Neuropeptides in insect mushroom bodies

Owing to their experimental amenability, insect nervous systems continue to be in the foreground of investigations into information processing in – ostensibly – simple neuronal networks. Among the cerebral neuropil regions that hold a particular fascination for neurobiologists are the paired mushroom bodies, which, despite their function in other behavioral contexts, are most renowned for their role in learning and memory. The quest to understand the processes that underlie these capacities has been furthered by research focusing on unraveling neuroanatomical connections of the mushroom bodies and identifying key players that characterize the molecular machinery of mushroom body neurons. However, on a cellular level, communication between intrinsic and extrinsic mushroom body neurons still remains elusive. The present account aims to provide an overview on the repertoire of neuropeptides expressed in and utilized by mushroom body neurons. Existing data for a number of insect representatives is compiled and some open gaps in the record are filled by presenting additional original data.

► Mushroom body-associated immunoreactivity towards neuropeptides is reviewed. ► Occurrence and distribution of 8 major neuropeptides is documented in selected taxa. ► Kenyon cells and extrinsic neurons employ variable neuropeptides in different taxa. ► Evolutionary trends in mushroom body-associated peptide expression are discussed.