Ovarian maturation and spawning in the tiger shrimp, Penaeus monodon by serotonin and dopamine injection

Abstract

The effect of serotonin (5-hydroxytryptamine, 5-HT) injection on the ovarian maturation and spawning of wild Penaeus monodon was investigated. The neurotransmitter was evaluated at 20 μg g-1 body weight (b.w) and 50 μg g-1 (b.w) applied at day 2, 12 and 22. The effect was compared against a control group, which received the injection of the sterile vehicle solution (NaCl 0.85%), and an unilaterally eyestalk ablated group. 5-HT induced ovarian maturation and spawning at both doses tested, generating more spawnings at 50 μg g-1 (b.w). However, unilateral eyestalk ablation induced a sooner and a higher rate of maturation and spawning. Dopamine  reduce ovarian maturation and spawning in P.monodon compared to 5-HT.Our findings may be the result of 5-HT interaction with the release of different neurohormones and inhibition of methyl farnesoate synthesis. Additionally, gonad inhibiting hormone may have an intense control over ovaries and hepatopancreas. Spawning obtained by serotonin treatment showed excellent quality, and it was not statistically different (P>0.05) from unilaterally eyestalk ablated females. Further research is necessary in order to increase the spawning activity and define the duration of the reproductive performance of serotonin and dopamine treated females.