Enhanced cognitive function and antidepressant-like effects after krill oil supplementation in rats.
BACKGROUND
The purpose of the study was to evaluate the effects of krill oil (KO) on cognition and depression-like behaviour in rats.


METHODS
Cognition 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.


RESULTS
After 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.


CONCLUSIONS
These 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.
Department of Biomedicine and KG Jebsen Centre for Research onNeuropsychiatric Disorders, University of Bergen, Jonas Lies vei 91, BergenNO-5009, Norway.
Karin
K
Wibrand
Kjetil
K
Berge
Michaël
M
Messaoudi
Anaïs
A
Duffaud
Debabrata
D
Panja
Clive R
CR
Bramham
Lena
L
Burri
D000818:Animals; D000928:Antidepressive Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001362:Avoidance Learning / Q000187:drug effects; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D003071:Cognition / Q000187:drug effects*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D003863:Depression / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D004042:Dietary Fats, Unsaturated / Q000302:isolation & purification / Q000494:pharmacology*; D033201:Euphausiacea / Q000737:chemistry*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects; D007099:Imipramine / Q000494:pharmacology; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009473:Neuronal Plasticity / Q000187:drug effects; D018697:Nootropic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D017397:Prefrontal Cortex / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013550:Swimming
D000928:Antidepressive Agents; D019208:Brain-Derived Neurotrophic Factor; D003598:Cytoskeletal Proteins; D004042:Dietary Fats, Unsaturated; D009419:Nerve Tissue Proteins; D018697:Nootropic Agents; C092069:activity regulated cytoskeletal-associated protein; D007099:Imipramine