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.