Evolutionary Aspects of the Neuromodulation of Nociceptive Behaviors¹

Abstract

There is accumulating evidence for a phylogentic continuity in the expression and regulation of fundamental behaviors of essential survival value. The ability to detect and respond to aversive environmental stimuli is a basic feature of all animals that is expressed in the term “nociception.” Nociceptive responses provide an index of the sensitivity of individuals to actual or potential aversive physical stimuli. Measurements of alterations in nociceptive responses (antinociception or analgesia, hyperanalgesia) are commonly used to monitor the behavioral and physiological status of animals following exposure to either noxious or potentially damaging stimuli. In this paper the neuromodulation of the nociceptive and analgesic behaviors of molluscs (the land snail, Cepaea nemoralis) and mammals (rodents) is considered. Behavioral and pharmacological evidence is presented to suggest that opioid neuropeptides are similarly involved in the modulation of the nociceptive responses of rodents and snails. The FMRFamide-related family of neuropeptides are also shown to be involved in the modulation of nociceptive behaviors, though with apparently different roles in molluscs and mammals. It is proposed that comparative investigations of the mediation of basic phylogenetically conserved functions, such as nociception, are a useful means to determine and analyse, general features of behavioral neuromodulation by neuropeptides.

Author notes

¹From the Symposium on Behavioral Neuromodulators: Cellular, Comparative and Evolutionary Patterns presented at the Annual Meeting of the American Society of Zoologists, December 27–30, 1987 at New Orleans, Louisiana.