Hydrogen sulfide (H₂S) and polysulfides (H₂S_n, n ≥ 2) are signaling molecules produced by 3-mercaptopyruvate sulfurtransferase (3MST) that play various physiological roles, including the induction of hippocampal long-term potentiation (LTP), a synaptic model of memory formation, by enhancing N-methyl-d-aspartate (NMDA) receptor activity. However, the presynaptic action of H₂S/H₂S_n on neurotransmitter release, regulation of LTP induction, and animal behavior are poorly understood. Here, we showed that H₂S/H₂S₂ applied to the rat hippocampus by in vivo microdialysis induces the release of GABA, glutamate, and d-serine, a co-agonist of NMDA receptors. Animals with genetically knocked-out 3MST and the target of H₂S₂, transient receptor potential ankyrin 1 (TRPA1) channels, revealed that H₂S/H₂S₂, 3MST, and TRPA1 activation play a critical role in LTP induction, and the lack of 3MST causes behavioral hypersensitivity to NMDA receptor antagonism, as in schizophrenia. H₂S/H₂S_n, 3MST, and TRPA1 channels have therapeutic potential for psychiatric diseases and cognitive deficits.