The Effect of Vitex Agnuse Castus Fruit Powder on Hypothalamic GnRH Gene Expression in Laying Hens

Gonadotropin-releasing hormone (GnRH) is a key regulatory molecule of the hypothalamus–pituitary gonadal axis which induces transcription of luteinizing hormone (LH) from the anterior pituitary. Research has shown that estrogen plays an important role in regulating GnRH. Also, recent experiments indicated that Vitex agnus-castus (VAC) has high levels of phytoestrogen. Hence, this research was performed to investigate the effect of Vitex Agnuse Castus (VAC) fruit powder on GnRH and LH genes expression in laying hens using Real time qPCR technique. For this purpose, 90 Hy-line W-36 leghorn (at 72 to 80 weeks old) were used in a completely randomized design with 3 treatments, 5 replicates and 6 hens per replicate for 56 days as an experimental period. The three experimental treatments were: 1- control diet (basal diet without any additives), 2- basal diet plus 1% VAC fruit powder, 3- Basal diet plus 2% VAC fruit powder. At the end of the experiment one hens were slaughtered and their hypothalamus was rapidly separated and transferred to the laboratory with liquid nitrogen. Then, RNA was extracted and used for cDNA synthesis. Finally, GnRH gene expression was evaluated by Real-Time qPCR. The ANOVA results showed that GnRH gene expression was significantly increased in treatment 3 (diet containing 2% VAC) compared to the control and 1% VAC groups (P <0.01). While, addition of 1% VAC fruit powder to diet had no significant effect on GnRH gene expression (P> 0.05). Furthermore, addition of 1 or 2 % VOC fruit powder had no significant effect on LH gene expression (P> 0.05). The results of this study showed that the addition of VOC fruit powder fruit powder up to 2% level could not affect the pituitary-hypothalamic axis of laying hens at 72 to 80 weeks old.