Norepinephrine 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 vannamei (18.3∼21.6 g), were individually injected with saline or norepinephrine 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, Na+, and total protein occurred at 2 h, and a reduction in hemolymph Cl− and K+ occurred at 2 h after in shrimp which had received NE at > 10− 8, > 10− 8, and 10− 6 mol shrimp− 1, respectively. All physiological parameters had returned to the control values 2∼4 h after receiving the norepinephrine. The injection of norepinephrine at > 10− 8 mol shrimp− 1 also significantly decreased the oxyhemocyanin / protein ratio of L. vannamei at 2 h as a result of elevation of hemolymph protein. These results suggest that stress-inducing norepinephrine causes a transient period of modulation of energy metabolism and osmoregulation, and a respiratory response in L. vannamei as it adapts to an environmental stress.