Studies On The Reproductive Effect Of FSH And LH In Scylla Paramamosain

FSH and LH are two gonadotropins hormones which have been discovered to have a significant regulating effect on gonadal development in vertebrates.The concentrations of estradiol,progesterone,testosterone,FSH and LH in hemolymph of Scylla paramamosain as well as the immuno-recognition of ER,AR,FSH and LH in the nervous system were examined by immunocytochemistry and ELISA.The results help to understand the mechanism of FSH and LH in regulating the reproduction of S. paramamosain.The main results and conclusions are as follows:1.The immunocytochemical research on ER,AR in nervous system of S. paramamosainThe locations of ER-IR and AR-IR neurons were similar.The estrogen receptors and androgen receptors widely existed in the nervous organs of S.paramamosain. This proves that the sex steroid hormones,bound with their receptors,may affect the secretion of other hormones and stimulate the development of S.paramamosain indirectly.2.The immunocytochemistry research on FSH,LH in the thoracic ganglion of S.paramamosainThe FSH-IR neurons strongly expressed in the thoracic ganglion mass of both mature and immature female/male crabs.LH had weak expression in mature female crabs.More LH-IR neurons had been observed in mature male crab than in immature male crabs.The results suggest that the FSH and LH may be two compositions of GSH and they possibly activate in the development of gonad.3.Concentrations of sex hormones in the hemolymph of female crabFor female crabs,E₂ got to its minimum in the previtellogenic stage(Phaseâ…¡) and reached a peak in late vitellogenic stage(Phaseâ…£).The nadir of 17α-OHP was in Phaseâ… ;then its concentration increased slightly in Phaseâ…¡and got its first peak in early vitellogenic stage(Phaseâ…¢).The maximum value presented in the phase after ovulation.FSH reached its peak at Phaseâ…¡.After a slight decline in Phaseâ…¢,FSH concentration plummeted to 0.105±0.031mIU/mL at near-mature phase and became undetectable at mature phase.The concentration of LH was low in general.It tended to increase until Phaseâ…£but decrease after that.For S.paramamosain,E₂ may play a positive role in the vitellogenesis and ovarian development.As the precursor of E₂,progesterone possibly changes rapidly into E₂ in the ovary.E₂ and progesterone are necessary in some phases of ovarian development and their concentrations are relevant to ovarian development.This may suggest that FSH and LH can promote the vitellogenesis and ovarian development by stimulating the release of estrogen in S.paramamosain.Combined with the distribution of estrogenic receptors in the brain and thoracic ganglion,E₂ and progesterone might have a regulating feedback on the release of FSH and LH.In the early phase of gonadal development they stimulate the FSH and LH release,while in the later phase they play a positive role.4.Concentrations of sex hormones in the hemolymph of male crabsFor male crabs,the peak of E₂ presented in spermatid phase and the minimum was in spermatozoon phase.After that a slight rise had been observed in the stationary phase.The concentration of T,which was higher in the stage of spermatogonium than in the stage of spermatocyte,reached a peak at the phase of spermatozoon.Then it declined a little in spermatozoon phase but increased in stationary phase.The concentration of FSH reached its peak at spermatid phase.As to the concentration of LH,it was low in general and the peak was in spermatozoon phase.There is a correlation between the profile of E₂ and T and the spermatic development.Which implies that these hormones may play a positive role in the process.FSH,combined with LH,may control the spermatic development by acting on androgenic gland to release androgenic gland hormone which can affect spermary. Immunoreactive cells of estrogen and its receptor can also be found in the brain and thoracic ganglion.This may suggest a feedback regulation mechanism between steroid hormones and gonadotrophic hormones.