Dopamine induces transient modulation of the physiological responses of whiteleg shrimp, Litopenaeus vannamei

Levels of glucose, lactate, Na+, K+, Cl-, protein, and oxyhemocyanin in the hemolymph and its osmolality were measured when the whiteleg shrimp (Litopenaeus vanammei; 20 +/- 1.5 g), were individually injected with saline or dopamine at 10(-8), 10(-7), or 10(-6) mol shrimp(-1). Results showed that elevations of hemolymph glucose and lactate occurred at between 2 and 4 h, increases in hemolymph osmolality, Cl-, Na+, and total protein occurred at 2 h, and a reduction in hemolymph oxyhemocyanin occurred at 4 h after the dopamine injection. All physiological parameters except K+ had returned to the control values 8-16 h after receiving the dopamine. The injection of dopamine also significantly decreased the oxyhemocyanin/protein ratio of L. vannamei at 2 h as a result of the elevation of hemolymph protein. These results suggest that stress-inducing dopamine causes a transient period of modulation of energy metabolism, osmoregulation, and a respiratory response in L. vannamei in adapting to an environmental stress. (c) 2005 Published by Elsevier B.V.