Endocrine Abstracts

In this study, pituitary of five carp fish were collected. The pituitary cells were dispersed enzymatically and cultivated as monolayers in MEM for 72 h. Then the culture media were collected and frozen in −20 °C.

The carp ovaries were also collected and their follicles were separated mechanically and incubated in BSS Cortland medium in 24 well microplates for 48 h in room temperature. Then the incubated ovarian follicles were divided in two groups:

A. Control group which were incubated in BSS medium.

B. Experimental group which divided to three subgroups according to treated with different concentration of collected pituitary medium (50, 100, 200 μl/ml).

Follicles culture media were collected after 72 h and were analyzed for 17-β-Oestradiol (E₂) and 17-α-Hydroxy progestron (P₄) content by radioimmunoassay (RIA).

The results showed that the steroid hormones (E₂ and P₄) secretion in incubated ovarian follicles were increased significantly by low concentration (50 μl/ml)of pituitary media (respectively P<0.001 and P<0.05) but the high concentration (200 μl/ml) decreased the secretion of E₂ and P₄ significantly (respectively P<0.01 and P<0.05).

The concentration of 100 μl/ml of pituitary culture media had not affected on steroid hormones secretion significantly.

The interesting finding is that pituitary culture media (which content gonadotropin hormones) were stimulated ovarian follicles for steroid secretion in vitro, whereas the high concentration of pituitary secretion decreased the responsiveness of the ovarian follicles which it may occurred due to down – regulation of the pituitary hormone receptors on the ovarian follicles.