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. 2000 May 15;20(10):3900–3908. doi: 10.1523/JNEUROSCI.20-10-03900.2000

Fig. 5.

Fig. 5.

Septohippocampal GABA-type but not cholinergic-type neurons rats are excited by muscarine.A, These whole-cell recordings were performed in brain slices taken from uninjected rats. Neurons were classified as septohippocampal cholinergic-type or GABA-type based on electrophysiological characteristics (see Results).A1 shows a fast-spiking, nonaccommodating, GABA-type MSDB neuron. A2, Chart recording from the same neuron shows the profound excitatory effect of bath-applied muscarine. An excitatory effect was observed in 87.5% of septohippocampal GABA-type neurons tested. Note the depolarizing sag in response to the hyperpolarizing pulses and the presence of an anode-break excitation after termination of the hyperpolarizing pulses. B,Whole-cell recording from a spontaneously firing cholinergic-type MSDB neuron. This cell exhibited a prominent slow afterhyperpolarization after a spike and strong inward rectification in response to hyperpolarizing pulses. Bath-applied muscarine (10 μm, 2 min) produced a 9 mV hyperpolarization that reversed after washout (washout not shown). Inhibitory effects of muscarine were observed in 62.5% of cholinergic-type MSDB neurons. C, Bar chart summarizes the effect of muscarine on cholinergic- and parvalbumin-type MSDB neurons. Note that although none of the ChAT-type neurons were excited by muscarine, 88% of Parv-type neurons responded to the agonists with an excitation. D, Bar chart shows that whereas muscarine produced a significant decrease in firing rate in ChAT-type neurons, it produced an increase in rate in Parv-type neurons.