Zn²⁺ enhances the intrinsic bursting activity of a rat thalamic relay neuron

Although zinc ion (Zn²⁺) reduced the low-threshold T-type Ca²⁺ current of a rat thalamic relay neuron (TRN), we observed that Zn²⁺ increased a bursting activity of TRN by altering the generation and maintenance of low-threshold spike (LTS). Interestingly and importantly, Zn²⁺ shifted dramatically the voltage-dependence of both steady-state inactivation and activation of the transient A-type K⁺ current (I_A) to a depolarizing direction. As I_A is one of the main factors in shaping thalamic LTS, such alterations of gating properties of I_A would contribute to the enhancement of TRN excitability under Zn²⁺.