RFamide Peptides in the Leech,Hirudo medicinalis

RFamide peptides have been localized to a number of neurons of the CNS of the leech, Hirudo medicinalis, using immunocytochemical techniques. The majority of this immunoreactivity appears to be due to the peptide FMRFamide. Most of the identified RFamide immunoreactive cells are cholinergic motor neurons, though some are interneurons. Superfused FMRFamide is active on the targets of these identified neurons; in a few well studied cases, it has been possible to show that FMRFamide mimics a specific physiological action of an identified neuron on its target. In the leech as in other phyla where they occur, RFamide peptides are widely distributed in neurons, and are neuromodulators with diverse physiological effects.