St John’s wort (Hypericum perforatum) diminishes cognitive impairment caused by the chronic restraint stress in rats
ABSTRACT In this study we tested the hypothesis that St John's wort (Hypericum perforatum) may counteract stress-induced memory impairment. Object recognition test and Morris water maze were used to determine whether administration of H. perforatum (350 mg kg(-1) for 21 days), standardized to 0.3% hypericin content, protects against non-spatial and/or spatial memory impairments due to chronic restraint stress (2h daily for 21 days). A group of rats administered the exogenous corticosterone at the dose of 5 mg kg(-1) daily for 21 days, yielding its similar plasma levels as these observed in stress was run in parallel. In the first experiment all rats were tested for recognition memory in the object recognition test. On the following day, the animals were tested in open field and elevated "plus" maze to control for the contribution of respectively, motor and emotional effects of our treatments to the memory tests. In the second experiment, new group of stressed animals was tested for spatial memory in the water maze. We observed that H. perforatum prevented the deleterious effects of both chronic restraint stress and long-term corticosterone on learning and memory as measured in both, the object recognition and the water maze tests. The herb not only prevented stress- and corticosterone-induced memory impairments, but it significantly improved recognition memory (p<0.01) in comparison to control. These results suggest that H. perforatum has a potential to prevent stress memory disorders.
- SourceAvailable from: Raju Senthil Kumar
- "H. perforatum commonly known as St. John's Wort is an herbaceous perennial plant that has been used in Portuguese and Turkinsh folklore medicine for the treatment of neurological disorders (Ross, 2001). The dried crude herb standardized to hypericins improved memory and learning dysfunction (Widy-Tyszkiewicz et al. 2002; Trofimiuk et al. 2005). Lu et al. (2001) reported that a standard extract of H. perforatum (hypericin) possessed neuroprotective activity. "
Article: Role of Medicinal Plants in Neurodegenerative Diseases with Special Emphasis to Alzheimer’s Disease”, by Mohamed Abdel Galil Hassan, Rajkapoor Balasubramanian, Ali Daw Masoud, Zamzam Elmahdi Burkan, Abdussalam Sughir and Raju Senthil Kumar in International Journal of Phytopharmacology, 5(6): 454-462, 2014 (Impact factor: 1.02).
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- "Time spent exploring the objects was measured manually using stopwatch. The difference in exploration between a previously seen object and a novel object was taken as an index of memory performance (recognition index, RI)    . "
ABSTRACT: Background The aim of the present study was to evaluate the involvement of the cholinergic receptors ligands in the memory-related responses in mice, using the novel object recognition (NOR) test. Methods The NOR test is based on natural, exploratory abilities of animals exposed to a new environment. In the first session, two copies of the same object were presented. In the next sessions (30 min and 24 h after), one of the familiar object and a new object were presented. Results The mice injected with nicotine (0.035 and 0.175 mg/kg, free base, sc) before the first session spent more time exploring the new object than the familiar one at the second and third session, indicating that nicotine improved cognition. In turn, the mice injected with scopolamine (0.3 and 1 mg/kg, ip) before the first session spent less time exploring the new object than the familiar one at the second and third trial, indicating that scopolamine impaired the memory performance. Additionally, the acute injection of drugs used in smoking cessation in humans: mecamylamine (0.5 and 1 mg/kg) and bupropion (5 and 10 mg/kg), prior to injections of nicotine (0.035 mg/kg) or scopolamine (1 mg/kg), significantly prevented nicotine-induced memory improvement or scopolamine-induced memory impairment, at the second and third session. Conclusions The results of our studies unveiling neuronal mechanisms for cholinergic system of memory processes, via both nicotinic and muscarinic cholinergic receptors, will be useful for development of more effective pharmacotherapies for memory impairment-like treatment of human disorders in which cholinergic pathways have been implicated.Pharmacological reports: PR 01/2014; 66(4):638–646. · 1.93 Impact Factor
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- "Three groups of animals (16, 17 and 16 rats) were subjected to chronic restraint stress  , 2 h daily for 21 days. The restraint was imposed during the light phase from 9:00 to 11:00 h. "
ABSTRACT: Long chain n-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may slow cognitive decline. DHA plays an important role in neural function and decreased plasma DHA are associated with cognitive decline in healthy elderly adults and in patients with Alzheimer's disease. In this study we tested a hypothesis that DHA protects cognitive functions of male Wistar rats against negative impact of prolonged restraint stress. Specifically, we attempted to characterize the preventive action of prolonged treatment with DHA enriched preparation (daily dose of DHA: 300mg/kg, p.o. for 21days) in comparison with positive control (fluoxetine: 10mg/kg daily, p.o. for 21days) against an impairment caused by chronic restraint stress (2h daily for 21days) on recognition memory tested in a object recognition task and on the spatial working memory tested in Morris water maze. We found that administration of DHA enriched preparation prevented deleterious effects of chronic restraint stress both on recognition (p<0.01) and on the working spatial memory (p<0.001).Physiology & Behavior 05/2013; 118. DOI:10.1016/j.physbeh.2013.05.002 · 2.98 Impact Factor