NEUROENDOCRINE INFLUENCE ON WHOLE ANIMAL AND TISSUE RESPIRATION AND ON OSMOIONIC REGULATION IN THE HOLOLIMNETIC SHRIMP MACROBRACHIUM-POTIUNA (MULLER, 1880)

The role of the supraesophageal ganglion (SEG) and the optic ganglia i n the eyestalks (ES) on the control of respiratory metabolism and osmo regulation was examined in a fresh-water shrimp, Macrobrachium potiuna . Results suggested that a factor(s) which depresses the total O-2 con sumption is present in SEG and ES extracts and in the hemolymph of M. potiuna. The extracts also modified the osmolality and the concentrati on of major ionic species in the hemolymph. In vitro experiments corro borated the above findings. Muscle metabolism was markedly depressed b y a factor(s) present in SEG and ES extracts as well as in the hemolym ph of M. potiuna adapted to fresh water or exposed to high salinity. T his effect probably offsets the tendency to a high O-2 consumption at low and high salinities as observed in intact animals. Additionally, S EG extracts can either stimulate or inhibit gill metabolism. These res ults agree with the effects noted in whole animal osmoregulatory respo nse. A preliminary inspection suggests that the molecule(s) involved i n such effects is heat stable and chymotripsin-sensitive. The compensa tory response which results from its action is possibly retained from movement from marine to fresh-water adaptation.