Figure 2. The slow inhibitory postsynaptic potential (IPSP) is induced by the activation of muscarinic acetylcholine (Ach) receptors.

A, B, attenuation of slow IPSP (current clamp; A) or inhibitory postsynaptic current (IPSC) (voltage clamp; B) by the application of gallamine (10 μm). The dashed black line, solid black line and grey line represent traces before, during and after gallamine applications. C, time course of the effect of gallamine (10 μm) on the amplitude of slow IPSC. D, E, current clamp recordings (D) or voltage clamp recordings (E) showing that the application of scopolamine abolished slow IPSP or IPSC (dashed line and continuous line represent traces before and during scopolamine applications, 20 μm and 1 μm in D and E, respectively). F, time course of the effect of scopolamine (1 μm) on the amplitude of slow IPSC. G, statistical comparison of the gallamine-induced (n= 3) and scopolamine-induced (n= 3) suppression of slow IPSC of the terminal nerve (TN)-gonadotrophin releasing hormone (GnRH) neurones in comparison with the vehicle application (n= 4). The averaged amplitude of 0.0–2.0 min before treatment was normalised to 100% and the averaged amplitude of 2.5–5.0 min after treatment was compared with this value. ***P < 0.001, Dunnett's test. H, puffer application of Ach (1 mm) on the TN-GnRH neurone immediately evoked a strong hyperpolarisation of the TN-GnRH neurone. Arrowhead indicates the time of Ach puffer application.