Modulatory Action by the Serotonergic System: Behavior and Neurophysiology in Drosophila melanogaster

Abstract EN

Serotonin modulates various physiological processes and behaviors.

This study investigates the role of 5-HT in locomotion and feeding behaviors as well as in modulation of sensory-motor circuits.

The 5-HT biosynthesis was dysregulated by feeding Drosophila larvae 5-HT, a 5-HT precursor, or an inhibitor of tryptophan hydroxylase during early stages of development.

The effects of feeding fluoxetine, a selective serotonin reuptake inhibitor, during early second instars were also examined.

5-HT receptor subtypes were manipulated using RNA interference mediated knockdown and 5-HT receptor insertional mutations.

Moreover, synaptic transmission at 5-HT neurons was blocked or enhanced in both larvae and adult flies.

The results demonstrate that disruption of components within the 5-HT system significantly impairs locomotion and feeding behaviors in larvae.

Acute activation of 5-HT neurons disrupts normal locomotion activity in adult flies.

To determine which 5-HT receptor subtype modulates the evoked sensory-motor activity, pharmacological agents were used.

In addition, the activity of 5-HT neurons was enhanced by expressing and activating TrpA1 channels or channelrhodopsin-2 while recording the evoked excitatory postsynaptic potentials (EPSPs) in muscle fibers.

5-HT2 receptor activation mediates a modulatory role in a sensory-motor circuit, and the activation of 5-HT neurons can suppress the neural circuit activity, while fluoxetine can significantly decrease the sensory-motor activity.