Effect of selected biogenic amines on reproduction in the fresh water edible crab, Oziotelphusa senex senex

Abstract

The increasing demand for high protein food from aquatic sources and the necessity to find an alternative for fisheries have given rise to a worldwide expansion of shellfish culture. The major bottleneck in crustacean aquaculture industry is the limited availability of quality seed. The present study was designed to elucidate the possible role(s) of selected biogenic amines on the regulation of reproduction in the fresh water edible crab, Oziotelphusa senex senex. Bilateral eyestalk ablation significantly increased ovarian index, mean oocyte diameter and ovarian vitellogenin levels. Injection of serotonin and melatonin also induced ovarian maturation in intact crabs. Injection of serotonin and melatonin into eyestalk ablated crabs did not further accelerate ovarian growth when compared with eyestalk ablated crabs. Given that serotonin and melatonin are able to stimulate ovarian growth and vitellogenin levels in intact crabs but not in eyestalk ablated crabs, it is clear that the stimulatory action of serotonin and melatonin is at the eyestalk through inhibition of release of vitellogenin inhibiting hormone from the X-organ-sinus gland complex. Injection of dopamine into intact crabs did not result in any change in reproduction. Whereas, injection of dopamine into eyestalk ablated crabs results in retarding ovarian growth when compared to eyestalk ablated crabs. From the results, we conclude that, dopamine regulated ovarian growth could be through inhibition of release of vitellogenin stimulating hormone from brain and thoracic ganglion or direct action of dopamine on ovaries but not mediated by eyestalk hormones.