Drugs used to kill gut bacteria found to prevent the growth of neurones in the brain

Recent studies looking to identify the side effects of certain antibiotics, have revealed that as well as killing off gut bacteria, they can also stop the growth of new brain cells in the hippocampus.

A research group in Germany exposed mice to prolonged antibiotic treatment (Ciprofloxacin) and compared their performance in memory tests and rate of neurogenesis (new brain cell formation) to a group of control mice who had not been treated with the drug. The drug treated mice not only showed poorer scores on memory tasks but staining of cells in the hippocampus showed a great reduction in the rate of new neuron formation. As the hippocampus is one of the major centres for memory generation, a decreased rate of neuron formation here may limit how well the region can function, resulting in the poor performance in memory tests.

In addition to this, the research team also detected a lower level of white blood cells (WBCs) in the brain, blood and bone marrow. Replacement of these cells resulted in improved memory and neurogenesis, suggesting a causal relationship between the levels of WBCs and memory. Administration of probiotics or regular exercise also returned memory and neuron formation to the levels seen in the control. These findings are particularly significant as they elucidate a potential way in which the detrimental effects of prolonged antibiotic use could be reversed or prevented. It also suggests a prospective treatment for neurocognitive disorders that are linked to memory degeneration e.g. Alzheimer’s and Schizophrenia. Further experimentation to look at the efficacy of probiotic treatment in patients with these conditions is being planned, as this could reveal a novel treatment option to improve memory.

http://www.cell.com/cell-reports/pdf/S2211-1247(16)30518-6.pdf