Fig. 2
From: Microbiota in neuroinflammation and synaptic dysfunction: a focus on Alzheimer’s disease
Hypothetical link between gut dysbiosis and mechanisms leading to the pathogenesis of AD. Alterations in the gut microbiota composition and function in AD patients increases permeability of the intestinal barrier and likely BBB, which creates a vicious cycle of enhancing inflammation at the gut and the CNS level. Early stages of AD (low concentrations of Aβ) are characterized by increased excitability of pyramidal neurons in the hippocampus subsequent to the increased glutamatergic neurotransmission, which in turn translates into presynaptic facilitation, enhanced fEPSP and LTP. Conversely, later stages of AD (high concentrations of Aβ) are associated with marked decrease in excitability and fEPSP, as well as reduced LTP and enhanced LTD, likely related to a decrease in the number of synaptic AMPA receptors and progressive memory loss. Created with Biorender.com