title: Pregabalin induces hepatic hypoxia and increases endothelial cell proliferation in mice, a process inhibited by dietary vitamin E supplementation.
abstract: The preceding article identified key components of pregabalin's mode of action on nongenotoxic hemangiosarcoma formation in mice, including increased serum bicarbonate leading to decreased respiratory rate, increased blood pH, increased venous oxygen saturation, increased vascular endothelial growth factor and basic fibroblast growth factor expression, increased hepatic vascular endothelial growth factor receptor 2 expression, and increased iron-laden macrophages. Increased platelet count and platelet activation were early, species-specific biomarkers in mice. Dysregulated erythropoiesis, macrophage activation, and elevations of tissue growth factors were consistent with the unified mode of action for nongenotoxic hemangiosarcoma recently proposed at an international hemangiosarcoma workshop (Cohen, S. M., Storer, R. D., Criswell, K. A., Doerrer, N. G., Dellarco, V. L., Pegg, D. G., Wojcinski, Z. W., Malarkey, D. E., Jacobs, A. C., Klaunig, J. E., et al. (2009). Hemangiosarcoma in rodents: Mode-of-action evaluation and human relevance. Toxicol. Sci. 111, 4-18). In this article, we present evidence that pregabalin induces hypoxia and increases endothelial cell (EC) proliferation in a species-specific manner. Dietary administration of pregabalin produced a significant 35% increase in an immunohistochemical stain for hypoxia (Hypoxyprobe) in livers from pregabalin-treated mice. Increased Hypoxyprobe staining was not observed in the liver, bone marrow, or spleen of rats, supporting the hypothesis that pregabalin produces local tissue hypoxia in a species-specific manner. Transcriptional analysis supports that rats, unlike mice, adapt to pregabalin-induced hypoxia. Using a dual-label method, increased EC proliferation was observed as early as 2 weeks in mouse liver and 12 weeks in bone marrow following pregabalin administration. These same assays showed decreased EC proliferation in hepatic ECs of rats, further supporting species specificity. Dietary supplementation with vitamin E, which is known to have antioxidant and antiangiogenic activity, inhibited pregabalin-induced increases in mouse hepatic EC proliferation, providing confirmatory  evidence for the proposed mode of action and its species-specific response.
authors.affiliation: Pfizer Worldwide Research & Development, Drug Safety Research & Development, Groton, Connecticut 06340, USA. kay.criswell@pfizer.com
authors.forename: Kay A
authors.initials: KA
authors.lastname: Criswell
authors.forename: Jon C
authors.initials: JC
authors.lastname: Cook
authors.forename: Dennis
authors.initials: D
authors.lastname: Morse
authors.forename: Michael
authors.initials: M
authors.lastname: Lawton
authors.forename: Christopher
authors.initials: C
authors.lastname: Somps
authors.forename: Leslie
authors.initials: L
authors.lastname: Obert
authors.forename: Marc
authors.initials: M
authors.lastname: Roy
authors.forename: Sharon
authors.initials: S
authors.lastname: Sokolowski
authors.forename: Petra
authors.initials: P
authors.lastname: Koza-Taylor
authors.forename: Jennifer
authors.initials: J
authors.lastname: Colangelo
authors.forename: Kimberly
authors.initials: K
authors.lastname: Navetta
authors.forename: Joseph
authors.initials: J
authors.lastname: Brady
authors.forename: David
authors.initials: D
authors.lastname: Pegg
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Wojcinski
authors.forename: Ramin
authors.initials: R
authors.lastname: Rahbari
authors.forename: Steven
authors.initials: S
authors.lastname: Duddy
authors.forename: Timothy
authors.initials: T
authors.lastname: Anderson
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D049109:Cell Proliferation / Q000187:drug effects*; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D005260:Female; D008099:Liver / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D000069583:Pregabalin; D014810:Vitamin E / Q000008:administration & dosage*; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000633:toxicity
chemical_list: D014810:Vitamin E; D000069583:Pregabalin; D005680:gamma-Aminobutyric Acid