Methylphenidate (MPH) abuse causes adverse neurobehavioral and neurochemical effects. Some herbal components such as crocin have shown neuroprotective properties. The current study evaluates the potential role of the cyclic AMP response element binding protein (CREB)-brain-derived neurotrophic factor (BDNF) signaling pathway in mediating the neuroprotective effects of crocin against MPH-induced neurotoxicity in rats. Seventy adult male rats were randomly divided into seven groups. Group 1 and 2 received 0.7 ml/rat of normal saline and 10 mg/kg of MPH, respectively. Groups 3, 4, 5, and 6 were treated simultaneously with MPH (10 mg/kg) and crocin (10, 20, 40, and 80 mg/kg, respectively) for 21 days. Group 7 was treated with crocin (80 mg/kg) alone for 21 days. The Morris water maze (MWM) and open field test were used to assess cognitive and locomotor activities. Hippocampal neurotoxicity parameters and levels of BDNF and CREB were evaluated. Simultaneous treatment with various doses of crocin reduced the MPH-induced cognition disturbances and hyperlocomotion. In addition, lipid peroxidation increased with MPH treatment and levels of the oxidized forms of glutathione (GSSG), interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and Bax increased. MPH treatment decreased levels of the reduced form of glutathione (GSH), P-CREB, Bcl-2, and BDNF in the hippocampus. MPH also reduced activity of superoxide dismutase, glutathione peroxidase, and glutathione reductase in the hippocampus. In contrast, crocin attenuated MPH-induced oxidative stress, inflammation, and apoptosis, and increased levels of P-CREB and BDNF. Thus, crocin-likely via stimulation of the P-CREB/BDNF signaling pathway-displayed neuroprotection against MPH-induced neurotoxicity.
This study investigated the impact of task types on English learners' receptive and productive vocabulary knowledge. A total of 125 (70 female and 55 male) first year ELT students from eight intact classes taking Academic Reading Course in the winter semester of 2017-2018 were assigned to four experimental groups randomly and a control group randomly assigned to one of five tasks of learning 45 target words. The design of the tasks was based on the involvement load hypothesis (ILH) arguing that learning of unfamiliar words to be contingent on the amount of task induced involvement. The components of involvement in ILH include need (N), search (S), and evaluation (E). In this study, the tasks induced the same or different involvement loads regarding the presence and strength of each component: writing (+N, +S, ++E), combining (+N, -S, +E), fill in the blank (+N, -S, +E), definition (+N, -S, +E), and control (-N, -S, -E). After the last treatment session, both receptive and productive knowledge of the target words were measured. Moreover, an unexpected delayed post-test was administered 1 month later. The results revealed that all output tasks were more effective than the control task in enhancing the participants' receptive and productive vocabulary knowledge.
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