(R)-methanandamide, but not anadamide, substitutes for Δ–9-THC in a drug-discrimination procedure.

Fourteen male rats were trained to discriminate between injections of 2 mg/kg delta-9 tetrahydrocannabinol (Δ–9-THC) and vehicle in a 2-lever operant drug-discrimination paradigm. Following training, substitution tests using a cumulative dosing procedure revealed that anandamide (0.5-16 mg/kg ip), the putative endogenous cannabinoid receptor ligand, failed to generalize to the discriminative stimulus properties of the training dose of Δ–9-THC. However, dose-dependent generalization to the Δ–9-THC cue was observed following administration of both CP-55,940 (0.05-0.8 mg/kg ip), a synthetic cannabinoid, and (R)-methanandamide (0.5-8 mg/kg ip), a metabolically stable analog of anandamide. Collectively, these results demonstrate a cannabinoid-specific in vivo effect of an anandamide compound and suggest that the naturally occurring form of anandamide may be metabolized too rapidly to produce a cannabimimetic interoceptive state when administered peripherally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

从WTO蕴涵的教育理念看中国成人高等教育的变革

加入WTO,标志着我国改革开放进入了一个新的里程,这不仅意味着中国的经济将发生深刻变化,而且WTO的游戏规则和其所蕴涵的教育理念也将对中国教育尤其是对我国的成人高等教育产生亘久而深远的影响,成人高等教育传统的教育观念、教学模式、教育体制等将因此发生根本变革.     

Effects of acute trimethyltin exposure on appetitive acquisition and extinction performance in the adult rat.

16 adult male Sprague-Dawley rats were given an intragastric infusion of 7 mg/kg of trimethyltin chloride (TMT), and 16 additional Ss (controls) received saline, to investigate TMT's effect on Ss' appetitive acquisition and extinction performance. Ss from each condition were divided into 2 equal groups and trained with either partial or continuous reinforcement (PRF or CRF) in a straight-alley maze 21 days after dosing. The acquisition training phase contained 40 trials (4 trials/day) and was followed by 20 trials of extinction training (4 trials/day). Analyses performed on total speed revealed that TMT Ss performed at lower levels during acquisition than controls, regardless of schedule condition. Also, the rate of resistance to extinction was significantly reduced for TMT Ss compared with that of controls, regardless of the training schedules used during acquisition. A PRF extinction effect was observed for both control and TMT Ss, independent of dose regimen. PRF training occasioned greater persistence during extinction than did CRF training. Findings are discussed in terms of issues relating to TMT-induced hippocampal lesions. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immunization against learned helplessness in man.

Immunization against learned helplessness has been found in dogs and rats; the present experiments tested for the same effect in humans. In Exp I, 38 college students were divided into 4 groups. A helplessness control group received no immunization training, whereas 3 other groups received either a 0, 50, or 100% schedule of success on a series of discrimination problems. All groups were then given insoluble problems and were subsequently tested on a human shuttle box. An immunization effect against helplessness was produced; the 50% immunization schedule produced performance significantly superior to the helplessness control and 0% groups. The 100% group failed to produce the immunization effect. Exp II with 45 Ss involved a partial replication of the 1st experiment, but anagram solutions were used as the test task. Also, control groups based on the triadic design were included in Exp II. Results for the 2nd experiment essentially paralleled the results from Exp I. Immunization effects were shown following a 50% schedule but not following either 0 or 100% immunization schedule. These findings lend substantial support to the stimulus–response explanation of helplessness phenomena over the expectancy-of-independence explanation. Implications of the study for the helplessness model of depression and for strategies in clinical therapy are also discussed. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of acquisition training schedule on extinction and reinstatement of cocaine self-administration in male rats.

Partial reinforcement is known to increase resistance to extinction (Rn) relative to training with continuous reinforcement. This phenomenon, referred to as the partial reinforcement extinction effect, is one of the most robust in learning and conditioning studies. Experiment 1 investigated manipulations known to affect the partial reinforcement extinction effect and determined their possible relevance for drug use patterns. Male rats received intravenous cocaine self-administration training under partial reinforcement (FR-10) training or continuous reinforcement (FR-1) conditions with either a low (0.25 mg/kg infusion) or a high cocaine dose (1.00 mg/kg infusion). Animals were placed on an extinction (recurrent nonreward) schedule for 10 days (1-hr sessions) prior to being tested for cue-induced reinstatement (single 2-hr session). Experiment 2 involved acquisition of cocaine self-administration under FR-1 conditions of short training (15 days) or extended training (30 days) with a low dose (0.25 mg/kg infusion) or a medium dose (0.50 mg/kg infusion) of cocaine reward prior to extinction or reinstatement. Experiment 1 showed that rats trained with FR-10-high dose outcomes exhibited greater Rn than the remaining groups. Additionally, FR-10-high dose and FR-10-low dose rats were more likely to return to active drug seeking during the reinstatement test. In Experiment 2, rats trained under FR-1-medium dose conditions were more persistent during extinction following short acquisition training than comparable rats experiencing extended acquisition training. The reinstatement test was conducted following extinction, in which it was observed that overtraining under FR-1-medium dose reward schedules resulted in a decrease in the tendency to return to active drug seeking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shifting development in mid-childhood: The influence of between-task interference.

Performance on the task-switching paradigm is greatly affected by the amount of conflict between tasks. Compared to adults, children appear to be particularly influenced by this conflict, and this suggests that the ability to resolve interference between tasks improves with age. The authors used the task-switching paradigm to investigate how this ability develops in mid-childhood. Experiment 1 compared the ability of 5- to 8-year-olds and of 9- to 11-year-olds to switch between decisions about the color and shape of an object. The 5- to 8-year-olds were slower to switch task and experienced more interference from the irrelevant task than did the 9- to 11-year-olds, which suggests a developmental improvement in resolving conflict between tasks during mid-childhood. In Experiment 2, the influence of stimulus and response interference at different ages was examined by separating the color and shape dimensions of the stimulus and reducing overlap between responses. The results support the development of conflict resolution in task switching during mid-childhood. They also revealed that a complex interplay of factors, including the tasks used and previous experience with the task, affected children’s shifting performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of consistency, frequency, and semantics on learning to read: An artificial orthography paradigm.

Two experiments explored learning, generalization, and the influence of semantics on orthographic processing in an artificial language. In Experiment 1, 16 adults learned to read 36 novel words written in novel characters. Posttraining, participants discriminated trained from untrained items and generalized to novel items, demonstrating extraction of individual character sounds. Frequency and consistency effects in learning and generalization showed that participants were sensitive to the statistics of their learning environment. In Experiment 2, 32 participants were preexposed to the sounds of all items (lexical phonology) and to novel definitions for half of these items (semantics). Preexposure to either lexical phonology or semantics boosted the early stages of orthographic learning relative to Experiment 1. By the end of training, facilitation was restricted to the semantic condition and to items containing low-frequency inconsistent vowels. Preexposure reduced generalization, suggesting that enhanced item-specific learning was achieved at the expense of character-sound abstraction. The authors' novel paradigm provides a new tool to explore orthographic learning. Although the present findings support the idea that semantic knowledge supports word reading processes, they also suggest that item-specific phonological knowledge is important in the early stages of learning to read. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Glucuronidation of dihydrocodeine by human liver microsomes and the effect of inhibitors

1. Glucuronidation is the major route of metabolism of dihydrocodeine (DHC) and accounts for 25-30% of an oral dose in urine. The kinetics of DHC-6-glucuronide formation in liver microsomes from five human donors and the effect of a number of potential inhibitor drugs were examined using a newly developed and validated HPLC assay. 2. The formation of DHC-6-glucuronide exhibited atypical kinetics that conformed to the Hill equation. The mean intrinsic dissociation constant (Ks) and maximum velocity (Vmax) values were 1566 micromol/L and 0.043 micromol/min per g, respectively. The Ks and Vmax values varied 1.5- and 3.5-fold, respectively. 3. Seven drugs were tested for inhibitory effects on DHC glucuronidation at low (50 micromol/L) and high (500 micromol/L) concentrations. At 50 micromol/L, only diclofenac produced greater than 50% inhibition, while at concentrations of 500 micromol/L inhibition was greater than 35% for diclofenac, amitriptyline, oxazepam, naproxen, chloramphenicol and probenecid, but not paracetamol. 4. The present study found little interindividual variation in the activity of human liver microsomes for glucuronidation of DHC. Comparison of the results from the inhibition studies with those reported previously for codeine and morphine suggest that the UDP-glucuronosyltransferase isoform UGT2B7 is involved in the glucuronidation of DHC.