Enhancement of Vitellogenin Synthesis by Serotonin in the Giant Freshwater Prawn Macrobrachium rosenbergii (de Man)

Serotonin (5-hydroxytryptamine, 5 HT) plays important roles in regulating diverse physiological processes in crustaceans. The stimulatory effect of 5 HT on vitellogenin (Vg) synthesis in the giant freshwater prawn Macrobrachium rosenbergii (de Man) is presented in this paper. During a 16 d experimental period, hemolymph was collected from both intact and bilateral eyestalk-ablated prawns 2 d after the administration of 5 HT, which was periodically injected into prawns on day 2 and every 4th day thereafter. The vitellogenin concentration in the hemolymph was quantified using an ELISA technique. The results showed that 5 HT enhanced the process of Vg synthesis in a dose-dependent manner. The fact that 5 HT is able to stimulate Vg synthesis in eyestalk-ablated prawns in a similar manner as in intact prawns, and that the synthesis and release of Vg from the hepatopancreas and the increment of total Vg mRNA in hepatopancreas were all enhanced by 5 HT stimulation in the presence of ganglion tissues in vitro suggest that the stimulatory action of 5 HT on Vg synthesis is mediated through a factor, likely a vitellogenesis-stimulating hormone in brain, and thoracic and abdominal ganglion tissues.