Antidepressant-Like Effects of Cistanche tubulosa Extract on Chronic Unpredictable Stress Rats Through Restoration of Gut Microbiota Homeostasis

Abstract

Growing evidence shows that neuropsychiatric disorders, such as depression, are linked with gut microbiome through the gut-brain axis. Cistanches Herba is well known for the treatment of "kidney-yang" deficiency in traditional Chinese medicine (TCM), and has been used for treatment of neurodegenerative diseases in recent years. In this study, chronic unpredictable stress (CUS)-induced depression model was established to explore the impact of Cistanche tubulosa extract (CTE) on behavioral tests, monoamine neurotransmitters and neurotrophic factors in hippocampus and colon, gut microbiota composition, and short-chain fatty acids (SCFAs) production. Moreover, correlation analysis was used to evaluate the functional relationship between altered gut microbiota, changed neurotransmitters and neurotrophins in hippocampus and colon, and disturbed concentration of SCFAs. CTE significantly improved depression-like behaviors in rats under CUS. Brain level of 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) expression in CUS rats were restored by CTE. The relative abundance of gut microbiota and the concentrations of acetate and hexanoic acid could also be modulated by CTE treatment. We further showed that the application of CTE in CUS rats led to strong correlation among disrupted gut microbiota composition, hippocampus neurotransmitter levels, and production of neuroactive metabolite SCFAs. Altogether, these results identify CTE as a potential treatment for depressive symptoms by restoring homeostasis of gut microbiota for microbiota-gut-brain axis disorders, opening new avenues in the field of neuropsychopharmacology.

Keywords: Cistanche tubulosa; antidepressant; chronic unpredictable stress; gut microbiota; microbiota–gut–brain axis.

FIGURE 1

Effects of CTE on behavioral test of CUS rats: (A) forced swimming test, (B) sucrose preference test, (C) open-field test, and (D) novelty-suppressed feeding test in CUS rats. Ctrl, control; CUS, chronic unpredictable stress; FLX, fluoxetine; CTEH, C. tubulosa extract high dose; CTEL, C. tubulosa extract low dose. ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001 (n = 8, mean ± SEM).

FIGURE 2

The changes of monoamine neurotransmitter levels in hippocampus and colon of CUS rats treated with CTE: 5-HT (A), NE (B), and BDNF (C) in hippocampus, and 5-HT in colon (D). Ctrl, control; CUS, chronic unpredictable stress; FLX, fluoxetine; CTEH, C. tubulosa extract high dose; CTEL, C. tubulosa extract low dose. ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001 (n = 8, mean ± SEM).

FIGURE 3

3D diagram of Weighted UniFrac PCoA of intestinal microbiota extracted from rat fecal samples (A). Microbial distribution at phylum level (B). Microbial distribution at genus level (C). Ctrl, control; CUS, chronic unpredictable stress; FLX, fluoxetine; CTEH, C. tubulosa extract high dose; CTEL, C. tubulosa extract low dose.

FIGURE 4

Relative abundance of selected genera with significant differences among each group. Relative abundance of Bacteroides (A), Ruminococcus (B), Parabacteroides (C), Butyricimonas (D), Deinococcus (E), Weissella (F), Trichococcus (G), and Brachybacterium (H). Ctrl, control; CUS, chronic unpredictable stress; FLX, fluoxetine; CTEH, C. tubulosa extract high dose; CTEL, C. tubulosa extract low dose. ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001 (n = 8, mean ± SEM).

FIGURE 5

Relative abundance of Deinococcus in different taxonomic levels: (A) class level, (B) order level, (C) family level, (D) genus level. Relative abundance of selected species with significant differences among each group. Relative abundance of Weissella beninensis (E), and Brachybacterium conglomeratum (F). Ctrl, control; CUS, chronic unpredictable stress; FLX, fluoxetine; CTEH, C. tubulosa extract high dose; CTEL, C. tubulosa extract low dose. ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001 (n = 8, mean ± SEM).

FIGURE 6

The changes of SCFAs in fecal samples of CUS rats treated with CTE: (A) acetate, (B) propionate, (C) butyrate, (D) isobutyrate, (E) valeric acid, (F) isovaleric acid, (G) hexanoic acid, and (H) total SCFAs. Ctrl, control; CUS, chronic unpredictable stress; FLX, fluoxetine; CTEH, C. tubulosa extract high dose; CTEL, C. tubulosa extract low dose. ^∗P < 0.05, ^∗∗P < 0.01 (n = 8, mean ± SEM).

FIGURE 7

Heat map summarizing the Pearson’s correlation between 5-HT, NE, and BDNF in hippocampus, 5-HT in colon, gut microbiota, and SCFAs. ^∗P < 0.05, ^∗∗P < 0.01.