Effects of age on a new animal model of tardive dyskinesia.

The effects of age were studied on a new animal model of tardive dyskinesia, i.e., the quantification of oral dyskinesia in rats repeatedly treated with reserpine. Adult and old rats received two injections of reserpine (0.5 or 1.0 mg/kg s.c.) or vehicle, separated by 48 h. One, 10, 25 and 40 days after the second injection of reserpine or vehicle, the animals were observed for quantification of the behavioral parameters of oral dyskinesia: tongue protrusion and vacuous chewing movement frequencies and duration of twitching of the facial musculature. Phenomenologically, control old rats and reserpine-treated adult animals showed very similar oral dyskinesia. When compared to control adult rats, the significant increase in tongue protrusion frequency induced by reserpine treatment was more persistent in the old rats than in the adult animals. Because it is well known that age increases the persistence of tardive dyskinesia, our data provide further support for the validation of reserpine-induced oral dyskinesia as an animal model of tardive dyskinesia. In addition, the possibility is raised that a common pathophysiological mechanism may underlie tardive dyskinesia and age- and reserpine-induced oral dyskinesia.

Naltrexone potentiates the anxiolytic effects of chlordiazepoxide in rats exposed to novel environments.

RATIONALE: Both novelty and naloxone have been reported to modify the anxiolytic-like effect of benzodiazepines in the elevated plus maze. In addition, it has been largely demonstrated that novelty alters endogenous opioid activity. OBJECTIVES: The present study was designed to examine a possible interaction between novelty and naltrexone effects on the behavior of chlordiazepoxide-treated rats in two animal models of anxiety. METHODS: Thirty minutes after acute intraperitoneal treatment with saline or naltrexone and saline or chlordiazepoxide, male Wistar rats were exposed for the first time to the elevated plus maze apparatus or the social interaction arena for the quantification of the percentage of time spent in the open arms or the time of active social interaction, respectively. The effects of naltrexone and/or chlordiazepoxide on the plus maze and the social interaction tests were also evaluated after previous exposure to the respective apparatus. RESULTS: Naltrexone dose dependently increased the percentage of time spent in the open arms of the elevated plus maze in chlordiazepoxide-treated (5 mg/kg i.p.) rats exposed for the first time to the apparatus. Similarly, naltrexone (5 mg/kg i.p.) increased the time spent in active social interaction by chlordiazepoxide-treated rats exposed to an unfamiliar arena. In both experiments, naltrexone had no effect when administered alone. When both the plus maze and the social interaction tests were conducted after previous exposure to the respective apparatus, naltrexone did not modify the behavior of chlordiazepoxide- or saline-treated rats. CONCLUSIONS: These data suggest that the anxiolytic-like effects of chlordiazepoxide can be modified by opioid mechanisms in novel environments.

Inalaçäo de oxido nitrico em SARA / Inhaled nitric oxide in ARDS

Os autores discutem sua experiência preliminar na administração de NO em nove pacientes adultos(30-75 anos)com SARA (LIS _> 3). A concentração de No foi ajustada a partir do efeito da inalação(de 1,5,10 ou 20 ppm)deste gás sobre a oxigenação arterial(Pa)2/FIO2). Observou-se em sete pacientes,melhora clinicamente significativa(_> 20 por cento do controle)da oxigenação. Em seis casos,a melhora permitiu interromper a administração de NO. Três mortes(choques hemorrágicos e séptico e broncopneumonia)foram registrados durante o tratamento,sem que fosse possível estabelecer relação causal entre a inalação de NO e o decesso.Discutem ainda diversos aspectos da utilização de NO na SARA. concluem que a inalação de NO representa alternativa simples,segura e eficaz no controle da hipoxemia grave,podendo com vantagem ser associada as alternativas(PEEO e posição prona)correntemente disponíveis em ventilação artificial