ABSTRACT
L-theanine has been shown to have a therapeutic effect on depression.However,whether L-theanine has an excellent preventive effect on depression in children and adolescents and what its mechanism is have not been well explained.Given the complexity of the pathogenesis of depression,this study investigated the preventive effect and mechanism of L-theanine on depression in juvenile rats by combining serum and hippocampal metabolomic strategies.Behavioral tests,hippocampal tissue sections,and serum and hippocampal biochemical indexes were studied,and the results confirmed the preventive effect of L-theanine.Untargeted reversed-phase liquid chromatography-quadrupole-time-of-flight mass spec-trometry and targeted hydrophilic interaction liquid chromatography-triple quadrupole mass spec-trometry were developed to analyze the metabolism changes in the serum and hippocampus to screen for potential biomarkers related to L-theanine treatment.The results suggested that 28 abnormal me-tabolites in the serum and hippocampus that were considered as potential biomarkers returned to near-normal levels after L-theanine administration.These biomarkers were involved in various metabolic pathways,mainly including amino acid metabolism and lipid metabolism.The levels of amino acids and neurotransmitters in the phenylalanine,tryptophan,and glutamic acid pathways were significantly reduced after L-theanine administration compared with chronic unpredictable mild stress-induced rats.In summary,L-theanine had a significant preventive effect on depression and achieved its preventive results on depression by regulating various aspects of the body,such as amino acids,lipids,and inflammation.This research systematically analyzed the mechanism of L-theanine in preventing depression and laid the foundation for applying L-theanine to prevent depression in children and adolescents.
ABSTRACT
Objective To evaluate the protective effect of dietary n-3 polyunsaturated fatty acids (PUFA) on ultraviolet-induced acute skin photodamage in SKH-1 hairless mice,and to explore its mechanism.Methods Totally,50 SKH-1 hairless mice were equally divided into 5 groups to be fed with forages with the ratios of n-3 PUFA to fatty acid being 0,12.5％,25％,50％ and 100％ respectively (control group,12.5％,25％,50％ and 100％ n-3 PUFA groups).On day 8 after feeding,the back of mice in the 5 groups were irradiated by a solar ultraviolet simulator at 2 minimum erythema doses (MED) to establish an acute photodamage model.After 24 hours,cutaneous reactions on the back of mice were observed by naked eyes and dermoscopy,and skin biopsy specimens were subjected to hematoxylin and eosin (HE) staining for observing the epidermal structure,intercellular edema,inflammatory cell infiltration and photodamaged cells.Immunohistochemical staining was performed to determine the expression of inflammatory cytokines including interleukin-1 beta (IL-1β),IL-6 and tumor necrosis factor alpha (TNF-α),and enzyme-linked immunosorbent assay (ELISA) to measure the protein expression of the above 3 inflammatory cytokines in the tissue homogenate.Results Compared with the control group and 12.5％ n-3 PUFA group,the 25％,50％ and 100％ n-3 PUFA groups all showed a milder degree of acute skin photodamage,epidermis thickening,intercellular edema,and inflammatory cell infiltration.The number of photodamaged cells per high-power field (× 100) was significantly higher in the control group and 12.5％ n-3 PUFA group (17.50 ± 4.93,14.25 ± 1.71,respectively) than in the 25％,50％ and 100％ n-3 PUFA groups (6.50 ± 1.73,4.75 ± 2.06,4.50 ± 1.73,respectively;F =19.1,P ＜ 0.001).Immunohistochemical results showed that IL-1β,IL-6 and TNF-α were expressed to different extents in the epidermis and dermis among the 5 groups at 24 hours after ultraviolet radiation.Compared with the control group and 12.5％ n-3 PUFA group,the 25％,50％ and 100％ n-3 PUFA groups showed significantly lower expression of the above 3 inflammatory cytokines (P ＜ 0.001).ELISA revealed that the levels of IL-1β,IL-6 and TNF-α in the skin tissues of the mice were significantly lower in the 25％,50％ and 100％ n-3 PUFA groups than in the control group and 12.5％ n-3 PUFA group (P ＜ 0.05).Conclusions When the ratio of n-3 PUFA to fatty acid reaches more than 25％,dietary n-3 PUFA has protective effects against ultraviolet-induced acute photodamage,.Moreover,the higher the content of n-3 PUFA is,the stronger the protective effect is.It is suggested that n-3 PUFA may inhibit the inflammatory reaction through the arachidonic acid pathway.