Abstract: To explore the neuronal mechanisms underlying pesticides intoxication in adult honeybees, the primary culture of brain neurons of adult honeybees and electrophysiological recordings are required. However, little is known of the electrophysiological properties and sodium currents or potassium currents in normal adult honeybee brain neurons. We first dissociated neurons from brains of adult Apis mellifera by gentle trituration after a 15-min incubation with papain. This preparation resulted in a large number of isolated viable neurons. Using the whole-cell configuration of the patch-clamp technique, we investigated the neuronal responses of the isolated neurons to the current or voltage stimulation. Current-clamp data showed that the tested neurons showed no spontaneous discharges but were capable of firing a single action potential in response to depolarizing current injection. The mean current threshold for action potential was 60.8±6.3 pA and the mean voltage threshold −27.4±2.3 mV. Under voltage clamp, sodium currents were isolated by blockade of potassium channel and calcium channel. The sodium current was activated at command potentials more positive than −40 mV with a maximum around −10 mV and a halfmaximal voltage for inactivation of −58.4 mV. The neurons expressed at least two distinct K⁺ currents, a small transient current and a large sustained current (80% of total K⁺ current) with a half maximal voltage for activation of 3.86 mV. The large sustained potassium current showed little or no inactivation. The results suggest that the prominent sustained potassium current might account for the a single spiking in the recorded adult honeybee neurons. 

Key words: Apis mellifera, neuron, excitability, sodium current, potassium current, whole-cell patch-clamp