Neural Modulation of Foraging Strategies in C. elegans

BLANCO, M.G.; DE ROSA, M.J.; ALKEMA, M.J.; ZABALA, M.A; RAYES, D.H.

Rosario

Congreso; SEcond LAtin American Worm meeting; 2020

Despite theintermodulation between serotonergic and adrenergic signals is crucialthroughout the animal kingdom, the molecular and cellular mechanisms underlyingthis interrelation are poorly understood. Given its simplicity and the highlyconserved neurological pathways, Caenorhabditiselegans is a powerful model organism that can be used toprovide insights into the neural circuits linking 5-TH and catecholamines.When food-deprived wormsencounter food, 5-HT is released to slow-down their locomotion and to stimulatepharyngeal pumping. In contrast, Tyramine (TA) and Octopamine (OA),invertebrate counterparts for adrenaline and noradrenaline, stimulatelocomotion and decrease pharyngeal pumping. We found that well-fed tdc-1 (unable tosynthesize TA and OA) and tbh-1 (unableto synthesize OA) null mutants are hypersensitive to the slowing-down responseupon food encounter, resembling starved worms. Moreover, exogenous TA and OArecover the increased slowing-down locomotion of tdc-1 null mutants,suggesting that both, TA and OA, antagonize 5HT-dependent food-relatedbehaviors. Furthermore, our calcium imaging recordings showed that the peak ofactivity of serotoninergic neurons (ADF and NSM) upon encountering food issignificantly higher in a tdc-1 nullmutant background. Wealso found that tdc-1 nullmutants are hypersensitive to the paralysis produced by exogenous 5-HT.Therefore, we are using this assay to evaluate the paralysis of the differentTA and OA null receptor mutants to identify which receptors are involved inthis antagonism. Taken together, these results suggest that TA and OAcounteract with 5-HT by driving opposing food-related behaviors and byinhibiting 5-HT release