Different effects of L-arginine on morphine tolerance in sham and ovariectomized female mice

Objective  

The roles of gonadal hormones and nitric oxide (NO) on the analgesic effects of morphine, tolerance to morphine, and their interactions have been widely investigated. In the present study, the effect of l-arginine (an NO precursor) on morphine tolerance in sham and ovariectomized (OVX) female mice was investigated.     

Extended exposure to environmental cues,but not to sucrose,reduces sucrose cue reactivity in rats

In the present study, we examined the effects of extinction of sucrose-predictive contextual cues and/or sucrose satiation on the expression of sucrose cue reactivity in a rat model of relapse. Context extinction was imposed by housing rats in their home cage or in the operant conditioning chamber for 17 h prior to testing. For sucrose satiation, rats were allowed unlimited access to water or sucrose for 17 h prior to testing. Cue reactivity was assessed after either one (Day 1) or 30 (Day 30) days of forced abstinence from sucrose self-administration. An abstinence-dependent increase in sucrose cue reactivity was observed in all conditions (“incubation of craving”). Context extinction dramatically reduced lever responding on both Day 1 and Day 30. Sucrose satiation had no significant effect on cue reactivity in any condition. These results demonstrate that the context in which self-administration occurs maintains a powerful influence over cue reactivity, even after extended forced abstinence. In contrast, the primary reinforcer has little control over cue reactivity. These findings highlight the important role of conditioned contextual cues in driving relapse behavior.     

骄横而不奸恶大俗而见谐趣--论《红楼梦》中的薛蟠形象

人物创造 ,是《红楼梦》创作成就的主要标志。作者笔下的几百个人物形象 ,至少有几十、乃至上百个人物性格鲜明 ,栩栩如生 ,是文学史上不可多得的艺术形象。其中大部分为女性。男性人物除贾宝玉外 ,大多花笔墨较少 ,然亦不乏成功的典型形象 ,而薛蟠即是其中之一。但历来论者甚少 ,似乎对其不屑一顾。其实 ,笔者认为 ,此人也是曹雪芹精心设计、细致刻画 ,塑造最为鲜活生动的人物形象 ,是书中共性与个性有机结合、现实丑与艺术美高度统一的艺术典型。     

Sticks and stones will break my bones but failure feedback may not hurt me: gender differences in the relationship between achievement motive,coping strategies and environmental mastery

This study investigates the processes through which achievement motivation guides the selection of coping strategies which in turn affects environmental mastery post-failure feedback. Seventy-six college students received failure feedback after completing a professional aptitude test. Findings showed that gender moderated the relationship between Hope of Success (HS) and planful problem-solving coping but not between HS and escape-avoidance coping. No moderated mediation was found when HS was used to predict environmental mastery with gender as the moderator and either planful problem-solving or escape-avoidance coping as the mediator. Simple mediation analyses showed that planful problem-solving did not mediate the relationship between HS and environmental mastery. Instead, higher scores on HS predicted lower use of escape-avoidance coping which in turn predicted higher environmental mastery. Implications for the role of feedback in educational settings are discussed.