Changes in steroid hormones of fishes in contaminated water with heavy metals in Kor River

Objective: The Kor River is one of the longest Rivers of northwest Fars Province, which originates from Zagros Mountains and joins with Sivand River near city of Marvdasht and finally ends in Bakhtegan Lake. Doroudzan-Dam was built at the starting point of the River and many agricultural lands are being irrigated by this River and many big industries are operating at its vicinity. The present study has been undertaken to determine the effects of some heavy metals contamination on two major gonadal steroid hormones of fishes from the Kor River. Method & Materials: Samples were collected from three parts of the Kor River, upper zone (as control), Mid-Zone and Lower-Zone. From each sampling site, 75 fish specimens of two species, Cyprinus carpio and Capoeta sp. were caught (225 specimens in total), 500mg from each organ was dissolved in HCl (98%) and nitric acid (65%) C) and heavy metals assay solutions (3:7), left for 16 hours in waterbath (100) by ICP method. Before killing fishes, blood samples were taken, serum extracted and estradiol, progesterone and testosterone hormones in female and male fishes were measured, as previously described. Results & Conclusion: The results showed that the concentration of heavy metals in Mid-Zone were significantly (p<0.05) higher than the other two zones. No significant differences (p>0.05) in metals were seen between two carp species and also between male and female fishes. Estradiol hormone concentration in Mid-Zone and Lower-Zone female fishes were significantly lower than Upper-Zone (p<0.05), but no significant differences (p>0.05) were seen in progesterone and testosterone concentration in female fishes. Significant decrease (p<0.05) observed in progesterone and testosterone hormone concentrations of male fishes from Mid-Zone and the other two zones and progesterone hormone concentration in male fishes were significantly (p<0.05) higher than the other two zones, but no difference observed in estradiol concentration in those fish. The results confirmed that heavy metals exposure can effectively decrease estradiol and testosterone secretion in female and male fish, respectively, and decrease the reproductive efficiency and sperm and ovum quality and quantity.

Keywords:

heavy metals , fish , hormone , contamination , the Kor River , Fars , IRAN