Influence of microbiome on withdrawal-like behavior in Planaria

The microbiome of animals can influence health status, disease susceptibility and can also influence host behavior. This study investigates the effect of microbiome alteration on animal behavior using the planarian model system. For this, Girardia tigrina (Brown Planaria) and Phagocata gracilis (Black Planaria) were investigated. These flatworms possess a primitive nervous system and exhibit similar addictive and withdrawal behaviors to mammals. Here we tested the hypothesis that alteration of planarian microbiome using the broad-spectrum antibiotics kanamycin and ampicillin could influence the worms behavior and withdrawal response to nicotine. After antibiotic treatment period of seven days, the behavior and withdrawal response of four groups of brown and black planaria was analyzed by recording the worms motility on a 1 cm2 grid. Results support the hypothesis as treatment significantly altered behavior in black worms. The microbiomes of antibiotic treated planaria were analyzed using conventional culture techniques, microscopy and metagenomic methods. Alpha proteobacteria including Sphingomonadaceae were detected in both Brown and Black planarians. This study suggests chemotherapeutic alteration of an animals microbiome can influence motility behavior and withdrawal responses to addictive substance and sheds light on the species composition of Planarian microbiomes.