Figure 4

Low-frequency stimulation and DHPG evoked long-term depression (LTD) in the ipsilateral and contralateral side of the Dm. (a) LTD of the contralateral side of the Dm. (b) LTD of the ipsilateral side of the Dm. Low-frequency stimulation (1 Hz) was applied (arrow) in the Dl division. The amplitude of the PS in both sides after LTD induction was 80% smaller than the baseline amplitude, and this reduction could last at least 1 hour (point 2 compared to point 1, contralateral: 77.13 ± 3.34%, n = 11, p = 0.0988; ipsilateral: 75.92 ± 6.11%, n = 11, p = 0.1525). Each point represents the mean ± SEM of the PS amplitude. n = 11. (c) The effect of DHPG on LTD induction in the contralateral side with Dm induction. (d) The effect DHPG on LTD induction in the ipsilateral side with Dm induction. The amplitude of the PS in both sides after LTD induction was 70% smaller than the baseline amplitude, and this reduction could last at least 1 hour (point 2 compared to point 1, contralateral: 62.42 ± 7%, n = 9, p = 0.0001; ipsilateral: 67.17 ± 3.1%, n = 9, p < 0.0001). (e) The comparison of the PS amplitude with DHPG-induced LTD in the contralateral and ipsilateral Dm. The PS amplitude of the contralateral side was smaller than that of the ipsilateral side in the 25–35-min period (n = 9, F_{(1, 16)} = 4.809, p = 0.0434). DHPG (40 µM) was applied for 10 min after 10 min of baseline recording. (f) Co-administration of the mGluR antagonist LY36738 significantly attenuated the DHPG-induced contralateral LTD but not the ipsilateral LTD. (n = 5, p = 0.0134 & p = 0.0536 compared with corresponding control group respectively) Each point represents the mean ± SEM of the PS amplitude. n = 9.