Objective: 

TRPC channels, a family of non-selective cation channels, are believed to support Ca²⁺ entry as well as membrane depolarization. Area of lateral septum, being a part of limbic system of the brain and responsible for regulation of emotional and behavioral reactions, is enriched with TRPC proteins and, in particular, TRPC4s. Our work was aimed to clarify possible involvement of TRPC channels in modulation of firing activity in this brain region.

Methods: 

We used conventional patch-clamp technique in whole-cell current-clamp mode to record action potentials (APs) from 8–14 day-old cultured neurons of lateral septum derived form wild-type (WT), TRPC4 single (C4-/-) and TRPC1/C4 double (C1C4(-/-)²) knockout mice.

Results: 

TRPC4-deficient neurons showed a tendency to produce more frequent spontaneous firing activity in comparison with wild-type ones. Upon TRPC channels activation by intracellular GTPgS, AP series evoked by 500-ms current injections revealed statistically significant difference in AP and firing parameters between septal neurons of WT, C4-/- and C1C4(-/-)² knockouts. Phenomenon of after-depolarization (ADP), that follows a series of APs and whose size is believed to be an index for action potential firing mode, was significantly less pronounced in C4-/- neurons, than in WT ones.

Conclusions: 

Our findings let us conclude that absence of TRPC1 and/or C4 channels strongly alters firing properties of neurons of lateral septum and shape single action potentials generated by them.