Almost all venomous animals use their venoms for defensive purposes—many solely. Defensive stings or bites are often associated with intense pain caused by toxins that directly target sensory neurons, hijacking or overstimulating neuronal transmission.
Some of the most painful stings known are from ants (Hymenoptera: Formicidae). I will present my research on the identification and pharmacological characterisation of pain-causing toxins from ant venoms. These include (i) structurally diverse pore-forming amphipathic peptides related to melittin, which cause “short, sharp pain”;1 (ii) a new class of unusual lipophilic peptide toxins that potently modulate vertebrate neuronal voltage-gated sodium channels to cause longer-lasting, intense pain;(2 and unpublished) and (iii) EGF-like peptide toxins which mimic vertebrate EGF-like hormones to cause long-lasting hypersensitivity.3
The identification and characterisation of new pain-causing toxins from ant venoms has provided new knowledge about their chemical defence; highlighted the role of certain ion channels and receptors in mammalian pain signalling; and provided a suite of new peptide tools to study these. A better understanding of our own pain physiology may ultimately lead to the development of new or improved pain treatments.