Serotonin (5-Hydroxytryptamine, 5-HT) and the 5-HT₂ receptor modulate cardiovascular and autonomic function in part through actions in the nTS, the primary termination and integration point for cardiorespiratory afferents in the brainstem. In other brain regions, 5-HT₂ receptors (5-HT₂R) modify synaptic transmission directly, as well as through 5-HT_2AR-induced endocannabinoid release. This study examined the role of 5-HT_2AR as well as their interaction with endocannabinoids on neurotransmission in the nucleus tractus solitarii (nTS). Excitatory postsynaptic currents (EPSCs) in monosynaptic nTS neurons were recorded in the horizontal brainstem slice during activation and blockade of 5-HT_2ARs. 5-HT_2AR activation augmented solitary tract (TS) evoked EPSC amplitude whereas 5-HT_2AR blockade depressed TS-EPSC amplitude at low and high TS stimulation rates. The 5-HT_2AR-induced increase in neurotransmission was reduced by endocannabinoid receptor block and increasedendogenous endocannabinoids in the synaptic cleft during high frequency, but not low, TS stimulation. Endocannabinoids did not tonically modify EPSCs. These data suggest 5-HT acting through the 5-HT_2AR is an excitatory neuromodulator in the nTS and its effects are modulated by the endocannabinoid system.
Copyright © 2013. Published by Elsevier B.V.

PMID:

 

24041777

 

[PubMed – as supplied by publisher]