Co-activation of both 5-HT1A and 5-HT7 receptors induced attenuation of glutamatergic synaptic transmission in the rat visual cortex. (1st November 2018) - Li, Yan-Hai
Highlights: Bath application of 5-HT reduced the AMPA- mEPSCs. Exogenous application of 5-CT or 8-OH-DPAT mimicked 5-HT in its effect. Co-activation of both 5-HT1A and 5-HT7 receptors modulated AMPA- mEPSCs. A block of 5-HT1A or 5-HT7 receptors alone had no effects on AMPA- mEPSCs. Abstract: It has been suggested that functional interactions between the 5-HT receptor subtypes may modulate glutamatergic synaptic transmission. In this study, we used whole-cell patch-clamp recordings to test the role of 5-HT receptors in mediating the AMPA receptor-mediated miniature excitatory postsynaptic currents (mEPSCs) in layer II/III pyramidal neurons of the rat visual cortex. We found that the AMPA receptor-mediated component of mEPSCs could be inhibited by exogenously applied 5-HT. 5-HT significantly reduced the glutamatergic mEPSC amplitude and increased the inter-event interval of glutamatergic mEPSCs. Bath application of 5-CT or 8-OH-DPAT (the 5-HT1A and 5-HT7 receptor agonist) mimicked 5-HT in its effect on mEPSCs. Additionally, a selective antagonist for the 5-HT7 receptor, SB-269970, displayed no influence on the inhibition of glutamatergic synaptic transmission by 5-CT or 8-OH-DPAT. Similar results were obtained by exogenously applied WAY-100135, the selective 5-HT1A receptor antagonist. However, the inhibition of glutamatergic synaptic transmission by 5-CT or 8-OH-DPAT was completely blocked by co-application of WAY-100135 and SB-269970. Altogether, our results indicated that 5-HT suppressed glutamatergic synaptic transmission by co-activation of synaptic 5-HT1A receptors and 5-HT7 receptors in layer II/III pyramidal neurons of the rat visual cortex.