Serotonin 2A receptors augment synaptic transmission in the nucleus tractus solitarii (nTS)

Abstract

The nTS is the primary termination and integration point for cardiorespiratory afferents in the brainstem. Serotonin (5‐Hydroxytryptamine, 5‐HT) in the nTS plays a profound role in modulating synaptic and cardiovascular function. This study examined the role of the 5‐HT 2A receptor subtype in mediating neurotransmission in the nTS. Excitatory postsynaptic currents in monosynaptic nTS neurons were recorded in the horizontal brainstem slice in the presence of a 5‐HT2A receptor agonist (TCB‐2) or antagonist (MDL11939). TCB‐2 augmented solitary tract (TS) evoked EPSC amplitude elicited at 0.5 and 20 Hz. Conversely, MDL11939 depressed TS‐EPSCs amplitude evoked at 0.5 and 20 Hz. TCB‐2 and MDL11939 did not alter the TS‐EPSC paired‐pulse ratio, magnitude of depression from the first event or decay time. TCB‐2 did not alter miniature (m)EPSC amplitude or frequency, whereas MDL11939 increased mEPSC frequency but not amplitude. These data suggest the 5‐HT2A receptor is an excitatory neuromodulator in the nTS. Support: HL 085108.