<i>Bifidobacterium animalis</i> subsp. <i>lactis</i> A6 attenuates hippocampal damage and memory impairments in an ADHD rat model

Attention deficit hyperactivity disorder (ADHD) is commonly accompanied by learning and memory deficits. This study aimed to demonstrate the effects of probiotic <i>Bifidobacterium animalis</i> subsp. <i>lactis</i> A6 (BAA6) on behaviour and memory function in spontaneously hypertensive rats (SHRs). The results showed that BAA6 treatment ameliorated spatial working memory deficits and inhibited hippocampal neuron loss in SHRs. The levels of neurotransmitters such as acetylcholine, dopamine, and norepinephrine, and the brain derived neurotrophic factor increased and that of glutamate decreased in the brain tissue of SHRs after BAA6 administration. Moreover, BAA6 reduced the levels of pro-inflammatory cytokines TNF-α and IL-1β, and increased the levels of anti-inflammatory IL-10 and antioxidant glutathione in SHRs. 16S rRNA high-throughput sequencing showed that BAA6 treatment changed the gut microbiota composition. BAA6 promoted beneficial <i>Lactobacillus</i>, <i>Romboutsia</i>, <i>Blautia</i>, and <i>Turicibacter</i>, and decreased the enrichment of bacterial genera such as <i>Dietzia</i>, <i>Sporosarcina</i>, <i>Brevibacterium</i>, <i>NK4A214</i>_group, <i>Atopostipes</i>, and <i>Facklamia</i> negatively associated with neurotransmitter release and anti-inflammatory effects in SHRs. Together, these results suggested that BAA6 improved memory function by ameliorating hippocampal damage, abnormal neurotransmitter release and cerebral inflammation by reshaping the gut microbiota in SHRs. This study provides a scientific basis for the development and application of BAA6 as a promising dietary intervention to reduce the risk of ADHD.