Effects Of Tualang Honey On Memory Performance, Depressive-Like Behaviour, Histological And Biochemical Changes In Young And Old Male Rats Exposed To Loud Noise Stress
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Date
2016-05
Authors
Azman, Khairunnuur Fairuz
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Ageing and stress exposure may lead to memory impairment and depression while oxidative stress is thought to be one of the underlying mechanisms involved. The search for cognitive enhancers from natural products derivatives possessing antioxidants has gained much attention. Thus, this study aimed to examine the effects of ageing and stress on memory performance and depressive-like behaviour, and to elucidate the possible mechanisms underlying therapeutic efficacy of Tualang honey in improving memory performance and depressive symptoms in young and old male rats exposed to loud noise stress. Ninety six male Sprague Dawley rats were divided into eight groups: i) unstressed young with placebo, ii) unstressed young with honey, iii) stressed young with placebo, iv) stressed young with honey, v) unstressed old with placebo, vi) unstressed old with honey, vii) stressed old with placebo and viii) stressed old with honey. The honey supplementation was given orally, 200 mg/kg body weight for 35 days. All animals were subjected to novel object recognition test (NORT) and forced swim test (FST) prior to honey supplementation as well as before and after the noise stress procedure. Upon completion of the experiment, rats were lightly anaesthetised with ether and immediately killed by decapitation, and their blood and brain samples were collected. The right brain hemisphere was homogenised and used to measure levels/activities of antioxidant enzymes, oxidative markers, total antioxidant capacity (TAC), brain-derived neurotrophic factor (BDNF)
and acetylcholinesterase (AChE) using commercially available assay kits. The left brain hemisphere was fixed in 10% formalin for histological study of medial prefrontal cortex (mPFC) and hippocampus. Serum corticosterone, adrenocorticotropic hormone (ACTH) and testosterone levels were also measured using commercially available assay kits. The present study demonstrated that there were significant main effects of age on depressive-like behaviour, levels/activities of corticosterone, ACTH, testosterone, TAC, SOD, GPx, GR, CAT, MDA, PCO, BDNF, AChE and number of Nissl-positive cells in the mPFC and all the hippocampal regions. There were significant main effects of stress on memory performance, depressive-like behaviour, levels/activities of corticosterone, ACTH, testosterone, TAC, SOD, GPx, GR, CAT, MDA, PCO, BDNF and number of Nissl-positive cells in the mPFC and hippocampal CA2 and CA3 regions. Tualang honey supplementation was able to improve memory performance and depressive-like behaviour, increase the levels/activities of TAC, SOD, GR, BDNF, testosterone and enhance the neuronal proliferation in the mPFC and hippocampus, and decrease the levels/activities of MDA, PCO, corticosterone, ACTH and AChE. In conclusion, Tualang honey has the potential to be used as an alternative therapy to protect against memory decline and depressive symptoms due to stress exposure and/or ageing.
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Keywords
Ageing and stress exposure may lead , to memory impairment and depression.