Ovulation induced in African catfish (Clarias gariepinus, Burchell 1822) by hormones produced in the primary culture of pituitary cells

This study examined the potential of catfish pituitary cells to proliferate in culture media and that of hormones produced in their primary culture to induce spawning in African catfish. The trypsinized pituitary cells were cultured in three culture media RPMI 1640, McCoy 5a and M2 media with addition of 10% fetal bovine serum. Female catfish (800±200 g) were induced using the culture medium that gave the shortest population doubling time and highest cell count (RPMI 1640). The eggs were fertilized with sperm cells in vitro. The fertilization and hatchability rates were determined. The blood samples of the induced spawners were collected at O (before injection), 3, 6, 9 and 12 h, respectively after injection. The collected samples of blood plasma were analyzed using enzyme-linked immunosorbent assay for quantitative determinations of Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH). A significant increase in the cell counts over the initial seeding density of 4.1 × 106/ml after 12 h of culture was established in each of the three culture media used. The induced spawning bio-assay which served as a biochemical marker for gonadotrophin specific function showed that  97.5 g/kg of mature oocytes were spawned from cultured pituitary cells (CPC), 127.5 g/kg from induction with fresh pituitary gland (FPG) and 157 g/Kg from gonadotrophin releasing hormone analogue (Ovaprim) induced catfishes (800±200 g). The fertilization rate of cultured pituitary cells (CPC) differed significantly (P 0.05). The results of the plasma gonadotrophin revealed that the highest levels of plasma LH and FSH were reached between 9 and 12 h of ovulation in all the inducers used. The two pituitary based hormones (FSH and LH) played complementary roles during ovulation and spawning of catfish eggs. This study provides an insight to the possibility of using hormones from the primary culture of pituitary cells to induce spawning in African catfish. Key words: Pituitary cells, primary culture, induced spawning, ovulation.