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Physiology, Biochemistry, and Toxicology

Poster: PBT, Physiology and Toxicology

D3364: Neurochemical modulation by histamine and serotonin in Anopheles stephensi

Tuesday, November 11, 2025
9:00 AM - 5:00 PM Pacific
Location: Exhibit Hall A-A1, OCC
Poster Display
Nearly half the world’s population, approximately 3.3 billion people, are at risk of malaria. Anopheles stephensi, a highly competent urban malaria vector species, is rapidly invading and spreading across Africa. Blood levels of histamine and serotonin (5-HT) are altered in people with severe malaria, and, at these levels, ingestion by mosquitoes produced broad effects on behaviors, including the tendency to take a second blood meal, flight behavior, and visual object inspection. However, how histamine and 5-HT modulate these behaviors remains unknown. In particular, little is known about the levels of these neuromodulators and how they are affected upon ingestion of biogenic amines. Here, we used ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) to quantify key neurotransmitters and their precursors in mosquitoes fed histamine and 5-HT at levels associated with severe malaria or healthy individuals, with emphasis on the histamine and 5-HT biosynthetic pathways. We also employed ribonucleic acid fluorescence in situ hybridization (RNA-FISH) to characterize spatial expression patterns of histamine and 5-HT receptors within the mosquito brain and midgut. Our results revealed variations in neurotransmitter levels across tissues in mosquitoes fed different levels of histamine and 5-HT relative to controls (water). RNA-FISH further showed distinct expression patterns of histamine and 5-HT receptors in the brain and midgut. Together, these findings suggest that neurochemical profiles in A. stephensi are greatly changed following ingestion of exogenous biogenic amines, which might help uncover mechanisms of histaminergic and serotonergic modulation of behaviors and offer a basis for innovative transmission-blocking strategies against malaria.