Effects of serotonin, dopamine, octopamine, and spiperone on ovarian maturation and embryonic development in the giant freshwater prawn, Macrobrachium rosenbergii (De Man, 1879)

Abstract

Mature female Macrobrachium rosenbergii in stage I of their ovarian cycle were divided into 17 groups (14 experimental groups and 3 controls) of 28 animals each. Animals in each experimental group were injected intramuscularly with 2-3 doses of serotonin (5-HT), dopamine (DA), octopamine (OA), spiperone (SP), or 5-HT plus SP, at four-day intervals from day 1 to 49. Five animals each in every group were sacrificed, respectively, at day 14, 25, and 49 to evaluate the gonadosomatic index (GSI) and oocyte diameters. The experimental groups that received the doses of 2.5 × 10-5, 2.5 × 10-6mol of 5-HT/prawn, 2.5 × 10-5, 2.5 × 10-6, 2.5 × 10-7mol of 5-HT/prawn plus 2.7 × 10-7mol of SP/prawn, as well as SP alone at the dose of 5.4 × 10-7mol of SP/prawn, exhibited significantly shorter periods of ovarian maturation and embryonic development, as well as increased GSI values and oocyte diameters, when compared with vehicle-injected and untreated control groups. In contrast, groups injected with DA and OA at similar doses showed decreased ovarian maturation, oocyte diameters, and embryonic periods, but no differences in GSI, when compared with control groups. For the number of eggs per spawn, the groups of animals that received 5-HT at doses of 2.5 × 10-5and 2.5 × 10-6mol/prawn, 5-HT at doses of 2.5 × 10-5mol plus SP at 2.7 × 10-7mol/prawn, 5-HT at 2.5 × 10-6mol plus SP at 2.7 × 10-7mol/prawn, and SP at a dose of 2.7 × 10-7mol/prawn, yielded higher numbers than the control groups, and with a significant difference (P < 0.05). All DA and OA injected groups showed lower numbers of eggs when compared to the control groups. Eggs from all these experimental groups exhibited equally good quality both among each other and in comparison with control groups, as judged from the percentage of fertilized eggs. © 2009 Brill Academic Publishers.