Study On The Role Of Two Kinds Of Reproductive Hormones In Gonadal Developmental Cycle Of Tribolodon Brandti

The Tribolodon brandti belong to the family of Cyprinidae,is the only one known as reproductive anadromous spawning fish in Cyprinidae.In this study,use of tissue sections biology statistics,enzyme-linked immunosorbent assay and fluorescence quantitative techniques to analysis the histological changes of testes and ovaries,hormone levels and gene expression during the reproductive cycle of Tribolodon brandti.The results are as follows:1.Using the histological methods,the gonadal development,structures of gonad,spawning time and type of reproduction in Tribolodon brandti were studied.The testes of Tribolodon brandti have typical lobular structures,and can be divided into six developmental stages.According to the characteristics of the ovaries and the types of ovarian germ cells,the oogenesis process can also be divided into six developmental stages.The microscopic observation showed that the gonadal development of sexual mature Tribolodon brandti differentiated to stage III at the end of September,and stayed at the phase III in the winter period.While the gonadal development of immature juveniles age 2+ was at the phase II and remained such stage during the winter period.In the late April and early May,gonadal development of sexual mature males differentiated to the phase ?,but in the females it was not until late May or early June that they reached to the developmental phase ?.Taken together,gonadal development of the males was faster than that of the females.No significant difference was observed in the gonad development of 2-3-year-old juvenile cultured in either fresh water or weak alkali water environment.The body weight 2+-year-old group in the weak alkali water were significantly higher than that in the fresh water,but no significant difference was found between 3+-year-old groups reared in weak alkali environment and those in fresh water.Meanwhile,significant differences of body weight existed between females and males in the weak alkali as well as in the fresh water.In the gonad development cycle,the average condition factor of female and male ranged from 1.313 to 1.697.During the sexual cycle,the male gonad index began to rise significantly from the II period,while the female gonad index was significantly different among development periods,with the peak value of 14.22 in the period of ?.The conclusion could be drawn that the gonadal development peak of Tribolodon brandti appears only once a year,the ovary is partial synchronic,and this species is iteroparous.2.With the development of the ovary,the serum FSH content gradually increased and reached the maximum at the stage ?,which was significantly higher than that of other stages,and there was a slight decrease in the stage ?.However,serum LH levels reached the maximum at stage ?.In the male,with the continuous development of the testis,serum FSH content gradually increased,the change profiles was similar to the female,also reached the maximum at the stage ?,and then began to decline.The serum LH content generally increased,but decreased slightly in the stage III,then increased and reached the peak at the stage ?.There was only one the peak of FSHR expression in the ovarian development cycle.The expression of FSHR increased slowly from stage II to stage III,significantly increased from stage III to stage IV and reached the maximum at stage ?.The trend pattern of LHR was similar to that of FSHR.With the development of ovary,the expression of LHR increased gradually,and peaked at stage ?.The expression level of FSHR in males was similar to that in females.The expression of FSHR was lower in the stage II and III,increased rapidly and reached the maximum in the stage ?,and then decreased slightly at the stage ?.LHR grew slowly from the stage II to the stage ? during the development of the testes,and increased sharply in the stage ?,reached the peak value,which was significantly higher than that of other stages.While different from females,at stage ? of LHR expression was significantly higher than other stages in males.3.In the process of gonadal development,the serum E2 content gradually increased,and reached the maximum at the stage ?,and then began to decline.The change of T content in serum was similar to that of E2 in ovarian development,and reached the maximum at the late stage of yolk(stage ?).During the development of ovary,the serum P content reached the maximum at the stage ?(ovulation period),indicated that serum P may play an important role in the final maturation of the ovary;The serum E2 level in the development of the male was lower than female,peaked at stage ?,and then decreased slightly during spermiation period(stage ?).The serum T content gradually increased with the continuous development of the testis and reached the peak in the stage ?.During the development of testes,the change pattern of P in serum was similar to that of E2,which reached the maximum at the stage ? and then decreased slightly in the stage ?.The expression of ER?2 in the ovary was higher in the pre-ovarian stage(?and ?),with the ovarian oocytes development ER?2 expression began to decline and reached the lowest value at the stage ?.The expression pattern of AR in the male and female gonad was similar,reaching the maximum at the stage ?,and then gradually decreased.The expression level of PGR in male and female gradually increased with the development of gonads and reached the maximum at the stage ?.