Effect of dietary administration of lactobacillus casei on reproduction related genes expression (Vitellogenin and Estrogen receptor) and gonad histology in female zebrafish (Danio rerio)

The present study investigates the effect of different levels of probiotic Lactobasillus casei on expression of genes related to reproduction, vitellogenin (Vit), estrogen receptor (ER) and P۴۵۰ aromatase (Cyp۱۹a) in Zebrafish (Danio rerio). For this purpose, Zebrafish with average wight of ۰.۱۵+۰.۰۱ gr fed on diet supplemented with ۰%, ۱۰۵, ۱۰۶ and ۱۰۷ CFU/gr of probiotic for ۶ weeks. After this period and sex determination, females fed with probiotic for ۱ month. At the end of feeding trial, tissue sections of the gonad were prepared. RNA extracted from liver and brain, cDNA syntesised with Superscript RTase kit and PCR were done using primers relate to Vit, ER and Cyp۱۹a and Beta-actin as housekeeping genes. Evaluation reproduction gene expression showed increase in fish fed probiotic compare to control. Vit and Cyp۱۹a gene expression showed significant increases in fish fed ۱۰۶ and ۱۰۷ CFU/gr of probiotic compared to ۱۰۵. ER gene expression showed significant increases in fish fed ۱۰۷ CFU/gr of probiotic compared to two other probiotic-fed groups. In gonad histology, in control group, oocytes are at the end of the third stage and the beginning of the fourth stage and a few oocytes at the end of the fourth stage. In treatment ۲, fed with ۱*۱۰ ۵ CFU/g lactobacillus caesi, oocytes were at the end of the third and at the beginning of the fourth stage, in the treatment fed with ۱*۱۰۶ CFU/g, oocytes were in the fourth stage of sexual activity and in ۱*۱۰ ۷ CFU/g, oocytes were in the fifth, the oocyte nucleus completely disappeared and the eggs are ready for ovulation and fertilization.According to the results it seems that using probiotic could considered as a new strategy for improving reproductive performance.

Keywords:

Reproduction , Probiotic , Zebrafish , Gene expression , Gonad histology