Impact of melatonin injection in improving ovarian function in aged female pigeon

Melatonin (MT) has been shown to extend laying period in aged hens, but its effects on aging pigeons remain unclear. 36 pairs of 5-year-old White King pigeons were assigned to either a treatment group receiving 1 mg of MT for five days or a control group given saline. The effect of MT injection on egg production in pigeon, assess histological characteristics of follicles, antioxidant parameters level and the related gene mRNA levels, steroid hormone levels and the expressions of synthesis genes on the fifth day of the laying interval. MT treatment significantly improved various aspects of egg quality. Moreover, MT increased follicle diameter and granulosa cell layer (GCL) thickness (P < 0.05). MT levels were elevated in plasma and hierarchy follicles yolks (P < 0.05). Progesterone concentrations rose in plasma (P < 0.05), however, estradiol levels decreased in plasma, F1 and F2 yolks (P < 0.05). MT also reduced ROS and MDA levels in plasma and F1 yolk (P < 0.05). Meanwhile, activities of SOD, TAC, and GSH-PX were significantly increased (P < 0.05). MT upregulated SOD1, CAT, and BCL2 mRNA levels in ovary and F1 GCL (P < 0.05). MT significantly increased ovarian expressions of HSD3B1 and CYP11A1, reducing HSD17B1 mRNA levels (P < 0.05); In F1 and F2 GCL, CYP11A1, CYP17A1, and CYP19A1 expressions were all elevated (P < 0.05). These findings suggest that MT promotes hierarchy follicle maturation, reduces apoptosis, thus extending egg-laying period in aging pigeons.