Chapter 3 Aplysia neuropeptides

Abstract

Publisher Summary The gastropod mollusk, Aplysia californica , is a good model system for the studies of peptides in the central nervous system because of the relatively small number and accessibility of its neurons. The central nervous system in Aplysia consists of about 20,000 neurons, many of which can be easily identified based on size, color, shape, location, and electrical properties. The central nerve cells of Aplysia are clustered into four pairs of symmetric ganglia—the buccal, cerebral, pedal, and pleural ganglia—and a single asymmetric abdominal ganglion. The best studied of the Aplysia ganglia is the abdominal ganglion, which mediates several well characterized reflex and fixed action patterns, as well as a number of visceral functions. The neurons of the paired buccal ganglia are largely responsible for controlling the muscles involved in the biting and swallowing movements of feeding. Many abdominal and buccal ganglion neurons use bioactive peptides as neurotransmitters and hormones in addition to classical transmitter molecules, such as acetylcholine, serotonin and glycine. Both, molecular and cell biological techniques are used to elucidate the structures and functions of several neuropeptides, which are involved in mediating a variety of physiological and behavioral events in Aplysia .