Neuroendocrinology of Osmoregulation in Decapod Crustacea

Abstract

Experimental evidences for neuroendocrine control of osmoreregulation in decapod crustaceans are mounting. The eyestalk system, brain and thoracic ganglionic centers, and the pericardial organ appear to be involved in this control. Evidences based on experimentation with eyestalk removal and the injection of extracts of neuroendocrine centers are presented. Neuroendocrine extracts affect the movements of salts and water in the gills, stomach, intestine and antennal glands. The pericardial organ material may affect osmoregulation by increasing rate of circulation and influencing salt movement. Three factors have been partially separated from CNS tissues. A factor of the freshwater crayfish, and other freshwater decapods, increases the influx of salt. Two factors from an estuarine crab influence the movement of water, an acetone-soluble factor increasing its influx and a water-soluble factor decreasing influx and increasing efflux. The factors may be involved in the adaptation of the animals to their osmotic environments. None of the factors have yet been identified in circulation nor in effector tissues. Future research must place special emphasis on the identification of the CNS factors in circulation as well as in secretory cells and effector tissues to establish their true hormonal nature.