Cisplatin-triggered sensory dysfunction in NER-defective C. elegans involves GABAergic and cholinergic signaling

Cisplatin (CisPt) is a widely used anticancer drug that causes neurotoxicity as a dose-limiting adverse effect. DNA damage contributes to CisPt-induced neurotoxicity, yet the molecular mechanisms involved remain unclear. Here, we aim to identify pathophysiological mechanisms contributing to DNA damage-driven development of sensory neuronal dysfunction using the 3R-compliant model organism Caenorhabditis elegans. To this end, we employed the nucleotide excision repair (NER)-deficient ercc-1 mutant, which shows enhanced CisPt-induced sensory dysfunction as monitored by the chemotaxis assay, to elucidate drug-induced alterations in neurotransmission and transcriptome. We found that CisPt reduces gamma-aminobutyric acid (GABA) levels in the nematode and that GABA supplementation rescues ercc-1 mutants from CisPt-evoked sensory neurotoxicity, pointing to a neuroprotective function of GABA in the context of our study. Moreover, CisPt impairs the morphological integrity of GABAergic neurons particularly in ercc-1 mutants, which again is rescued by GABA substitution. Conversely, the cholinergic agonist carbachol impairs sensory function and exacerbates the neurotoxic effects of CisPt in ercc-1 mutants, indicating detrimental effects resulting from cholinergic excitation. Transcriptome analysis revealed that CisPt treatment stimulates a broard transcriptional response, including pathways involved in the regulation of neuronal communication, including acetylcholine-mediated neurotransmission, with pronounced effects occurring in the absence of ERCC-1. Based on these finding we suggest impaired GABAergic signaling and the loss of neuronal integrity GABAergic neurons as well as excessive cholinergic excitation as key mechanisms linking CisPt-induced DNA damage in NER defective nematodes to sensory dysfunction. Hence, targeting the balance between GABAergic inhibition and cholinergic excitation is suggested to counteract sensory neurotoxicity triggered by CisPt.