Neuroendocrine regulation of salt and water balance in the crayfish Procambarus clarkii

1. 1. The injection of brain extracts into eyestalk-ligated, nephroporeplugged crayfish prevents to some extent the rapid increase in weight found in eyestalk-ligated, nephropore-plugged animals. 2. 2. The injection of brain or eyestalk extract into eyestalk-ligated crayfish prevents the decrease in chloride concentration of the blood found in eyestalkless animals. 3. 3. The blood osmotic and sodium concentrations of eyestalk-ligated animals increase more rapidly than normal animals when placed in a hyperosmotic medium. 4. 4. There is a greater flow of urine in eyestalk-ligated animals as compared to normal animals. 5. 5. It is suggested that a brain-eyestalk neuroendocrine system is involved in the regulation of salt and water balance in crayfish.