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ÖZBEYLİ, DİLEK

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Author: YÜKSEL, MERAL × Subject: Acute stress ×

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    Protective effect of low dose caffeine on psychological stress and cognitive function
    (PERGAMON-ELSEVIER SCIENCE LTD, 2017) AKAKIN, DİLEK; Cakir, Ozgur Kasimay; Ellek, Nurfitnat; Salehin, Nabila; Hamamci, Rabia; Keles, Hulya; Kayali, Damla Gokceoglu; Akakin, Dilek; Yuksel, Meral; Ozbeyli, Dilek
    Introduction: Caffeine is an adrenergic antagonist that enhances neuronal activity. Psychological stress depresses cognitive function. Aim: To investigate the effects of acute and chronic low dose caffeine on anxiety-like behavior and cognitive functions of acute or chronic psychological stressed rats. Material-method: Acute or chronic caffeine (3 mg/kg) was administered to male Sprague Dawley rats (200-250 g, n = 42) before acute (cat odor) and chronic variable psychological stress (restraint overcrowding stress, elevated plus maze, cat odor, forced swimming) induction. Anxiety and cognitive functions were evaluated byhole-board and object recognition tests. The brain glutathione and malondialdehyde assays, myeloperoxidase, nitric oxide (NO), superoxide dismutase (SOD), luminol and lucigenin activity and histological examination were done. ANOVA and Student's t-test were used for statistical analysis. Results: The depressed cognitive function with chronic stress exposure and the increased anxiety-like behavior with both stress inductions were improved via both caffeine applications (p < 0.05-0.001). Both caffeine pretreatments in chronic stressed rats, and chronic caffeine in acute stressed ones reduced the elevated myeloperoxidase activities (p < 0.05-0.01). The increased malondialdehyde, lucigenin and NO levels with acute stress were inhibited with chronic caffeine (p < 0.05-0.01), malondialdehyde and NO levels were declined by acute caffeine (p < 0.001). Acute caffeine decreased SOD activity (p < 0.01) and improved glutathione (p < 0.01) and luminol levels (p < 0.05). The induced histological damage with both stress exposures was ameliorated with chronic caffeine. Conclusion: The increased anxiety-like behavior and depleted cognitive functions under stress conditions were improved with both acute and predominantly chronic caffeine pretreatments by decreasing oxidative damage parameters. (C) 2016 Elsevier Inc. All rights reserved.
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    Protective effect of exercise and sildenafil on acute stress and cognitive function
    (PERGAMON-ELSEVIER SCIENCE LTD, 2015) AKAKIN, DİLEK; Ozbeyli, Dilek; Gokalp, Ayse Gizem; Koral, Tolga; Ocal, Onur Yuksel; Dogan, Berkay; Akakin, Dilek; Yuksel, Meral; Kasimay, Ozgur
    Introduction: There are contradictory results about the effects of exercise and sildenafil on cognitive functions. Aim: To investigate the effects of sildenafil pretreatment and chronic exercise on anxiety and cognitive functions. Method: Wistar rats (n = 42) were divided as sedentary and exercise groups. A moderate-intensity swimming exercise was performed for 6 weeks, 5 days/week, 1 h/day. Some of the rats were administered orogastrically with sildenafil (25 mg/kg/day) either acutely or chronically. Exposure to cat odor was used for induction of stress. The level of anxiety was evaluated by elevated plus maze test, while object recognition test was used to determine cognitive functions. Brain tissues were removed for the measurement of myeloperoxidase (MPO), malondialdehyde (MDA), nitric oxide levels, lucigenin-enhanced chemiluminescence, and for histological analysis. Results: Increased MPO and MDA levels in sedentary-stressed rats were decreased with sildenafil applications. Chronic exercise inhibited the increase in MPO levels. Increased nitric oxide and lucigenin chemiluminescence levels in sedentary-stressed rats, were diminished with chronic sildenafil pretreatment. The time spent in the open arms of the plus maze was declined in sedentary-stressed rats, while chronic sildenafil pretreatment increased the time back to that in non-stressed rats. Acute sildenafil application to exercised rats prolonged the time spent in open arms as compared to non-treated exercise group. The time spent with the novel object, which was decreased in sedentary-stressed rats, was increased with sildenafil pretreatment. Our results suggest that sildenafil pretreatment or exercise exerts a protective effect against acute stress and improves cognitive functions by decreasing oxidative damage. (C) 2015 Elsevier Inc All rights reserved.