Effect of etomidate on the reuniens neuronal activity

To explore the effect of etomidate on the neuronal activity of ventral thalamic reuniens nucleus and the underlying mechanisms.

Whole-cell patch clamp method was used to explore the effect of etomidate on the activity of ventral thalamic reuniens neurons in the acute brain slices obtained from 4-5 weeks old C57BL/6J mice. The electrophysiological characteristics of ventral thalamic reuniens neurons were recorded in the current clamp mode, and then the effects of etomidate (0.5, 2.0, 8.0 μmol/L etomidate groups) and intralipid (intralipid group) on the discharge frequency and membrane potential of ventral thalamic reuniens neurons were recorded. During the experiment, the ventral thalamic reuniens neuron firing rates (RNFRs) were recorded as F_B, F_D and F_w before, after administration, and after elution; and the membrane potential was recorded as MP_B and MP_D before, after administration. The chlorine channel of gamma-amino butyric acid Type A (GABAA) receptor was blocked with 100 μmol/L picrotoxin (PTX). The RNFRs were recorded as F_BS, F_ETO and F_ETO+PTX before, after perfusing etomidate with sub-anesthesia concentration (0.5 μmol/L) and after perfusing both PTX and etomidate.

In the intralipid group, there was no significant difference among the F_B, F_D and F_w (P>0.05). But in the etomidate groups (0.5, 2.0, 8.0 μmol/L), the F_D was less than the F_B, there was significant difference (all P<0.01); the F_w was higher than the F_D, there was significant difference (all P<0.05). Moreover, there was significant difference in the inhibitory degree of the RNFRs between the 0.5 μmol/L etomidate group and the 8.0 μmol/L etomidate group (P<0.05). In the experiment to explore the mechanism of etomidate (0.5 μmol/L), the F_ETO was compared with the F_BS, there was significant difference (P<0.01); but when the F_ETO+PTX was compared with the F_BS, there was no significant difference (P>0.05).

Etomidate can inhibit the activity of ventral thalamic reuniens neurons in concentration-dependent manner, and which is reversible. Etomidate with sub-anesthetic concentration inhibits the activity of ventral thalamic reuniens neurons via targeting the GABA_A receptor.