Evaluation of the physiological activity of venom from the Eurasian water shrew .

BACKGROUND

Animal toxins can have medical and therapeutic applications. Principally, toxins produced by insects, arachnids, snakes and frogs have been characterized. Venomous mammals are rare, and their venoms have not been comprehensively investigated. Among shrews, only the venom of has been analysed so far, and blarina toxin has been proven to be its main toxic component. It is assumed that employs its venom to hunt larger prey. However, the toxic profile, properties and mode of action of its venom are largely unknown. Therefore, we analysed the cardio-, myo- and neurotropic properties of venom and saliva of non-venomous (control tests) in vitro in physiological bioassays carried out on two model organisms: beetles and frogs. For the first time, we fractionated venom and saliva by performing chromatographic separation. Next, the properties of selected compounds were analysed in cardiotropic bioassays in the heart.

RESULTS

The venom of caused a high decrease in the conduction velocity of the frog sciatic nerve, as well as a significant decrease in the force of frog calf muscle contraction. We also recorded a significant decrease in the frog heart contractile activity. Most of the selected compounds from venom displayed a positive chronotropic effect on the beetle heart. However, one fraction caused a strong decrease in the heart contractile activity coupled with a reversible cardiac arrest. We did not observe any responses of the insect heart and frog organs to the saliva of . Preliminary mass spectrometry analysis revealed that calmodulin-like protein, thymosin β-10, hyaluronidase, lysozyme C and phospholipase A2 are present in the venom of , whereas thymosin β4, lysozyme C and β-defensin are present in saliva.

CONCLUSION

Our results showed that venom has stronger paralytic properties and lower cardioinhibitory activity. Therefore, it is highly probable that might use its venom as a prey immobilizing agent. We also confirmed that is not a venomous mammal because its saliva did not exhibit any toxic effects.