A Diet Enriched with Lacticaseibacillus rhamnosus HN001 and Milk Fat Globule Membrane Alters the Gut Microbiota and Decreases Amygdala GABA a Receptor Expression in Stress-Sensitive Rats

Abstract

Brain signalling pathways involved in subclinical anxiety and depressed mood can be modulated via the gut brain axis (GBA), providing the potential for diet and dietary components to affect mood. We investigated behavioural, physiological and gut microbiome responses to the Lacticaseibacillus rhamnosus strain HN001 (LactoB HN001™), which has been shown to reduce postpartum anxiety and depression, and a milk fat globule membrane-enriched product, Lipid 70 (SurestartTM MFGM Lipid 70), which has been implicated in memory in stress-susceptible Wistar Kyoto rats. We examined behaviour in the open field, elevated plus maze and novel object recognition tests in conjunction with the expression of host genes in neuro-signalling pathways, and we also assessed brain lipidomics. Treatment-induced alterations in the caecal microbiome and short-chain fatty acid (SCFA) profiles were also assessed. Neither ingredient induced behavioural changes or altered the brain lipidome (separately or when combined). However, with regard to brain gene expression, the L. rhamnosus HN001 + Lipid 70 combination produced a synergistic effect, reducing GABAA subunit expression in the amygdala (Gabre, Gat3, Gabrg1) and hippocampus (Gabrd). Treatment with L. rhamnosus HN001 alone altered expression of the metabotropic glutamate receptor (Grm4) in the amygdala but produced only minor changes in gut microbiota composition. In contrast, Lipid 70 alone did not alter brain gene expression but produced a significant shift in the gut microbiota profile. Under the conditions used, there was no observed effect on rat behaviour for the ingredient combination. However, the enhancement of brain gene expression by L. rhamnosus HN001 + Lipid 70 implicates synergistic actions on region-specific neural pathways associated with fear, anxiety, depression and memory. A significant shift in the gut microbiota profile also occurred that was mainly attributable to Lipid 70.

Milk Fat Globule Membranes for Mental Health across the Human Lifespan

“…In a rodent model of stress, supplementation with the MFGM product Lipid 70 [ 63 ] and L. rhamnosus HN001 synergistically altered GABA subunit expression in the limbic system, specifically the amygdala and hippocampus. Lipid 70 supplementation was independently associated with a shift in the microbiota of the large intestine and short-chain fatty acid levels [ 64 ]. However, supplementation with either product in isolation or conjunction was not associated with changes in anxiety, depression, or stress symptoms.…”

“…Stress induces changes to the gut microbiome, making the gut microbiota and stress direct targets for intervention [ 43 ]. Enhanced gene expression in the brain of rats supplemented with a probiotic and MFGM demonstrates the synergistic action of the two on neural pathways associated with anxiety, fear and depression [ 64 ]. In other animal models, phospholipids supplemented via a buttermilk concentrate exert protective effects against chronic stress and anxiety-like behaviours [ 15 ].…”