RESUMEN
Food restriction has been shown to be beneficial for a number of brain processes. In the current study, we characterized the impact of food restriction on hippocampal damage 70 days following ischemia. We assessed memory and cognitive flexibility of ad libitum fed (AL) and food-restricted (FR) animals using complex delayed non-matching- and matching-to-sample tasks in the radial arm maze. Our findings demonstrate that food restriction led to significant improvement of ischemia-induced memory impairments. FR ischemic animals rapidly reached comparable performance as both AL and FR sham animals in delayed-non-matching (win-shift) and matching (win-stay) radial arm maze tasks. They also made considerably fewer microchoices in the retention trials than AL ischemic animals. In contrast, AL ischemic rats showed persistent spatial memory impairments in the same paradigms. Assessment of basal and stress-induced corticosterone (CORT) secretion revealed no significant differences in baseline levels in AL and FR rats prior to or following global ischemia. However, FR animals showed a more pronounced attenuation of CORT secretion 45 min following restraint. Both FR and AL ischemic rats had comparable cell loss within CA1 and CA3 subfields of Ammon's horn (CA1 and CA3) at 70 days following reperfusion, although a trend toward increased CA3 cell survival was observed in FR ischemic rats. The functional sparing in the FR ischemic animals in the face of equivalent hippocampal cell loss suggests that food restriction somehow enhanced the efficacy of remaining hippocampal or extrahippocampal neurons following ischemia. In the current study, this phenomenon was not associated with diet- and or ischemia-related alterations of vesicular glutamate transporter 1 expression in various hippocampal regions although lower vesicular GABA transporter immunostaining was present in the CA1 stratum oriens and the CA3 stratum radiatum in FR sham and ischemic rats.
Asunto(s)
Isquemia Encefálica/complicaciones , Restricción Calórica/métodos , Privación de Alimentos , Aprendizaje por Laberinto , Trastornos de la Memoria/dietoterapia , Recuperación de la Función , Animales , Peso Corporal , Encéfalo/metabolismo , Encéfalo/fisiopatología , Supervivencia Celular , Cortisona/sangre , Cortisona/metabolismo , Modelos Animales de Enfermedad , Hipocampo/irrigación sanguínea , Hipocampo/patología , Hipocampo/fisiopatología , Masculino , Trastornos de la Memoria/etiología , Trastornos de la Memoria/fisiopatología , Degeneración Nerviosa/etiología , Degeneración Nerviosa/fisiopatología , Degeneración Nerviosa/terapia , Neuronas/metabolismo , Neuronas/patología , Ratas , Ratas Wistar , Daño por Reperfusión/complicaciones , Estrés Psicológico/metabolismo , Estrés Psicológico/fisiopatología , Proteína 1 de Transporte Vesicular de Glutamato/metabolismoRESUMEN
The objective of this article is to understand the evolution of the practice of "elsewhere" and "otherwise" that alternative community resources in Québec have consistently advocated. Towards this end, we begin by identifying the meaning and significance of the ideas of "elsewhere" and "otherwise" in the context of the transformation of Quebec's mental health system since 1989. Then we present the results of an exploratory study carried out between 1997 and 1999 in which the coordinators as well as members of 6 community mental health organisations in a semi-urban region of Quebec were interviewed. The results of the study suggest the validity of certain fears that community resources are becoming "deradicalized." The analysis presented here suggests the unfolding of a complex process involving the integration of alternative resources into the broader public mental health system, internal dynamics, and the emerging limitations of the vision of "elsewhere" and "otherwise" that has guided them until now. Twenty years after alternative community resources appeared on the Quebec mental health scene, is it time to reform the philosophy of "elsewhere" and "otherwise"?
Asunto(s)
Servicios Comunitarios de Salud Mental/tendencias , Prestación Integrada de Atención de Salud/tendencias , Recursos en Salud/tendencias , Predicción , Humanos , QuebecRESUMEN
Repetitive stimulation of mammalian fast-twitch skeletal muscles will normally result in a positive staircase response. This phenomenon was investigated in the rat gastrocnemius muscle following a 2-week period of tetrodotoxin-induced disuse. Muscle inactivity was imposed by superfusing tetrodotoxin in saline over the left sciatic nerve via an implanted osmotic pump. In situ isometric contractile responses to double pulse stimulation and repetitive stimulation at 10 Hz were determined the day after removal of the pump. Two weeks of disuse resulted in 40% muscle weight loss. A twitch contraction gave the same force when expressed per gram of wet muscle weight in control muscles, 317 +/- 24.6 (means +/- SE) g/g, as compared with tetrodotoxin-treated muscles, 328 +/- 24.2 g/g. Both contraction time and half-relaxation time were prolonged following treatment with tetrodotoxin. Repetitive stimulation at 10 Hz resulted in a positive staircase response in the control muscles, but not in muscles of the tetrodotoxin-treated rats. The observed changes in the time course of the twitch contraction with repetitive stimulation following tetrodotoxin-induced disuse are consistent with alterations in sarcoplasmic reticulum handling of calcium. It is not certain if there is a change following disuse in the mechanism normally associated with staircase or if this mechanism is merely opposed by an early fatigue.