Habituation-Like Decrease of Acetylcholine-Induced Inward Current in Helix Command Neurons: Role of Microtubule Motor Proteins

Abstract

The role of kinesin and dynein microtubuleassociated molecular motors in the cellular mechanism of depression of acetylcholine-induced inward chloride current (ACh-current) was examined in command neurons of land snails (Helix lucorum) in response to repeated applications of ACh to neuronal soma. This pharmacological stimulation imitated the protocol of tactile stimulation evoking behavioural habituation of the defensive reaction.In this system, a dynein inhibitor (erythro-9-(2-hydroxy-3-nonyl)adenine, 50 lM) decreased the ACh-current depression rate. Kinesin Eg5 inhibitors (Eg5 inhibitor III, 10 lM and Eg5 inhibitor V, trans-24, 15 lM) reduced the degree of current depression, and Eg5 inhibitor V also reduced the initial rate of depression. The results of electrophysiological experiments in combination with mathematical modelling provided evidence of the participation of dyneins and kinesin Eg5 proteins in the radial transport of acetylcholine receptors in command neurons of H. lucorum in the cellular analogue of habituation. Furthermore, these results suggest that the reciprocal interaction between dynein and kinesin proteins located on the same vesicle can lead to reverse their usual direction of transport (dyneins-in exocytosis and kinesin Eg5-in endocytosis).Keywords EHNA Á Eg5-inhibitor-III Á Eg5-inhibitor-V trans-24 Á Short-term depression of ACh-induced chloride current Á Command neurons Á Helix lucorum Á Habituation

Responses of Withdrawal Interneurons to Serotonin Applications in Naïve and Learned Snails Are Different

“…Questions concerning the mechanisms of learning and memory are still open. Experimental data show that the cellular processes associated with learning occur at least at two levels: long-term modifications of the synaptic transmission efficiency (presynaptic level) and changes in the endogenous properties of the whole neuron and its membrane potential (postsynaptic level; Balaban, 2002 , 2017 ; Crow, 2004 ; Hawkins et al, 2006 ; Jin et al, 2009 ; Saar and Barkai, 2009 ; Gainutdinov et al, 2011 ; Hu et al, 2011 ; Vasil’yeva et al, 2015 ). Several specific tasks can be distinguished within the problem of cellular mechanisms of learning.…”