Sexual dimorphism for protein kinase cε signaling in a rat model of vincristine-induced painful peripheral neuropathy

Abstract

Painful peripheral neuropathy is a major dose-limiting adverse effect of many cancer chemotherapeutic agents, such as the vinca alkaloids and taxanes. Recent studies demonstrate sexual dimorphism in second-messenger signaling for primary afferent nociceptor sensitization, and a role of second messengers in the models of metabolic and toxic painful peripheral neuropathies. This study tested the hypothesis that sexual dimorphism alters the severity and second-messenger signaling pathways for enhanced nociception in an animal model of vincristine-induced painful peripheral neuropathy. I.V. injection of vincristine induced mechanical hyperalgesia that was greater in female rats. Gonadectomy in the females but not the males abolished the sex-dependent difference in mechanical hyperalgesia; this effect of gonadectomy in females was reversed by estrogen replacement. Inhibition of protein kinase Cε (PKCε) attenuated vincristine-induced hyperalgesia in males and ovariectomized females, but not in normal females or in estrogen-replaced ovariectomized females. Inhibitors of protein kinase A, protein kinase G, p42/p44-mitogen activated protein kinase and nitric oxide synthase also attenuated vincristine-induced hyperalgesia, but to a similar degree in both sexes. These data demonstrate an estrogen-dependent sexual dimorphism in vincristine-induced hyperalgesia (female>male) and an unexpected opposite sexual dimorphism in the contribution of PKCε to the severity of this hyperalgesia (male>female).