Translation of paclitaxel-induced peripheral neurotoxicity from mice to patients: the importance of model selection

Astrocytes in the rostral ventromedial medulla mediate the analgesic effect of electroacupuncture in a rodent model of chemotherapy-induced peripheral neuropathic pain

ABSTRACT

Chemotherapy-induced peripheral neuropathic pain aggravates cancer survivors' life burden. Electroacupuncture (EA) has exhibited promising analgesic effects on neuropathic pain in previous studies. We investigated whether EA was effective in a paclitaxel-induced neuropathic pain mouse model. We further explored the functional role of astrocytes in the rostral ventromedial medulla (RVM), a well-established pain modulation center, in the process of neuropathic pain as well as the analgesic effect of EA. We found that paclitaxel induced mechanical allodynia, astrocytic calcium signaling, and neuronal activation in the RVM and spinal cord, which could be suppressed by EA treatment. Electroacupuncture effectively alleviated paclitaxel-induced mechanical allodynia, and the effect was attenuated by the chemogenetic activation of astrocytes in the RVM. In addition, inhibiting astrocytic calcium activity by using either IP3R2 knockout (IP3R2 KO) mice or microinjection of AAV-mediated hPMCA2 w/b into the RVM to reduce non-IP3R2-dependent Ca2+ signaling in astrocytes exhibited an analgesic effect on neuropathic pain, which mimicked the EA effect. The current study revealed the pivotal role of the RVM astrocytes in mediating the analgesic effects of EA on chemotherapy-induced peripheral neuropathic pain.

Ion Channel and Transporter Involvement in Chemotherapy-Induced Peripheral Neurotoxicity

The peripheral nervous system can encounter alterations due to exposure to some of the most commonly used anticancer drugs (platinum drugs, taxanes, vinca alkaloids, proteasome inhibitors, thalidomide), the so-called chemotherapy-induced peripheral neurotoxicity (CIPN). CIPN can be long-lasting or even permanent, and it is detrimental for the quality of life of cancer survivors, being associated with persistent disturbances such as sensory loss and neuropathic pain at limb extremities due to a mostly sensory axonal polyneuropathy/neuronopathy. In the state of the art, there is no efficacious preventive/curative treatment for this condition. Among the reasons for this unmet clinical and scientific need, there is an uncomplete knowledge of the pathogenetic mechanisms. Ion channels and transporters are pivotal elements in both the central and peripheral nervous system, and there is a growing body of literature suggesting that they might play a role in CIPN development. In this review, we first describe the biophysical properties of these targets and then report existing data for the involvement of ion channels and transporters in CIPN, thus paving the way for new approaches/druggable targets to cure and/or prevent CIPN.