抗生素和低聚半乳糖干预对大鼠行为和神经递质的影响

Effects of antibiotics and galacto-oligosaccharide on behaviors and neurotransmitters in rats

摘要:

低聚半乳糖(galacto-oligosaccharides, GOS)作为益生元可以调节肠道菌群，改善大脑发育；相反，抗生素可以通过干扰肠道菌群影响神经系统。然而，抗生素和低聚半乳糖如何调节大脑神经递质及动物行为尚不清楚。目的 以断奶SD (Sprague-Dawley, SD)大鼠为试验动物，探究抗生素和低聚半乳糖干预对动物行为和神经递质的影响。方法 选取40只3周龄雄性SD大鼠，分为4组：对照组(CON组)、抗生素组(ABX组)、低聚半乳糖组(GOS组)和抗生素+低聚半乳糖组(AG组)。对照组饮用灭菌水，其余三组饮用含有抗生素、低聚半乳糖或抗生素+低聚半乳糖的灭菌水，其中低聚半乳糖浓度为5 g/L，抗生素由氨苄青霉素、万古霉素、盐酸环丙沙星、亚胺培南、甲硝唑组成，试验为期16 d。结果 与GOS组相比，ABX组大鼠体重显著下降低(P<0.05)；ABX、GOS、AG三组肝脏指数显著低于CON组(P<0.05)；大鼠行为分析显示，与CON组相比，ABX组趋光性指数(明暗箱试验中明箱时间占比)和理毛次数显著降低(P<0.05)，GOS组理毛次数显著低于CON组(P<0.05)。AG组在旷场的静止时间显著高于其他三组(P<0.05)，运动距离、时间和运动速度显著低于ABX和GOS两组(P<0.05)。与CON组相比，ABX组海马体去甲肾上腺素的浓度显著增加，左旋多巴浓度显著降低(P<0.05)；与CON组相比，含有低聚半乳糖的GOS和AG两组去甲肾上腺素浓度显著增加(P<0.05)，而左旋多巴和肾上腺素浓度显著下降(P<0.05)。与CON组相比，ABX和AG组的微生物多样性下降(P<0.05)，Escherichia_Shigella是ABX、AG两组的优势菌，GOS组的Chao1指数显著低于对照组(P<0.05)，GOS组优势菌主要是厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidota)；与ABX组相比，AG组乳杆菌属(Lactobacillus)显著增加(P<0.05)。结论 与对照组相比，抗生素会减少焦虑样行为，同时降低海马神经递质左旋多巴胺、增加去甲肾上腺素，并增加潜在致病菌；低聚半乳糖改善了大鼠生长，对大鼠行为无明显影响，但增加了Lactobacillus丰度，并减少海马左旋多巴胺和肾上腺素；联合使用抗生素和低聚半乳糖降低大鼠运动能力，增加焦虑样行为。

关键词:抗生素;低聚半乳糖;肠道微生物;社交行为;神经递质

Abstract:

Galacto-oligosaccharides (GOS) as prebiotics can regulate gut microbiota to improve brain development, whereas antibiotics can affect the nervous system by interfering with gut microbiota. The mechanisms of antibiotics and GOS in regulating brain neurotransmitters and animal behaviors remain unknown.Objective To investigate the effects of antibiotics and GOS on the behaviors and neurotransmitters in weaned Sprague-Dawley (SD) rats.Methods Forty 3-week-old male SD rats were selected and assigned into four groups: control (CON, sterilized water), antibiotics (ABX), GOS (5 g/L), and antibiotics+GOS (AG). The antibiotics used in the experiment were composed of ampicillin, vancomycin, ciprofloxacin hydrochloride, imipenem, and metronidazole. The experiment lasted for 16 days.Results The body weight of rats in the ABX group was lower than that in the GOS group (P<0.05), and the liver index in the ABX, GOS, and AG groups was lower than that in the CON group (P<0.05). Compared with the CON group, the ABX group showcased decreased phototaxis index (percentage of time in bright during bright-dark box test) and reduced times of self-grooming (P<0.05), and the GOS group had reduced times of self-grooming (P<0.05). The AG group had longer resting time in the open field than the other three groups (P<0.05) and shorter distance, shorter time, and slower movement than ABX and GOS groups (P<0.05). Compared with the CON group, the ABX group showcased elevated level of norepinephrine and lowered level of levodopa in the hippocampus (P<0.05). Compared with the CON group, the GOS and AG groups demonstrated elevated levels of norepinephrine and declined levels of levodopa and epinephrine (P<0.05). Compared with the CON group, the ABX and AG groups presented decreased microbial diversity (P<0.05), where Escherichia_Shigella became dominant. The Chao1 index in the GOS group was lower than that in the CON group (P<0.05). The dominant bacteria in the GOS group were Firmicutes and Bacteroidota. Compared with that in the ABX group, the relative abundance of Lactobacillus increased in the AG group (P<0.05).Conclusion ABX decreased anxiety-like behaviors compared with CON, while reducing levodopa and increasing norepinephrine in the hippocampus and enriching potentially pathogenic bacteria. GOS improved growth without influencing the behaviors of rats, and meanwhile it increased the relative abundance of Lactobacillus and decreased levodopamine and norepinephrine in the hippocampus. The combined use of ABX and GOS decreased the locomotor activity and increased the anxiety-like behaviors of rats.

Key words:antibiotics;galacto-oligosaccharides (GOS);gut microbiota;social behavior;neurotransmitters