title: Reversible neuronal and muscular toxicity of caffeine in developing vertebrates.
abstract: This study utilizes zebrafish embryos to understand the cellular and molecular mechanisms of caffeine toxicity in developing vertebrate embryos. By using a high concentration of caffeine, we observed almost all the phenotypes that have been described in humans and/or in other animal models, including neural tube closure defect, jittery, touch insensitivity, and growth retardation as well as a drastic coiled body phenotype. Zebrafish embryos exposed to 5mM caffeine exhibited high frequent movement, 10 moves/min comparing with around 3 moves/min in control embryos, within half an hour post exposure (HPE). They later showed twitching, uncoordinated movement, and eventually severe body curvature by 6HPE. Exposure at later stages resulted in the same phenotypes but more posteriorly. Surprisingly, when caffeine was removed before 6HPE, the embryos were capable of recovering but still exhibited mild curvature and shorter bodies. Longer exposure caused irreversible body curvature and lethality. These results suggest that caffeine likely targets the neuro-muscular physiology in developing embryos. Immunohistochemistry revealed that the motorneurons in treated embryos developed shorter axons, abnormal branching, and excessive synaptic vesicles. Developing skeletal muscles also appeared smaller and lacked the well-defined boundaries seen in control embryos. Finally, caffeine increases the expression of genes involved in synaptic vesicle migration. In summary, our results provide molecular understanding of caffeine toxicity on developing vertebrate embryos.
authors.affiliation: Biology Department, University of Wisconsin-River Falls, River Falls, WI 54022, USA.
authors.forename: Rufino S
authors.initials: RS
authors.lastname: Rodriguez
authors.affiliation: Biology Department, University of Wisconsin-River Falls, River Falls, WI 54022, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Haugen
authors.affiliation: Biology Department, University of Wisconsin-River Falls, River Falls, WI 54022, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rueber
authors.affiliation: Biology Department, University of Wisconsin-River Falls, River Falls, WI 54022, USA. Electronic address: cheng-chen.huang@uwrf.edu.
authors.forename: Cheng-Chen
authors.initials: CC
authors.lastname: Huang
mesh_terms: D000818:Animals; D002110:Caffeine / Q000633:toxicity*; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects* / Q000473:pathology; D009068:Movement; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology; D019170:Somites / Q000187:drug effects; D013572:Synaptic Vesicles / Q000187:drug effects / Q000502:physiology; D015027:Zebrafish / Q000196:embryology
chemical_list: D002110:Caffeine
keywords: Caffeine; Neuromuscular; Synaptic vesicle; Zebrafish