The Journal of Physiology | 2019
5‐HT2A receptor activation enhances NMDA receptor‐mediated glutamate responses through Src kinase in the dendrites of rat jaw‐closing motoneurons
Abstract
5‐HT increases the excitability of brainstem and spinal motoneurons, including the jaw‐closing motoneurons, by depolarizing the membrane potential and decreasing the medium‐duration afterhyperpolarization. In this study, we focused on how 5‐HT enhances postsynaptic glutamatergic responses in the dendrites of the jaw‐closing motoneurons. We demonstrate that 5‐HT augments glutamatergic signalling by enhancing the function of the GluN2A‐containing NMDA receptor (NMDAR) through the activation of 5‐HT2A receptors (5‐HT2ARs) and Src kinase. To enhance glutamatergic responses, activation of the 5‐HT2ARs must occur within ∼60 μm of the location of the glutamate responses. 5‐HT inputs to the jaw‐closing motoneurons can significantly vary their input–output relationship, which may contribute to wide‐range regulation of contractile forces of the jaw‐closing muscles.