Sastry B R, Chirwa S S, Goh J W, Maretic H, Pandanaboina M M
Life Sci. 1984 Mar 12;34(11):1075-86. doi: 10.1016/0024-3205(84)90021-3.
In transversely sectioned rat hippocampal slices, population spikes and population "EPSPs" were recorded from CA1 neurones in response to the stimulation of Schaffer collateral and commissural inputs. High frequency tetanic stimulation (400 Hz, 200 pulses) of an input induced LLP of the homosynaptic response without significantly changing the heterosynaptic response. This LLP was not interrupted by either a 400 Hz tetanus given to the heterosynaptic input or by verapamil (0.33 microM) which blocks Ca++ channels, but not transmitter release. A low frequency tetanus (20 Hz, 200 pulses) given to an input induces co-occurring homosynaptic and heterosynaptic depressions of about 20 min duration. This tetanus could also mask an established LLP in homosynaptic or heterosynaptic pathway. Verapamil counteracts homo- and heterosynaptic depressions. The population spike as well as the population "EPSP" were depressed following iontophoretic application of Ca++ (2-100 nA) at the CA1 cell body area. These results indicate that homosynaptic and heterosynaptic depressions are at least partly due to an accumulation of Ca++ into CA1 neurones. An established LLP is not interrupted by LLP of another input. Homo- and heterosynaptic depressions mask, but not reverse, LLP.
在横切的大鼠海马切片中，记录了CA1神经元对刺激Schaffer侧支和联合输入的群体峰电位和群体“兴奋性突触后电位”。对一个输入进行高频强直刺激（400Hz，200个脉冲）可诱导同突触反应的长时程抑制（LLP），而异突触反应无明显变化。这种LLP不会被给予异突触输入的400Hz强直刺激或维拉帕米（0.33μM）打断，维拉帕米可阻断Ca++通道，但不影响递质释放。对一个输入给予低频强直刺激（20Hz，200个脉冲）可诱导同时出现持续约20分钟的同突触和异突触抑制。这种强直刺激也可掩盖同突触或异突触通路中已建立的LLP。维拉帕米可对抗同突触和异突触抑制。在CA1细胞体区域离子导入Ca++（2 - 100nA）后，群体峰电位以及群体“兴奋性突触后电位”均受到抑制。这些结果表明，同突触和异突触抑制至少部分是由于Ca++在CA1神经元中的积累所致。一个已建立的LLP不会被另一个输入的LLP打断。同突触和异突触抑制可掩盖但不能逆转LLP。
