Repetitive nociceptive stimulation elicits complex behavioral changes in Hirudo: evidence of arousal and motivational adaptations
Basic science published in J Exp Biol (2023)
Abstract
Appropriate responses to real or potential damaging stimuli to the body (nociception) are critical to an animal's short- and long-term survival. The initial goal of this study was to examine habituation of withdrawal reflexes (whole-body and local shortening) to repeated mechanical nociceptive stimuli (needle pokes) in the medicinal leech, Hirudo verbana, and assess whether injury altered habituation to these nociceptive stimuli. While repeated needle pokes did reduce shortening in H. verbana, a second set of behavior changes was observed. Specifically, animals began to evade subsequent stimuli by either hiding their posterior sucker underneath adjacent body segments or engaging in locomotion (crawling). Animals differed in terms of how quickly they adopted evasion behaviors during repeated stimulation, exhibiting a multi-modal distribution for early, intermediate and late evaders. Prior injury had a profound effect on this transition, decreasing the time frame in which animals began to carry out evasion and increasing the magnitude of these evasion behaviors (more locomotory evasion). The data indicate the presence in Hirudo of a complex and adaptive defensive arousal process to avoid noxious stimuli that is influenced by differences in internal states, prior experience with injury of the stimulated areas, and possibly learning-based processes.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
Hirudo verbana adapts withdrawal reflexes to repeated nociceptive stimuli with multi-modal evasion behavior distribution (early, intermediate, late evaders); prior injury accelerates evasion onset.
Por qué esto importa para la hirudoterapia
This study examined habituation of withdrawal reflexes (whole-body and local shortening) to repeated mechanical nociceptive stimuli (needle pokes) in the medicinal leech Hirudo verbana and found that, beyond simple habituation, animals developed evasion behaviors—hiding the posterior sucker or crawling away—with prior injury accelerating and intensifying these responses. The authors interpret these findings as evidence of a complex, adaptive defensive arousal process influenced by internal states, prior injury experience, and possibly learning. For ASH's domain, the relevance is indirect: this is basic neuroscience/behavioral research on the medicinal leech that informs understanding of nociception and behavioral plasticity in the species. It does not address hirudotherapy, salivary components, or therapeutic applications, so its practical relevance to ASH's domain is limited.
Citación
Repetitive nociceptive stimulation elicits complex behavioral changes in Hirudo: evidence of arousal and motivational adaptations.
Hoynoski J et al. · The Journal of experimental biology, 2023
Contexto clínico relacionado
Explore cómo esta investigación se conecta con la práctica clínica
Añadido a la biblioteca ASH: May 27, 2026 · Última actualización del sitio: June 18, 2026