Dopamine Modulates Excitatory Synaptic Transmission by Activating Presynaptic D1-like Dopamine Receptors in the RA Projection Neurons of Zebra Finches.

Songhua Wang,Wei Meng,Qingqin Wang,Dongfeng Li,Lihua Yao,Shaoyi Liu,Yalun Sun

doi:10.3389/fncel.2020.00126

Abstract

Songbirds are useful vertebrate study models for vocal learning and memory. The robust nucleus of the arcopallium (RA) receives synaptic inputs from both the posterior and anterior pathways of the song control system in songbirds. Hence, RA plays an important role in the control of singing. RA receives dopaminergic (DArgic) inputs that increase the excitability of RA projection neurons (PNs). However, the effects of DA on excitatory synaptic transmission are yet to be deciphered. In this study, the effects of DA on the excitatory synaptic transmission of the PNs in the RA of adult male zebra finches were investigated using a whole-cell patch-clamp recording. We observed that DA decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and miniature excitatory postsynaptic currents (mEPSCs). The effects of DA were mimicked by the D1-like DA receptor (D1R) agonist, SKF-38393, but not the D2-like DA receptor (D2R) agonist, Quinpirole. Also, the effects of DA were blocked by D1R antagonist, SCH-23390, but not the D2R antagonist, Sulpiride. These results demonstrate that DA modulates excitatory synaptic transmission by acting on D1R in the RA of adult male zebra finches.

Highlights

Birdsong is a complex learned behavior in Avians
We demonstrated that DA reduced excitatory synaptic transmissions in RA projection neurons (PNs)
We evaluated miniature excitatory postsynaptic currents (mEPSCs) to determine whether DA had presynaptic or postsynaptic effects

Summary

Introduction

Birdsong is a complex learned behavior in Avians. Learning and song production is mediated by a discrete set of interconnected brain nuclei, i.e., the song control system (Nottebohm et al, 1976). The song system can be divided into two pathways (Figure 1): the vocal motor pathway (VMP) that contributes to song production and the anterior forebrain pathway (AFP) that is essential for song learning and plasticity (Brainard and Doupe, 2000). The robust nucleus of the arcopallium (RA) is the key site that receives afferent inputs from both the HVC (letter-based name) and lateral magnocellular nucleus of the anterior nidopallium (LMAN; Mooney and Konishi, 1991). Understanding how the activation of DA could affect synaptic activity in the RA will provide a mechanistic understanding of the neural control of song behavior

Methods

Results

Conclusion