Neuropeptide F stimulates ovarian development and spawning in the female giant freshwater prawn, Macrobrachium rosenbergii, and its expression in the ovary …

Neuropeptide F (NPF) plays important roles in the regulation of a variety of physiological processes, including stimulation of food intake. At present, there is a current lack of basic knowledge regarding the effect of NPF in the control of female crustacean reproduction. In this study, we investigated expression of NPF in ovaries of female Macrobrachium rosenbergii (Mr) during ovarian development cycle, and its effects on ovarian maturation and spawning. MrNPF-immunoreactivity (-ir) was detected in the ovaries and its levels fluctuated during the ovarian maturation cycle: MrNPF-ir was more intense in the early- and mid-stages of ovarian development, and suddenly decreased in the mature stages. By RT-PCR, MrNPF transcript levels also increased during the early- and middle stages of ovarian development, and suddenly fell at late stage. The prawns were treated with varied doses of MrNPF and the effects were investigated by assessing the ovarian maturation period, oocyte diameter (OD), gonado-somatic index (GSI), and hemolymph vitellogenin (Vg) concentration. MrNPF-treated prawns showed significantly decreased ovarian maturation periods, and increased GSI, OD, and Vg levels compared with those of control groups. MrNPF also caused significantly earlier spawning compared with the control groups, while the mean fecundity between MrNPF-treated prawns and controls did not differ significantly. However, the numbers of eggs per spawn among experimental groups were higher compared with those of the controls. This work provides a novel and useful basic knowledge of NPF on female reproduction in crustaceans, and its possible use in aquaculture for accelerating and enhancing reproduction of the female prawns.