Table 1.

Main information of pre-clinical researches studying the correlation between carnitine level and depression in animal.

References	Samples	Subjects	Carnitine	Positive or negative	Main results	Depression scales or ways used
Zhang et al. (29)	Plasma and urine	Control: n = 11; excess fatigue: n = 11; depression: n = 11	C3:0, C4:0	+	C3:0 and C4:0 in the overtired and depressed rats were lower than the control group.	Tail-hanging test
Chen et al. (30)	Plasma	Control: n = 12; depression: n = 12; Alliummacrostemon-treated depression: n = 11	Carnitine and ACs (C10:1, C12:0, C14:2, C14:1, C14:0, C16:2, C16:1, C16:0, C18:2, C18:1, C18:0, C20:2, C20:1, C20:0, C14:0-OH, C16:1-OH, C16:0-OH, C18:2-OH, C18:1-OH)	+	Most medium-chain and long-chain ACs (C10:1, C12:0, C14:2, C14:1, C14:0, C16:2, C16:1, C16:0, C18:2, C18:1, C18:0, C20:2, C20:1, C20:0, C14:0-OH, C16:1-OH, C16:0-OH, C18:2-OH, C18:1-OH) increased in the depression group. After treatment, most of the ACs decreased to the normal level, except for the C18:2-OH, C18:2, C20:2, but the three ACs also showed a significant tendency to the normal level.	Tail suspension test
Zhao et al. (31)	Plasma	Control: n = 8; CUMS: n = 8; fluoxetine treatment: n = 8	LAC and carnitine	–	The concentrations of LAC and carnitine in the model group were significantly higher than those in the control group, but there was no significant difference in the concentrations of carnitine and LAC between the fluoxetine treatment group and the model group.	Sucrose consumption

Cm:n, Carnitine, in which “m” is the number of carbon atoms, “n” is the unsaturation. -OH represents hydroxylation, such as C18:1-OH = 3-hydroxy octadecenoyl carnitine.

ACs, acylcarnitines; CUMS, chronic unpredictable mild stress; LAC, acetyl-L-carnitine.