Figure 5. Postsynaptic receptors and transduction pathways involved in eCB-LTD.

(A) eCB-LTD was not affected by a mixture of the NMDAR antagonist MK801 (40 µM), the D1 receptor antagonist SCH23390 (25 µM) and the D2 receptor antagonist sulpiride (25 µM). (B) The mGluR5 antagonist MPEP (10 µM) completely blocked eCB-LTD (C) Bar graph summarizing experiments showing that the non subtype selective group 1mGluR antagonist LY341495 (50 µM) and the Phospholipase C inhibitor U73122 both prevented eCB-LTD induction. 45 min after the end of the tetanus, the fEPSPs was 76.6±2.64% (n = 62) of baseline in control and 95.8±4.85% (n = 12, p = 0.004 t-test) and 96.33±6.4% (n = 11, p = 0.0009 t-test) in LY341495, respectively. (D) eCB-LTD requires postsynaptic Ca²⁺ rise. Time course of all the experiments performed where the recording pipette was filled with BAPTA (20 mM, n = 11) and where eCB-LTD was completely blocked.