Akkermansia muciniphila Restores HPA Axis Signaling and Attenuates Post-Stroke Brain Injury under High-Fat Dietary Conditions
Description
Ischemic stroke prognosis is influenced not only by vascular factors but also by metabolic and neuroendocrine regulation. High-fat diet (HFD), a major driver of metabolic dysfunction, may modulate gut microbiota and hypothalamic–pituitary–adrenal (HPA) axis function, yet the extent and relevance of these effects in stroke remain unclear. In particular, direct experimental evidence supporting the full physiological pathway linking HFD, gut microbiota, hormonal regulation, and stroke outcome is lacking. In this study, we show that HFD-fed mice exhibit reduced hypothalamic corticotropin-releasing hormone (CRH) expression and circulating corticosterone levels, accompanied by aggravated neurological deficits, enhanced microglial activation, and increased neuronal apoptosis following middle cerebral artery occlusion (MCAO). To probe the role of the gut microbiota in this process, we performed fecal microbiota transplantation (FMT) from normal diet-fed donors and oral administration of Akkermansia muciniphila in HFD-fed mice. Both interventions restored hormone levels, improved behavioral recovery, and attenuated neuroinflammation and cell death. Microbiota analysis revealed that the reduction of Akkermansia induced by HFD feeding was partially reversed by the intervention. These findings provide direct evidence that HFD-associated gut dysbiosis contributes to impaired HPA axis activity and worsened stroke outcomes, and that microbiota-targeted strategies may restore endogenous hormonal balance and promote neuroprotection. This study establishes a functional link along the gut microbiota–HPA axis–stroke injury axis in the context of dietary metabolic stress.
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The 6-week-old male C57BL/6J mice used in the experiments were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. All animals were housed in the Laboratory Animal Resources Center at Tsinghua University, Beijing, where the center monitors and maintained the temperature, humidity, and a 12-hour light/dark cycle. The mice were kept in individual ventilated cages, each accommodating up to 6 mice, with free access to food and water. Mice were fed either a normal diet (ND) or a high-fat diet (60% kcal from fat, D12492, SPF Beijing Biotechnology Co.) continuously for 8 weeks. For the determination of plasma hormones and inflammatory factors, blood samples collected from mouse tail veins were gathered in clean centrifuge tubes. The specimens were immediately centrifuged at 3,000 rpm for 10 minutes, and the separated plasma samples were stored at −80°C until analysis. Plasma CRH, adrenocorticotropic hormone (ACTH), corticosterone concentrations were quantified using a hormone enzyme-linked immunosorbent assay (ELISA) kit (Hengyuan Biological Technology Co., Shanghai, China) following the manufacturer's protocols. The rotarod test was conducted by placing mice on a rotating rod with constant acceleration from 0 to 300 rpm over 300 seconds. The latency to fall was recorded for each mouse, and three consecutive trials were performed with 15-minute inter-trial intervals. Open field test The locomotor activity in mice was assessed using the open field test. Each mouse was placed in an open-field arena (50 cm × 50 cm × 30 cm) starting from the same initial position, and their movements were recorded for 15 minutes using a video tracking system. Data from the initial 5 minutes were excluded during analysis. The total distance traveled was quantified using EthoVision XT software (Noldus Information Technology, Wageningen, Netherlands).