Nociceptive Sensitization Reduces Predation Risk

• Published in: Current biology 2014-05, Vol.24 (10), p.1121-1125
• Main Authors: Crook, Robyn J., Dickson, Katharine, Hanlon, Roger T., Walters, Edgar T.
• Format: Article
• Language: English
• Subjects: Animals; Bass - physiology; Decapodiformes - physiology; Dicentrarchus labrax; Doryteuthis; Escape Reaction; Female; Food Chain; Male; Massachusetts; Nociception; Predatory Behavior
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2014.03.043

Sublethal injury triggers long-lasting sensitization of defensive responses in most species examined, suggesting the involvement of powerful evolutionary selection pressures [1]. In humans, this persistent nociceptive sensitization is often accompanied by heightened sensations of pain and anxiety [2]. While experimental [3] and clinical [4] evidence support the adaptive value of immediate nociception during injury, no direct evidence exists for adaptive benefits of long-lasting sensitization after injury. Recently, we showed that minor injury produces long-term sensitization of behavioral and neuronal responses in squid, Doryteuthis pealei [5, 6]. Here we tested the adaptive value of this sensitization during encounters between squid and a natural fish predator. Locomotion and other spontaneous behaviors of squid that received distal injury to a single arm (with or without transient anesthesia) showed no measurable impairment 6 hr after the injury. However, black sea bass given access to freely swimming squid oriented toward and pursued injured squid at greater distances than uninjured squid, regardless of previous anesthetic treatment. Once targeted, injured squid began defensive behavioral sequences [7, 8] earlier than uninjured squid. This effect was blocked by brief anesthetic treatment that prevented development of nociceptive sensitization [6, 9]. Importantly, the early anesthetic treatment also reduced the subsequent escape and survival of injured, but not uninjured, squid. Thus, while minor injury increases the risk of predatory attack, it also triggers a sensitized state that promotes enhanced responsiveness to threats, increasing the survival (Darwinian fitness) of injured animals during subsequent predatory encounters. •First demonstration of enhanced Darwinian fitness due to nociceptive sensitization•Natural predators pursue injured squid from greater distances than uninjured squid•Injured squid begin defensive behavior earlier, reducing predation risk•Preventing development of sensitization in injured squid increases predation risk Although nociceptive sensitization after injury is widespread among diverse animal species, there has been no direct evidence that it contributes to Darwinian fitness. Crook et al. show that injury-induced sensitization helps squid survive a subsequent predatory encounter—the first demonstration that this ancient form of plasticity is adaptive.