Dietary Supplementation With Icariin Affects Estrogen Synthesis, Vitellogenesis, and Oocyte Development in the Chinese Mitten Crab, Eriocheir sinensis

Abstract

In Eriocheir sinensis aquaculture, crabs feeding on an artificial diet without steroid hormones available in ice-fresh fish or snails show delayed ovarian maturation and late listing. Icariin (ICA), a safe plant-derived monomer compound, can effectively promote estradiol (E 2) synthesis and ovarian development in mammals, but its effect in crustaceans has not been reported. We investigated the effects of ICA on estrogen synthesis, vitellogenesis, and oocyte development in Chinese mitten crabs fed with one of four diets containing 0, 50, 100, and 200 mg/kg ICA, respectively, for 8 weeks. Results showed that vitellogenin (VTG) contents, gonadosomatic indexes (GSIs), and oocyte volumes in ICA50 and ICA 100 crabs were significantly higher than those in the control. The highest upregulated expression of VTG in hepatopancreases and ovaries was detected in ICA100 crabs. Hemolymph E 2 contents were also significantly increased in ICA100 crabs. Enzyme-linked immunosorbent assay (ELISA) and western blot analysis indicated that the increase in E 2 concentrations was attributable to an elevation in aromatase protein levels in ovaries through the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)/cAMP response element binding (CREB) protein pathway. These findings suggest that ICA could serve as a natural additive to resolve the problem of delayed ovarian maturation of crabs raised in ponds.

Effects of effective microorganisms on the growth performance, nutritional composition and flavour quality of the pond‐culturedEriocheir sinensis

“…Those tissues were frozen in liquid nitrogen immediately and stored at −70°C for further analysis. The gonadal somatic index (GSI) and hepatosomatic index (HSI) of the crab were calculated as the percentage of tissue wet weight to body wet weight (Zheng et al., 2020). The meat yield (MY) of the crab was calculated using the following formulae: MY (%) = 100 × muscle wet weight/body wet weight.…”

Investigation of the regulatory effect of icariin on the hepatopancreas glycolipid metabolism and energy metabolism of female Eriocheir sinensis during exogenous vitellogenesis based on the transcriptomics and metabolomics

“…The concrete formulation (Table S1), and processing flow of the diets, and the culture conditions and daily management are consistent with the previous description (Zheng et al, 2019). Our previous basic research showed that after 2 months' feeding trial, the growth of all juvenile crabs in each group entered into the key exogenous vitellogenic stage, but the ovarian development progress and nutrient deposition status between each group presented the difference, showing as the haemolymph E 2 contents, VTG contents and gonadosomatic indexes (GSIs) in ICA50 (E 2 = 71.72 pg/ml; GSI = 3.81%; VTG = 607.15 ng/ml) and ICA 100 (E 2 = 86.06 pg/ml; GSI = 4.65%; VTG = 635.61 ng/ml) crabs were significantly higher than those in the control (E 2 = 42.82 pg/ml; GSI = 2.02%; VTG = 486.18 ng/ml) (Zheng et al, 2020). In addition, the growth performance of crabs in each group showed difference (Zheng et al, 2019), showing as carbs in ICA 100 group had the highest final weight (FW = 72.93 g) and weight gain rate (WGR = 118.36%) compared with the control group (FW = 64.88 g; WGR = 92.93%).…”

“…Icariin is the main flavonoid bioactive component in Epimedium (Li et al, 2015). According to the previous research results on the nutrition physiology of E. sinensis in our laboratory, icariin has the effects of antioxidation, enhancing immunity, promoting sex steroid hormone synthesis, vitellogenesis and ovarian nutrients deposition, suggesting that icariin has the potential to be used as a new functional feed additive in aquatic animals culturing (Zheng et al, 2019(Zheng et al, , 2020. Recent studies have shown that icariin has preventive and therapeutic effects on metabolic diseases such as diabetes, insulin resistance, obesity and dyslipidaemia (Li et al, 2020;Zheng et al, 2016;Aljehani et al, 2020;Wang, Gao, et al, 2020;Wang, Xiong, et al, 2020).…”

“…After 2-month feeding trial, a part of the haemolymph, hepatopancreas and ovary samples were obtained and stored at −80°C for further biochemical, molecular and omics analyses, and another part of hepatopancreas tissue was further treated for oil o red staining and ultrastructure observation. With aspect to the determination of biochemical indicators, the detailed sampling and pretreatment methods of haemolymph, hepatopancreas and ovary tissue were as same as our previous reports (Zheng et al, 2019(Zheng et al, , 2020. The biochemical indicators including haemolymph triglyceride (TG), total cholesterol (T-CHO), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), glucose and hepatopancreas glycogen were determined using commercial assay kits (A110-1-1, A111-1-1, A113-1-1, A112-1-1, F006-1-1 and A043-1-1, Nanjing Jiancheng Bioengineering Institute, China) according to the manufacturers' protocols.…”

“…Thus, it can be seen that the function of icariin is not only antioxidant, immune-regulation and promoting gonadal development but also has excellent research potential in glucose-lipid metabolism and energy metabolism; this enlightens us that there is still a large space for the study of icariin on energy metabolism-regulation in aquatic animals. In this study, the sampling period of the E. sinensis was the initial stage of rapid ovarian development (early October, exogenous vitellogenesis stage) (Zheng et al, 2020). In this period, the crabs need an abundant energy supply, and the metabolism and transfer of nutrients are very active, so it is a good research model of material metabolism and energy metabolism.…”