Milk fat globule membrane ameliorates depressive-like behaviors in chronic unpredictable mild stress rats by modulating the microbiota-gut-brain axis

Depression is one of the common psychiatric disorders, and it has been reported that the imbalance in the microbiota-gut-brain (MGB) axis contributes to the pathogenesis of depression. Milk fat globule membrane (MFGM) can impact the gut-brain axis by regulating the intestinal flora and metabolite production. The aim of this study was to investigate whether MFGM could ameliorate depressive-like behaviors induced by chronic unpredictable mild stress (CUMS) and further elucidate the potential mechanism through a fecal microbiota transplantation (FMT) experiment. Male Sprague-Dawley rats were provided with an MFGM diet for 5 weeks after the induction with CUMS. Depressive-like behaviors were assessed, and the levels of neurotransmitters, neuroendocrine hormones, microbiota, short-chain fatty acids (SCFAs), and tight junction proteins, including occludin and zonula occludens-1 (ZO-1), were measured. It was revealed that MFGM could alleviate the depressive-like behaviors in CUMS rats. MFGM up-regulated the expression of occludin and ZO-1 and ameliorated intestine pathological changes in CUMS rats. Moreover, MFGM increased the levels of 5-hydroxytryptamine (5-HT), dopamine (DA), and norepinephrine and decreased the levels of neuroendocrine hormones in CUMS rats. Furthermore, it was confirmed that the concentrations of SCFAs, DA, 5-HT, and tight junction proteins significantly increased in the recipient rats that were inoculated with the fecal microbiota from the rats after MFGM treatment. These findings demonstrated that MFGM could alleviate depressive-like behaviors in CUMS rats and was possibly associated with modulation of the gut microbiota and up-regulation of SCFAs and monoamine neurotransmitters.