Changes in Kiss1 gene expression in the brain tissue of the male and female Caspian kutum (Rutilus kutum) in different stages of gonadal growth

The Caspian kutum is one of the most important economic and native species of the Caspian Sea. Kisspeptin neurons act as a central processor in the transmission of peripheral signals to gonadotropin receptor (GnRH) neurons. To investigate the role of kisspeptin, especially Kiss1 in the reproduction of the Caspian kutum, the expression of the Kiss1 gene in brain tissue was evaluated using real-time PCR. For this purpose, 36 pieces of fish were caught from Anzali shores from November 1997 to May 1998 with an average weight of 650±50 g and a length 35.5±0.2 cm and brain tissue was separated. After extraction of total RNA and cDNA synthesis from brain tissue, expression of the Kiss1 gene was performed using real-time PCR technique by reference gene-actin-β. Data were evaluated using one-way analysis of variance (ANOVA) and Tukey post-test and 95% confidence level and the significant difference in expression of the Kiss1 gene was calculated per month in both sexes. The results showed that the expression level of the Kiss1 gene in the brain tissue of male and female fish showed a significant difference in different months (p< 0.05). The highest expression of the Kiss1 gene in both sexes was reported in May during the Caspian kutum spawning. In addition, morphohistology of gonads showed that the highest sexual maturity was from March to May. In conclusion, it seems that it can be stated that Kiss1 has the highest level of expression in the months when the Caspian kutum reaches its sexual maturity.