The effects of short neuropeptide F on ovarian maturation and spawning in female giant freshwater prawn, Macrobrachium rosenbergii, and associated regulatory mechanisms

In the present study, we investigated the effects of two short neuropeptide F (Mro-sNPF) mature sequences, namely APALRLRFamide and DRTPALRLRFamide, on ovarian maturation and spawning in Macrobrachium rosenbergii females. At doses of 10(-5) and 10(-6) mol/prawn, both Mro-sNPF peptides significantly shortened the ovarian developmental period (P < 0.05), but enhanced the gonadosomatic index (GSI), oocyte diameter (OD), and cell proliferation, compared with control values (P < 0.05). However, at the lowest dose (10 7 mol/prawn), neither peptide significantly affected ovarian maturation, GSI, nor OD compared with the control values. Females treated with the two peptides at the dose of 10 5 or 10 6 mol/prawn attained mature oocyte stages faster than did control females. Treatment with both peptides significantly elevated hemolymph vitellogenin concentrations and upregulated MrEcR transcripts, compared with the control treatment (P < 0.05). Finally, both Mro-sNPFs induced spawning by shortening its duration by half (similar to 1.5 days) compared with the control duration (similar to 3.1 days) (P < 0.05). The number of eggs per spawn was approximately 15.4 x 10(4) eggs in the experimental group and in the control group (similar to 15.35 x 10(4) eggs), albeit without significance. Therefore, among the treatment groups, using APALRLRFamide at 10(-5) mol/prawn showed promising effects on the induction of ovarian maturation and spawning. Taken together, Mro-sNPF peptides can promote ovarian development and spawning, indicating their potential application to stimulate gamete and larval production in this important crustacean aquaculture species.