Abstract
BackgroundThe purpose of the study was to evaluate the effects of krill oil (KO) on cognition and depression-like behaviour in rats.MethodsCognition was assessed using the Aversive Light Stimulus Avoidance Test (ALSAT). The Unavoidable Aversive Light Stimulus (UALST) and the Forced Swimming Test (FST) were used to evaluate the antidepressant-like effects of KO. Imipramine (IMIP) was used as the antidepressant reference substance.ResultsAfter 7 weeks of KO intake, both males and females treated with KO were significantly better in discriminating between the active and the inactive levers in the ALSAT from day 1 of training (p<0.01). Both KO and IMIP prevented resignation/depression on the third day in the UALST. Similarly, a shorter immobility time was observed for the KO and IMIP groups compared to the control in the FST (p<0.001). These data support a robust antidepressant-like potential and beneficial cognitive effect of KO. Changes in expression of synaptic plasticity-related genes in the prefrontal cortex and hippocampus were also investigated. mRNA for brain-derived neurotrophic factor (Bdnf) was specifically upregulated in the hippocampus of female rats receiving 7 weeks of KO supplementation (p=0.04) and a similar trend was observed in males (p=0.08). Males also exhibited an increase in prefrontal cortex expression of Arc mRNA, a key protein in long-term synaptic plasticity (p=0.05). IMIP induced clear effects on several plasticity related genes including Bdnf and Arc.ConclusionsThese results indicate that active components (eicosapentaenoic acid, docosahexaenoic acid and astaxanthin) in KO facilitate learning processes and provide antidepressant-like effects. Our findings also suggest that KO might work through different physiological mechanisms than IMIP.
Highlights
The purpose of the study was to evaluate the effects of krill oil (KO) on cognition and depression-like behaviour in rats
These results indicate that active components in KO facilitate learning processes and provide antidepressant-like effects
Our findings suggest that KO might work through different physiological mechanisms than IMIP
Summary
The purpose of the study was to evaluate the effects of krill oil (KO) on cognition and depression-like behaviour in rats. One hypothesis is that n-3 PUFAs exert their effect on the nervous system by regulating cyclic AMP (cAMP), cAMP response element binding protein (CREB), and the expression of downstream target genes such as brain-derived neurotrophic factor (BDNF) [17,18]. This is in line with studies showing that expression of BDNF and activation of the BDNF receptor, is reduced in the hippocampus and neocortex of rodents subjected to behavioural stress but enhanced following treatment with antidepressant drugs [19,20,21,22,23,24,25]
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