Serotonin (5-HT) acts as a potent regulator of neuronal firing rates, influencing voluntary muscle contraction force and potentially mediating central nervous system exercise-induced fatigue.
This review highlights the role of serotonergic neuromodulation in regulating motoneurone excitability and its potential contribution to central fatigue during exercise in humans.
Ionotropic inputs to motoneurones have the capacity to depolarise and hyperpolarise the motoneurone, whereas neuromodulatory inputs control the state of excitability of the motoneurone. Intracellular recordings of motoneurones from in vitro and in situ animal preparations have provided extraordinary insight into the mechanisms that underpin how neuromodulators regulate neuronal excitability. However, far fewer studies have attempted to translate the findings from cellular and molecular studies into a human model. In this review, we focus on the role that serotonin (5-HT) plays in muscle activation in humans. 5-HT is a potent regulator of neuronal firing rates, which can influence the force that can be generated by muscles during voluntary contractions. We firstly outline structural and functional characteristics of the serotonergic system, and then describe how motoneurone discharge can be facilitated and suppressed depending on the 5-HT receptor subtype that is activated. We then provide a narrative on how 5-HT effects can influence voluntary activation during muscle contractions in humans, and detail how 5-HT may be a mediator of exercise-induced fatigue that arises from the central nervous system.
Kavanagh et al. (Fri,) conducted a review in Muscle activation and exercise-induced fatigue. Serotonin (5-HT) neuromodulation was evaluated. Serotonin (5-HT) acts as a potent regulator of neuronal firing rates, influencing voluntary muscle contraction force and potentially mediating central nervous system exercise-induced fatigue.