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10-Minute Presentation

Physiology, Biochemistry, and Toxicology

10-min: PBT, Genetics

Effects of histamine and serotonin on Anopheles stephensi spectral sensitivity of circadian entrainment

Wednesday, November 13, 2024
1:54 PM – 2:06 PM MST
Location: Phoenix Convention Center, 121 C, PCC
Oral Presentation
Anopheles mosquitoes, vectors that transmit the parasitic agents of malaria, exhibit circadian rhythms in their biology, including flight behavior, physiology, and interactions with pathogens. Light-dark cycles serve as the primary external cues for entraining circadian activity and synchronizing the circadian clock. Upon exposure to light, mosquito retinal photoreceptors become active, triggering neural signaling pathways. These pathways interact with the circadian clock in the brain, modulating mosquito vision to help them find hosts, nectar, and oviposition sites. Given changes in blood levels of histamine and serotonin (5-HT) associated with severe malaria and key roles of these biogenic amines in insect neurophysiology, we investigated the impact of ingested histamine and 5-HT at healthy levels (1nM histamine, 1.5µM 5-HT) or malaria-associated levels (10nM histamine, 0.15µM 5-HT) on Anopheles stephensi visual sensitivity during different circadian phases. To test this, we provisioned healthy or malaria-associated biogenic amine levels to female A. stephensi and monitored their circadian activity. During the transition between light and dark phases, we assessed mosquito retinal sensitivity using electroretinogram (ERG) during exposure to a variety of monochromatic stimuli. Our data indicated that biogenic amines provisioned to A. stephensi altered their spectral sensitivities between different circadian phases. These findings provide a basis for further investigations into how sensory systems, particularly those involved with histaminergic and serotonergic pathways, modulate mosquito behaviors in relation to circadian rhythm. Further, these studies offer promising avenues for manipulating host-seeking activities and, consequently, parasite transmission in mosquitoes, presenting potential targets for effective disease control strategies.