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Suramin is a trypan blue analogon originally developed to treat protozoan infections, which was found to have diverse antitumor effects. One of the most severe side effects in clinical trials was the development of a peripheral sensory-motor polyneuropathy. In this study, we aimed to investigate suramin-induced neuropathy with a focus on calcium (Ca2+) homeostasis as a potential pathomechanism. Adult C57Bl/6 mice treated with a single injection of 250 mg/kg bodyweight suramin developed locomotor and sensory deficits, which were confirmed by electrophysiological measurements showing a predominantly sensory axonal-demyelinating polyneuropathy. In a next step, we used cultured dorsal root ganglia neurons (DRGN) as an in vitro cell model to further investigate underlying pathomechanisms. Cell viability of DRGN was significantly decreased after 24-hour suramin treatment with a calculated IC50 of 283 µM. We detected a suramin-induced Ca2+ influx into DRGN from the extracellular space, which could be reduced with the voltage-gated calcium channel (VGCC) inhibitor nimodipine. Co-incubation of suramin and nimodipine partially improved cell viability of DRGN after suramin exposure. In summary, we describe suramin-induced neurotoxic effects on DRGN as well as potentially neuroprotective agents targeting intracellular Ca2+ dyshomeostasis [ABSTRACT FROM AUTHOR]

Polyneuropathy is a frequent and potentially severe side effect of clinical tumor chemotherapy. The goal of this study was to characterize paclitaxel-, cisplatin-, vincristine- and bortezomib-induced neuropathy in C57BL/6 mice with a comparative approach. The phenotype of the animals was evaluated at four time points with behavioral and electrophysiological tests, followed by histology. Treatment protocols used in this study were well tolerated and induced a sensory and predominantly axonal polyneuropathy. Behavioral testing revealed normal motor coordination, whereas all mice receiving verum treatment developed mechanical allodynia and distinct gait alterations. Electrophysiological evaluation showed a significant decrease of the caudal sensory nerve action potential amplitude for all cytostatic agents and a moderate reduction of nerve conduction velocity for cisplatin and paclitaxel. This finding was confirmed by histological analysis of the sciatic nerve which showed predominantly axonal damage: Paclitaxel and vincristine affected mostly large myelinated fibers, bortezomib small myelinated fibers and cisplatin damaged all types of myelinated fibers to a similar degree. Neuropathic symptoms developed faster in paclitaxel and vincristine treated animals compared to cisplatin and bortezomib treatment. The animal models in this study can be used to elucidate pathomechanisms underlying chemotherapy-induced polyneuropathy and for the development of novel therapeutic and preventative strategies. [ABSTRACT FROM AUTHOR]

Neuropathic pain as a symptom of sensory nerve damage is a frequent side effect of chemotherapy. The most common behavioral observation in animal models of chemotherapy induced polyneuropathy is the development of mechanical allodynia, which is quantified with von Frey filaments. The data from one study, however, cannot be easily compared with other studies owing to influences of environmental factors, inter-rater variability and differences in test paradigms. To overcome these limitations, automated quantitative gait analysis was proposed as an alternative, but its usefulness for assessing animals suffering from polyneuropathy has remained unclear. In the present study, we used a novel mouse model of paclitaxel induced polyneuropathy to compare results from electrophysiology and the von Frey method to gait alterations measured with the Catwalk test. To mimic recently improved clinical treatment strategies of gynecological malignancies, we established a mouse model of dose-dense paclitaxel therapy on the common C57Bl/6 background. In this model paclitaxel treated animals developed mechanical allodynia as well as reduced caudal sensory nerve action potential amplitudes indicative of a sensory polyneuropathy. Gait analysis with the Catwalk method detected distinct alterations of gait parameters in animals suffering from sensory neuropathy, revealing a minimized contact of the hind paws with the floor. Treatment of mechanical allodynia with gabapentin improved altered dynamic gait parameters. This study establishes a novel mouse model for investigating the side effects of dose-dense paclitaxel therapy and underlines the usefulness of automated gait analysis as an additional easy-to-use objective test for evaluating painful sensory polyneuropathy. [ABSTRACT FROM AUTHOR]