D2-type dopamine receptors are crucial for GABAergic transmission in VIP interneurons

<p><span style="font-size:11pt;line-height:107%;font-family:&#39;calibri&#39; , sans-serif">The
fundamental property of the nervous system is its plasticity, which enables
both learning processes and adaptation to a new environment. At the cellular
and molecular level, the basis of neuroplasticity processes is various forms of
synaptic plasticity, considered to be the main substrate of memory. Despite the
critical role of VIP interneurons in these processes, no data show what factors
regulate the plasticity of inhibitory synapses in these cells. An attractive
candidate in this context is dopamine, since, as we know, dopaminergic
neuromodulation is a key factor influencing cognitive functions and information
processing in the hippocampus. However, the involvement of dopaminergic
receptors in the plasticity of GABAergic synapses is practically unexplored. Herein,
we checked the role of dopamine receptors (DRs) in the plasticity of inhibitory
transmission at synapses onto VIP interneurons in the CA1 region. We found that
the obtained results depend on the type of VIP interneuron and dopaminergic D2
receptors. Especially, the bath application of the dopamine agonist quinpirole significantly
increased the amplitude of mIPSCs measured from type 1 of VIP interneurons but
not type 2. The opposite effect was observed in the presence of D2 Rs
antagonist sulpiride. Moreover, the frequency and kinetics of mIPSCs was also
affected by D2Rs blockade/activation. This pharmacological approach provides
the first evidence that  D2  dopamine receptors modulate GABAergic transmission
in the CA1 region of the hippocampus.</span></p>