Zn²⁺ enhancement of LTP requires activation of postsynaptic NMDA receptors.

(A) ZnCl2 (1μM, light circles, n = 9) does not alter basal synaptic transmission after 1 hour of exposure compared to control slices (dark circles, n = 5; P>0.05, Student’s t-test). (B) Summary of baseline responses showing that ZnCl2 did not alter baseline synaptic transmission compared to untreated control slices. (C) TBS did not induce LTP in the presence of either 50μM D-AP5 (filled circles, n = 6), or 1μM ZnCl2 + 50μM D-AP5 (light circles, n = 7). (D) Summary of mean fEPSP slopes 50 minutes post TBS. There was no significant difference between D-AP5 alone and 1μM ZnCl2 LTP + D-AP5 at 50 minutes post TBS. (P>0.05, Student’s t-test) (E) Sample of control paired-pulse evoked SCH-CA1 EPSCs (dark trace, average of 6 responses) versus EPSCs in 1μM [ZnCl2] (light trace, average of 6 responses) during a paired-pulse stimulus at an interval of 50ms. (F) Paired-pulse profiles of PPF ratios at interpulse intervals from 10–500 msec in control (n = 6, dark circles) vs. 1μM [ZnCl2] (n = 6, gray circles), showing no significant differences (P>0.05, Student’s t-test). Statistical data are presented as mean ± SEM.