspiratory scan. Chest wall movement was defined as the lung volume change minus the volume change that resulted from diaphragm excursion. Results The two rats that received neostigmine exhibited a smaller relative contribution of diaphragm movement to the total change in lung volume compared with the two rats that received sugammadex or saline (chest wall contribution (%): 26.69 and 25.55 for neostigmine; -2.77 and 15.98 for sugammadex; 18.82 and 10.30 for saline). Conclusion This pilot study in rats demonstrated an increased relative contribution of chest wall expansion after neostigmine compared with sugammadex or saline. This smaller relative contribution of diaphragm movement may be explained by a neostigmine-induced decrease in phrenic nerve activity or by remaining occupied acetylcholine receptors after neostigmine.

Resumo Objetivos As reduções da atividade do diafragma estão associadas ao desenvolvimento de atelectasia no período pós-operatório. A reversão com neostigmina também está associada ao aumento de atelectasia. Avaliamos os efeitos de neostigmina, sugamadex e da reversão espontânea sobre a ventilação pulmonar regional e o fluxo aéreo. Métodos Seis ratos Sprague-Dawley foram paralisados com rocurônio e mecanicamente ventilados até a recuperação da sequência de quatro estímulos atingir relação 0,5. Administramos neostigmina (0,06 mg.kg-1), sugamadex (15 mg.kg-1) ou solução salina (n = 2 por grupo). As tomografias foram feitas durante o ciclo respiratório. Modelos tridimensionais dos lobos pulmonares foram gerados com a tecnologia de imagem funcional respiratória e os volumes lobares foram calculados durante o ciclo respiratório. A superfície diafragmática foi segmentada para as varreduras expiratória final e inspiratória final. A alteração total no volume foi relatada pela alteração do volume pulmonar da varredura expiratória final para a varredura inspiratória final. O movimento da parede torácica foi definido como a variação do volume pulmonar menos a alteração no volume resultante da excursão do diafragma. Resultados Os dois ratos que receberam neostigmina apresentaram uma contribuição relativa menor do movimento do diafragma para a alteração total do volume pulmonar em comparação com os dois ratos que receberam sugamadex ou solução salina (contribuição da parede torácica (%): 26,69 e 25,55 para neostigmina; -2,77 e 15,98 para sugamadex; 18,82 e 10,30 para solução salina). Conclusão Este estudo piloto com ratos demonstrou uma contribuição relativa aumentada de expansão da parede torácica após neostigmina em comparação com sugamadex ou solução salina. Essa contribuição relativa menor de movimento do diafragma pode ser explicada por uma redução induzida por neostigmina na atividade do nervo frênico ou por receptores de acetilcolina permanecerem ocupados após a administração de neostigmina.

[Functional respiratory imaging after neostigmine- or sugammadex-enhanced recovery from neuromuscular blockade in the anesthetised rat: a randomised controlled pilot study]. / Imagem funcional da respiração após aceleração da recuperação do bloqueio neuromuscular com neostigmina ou sugamadex em ratos anestesiados: estudo piloto controlado e randomizado.

OBJECTIVES: Reductions in diaphragm activity are associated with the postoperative development of atelectasis. Neostigmine reversal is also associated with increased atelectasis. We assessed the effects of neostigmine, sugammadex, and spontaneous reversal on regional lung ventilation and airway flow. METHODS: Six Sprague-Dawley rats were paralysed with rocuronium and mechanically ventilated until recovery of the train-of-four ratio to 0.5. We administered neostigmine (0.06mg.kg-1), sugammadex (15mg.kg-1), or saline (n=2 per group). Computed tomography scans were obtained during the breathing cycle. Three-dimensional models of lung lobes were generated using functional respiratory imaging technology, and lobar volumes were calculated during the breathing cycle. The diaphragmatic surface was segmented for the end-expiratory and end-inspiratory scans. The total change in volume was reported by the lung volume change from the end-expiratory scan to the end-inspiratory scan. Chest wall movement was defined as the lung volume change minus the volume change that resulted from diaphragm excursion. RESULTS: The two rats that received neostigmine exhibited a smaller relative contribution of diaphragm movement to the total change in lung volume compared with the two rats that received sugammadex or saline (chest wall contribution (%): 26.69 and 25.55 for neostigmine; -2.77 and 15.98 for sugammadex; 18.82 and 10.30 for saline). CONCLUSION: This pilot study in rats demonstrated an increased relative contribution of chest wall expansion after neostigmine compared with sugammadex or saline. This smaller relative contribution of diaphragm movement may be explained by a neostigmine-induced decrease in phrenic nerve activity or by remaining occupied acetylcholine receptors after neostigmine.

The effect of sugammadex on postoperative cognitive function and recovery / O efeito de sugamadex sobre a função cognitiva e recuperação no pós-operatório

Abstract Background and objective: Sugammadex is the first selective relaxant binding agent. When compared with neostigmine, following sugammadex administration patients wake earlier and have shorter recovery times. In this study, we hypothesized that fast and clear awakening in patients undergoing general anesthesia has positive effects on cognitive functions in the early period after operation. Methods: Approved by the local ethical committee, 128 patients were enrolled in this randomized, prospective, controlled, double-blind study. Patients were allocated to either Sugammadex group (Group S) or the Neostigmine group (Group N). The primary outcome of the study was early postoperative cognitive recovery as measured by the Montreal Cognitive Assessment (MoCA) and Mini Mental State Examination (MMSE). After baseline assessment 12-24 h before the operation. After the operation, when the Modified Aldrete Recovery Score was ≥9 the MMSE and 1 h later the MoCA tests were repeated. Results: Although there was a reduction in MoCA and MMSE scores in both Group S and Group N between preoperative and postoperative scores, there was no statistically significant difference in the slopes (p > 0.05). The time to reach TOF 0.9 was 2.19 min in Group S and 6.47 min in Group N (p < 0.0001). Recovery time was 8.26 min in Group S and 16.93 min in Group N (p < 0.0001). Conclusion: We showed that the surgical procedure and/or accompanying anesthetic procedure may cause a temporary or permanent regression in cognitive function in the early postoperative period. However, better cognitive performance could not be proved in the Sugammadex compared to the Neostigmine.

Resumo Justificativa e objetivo: Sugamadex é o primeiro agente de ligação relaxante seletivo. Após a administração de sugamadex, os tempos de despertar e de recuperação dos pacientes são menores, em comparação com neostigmina. Neste estudo, a hipótese foi que um despertar mais rápido e claro dos pacientes submetidos à anestesia geral tem efeitos positivos sobre as funções cognitivas no pós-operatório imediato. Métodos: Após a aprovação do Comitê de Ética local, 128 pacientes foram incluídos neste estudo prospectivo, randômico, controlado e duplo-cego. Os pacientes foram designados para o grupo sugamadex (Grupo S) ou grupo neostigmina (Grupo N). O desfecho primário do estudo foi a recuperação cognitiva no pós-operatório imediato, de acordo com a mensuração da Avaliação de Montreal da Função Cognitiva (MoCA) e com o Mini Exame do Estado Mental (MMSE), após a avaliação inicial 12-24 h antes da operação. Após a operação, quando o escore de recuperação de Aldrete modificado era ≥ 9, o teste MMSE e, uma hora depois, o teste MoCA foram repetidos. Resultados: Embora tenha havido uma redução nos escores de MoCA e MMSE tanto no Grupo S quanto no Grupo N, entre os escores pré- e pós-operatório não houve diferença estatisticamente significativa nas reduções (p > 0,05). O tempo para atingir TOF 0,9 foi de 2,19 min no Grupo S e de 6,47 min no Grupo N (p < 0,0001). O tempo de recuperação foi de 8,26 min no Grupo S e de 16,93 min no Grupo N (p < 0,0001) Conclusão: Mostramos que o procedimento cirúrgico e/ou procedimento anestésico de acompanhamento pode causar uma regressão temporária ou permanente da função cognitiva no pós-operatório imediato. No entanto, um desempenho cognitivo melhor não pode ser provado no grupo sugamadex em comparação com o grupo neostigmina.

The effect of sugammadex on postoperative cognitive function and recovery.

BACKGROUND AND OBJECTIVE: Sugammadex is the first selective relaxant binding agent. When compared with neostigmine, following sugammadex administration patients wake earlier and have shorter recovery times. In this study, we hypothesized that fast and clear awakening in patients undergoing general anesthesia has positive effects on cognitive functions in the early period after operation. METHODS: Approved by the local ethical committee, 128 patients were enrolled in this randomized, prospective, controlled, double-blind study. Patients were allocated to either Sugammadex group (Group S) or the Neostigmine group (Group N). The primary outcome of the study was early postoperative cognitive recovery as measured by the Montreal Cognitive Assessment (MoCA) and Mini Mental State Examination (MMSE). After baseline assessment 12-24h before the operation. After the operation, when the Modified Aldrete Recovery Score was ≥9 the MMSE and 1h later the MoCA tests were repeated. RESULTS: Although there was a reduction in MoCA and MMSE scores in both Group S and Group N between preoperative and postoperative scores, there was no statistically significant difference in the slopes (p>0.05). The time to reach TOF 0.9 was 2.19min in Group S and 6.47min in Group N (p<0.0001). Recovery time was 8.26min in Group S and 16.93min in Group N (p<0.0001). CONCLUSION: We showed that the surgical procedure and/or accompanying anesthetic procedure may cause a temporary or permanent regression in cognitive function in the early postoperative period. However, better cognitive performance could not be proved in the Sugammadex compared to the Neostigmine.

Neutrophil Recruitment and Articular Hyperalgesia in Antigen-Induced Arthritis are Modulated by the Cholinergic Anti-Inflammatory Pathway.

The cholinergic anti-inflammatory pathway (CAP) is a complex neuroimmune mechanism triggered by the central nervous system to regulate peripheral inflammatory responses. Understanding the role of CAP in the pathogenesis of rheumatoid arthritis (RA) could help develop new therapeutic strategies for this disease. Therefore, we investigated the participation of this neuroimmune pathway on the progression of experimental arthritis. Using antigen-induced arthritis (AIA) model, we investigated in mice the effects of vagotomy or the pharmacological treatments with hexamethonium (peripheral nicotinic receptor antagonist), methylatropine (peripheral muscarinic receptor antagonist) or neostigmine (peripheral acetylcholinesterase inhibitor) on AIA progression. Unilateral cervical vagotomy was performed 1 week before the immunization protocol with methylated bovine serum albumin (mBSA), while drug administration was conducted during the period of immunization. On day 21, 6 hr after the challenge with mBSA injection in the femur-tibial joint, the local neutrophil migration and articular mechanical hyperalgesia were assessed. Herein, we observed that vagotomy or blockade of peripheral nicotinic (but not muscarinic) receptors exacerbated the clinical parameters of this disease. Moreover, peripheral acetylcholinesterase inhibition by neostigmine treatment promoted a reduction of neutrophil recruitment in the knee joint and articular hyperalgesia. Our results demonstrated that peripheral activation of CAP modulates experimental arthritis, providing a pre-clinical evidence of a potential therapeutic strategy for RA.

Comparison of effects of sugammadex and neostigmine on QTc prolongation in rabbits under general anesthesia.

PURPOSE: To compare the effects of sugammadex and neostigmine, used to antagonize the effects of rocuronium, on the QTc interval. METHODS: This study used 10 adult New Zealand white rabbits of 2.5-3.5 kg randomly divided into two groups: sugammadex group (Group S, n:5) and neostigmine group (Group N, n:5). For general anesthesia administering 2 mg/kg iv propofol and 1 mcg/kg iv fentanyl, 0.6 mg/kg iv rocuronium was given. Later to provide reliable airway for all experimental animals V-Gel Rabbit was inserted. The rabbits were manually ventilated by the same anesthetist. After the V-Gel Rabbit was inserted at 2, 5, 10, 20, 25, 27, 30 and 40 minutes measurements were repeated and recorded. At 25 minutes after induction Group N rabbits were given 0.05 mg/kg iv neostigmine + 0.01 mg/kg iv atropine. Group S were administered 2 mg/kg iv sugammadex. RESULTS: Comparing the QTc interval in the rabbits in Group S and Group N, in the 25th, 27th and 30th minute after muscle relaxant antagonist was administered the QTc interval in the neostigmine group rabbits was significantly increased (p<0.05). CONCLUSION: While sugammadex, administered to antagonize the effect of rocuronium, did not significantly affect the QTc interval, neostigmine+atropine proloned the QTc interval.

Comparison of effects of sugammadex and neostigmine on QTc prolongation in rabbits under general anesthesia

PURPOSE: To compare the effects of sugammadex and neostigmine, used to antagonize the effects of rocuronium, on the QTc interval. METHODS: This study used 10 adult New Zealand white rabbits of 2.5-3.5 kg randomly divided into two groups: sugammadex group (Group S, n:5) and neostigmine group (Group N, n:5). For general anesthesia administering 2 mg/kg iv propofol and 1 mcg/kg iv fentanyl, 0.6 mg/kg iv rocuronium was given. Later to provide reliable airway for all experimental animals V-Gel Rabbit was inserted. The rabbits were manually ventilated by the same anesthetist. After the V-Gel Rabbit was inserted at 2, 5, 10, 20, 25, 27, 30 and 40 minutes measurements were repeated and recorded. At 25 minutes after induction Group N rabbits were given 0.05 mg/kg iv neostigmine + 0.01 mg/kg iv atropine. Group S were administered 2 mg/kg iv sugammadex. RESULTS: Comparing the QTc interval in the rabbits in Group S and Group N, in the 25th, 27th and 30th minute after muscle relaxant antagonist was administered the QTc interval in the neostigmine group rabbits was significantly increased (p<0.05). CONCLUSION: While sugammadex, administered to antagonize the effect of rocuronium, did not significantly affect the QTc interval, neostigmine+atropine proloned the QTc interval. .

Sugammadex versus neostigmine in pediatric patients: a prospective randomized study / Sugammadex versus neostigmina em pacientes pediátricos: estudo prospectivo e randomizado / Sugammadex versus neostigmina en pacientes pediátricos: estudio prospectivo y aleatorizado

Background and objectives: Acetylcholinesterase inhibitors may cause postoperative residual curarization when they are used for reversal of neuromuscular blockade. Sugammadex reverses neuromuscular blockade by chemical encapsulation and is not associated with the side effects that may occur with the use of anticholinesterase agents. Because of increased outpatient surgical procedures postoperative residual curarization and rapid postoperative recovery have a greater importance in the pediatric patient population. The aim of this study was to compare the efficacy of sugammadex and neostigmine on reversing neuromuscular blockade in pediatric patients undergoing outpatient surgical procedures. Methods: 80 patients, aged 2-12 years, scheduled for outpatient surgery were enrolled in this randomized prospective study. Neuromuscular blockade was achieved with 0.6 mgkg−1 rocuronium and monitorized with train-of-four. Group RN (n = 40) received 0.03 mgkg−1 neostigmine, Group RS (n = 40) received 2 mgkg−1 sugammadex for reversal of rocuronium. Extubation time (time from the reversal of neuromuscular blockade to extubation), train-of-four ratio during this time, time to reach train-of-four > 0.9, and probable complications were recorded. Results: There was no significant difference between the patients' characteristics. Extubation time and time to reach train-of-four > 0.9 were significantly higher in Group RN (p = 0.001, p = 0.002). Train-of-four at the time of neostigmine/sugammadex injection in Group RN were significantly higher than in the RS group (p = 0.020). Extubation train-of-four ratio was significantly lower in Group RN (p = 0.002). Conclusion: Sugammadex provides safer extubation with a shorter recovery time than neostigmine in pediatric patients undergoing outpatient surgical procedures. .

Justificativa e objetivos: Os inibidores da acetilcolinesterase podem causar curarização residual no pós-operatório quando usados para reverter o bloqueio neuromuscular. Sugamadex reverte o bloqueio neuromuscular por encapsulação química e não está associado aos efeitos colaterais que podem ocorrer com o uso de agentes anticolinesterase. Devido ao aumento dos procedimentos cirúrgicos ambulatoriais. A curarização residual e a rápida recuperação no pós-operatório são muito importantes para a população de pacientes pediátricos. O objetivo deste estudo foi comparar a eficácia de sugamadex e neostigmina na reversão do bloqueio neuromuscular em pacientes pediátricos submetidos a procedimentos cirúrgicos ambulatoriais. Métodos: 80 pacientes, com idades entre 2-12 anos, programados para cirurgias ambulatoriais foram incluídos neste estudo prospectivo e randomizado. O bloqueio neuromuscular foi obtido com 0,6 mgkg−1 de rocurônio e monitorizado com a interpretação da sequência de quatro estímulos. O Grupo RN (n = 40) recebeu 0,03 mgkg−1 de neostigmina e o Grupo RS (n = 40) recebeu 2 mgkg−1 de sugamadex para a reversão de rocurônio. O tempo de extubacão (tempo desde a reversão do bloqueio neuromuscular até a extubação), a razão da sequência de quatro estímulos durante esse tempo, o tempo para atingir uma sequência de quatro estímulos > 0,9 e as complicações prováveis foram registrados. Resultados: Não houve diferença significativa entre as características dos pacientes. Os tempos de extubação e para atingir uma sequência de quatro estímulos >0,9 foram significativamente maiores no Grupo RN (p = 0,001, p = 0,002). A sequência de quatro estímulos ...

Introducción y objetivos: Los inhibidores de la acetilcolinesterasa pueden causar anestesia residual en el postoperatorio cuando se usan para revertir el bloqueo neuromuscular. El sugammadex revierte el bloqueo neuromuscular por encapsulación química y no está asociado con los efectos colaterales que pueden ocurrir con el uso de agentes anticolinesterasa. Debido al aumento de los procedimientos quirúrgicos ambulatorios, la anestesia residual y la rápida recuperación en el postoperatorio son muy importantes para la población de pacientes pediátricos. El objetivo de este estudio fue comparar la eficacia del sugammadex y la neostigmina en la reversión del bloqueo neuromuscular en pacientes pediátricos sometidos a procedimientos quirúrgicos ambulatorios. Métodos: 80 pacientes, con edades entre 2 y 12 años, programados para cirugía ambulatoria fueron incluidos en este estudio prospectivo y aleatorizado. El bloqueo neuromuscular se obtuvo con 0,6 mg kg−1 de rocuronio y fue monitorizado con la interpretación de la secuencia de 4 estímulos. El grupo RN (n = 40) recibió 0,03 mg kg−1 de neostigmina y el grupo RS (n = 40) recibió 2 mg kg−1 de sugammadex para la reversión de rocuronio. Se registraron el tiempo de desintubación (tiempo desde la reversión del bloqueo neuromuscular hasta la desintubación), la razón de la secuencia de 4 estímulos durante ese tiempo, el tiempo para alcanzar una secuencia de 4 estímulos > 0,9 y las complicaciones probables. Resultados: No hubo diferencia significativa entre las características de los pacientes. Los tiempos de desintubación y para alcanzar una secuencia de 4 estímulos > 0,9 fueron significativamente mayores en el grupo RN (p = 0,001, p = 0,002). La secuencia de 4 estímulos en el momento de la inyección de neostigmina/sugammadex ...

Some current challenges in research on air pollution and health / Desafíos actuales de la investigación sobre contaminación del aire y salud

This commentary addresses some of the diverse questions of current interest with regard to the health effects of air pollution, including exposure-response relationships, toxicity of inhaled particles and risks to health, multipollutant mixtures, traffic-related pollution, accountability research, and issues with susceptibility and vulnerability. It considers the challenges posed to researchers as they attempt to provide useful evidence for policy-makers relevant to these issues. This commentary accompanies papers giving the results from the ESCALA project, a multi-city study in Latin America that has an overall goal of providing policy-relevant results. While progress has been made in improving air quality, driven by epidemiological evidence that air pollution is adversely affecting public health, the research questions have become more subtle and challenging as levels of air pollution dropped. More research is still needed, but also novel methods and approaches to address these new questions.

Este comentario aborda algunos de los temas de interés actual en relación con los efectos de la contaminación del aire sobre la salud, tales como las relaciones exposición-respuesta, la toxicidad y riesgos para la salud de las partículas inhaladas, las mezclas de contaminantes múltiples, la contaminación relacionada con el tráfico, la investigación sobre responsabilidad, y los problemas de susceptibilidad y vulnerabilidad. Considera los retos que se presentan a los investigadores que intentan proporcionar evidencia para los responsables políticos en estas cuestiones. Este texto acompaña otros trabajos con resultados del proyecto ESCALA, un estudio en varias ciudades de América Latina que tiene como objetivo general proporcionar resultados relevantes para la política pública. Aunque ha habido avances para mejorar la calidad del aire, gracias a la evidencia epidemiológica de que la contaminación aérea está afectando negativamente a la salud pública, las preguntas de investigación se han vuelto más sutiles y difíciles a medida que los niveles de contaminación se reducen. Se necesita más investigación, pero también nuevos métodos y enfoques capaces de enfrentar estas preguntas.

Paradoxical neostigmine-induced TOFfade: on the role of presynaptic cholinergic and adenosine receptors.

Neuromuscular transmission is clinically monitored using the train-of-four ratio (TOFratio), which is the quotient between twitch tension produced by the fourth (T4) and by the first (T1) stimulus within a train-of-four stimulation at 2Hz. Neostigmine causes a paradoxical depression of the TOFratio (TOFfade) that is amplified by intra-arterial atropine in cats. This led us to question the usefulness of the TOFratio as a sole testing element to control neostigmine-induced reversal of neuromuscular transmission block caused by non-depolarizing agents. We hypothesized that the inhibition of cholinesterase activity might increase acetylcholine bioavailability and consequently cholinoceptor activation, leading to concomitant adenosine release from nerve endings and skeletal muscle fibers. The involvement of presynaptic muscarinic and adenosine receptors in neostigmine-induced TOFfade in the rat phrenic nerve diaphragm was investigated. Blockade of adenosine A2A receptors with ZM241385 and of muscarinic M2 receptors with methoctramine or atropine amplified neostigmine-induced TOFfade. Notwithstanding TOFfade amplification, the blockade of M2 or A2A receptors increased both T1 and T4 twitch tensions above control during the first 3min of neostigmine application. Beyond that period, the T1 twitch tension returned to baseline, whereas T4 decreased further until the control value with neostigmine alone. Blockade of M1 receptors by pirenzepine did not change neostigmine-induced TOFfade, unless A2A receptors were concurrently blocked with ZM241385. Data indicate that the paradoxical neostigmine-induced fade involves presynaptic mechanisms that regulate transmitter release and synaptic adenosine accumulation, including the activation of adenosine A2A and muscarinic M2 receptors.

Efficacy of epidural lidocaine combined with tramadol or neostigmine on perineal analgesia in the horse.

REASONS FOR PERFORMING STUDY: Short duration of analgesia is among the limitations of a single epidural injection with lidocaine in horses. OBJECTIVES: To evaluate the effectiveness and safety of epidural lidocaine in combination with either tramadol or neostigmine for perineal analgesia in horses. METHODS: Epidural catheters were placed in 6 saddle horses that then were given 3 treatments: 2% lidocaine (0.2 mg/kg bwt) alone, 2% lidocaine (0.2 mg/kg bwt) plus tramadol (0.5 mg/kg bwt), and 2% lidocaine (0.2 mg/kg bwt) plus neostigmine (1.0 µg/kg bwt). The order of treatments was randomised. Haemodynamic variables, respiratory rate, rectal temperature, analgesia, motor block and behaviour scores were compared among the 3 treatments. These parameters were determined before drug administration (baseline), at 5, 10, 15, 30, 45, 60, 75 and 90 min, and every 30 min thereafter until loss of analgesia. RESULTS: Duration of analgesia was longer with lidocaine plus tramadol (210 ± 12 min) compared with lidocaine plus neostigmine (150 ± 35 min) or lidocaine alone (70 ± 12 min; P<0.05). All treatments produced mild or moderate motor block without behavioural changes. Other adverse effects were not observed in any of the horses. CONCLUSION AND POTENTIAL RELEVANCE: Further studies are required to demonstrate whether tramadol or neostigmine have a role in the management of post operative pain when coadministered with lidocaine.

Neuromuscular activity of the venoms of the Colombian coral snakes Micrurus dissoleucus and Micrurus mipartitus: an evolutionary perspective.

The venoms of coral snakes (genus Micrurus) are known to induce a broad spectrum of pharmacological activities. While some studies have investigated their potential human effects, little is known about their mechanism of action in terms of the ecological diversity and evolutionary relationships among the group. In the current study we investigated the neuromuscular blockade of the venom of two sister species Micrurus mipartitus and Micrurus dissoleucus, which exhibit divergent ecological characteristics in Colombia, by using the chick biventer cervicis nerve-muscle preparation. We also undertook a phylogenetic analysis of these species and their congeners, in order to provide an evolutionary framework for the American coral snakes. The venom of M. mipartitus caused a concentration-dependant inhibition (3-10 µg/ml) of nerve-mediated twitches and significantly inhibited contractile responses to exogenous ACh (1 mM), but not KCl (40 mM), indicating a postsynaptic mechanism of action. The inhibition of indirect twitches at the lower venom dose (3 µg/ml) showed to be triphasic and the effect was further attenuated when PLA2 was inhibited. M. dissoleucus venom (10-50 µg/ml) failed to produce a complete blockade of nerve-mediated twitches within a 3 h time period and significantly inhibited contractile responses to exogenous ACh (1 mM) and KCl (40 mM), indicating both postsynaptic and myotoxic mechanisms of action. Myotoxic activity was confirmed by morphological studies of the envenomed tissues. Our results demonstrate a hitherto unsuspected diversity of pharmacological actions in closely related species which exhibit divergent ecological characteristics; these results have important implications for both the clinical management of Coral snake envenomings and the design of Micrurus antivenom.

Peripheral control of inflammatory but not neuropathic pain by endogenous cholinergic system.

This study investigated the role of the cholinergic system in the modulation of inflammatory and neuropathic pain. The paw pressure test was used with inflammatory pain induced by intraplantar injection of carrageenan and neuropathic pain induced by sciatic nerve constriction. All drugs were locally administered into the right hindpaw of rats. Neostigmine, an acetylcholinesterase inhibitor (2, 4, 8 or 16 µg), inhibited the inflammatory pain induced by carrageenan (250 µg/paw), but not the hyperalgesia induced by prostaglandin E2 (2 µg/paw). Neostigmine (8 µg) increased the nociceptive threshold only in the treated paw, suggesting only a local effect. The muscarinic antagonist atropine (150, 300 and 600 µg) caused a reduction in the nociceptive threshold induced by carrageenan (125 µg/paw), but not by prostaglandin E2 (1 µg/paw). Atropine significantly decreased the nociceptive threshold only in the treated paw. On the other hand, in the presence of neuropathic pain, atropine (300 µg) did not alter the nociceptive threshold induced by constriction of the sciatic nerve. This study suggests that a peripheral endogenous cholinergic system involving muscarinic receptors may be activated during inflammation as a modulatory negative feedback control of inflammatory pain.

Relative contribution of pre- and post-synaptic effects to the neostigmine-induced recovery of neuromuscular transmission blocked by vecuronium.

The relative contribution of the pre- and post-synaptic effects to the neostigmine-induced recovery of neuromuscular transmission blocked by vecuronium was studied. A conjunction of myographical and electrophysiological techniques was employed. The preparation was the sciatic nerve-extensor digitorum longus muscle of the rat, in vitro. The physiological variables recorded were nerve-evoked twitches (generated at 0.1 Hz), tetanic contractions (generated at 50 Hz) and end-plate potentials (epps), generated in trains of 50 Hz. The epps were analyzed in: amplitude of first epp in the train; mean amplitude of the 30th to the 59th epp in the train (epps-plateau); half-decay time of the epp; early tetanic rundown of epps in the train; plateau tetanic rundown of epps in the train; quantal content of the epps and quantal size. In myographical experiments, a concentration of vecuronium was found (0.8 µm) that affected both twitches and tetanic contractions and a concentration of neostigmine was found (0.048 µm) that completely restored the twitch affected by vecuronium. The cellular effects of vecuronium and neostigmine, studied alone or in association, in the above-mentioned concentrations, were scrutinized by means of electrophysiological techniques. These showed that vecuronium alone decreased the peak amplitude, the quantal content of epps and the quantal size and reinforced the tetanic rundown of epps. Neostigmine alone increased the peak amplitude, the quantal content and the half-decay time of the epps. When employed in the presence of vecuronium, neostigmine increased both the quantal content of the epps (via a presynaptic effect) and the half-decay time of the epps (via a postsynaptic effect). Seeing the pre- and the post-synaptic effects of neostigmine were of similar magnitude, they permit to conclude that both these effects contributed significantly to the restoration by neostigmine of the neuromuscular transmission blocked by vecuronium.