NEUROHORMONES OF MOLLUSCA

Abstract

We may define neurohormones as substances of high physiological activity that are produced by nerve cells and released at their axon terminations to act as shortrange, brief-duration transmitter agents, or as long-range, long-duration circulatory hormones. The short-range transmitters may be referred to as neurohumors, and the more characteristic hormones as neurosecretory substances. I shall summarize, briefly, our knowledge of neurosecretion in molluscs, then deal with the neurohumors and, especially, with 5-hydroxytryptamine or serotonin, which has attracted so much attention during the past few years. NEUROSECRETION