Pregabalin Induces Hepatic Hypoxia and Increases EndothelialCell Proliferation in Mice, a Process Inhibited by DietaryVitamin 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.

Hemangiosarcoma in Mice Administered Pregabalin: Analysis of Genotoxicity, Tumor Incidence, and Tumor Genetics

“…Specifically, pregabalin induces macrophage activation and increased angiogenic growth factors in bone marrow, spleen, and liver tissues, with a high incidence of hemangiosarcomas in the mouse (Criswell et al, 2012a). Pregabalin also increased local tissue hypoxia and endothelial cell proliferation in mouse liver (Criswell et al, 2012b), which are hallmarks of nongenotoxic tumor formation. All of these changes were absent in the rat.…”

Pregabalin in Neuropathic Pain: Evidences and Possible Mechanisms

“…Administration of pregabalin with alcohol or benzodiazepines may synergistically depress neuronal conduction in the CNS possibly due to the enhancement of GABA mediated actions and inhibition of Ca 2+ mediated glutamate release at synapses [85]. In preclinical studies, pregabalin has been shown to induce bone marrow changes, hepatic hypoxia, endothelial cell proliferation and hemangiosarcoma in mice [86-88]. The combination of hypoxia and sustained increase in endothelial cell proliferation, angiogenic growth factors, dysregulated erythropoiesis, and macrophage activation has been hypo-thesized as the key event for the hemangiosarcoma formation in mice [89].…”

Pregabalin for the treatment of generalized anxiety disorder: an update

“…Knowledge of the mechanism of hemangioma induction has increased, and it is now thought that increased bicarbonate, and dysregulated erythropoiesis, macrophage activation, and increased angiogenic growth factors may all be important 91. Pregabalin appears to induce hypoxia and endothelial cell proliferation in a species-specific manner, but these effects can be inhibited by vitamin E, presumably due to its antioxidant and antiangiogenic properties 92. Based on an extensive dataset, a recent review concluded that the findings seen in mice are not relevant to humans at the clinical dose of pregabalin, and that use of pregabalin does not pose an increased risk for hemangiosarcoma in humans 93…”