α-Latrotoxin and Pain: A Nociceptor Perspective on Latrodectism

Alpha-latrotoxin (α-LTX) is the principal vertebrate-specific neurotoxin in widow spider (Latrodectus) venom and a powerful presynaptic secretagogue. Although its receptors, pore-forming activity and stimulation of neurotransmitter release have been studied extensively in central and motor neurons, its relationship to the severe, persistent pain of latrodectism remains poorly understood. This focused review re-examines α-LTX from a nociceptive perspective. The available evidence supports a model in which α-LTX binds adhesion G protein-coupled receptor L1 (ADGRL1; latrophilin-1) and neurexin-1α on susceptible sensory neurons; inserts a large cation-permeable pore; and promotes membrane depolarisation, calcium entry and release of pain-associated neuropeptides. The transcript-level gene expression of α-LTX receptor genes in dorsal root ganglion neurons and evidence of toxin-evoked neuropeptide release provide a molecular basis for direct nociceptor activation, although functional validation in defined nociceptor subclasses remains necessary. A comparison with the nociceptive ion channels transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1) highlights their convergence on calcium-dependent sensory excitation, while distinguishing α-LTX from toxins that modulate endogenous channels. We propose that the pain of latrodectism is a composite state in which direct nociceptor activation complements muscle spasm and tissue-derived signalling, positioning α-LTX as a distinctive probe of pain pathways.