Impact of antibiotic induced gut microbiota alteration on cognitive abilities and behaviours of mice

Thesis Type: Doctorate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Arts and Sciences, Department of Biology, Turkey

Approval Date: 2018


Supervisor: AYŞE GÜL GÖZEN


Recently arising studies with animal models show that there is a bidirectional communication between gut microbiota and central nervous system (CNS) through neural, endocrine and immune pathways which influences brain function and behavior. Apparently, gut microbiota may play a role in the regulation of anxiety, mood, cognition, and pain sensation. Gut microbiota may cause gastrointestinal disorders, such as irritable bowel syndrome (IBS), which can be comorbid with stress-related psychiatric conditions influencing memory and learning processes. In this context, overuse of antibiotics which are known to profoundly change the gut microbiota by reducing the necessary symbiotic bacteria may also influence brain functions leading to the development of anxiety-like-behavior and depression syndromes, and even cognitive deficits. The present study aimed to address this issue using an animal model. Experiments were carried on thirty 21-days old BALB/c mice. Two broad-spectrum antibiotics ampicillin (1g/L) and cefoperazone (1g/L) used in different combinations up to adult age. To screen the fluctuation of the gut microbiota populations denaturing gradient gel electrophoresis (DGGE) technique was applied. By the end of the antibiotic treatment, both the experimental and control mice were subjected to behavioral tests and biochemical assays. The behavioral test included open field (OF), elevated plus maze (EPM), novel object recognition test (NOR), and forced swim test (FST). In biochemical analyses, the level of the brain vi derived neurotrophic factor (BDNF) and Corticosterone, Serotonin receptor 5HT1A and NR2B subunits of N-methyl D-aspartate receptor (NMDA) were determined. The data were analysed comparatively. The results showed that in mice, a repeated antibiotic treatment applied during adolescence changes the gut microbiota composition and in parallel appears to influence the cognitive and affective behavior in young adults.