Lanthanum Impairs Learning and Memory by Activating Microglia in the Hippocampus of Mice

Lanthanum can induce neurotoxicity and impair cognitive function; therefore, research on the mechanism by which the ability to learning and memory is decreased by lanthanum is vitally important for protecting health. Microglia are a type of neuroglia located throughout the brain and spinal cord that play an important role in the central nervous system. When overactive, these cells can cause the excessive production of inflammatory cytokines that can damage neighboring neurons. The purpose of this study was to explore the effect of lanthanum in the form of lanthanum chloride (LaCl₃) on learning and the memory of mice and determine whether there is a relationship between hippocampal neurons or learning and memory damage and excessive production of inflammatory cytokines. Four groups of pregnant Chinese Kun Ming mice were exposed to 0, 18, 36, or 72 mM LaCl₃ in their drinking water during lactation. The offspring were then exposed to LaCl₃ in the breast milk at birth until weaning and then exposed to these concentrations in their drinking water for 2 months after weaning. The results showed that LaCl₃ impaired learning and memory in mice and injured their neurons, activated the microglia, and significantly overregulated the mRNA and protein expression of tumor necrosis factor alpha, interleukin (IL)-1β, IL-6, monocyte chemoattractant protein-1, and nitric oxide in the hippocampus. The results of this study suggest that lanthanum can impair learning and memory in mice, possibly by over-activating the microglia.