Listening to neuropeptides by microdialysis: echoes and new sounds?

Neuropeptides represent the largest class of neuromessengers in the central nervous system. They are involved in the regulation of growth processes, reproduction, social behavior, emotion/motivation and cognition. Particularly in subcortical structures, neuropeptides act as neuromodulators, which reach their target sites via diffusion through the extracellular space. This route of information transfer together with the ability of neurons to release neuropeptides from their whole membrane surface predisposes neuropeptides for microdialysis experiments. This review outlines the special characteristics of neuropeptide signaling in relation to other classes of neuromessengers. It further provides a survey of the application of the microdialysis technique for monitoring neuropeptide release patterns in laboratory rodents exemplarily for the two neuropeptides arginine vasopressin and oxytocin, discusses pros and cons of such experiments and outlines perspectives for future neuroendocrine studies in rats and mice.