Pycocyanin: A virulence factor of Pseudomonas aeruginosa in the disruption of brain homeostasis regulation in gold fish Carassius auratus

Recent reports reported that the oral and gut microorganisms are responsible for the regulation of the brain homeostasis mechanism. This brain homeostasis mechanism is affected by the colonization of non-periodontic microorganisms in the oral cavity and the gut compared to periodontic pathogens. Among the non-periodontic microorganisms, Pseudomonas aeruginosa is one of the gram-negative bacilli that play a major role in the development of cognitive impairment through the production of a secondary metabolite called pycocyanin.The present study aimed to test the effect of pycocyanin on the development of cognitive impairment for the first time with the help of a comparative two-staged behavioral analysis: non-infusive behavioral studies (NBS) and infusive behavioral studies (IBS) of goldfish Carassius auratus. Non-infusive behavioral experimental groups (BEGs) used in the NBS mimicked the condition of a healthy state and infusive behavioral experimental groups (BEGs) either received isolated metabolites and microbial cultures of the day – 3, 4, 5, and 6 in the form of oral infusions. Effect of metabolite/ microbial culture in the infusive study groups was proved by comparing the behavioral scores of non-infusive groups. Employed two-staged behavioral analysis proved that cognitive impairment induction (75-79%) was higher in the metabolite oral infusions compared to the microbial oral infusions in the behavioral study groups. Obtained results showed that induction of cognitive impairment resulted from reactive oxygen species (ROS) production and neuroinflammation was high in the brain regions due to the transportation of administrated metabolite from the gut to the brain in its purest form compared to the microbial oral infusions.