A Comparative study of synthetic carp GnRH and carp pituitary homogenate effects on in vitro steroidogenesis of oocytes in common carp (Cyprinus carpio)



Vitellogenic stage carp ovaries were collected
aseptically and the cells of ovarian follicles were dispersed by trypsin
treatment and cultivated as monolayer. Control cultures were grown in medium
M199 alone. Media for experimental cultures were supplemented either with 100 µl ml-1 of CPH
and CPS-carp GnRH (cultivated pituitary cell secretion affected by 10-6, 10-8, 10-10
M carp GnRH). The direct effect of these factors on 17-α-Hydroxy progesterone (17α -OHP < /font>) and
17β-Estradiol (E2) secretion of isolated
follicular cells in cell culture was assayed by appropriate Radioimmunoassay (RIA).
According to the results the E2 was a main hormone secreted by cultivated carp granulosa
and theca cells. Adding 100 µl ml-1of 10-6 M CPS-carp
GnRH had no significant effect on cultivated granulosa and theca cells
endocrine activity (P> 0.05). On the other hand, carp granulosa and theca
cells treated with the lower contents of CPS-carp GnRH (10-8, 10 -10 M) showed a 4.02 and 3.74-fold increase in E2
concentration and 4.27 and 3.64-fold increase in 17α
-OHP < /span> level, which was significantly higher than CPH (P <
0.05). Also, there was a significant increase of steroid secretion
in group stimulated with 100 µl ml-1 of CPS and CPH, but there were no significant
differences between them (P> 0.05).