Induction of vitellogenesis and reproductive maturation in tiger shrimp,<i>Penaeus monodon</i>by 17ß-estradiol and 17α-hydroxyprogesterone:<i>in vivo</i>and<i>in vitro</i>studies

Abstract

Ovarian explants of Penaeus monodon taken from different developmental stages (immature (transparent), immature (yellow), and vitellogenic (green)) were incubated for 24 h in medium 199 supplemented with either E2 or 17α-OHP. Exogenous E2 stimulate Vg mRNA synthesis in the immature (yellow) ovary only, while 17α-OHP stimulates mRNA synthesis only in vitellogenic ovary. However, in vitro treatment with both hormones resulted in significant increase in oocytes diameter at higher doses. In vivo assays were carried out by administrating these hormones alone or along with eyestalk ablation at a dose of 9 × 10−5 M per individual. After 7 days, significantly higher gonadosomatic index resulted in E2 and 17α-OHP treatment along with eyestalk ablation. Further, Vg mRNA transcript level was significantly higher in the group received both 17α-OHP and eyestalk ablation. Progesterone and estradiol receptors were characterized using western blotting. Discrete immunoreactive bands of estrogen Receptor (ER) (~78 kDa) and progesterone Receptor (PR) (~70 kDa) were detected in the ovary of wild brood stock. These findings suggest a reproductive role for these steroidal hormones, which could possibly be used in the induction of maturation and spawning in captive female penaeids.