Inhibition of PLCβ, IP3Rs or CB1Rs does not preclude induction of t-LTP. Contrarily to t-LTD, a significant t-LTP could be observed after inhibition of PLCβ (i-U73122, 5 μm), Ca2+-ATPase responsible of the refilling of the IP3R-gated calcium stores (thapsigargin, 0.5 μm), CB1Rs (AM251, 3 μm), group-I mGluRs (LY367395, 100 μm) or M1Rs (pirenzepine, 1 μm). ND: not determined. *P < 0.05, **P < 0.01, ***P < 0.001.