Memory-impairing effects of local anesthetics in an elevated plus-maze test in mice

Post-training intracerebroventricular administration of procaine (20 µg/µl) and dimethocaine (10 or 20 µg/µl), local anesthetics of the ester class, prolonged the latency (s) in the retention test of male and female 3-month-old Swiss albino mice (25-35 g body weight; N = 140) in the elevated plus-maze (mean ± SEM for 10 male mice: control = 41.2 ± 8.1; procaine = 78.5 ± 10.3; 10 µg/µl dimethocaine = 58.7 ± 12.3; 20 µg/µl dimethocaine = 109.6 ± 5.73; for 10 female mice: control = 34.8 ± 5.8; procaine = 55.3 ± 13.4; 10 µg/µl dimethocaine = 59.9 ± 12.3 and 20 µg/µl dimethocaine = 61.3 ± 11.1). However, lidocaine (10 or 20 µg/µl), an amide class type of local anesthetic, failed to influence this parameter. Local anesthetics at the dose range used did not affect the motor coordination of mice exposed to the rota-rod test. These results suggest that procaine and dimethocaine impair some memory process(es) in the plus-maze test. These findings are interpreted in terms of non-anesthetic mechanisms of action of these drugs on memory impairment and also confirm the validity of the elevated plus-maze for the evaluation of drugs affecting learning and memory in mice

Cardiovascular responses to microinjections of GABA or anesthetics into the rostral ventrolateral medulla of conscious and anesthetized rats

The rostral ventrolateral medulla (RVLM) contains neurons involved in tonic and reflex control of arterial pressure. We describe the effects of gamma-aminobutyric acid (GABA) and anesthetics injected into the RVLM of conscious and urethane (1.2 g/kg, iv) anesthetized Wistar rats (300-350 g). In conscious rats, bilateral microinjection of GABA (50 nmol/200 nl) induced a small but significant decrease in blood pressure (from 130 ± 3.6 to 110 ± 5.6 mmHg, N = 7). A similar response was observed with sodium pentobarbital microinjection (24 nmol/200 nl). However, in the same animals, the fall in blood pressure induced by GABA (from 121 ± 8.9 to 76 ± 8.8 mmHg, N = 7) or pentobarbital (from 118 ± 4.5 to 57 ± 11.3 mmHg, N = 6) was significantly increased after urethane anesthesia. In contrast, there was no difference between conscious (from 117 ± 4.1 to 92 ± 5.9 mmHg, N = 7) and anesthetized rats (from 123 ± 6.9 to 87 ± 8.7 mmHg, N = 7) when lidocaine (34 nmol/200 nl) was microinjected into the RVLM. The heart rate variations were not consistent and only eventually reached significance in conscious or anesthetized rats. The right position of pipettes was confirmed by histology and glutamate microinjection into the RVLM. These findings suggest that in conscious animals the RVLM, in association with the other sympathetic premotor neurons, is responsible for the maintenance of sympathetic vasomotor tone during bilateral RVLM inhibition. Activity of one or more of these premotor neurons outside the RVLM can compensate for the effects of RVLM inhibition. In addition, the effects of lidocaine suggest that fibers passing through the RVLM are involved in the maintenance of blood pressure in conscious animals during RVLM inhibition.

Effects of different general anesthetics on serum hemolysis and hepatic and muscular glycogenolysis in rats

Anesthetics can affect the structure and biological function of tissues and systems differentially. The aim of the present study was to compare three injectable anesthetics generally used in experiments with animals in terms of the degree of hemolysis and glycogenolysis occurring after profound anesthesia. Twenty-four male Wistar rats (330-440 g) were divided into three groups (N = 8): chloral hydrate (CH), ketamine + xylazine (KX), Zoletil 50® (zolazepam and tiletamine) + xylazine (ZTX). After deep anesthesia, total blood was collected. The liver and white (WG) and red gastrocnemius (RG) muscles were also immediately removed. The degree of serum hemolysis was quantified on the basis of hemoglobin concentration (g/L). Hepatic and muscular glycogen concentrations (mmol/kg wet tissue) were quantified by the phenol-sulfuric method. The CH and KX groups exhibited serum hemolysis (4.0 ± 2.2 and 1.9 ± 0.9 g/L, respectively; P < 0.05) compared to the ZTX group, which presented none. Only KX induced elevated glycogenolysis (mmol/kg wet tissue) in the liver (86.9 ± 63.2) and in WG (18.7 ± 9.0) and RG (15.2 ± 7.2; P < 0.05). The CH and ZTX groups exhibited no glycogenolysis in the liver (164.4 ± 41.1 and 176.8 ± 54.4, respectively), WG (28.8 ± 4.4, 32.0 ± 6.5, respectively) or RG (29.0 ± 4.9; 25.3 ± 8.6, respectively). Our data indicate that ZTX seems to be an appropriate general anesthetic for studies that seek to simultaneously quantify the concentration of glycogen and serum biochemical markers without interferences. ZTX is reasonably priced, found easily at veterinary markets, quickly induces deep anesthesia, and presents a low mortality rate.

Suboptimal use of inhaled corticosteroids in children with persistent asthma : inadequate physician prescription, poor patient adherence or both ?

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Presentación de cámara anestésica de bajo costo como herramienta didáctica para explicar los fundamentos de la anestesia general a estudiantes de medicina veterinaria

Se presenta el uso de una cámara anestésica de bajo costo, construida en vidrio, de fácil manejo y limpieza, como recurso didáctico, para explicar, en ratones de laboratorio, los fundamentos de la anestesia general inhalatoria a estudiantes de medicina veterinaria. La cámara permite adecuada dosificación del anestésico, garantiza la vida de los animales y disminuye la exposición de profesores y estudiantes a los gases anestésicos. Así, se pueden abordar didácticamente los aspectos básicos de la anestesia general inhalada, como el efecto de la concentración del anestésico en el aire inspirado y solubilidad.

Deposition of charged inhaled aerosols with transient airflow in sequential lung airway model

Transport and deposition of charged inhaled aerosols in double planar bifurcation representing generation three to five of human respiratory system has been studied under a light activity breathing condition. Both steady and oscillatory laminar inhalation airflow is considered. Particle trajectories are calculated using a Lagrangian reference frame, which is dominated by the fluid force driven by airflow, gravity force and electrostatic forces (both of space and image charge forces). The particle-mesh method is selected to calculate the space charge force. This numerical study investigates the deposition efficiency in the three-dimensional model under various particle sizes, charge values, and inlet particle distribution. Numerical results indicate that particles carrying an adequate level of charge can improve deposition efficiency in the airway model.

Numerical modeling of inhaled charged aerosol deposition in human airways

A new numerical modeling of inhaled charge aerosol has been developed based on a modified Weibel's model. Both the velocity profiles (slug and parabolic flows) and the particle distributions (uniform and parabolic distributions) have been considered. Inhaled particles are modeled as a dilute dispersed phase flow in which the particle motion is controlled by fluid force and external forces acting on particles. This numerical study extends the previous numerical studies by considering both space- and image-charge forces. Because of the complex computation of interacting forces due to space-charge effect, the particle-mesh (PM) method is selected to calculate these forces. In the PM technique, the charges of all particles are assigned to the space-charge field mesh, for calculating charge density. The Poisson's equation of the electrostatic potential is then solved, and the electrostatic force acting on individual particle is interpolated. It is assumed that there is no effect of humidity on charged particles. The results show that many significant factors also affect the deposition, such as the volume of particle cloud, the velocity profile and the particle distribution. This study allows a better understanding of electrostatic mechanism of aerosol transport and deposition in human airways.

Microbiological insights into respiratory infections and the opportunities for inhaled therapy

Respiratory infections represent the fourth most common cause of all deaths across age groups and countries. Treating these infections appropriately is a clear clinical priority and here we outline the types of therapy that are in current use for some of these infections. It is important that treatments are further improved and the potential of inhaled delivery to fulfil this need is considered. We describe novel methodologies that are being applied for the identification and enumeration of microorganisms in the respiratory tract, and propose that ways of improving therapy may arise from understanding better the etiology of respiratory infection and the impact of inhaled drug therapies. The potential for translational benefits for patients are also discussed.

Effects of inhaled Linalool in anxiety, social interaction and aggressive behavior in mice

Aromatherapy uses essential oils (EOs) for several medical purposes, including relaxation. The association between the use of aromas and a decrease in anxiety could be a valuable instrument in managing anxiety in an ever increasing anxiogenic daily life style. Linalool is a monoterpene commonly found as the major volatile component of EOs in several aromatic plant species. Adding to previously reported sedative effects of inhaled linalool, the aim of this study was to investigate the effects of inhaled linalool on anxiety, aggressiveness and social interaction in mice. Additionally, we investigated the effects of inhaled linalool on the acquisition phase of a step-down memory task in mice. Inhaled linalool showed anxiolytic properties in the light/dark test, increased social interaction and decreased aggressive behavior; impaired memory was only seen the higher dose of linalool. These results strengthen the suggestion that inhaling linalool rich essential oils can be useful as a mean to attain relaxation and counteract anxiety. (C) 2009 Elsevier GmbH. All rights reserved.

Inhaled linalool-induced sedation in mice

Linalool is a monoterpene often found as a major component of essential oils obtained from aromatic plant species., many of which are used in traditional medical systems as hypno-sedatives. Psychopharmacological evaluations of linalool (i.p. and i.c.v.) revealed marked sedative and anticonvulsant central effects in various mouse models. Considering this profile and alleged effects of inhaled lavender essential oil, the purpose of this study was to examine the sedative effects of inhaled linalool in mice. Mice were placed in an inhalation chamber during 60 min, in an atmosphere saturated with 1% or 3% linalool. Immediately after inhalation, animals were evaluated regarding locomotion, barbiturate-induced sleeping time, body temperature: and motor coordination (rota-rod test). The 1% and 3% linalool increased (p < 0.01) pentobarbital sleeping time and reduced (p<0.01) body temperature. The 3% linalool decreased (p<0.01) locomotion. Motor coordination was not affected. Hence, linalool inhaled for I h seems to induce sedation without significant impairment in motor abilities, a side effect shared by most psycholeptic drugs. (C) 2008 Elsevier GmbH. All rights reserved.

Micro and nanosystems for delivering local anesthetics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Benzocaine and eugenol as anesthetics for Brycon hilarii

A utilização de produtos anestésicos durante práticas de manejo é frequentemente empregada, porém doses corretas de diferentes fármacos e para espécies distintas ainda estão em fases de pesquisa. O objetivo do estudo foi determinar a melhor concentração de benzocaína e eugenol para juvenis de piraputanga (B. hilarii). Foram utilizados 104 juvenis de piraputanga com peso médio de 50,04 ± 20,80 g e comprimento total médio de 16,30 ± 12,32 cm adquiridos em uma piscicultura comercial localizada na região Oeste do Estado do Paraná. O trabalho foi conduzido no Laboratório de Aquicultura do Grupo de Estudos de Manejo na Aquicultura - GEMAq da Universidade Estadual do Oeste do Paraná (UNIOESTE). Os animais foram submetidos a cinco concentrações de benzocaína (50,0; 100,0; 150,0; 200,0 e 250,0 mg L-1) e sete concentrações de eugenol (50,0; 100,0; 150,0; 200,0; 250,0; 300,0 e 350 mg L-1), para a aferição dos tempos referentes à letargia. Para a recuperação, os animais foram mantidos em aquários livre do anestésico e observado o tempo em que retornaram às atividades normais. A melhor dose de benzocaína verificada foi de 100 mg L-1, enquanto a melhor dose de eugenol foi entre 100 e 150 mg L-1.