The vital functions of organisms are sustained through the interaction of specialized structures coordinated by strict signaling mechanisms. This balance can be disrupted by internal or external stressors, triggering the release of neurotransmitters essential for adaptation. Among these, serotonin (5-HT) has a poorly characterized role in adaptive responses to stress. In this work, we used Drosophila melanogaster, an organism lacking thermoregulatory capacity, as a model to investigate the role of serotonin in the locomotor response to thermal stress. Control flies exposed to increased temperature, either as an acute heat shock (AHS) or as a gradual increment (GTI), exhibited elevated locomotor activity. In contrast, we used flies deficient in components of the serotonergic pathway including tryptophan hydroxylase, the serotonin transporter (SerT), and receptors (5-HT1A, 5-HT1B, 5-HT2A, 5-HT2B, and 5-HT7) under both protocols (AHS y GTI) and analyzed their locomotor patterns. These preliminary results support a role for serotonin and it signaling in the adaptive response to thermal stress.