This review covers recent advances in our knowledge of the role of a group of the most prominent neurotransmitters and neuromodulators in the field of the immune reactions of the body. The neurotransmitters and neuromodulators covered are the three catecholamines (epinephrine, noradrenaline and dopamine), serotonin, acetylcholine (both nicotinic and muscarinic functions), and histamine.

Muscle contractions are driven by neurotransmitters released at neuromuscular junctions. In this issue, Beg et al. (2008) report that protons, in the absence of neurotransmitters and neurons, can stimulate muscle contractions involved in the defecation cycle of the worm Caenorhabditis elegans. Their results identify protons as a new intercellular messenger and suggest that proton-mediated inter...