ReferenceID 2144

Depressive-like phenotype evoked by lifelong nutritional omega-3 deficiency in female rats: Crosstalk among kynurenine, Toll-like receptors and amyloid beta oligomers

Brain Behav Immun

Depression is one of the most common psychiatric diseases and the prevalence of depressive symptoms in women is almost twice compared to men, although the reasons of this gender difference are not fully understood yet. R

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Reference Id
2144
Evidence Id
18734
Core Evidence Id
18734
Source Reference Id
4331
Herb2 Reference Id
HBREF005128
Subject Paper Key
HBIN032453_31987923
Pubmed Id
31987923
Doi
10.1016/j.bbi.2020.01.015
Paper Title
Depressive-like phenotype evoked by lifelong nutritional omega-3 deficiency in female rats: Crosstalk among kynurenine, Toll-like receptors and amyloid beta oligomers
Paper Abstract
Depression is one of the most common psychiatric diseases and the prevalence of depressive symptoms in women is almost twice compared to men, although the reasons of this gender difference are not fully understood yet. Recently, soluble amyloid beta (Abeta)1-42 peptide has been receiving great importance in the development of depression, also considering that depression is highly comorbid with Alzheimer's disease and other neurodegenerative illnesses. The central role played by Abeta in the development of depressive-like symptoms in rodents has been evidenced in environmental rodent model of depression. Indeed, we have previously found that lifelong exposure to n-3 polyunsaturated fatty acids (PUFA) deficient diet in female rats at 8 weeks of life leads to depressive like- symptoms and higher susceptibility to stress associated with increased Abeta levels. In order to understand if such effects were maintained over time, rats were exposed to the same diet regimen until 6 or 21 weeks of life. We found that both timepoints of exposure to n-3 PUFA deficient diet lead to depressive-like phenotype. Furthermore, a significant alteration in brain neurochemistry was retrieved. In particular, in hippocampal area a significant reduction in serotonin (5-HT) and noradrenaline (NA) content was evidenced. Considering the prominent role of NA in counterbalancing neuroinflammatory state, we quantified in the same brain area kynurenine levels, a metabolite of tryptophan implicated in inflammatory state and brought to the fore for its implication in depression. Interestingly, kynurenine levels were significantly increased in hippocampus (HIPP) of female rats exposed to such diet. In addition, lifelong deficiency in n-3 PUFA dietary intake led to systemic increase of corticosterone, hence hypothalamic pituitary adrenal (HPA) axis hyperactivation, and higher proinflammatory cytokine production. Increased production of kynurenine, along with HPA axis hyperactivation, have been associated with immune system modulation, particularly through Toll-like receptor type 2 (TLR2) and Toll-like receptor type 4 (TLR4) involvement. In addition, it has been shown that soluble forms of Abeta1-42 can induced depressive like-phenotype in consequence to a crosstalk between TLR4 and 5-HTergic system. Thus, considering that in this model we have previously reported increased plasma Abeta1-42 level, we quantified TRL2 and 4 expression in HIPP of treated rats. We found that chronic exposure to a diet characterized by very low n-3 PUFA content led to higher expression of TLR2 and TLR4 in HIPP of female treated rats, indicating an activation of the immune system and was accompanied by increased expression of oligomeric Abeta. Taken together, our data indicate that the pro-depressive effects induced by a diet poor in n-3 PUFA can be attributable to a shift of hippocampal tryptophan metabolism toward inflammatory metabolite ultimately corresponding to altered immune response and increased Abeta oligomerization.
Journal
Brain Behav Immun
Publish Year
2020
Experiment Subject
rat; men; women
Experiment Type
Animal Experiment
Phenotype Related
Alzheimer's Disease; Depressive Like- Symptoms; Psychiatric Diseases; Depressive-like Symptoms; Neurodegenerative Illnesses
Paper Title Cn
Paper Title En
Depressive-like phenotype evoked by lifelong nutritional omega-3 deficiency in female rats: Crosstalk among kynurenine, Toll-like receptors and amyloid beta oligomers
Bilingual Status
semi_complete