The influence of prostaglandin E 2 and the steroid hormones, 17α-hydroxyprogesterone and 17β-estradiol on moulting and ovarian development in the tiger prawn, Penaeus esculentus Haswell, 1879 (Crustacea: Decapoda)

Abstract

1. 1. During trials of 5 weeks duration, nine groups of adult female tiger prawns, Penaeus esculentus (carapace length >28 mm), were treated with prostaglandin E 2 (PGE 2) (0.1 μg/g body weight), 17α-hydroxyprogesterone (0.01 μg/g body weight), 17β-estradiol (0.01 μg/g body weight), or a combination of these. Both ovarian development and moulting were individually monitored during this time, and upon completion, ovaries were weighed and histologically examined. 2. 2. Those groups treated with PGE 2, whether alone or in unison with a steroid hormone, displayed significantly shorter moult cycles than did either the control or steroid treated groups ( P < 0.0001, two-way ANOVA; mean moult cycle duration for all PGE 2 treated groups, 14.46 ± 0.29 days). 3. 3. Neither 17α-hydroxyprogesterone or 17β-estradiol, whether alone or in combination with PGE 2, significantly effected moult cycle duration ( P > 0.05, two-way ANOVA; mean moult cycle duration of all non-PGE 2 treated groups, 17.30 ± 0.39 days). 4. 4. Histological examination showed that no treatment significantly stimulated ovarian development. There was also no significant increase in mean ovary weight relative to body weight. This result questions a body of opinion which suggests that both 17α-hydroxyprogesterone and 17β-estradiol are vitellogenin stimulating hormones.