ABSTRACT
Formaldehyde is one of the simplest organic small molecules containing C, H and O elements in the early stage of earth's evolution; however, it has been found to be existed in every eukaryotic cell and participate in "one carbon metabolism". Recent studies have shown that formaldehyde may act as a signal molecule to regulate memory formation. After electrical stimulation or learning activity, the levels of formaldehyde in rat brains were increased instantly, and N-methyl-D-aspartate (NMDA) receptor was activated to promote the formation of long-term potentiation (LTP) or spatial memory. On the contrary, after reducing the levels of formaldehyde in the brains, NMDA receptor could not be activated, which was accompanied by the deficits in both LTP and memory. Moreover, in the brains of normal aged rats and APP/PS1 transgenic mice, the concentrations of formaldehyde were abnormally increased, which directly inhibited NMDA receptor activity and impaired spatial memory. This article reviewed the physiological and pathophysiological functions of endogenous formaldehyde in learning and memory.