Expression of the Wnt signaling pathway and hair follicle development in  Rex rabbits of different ages

In the present study, we aimed to observe hair follicle development and describe the Wnt signaling pathways related to hair follicle development in Rex rabbits of different ages. Six Rex rabbits aged 15, 30, 60, 90, 120 and 150 days were selected, and skin samples were collected for hair follicle development and Wnt signaling pathway gene expression detection. The results revealed that the values for body weight, coat length, skin thickness, skin area, and skin weight of Rex rabbits were increased significantly with age ( p  < 0.05). The total hair follicle density, secondary hair follicle density and ratio of the secondary hair follicle density to the primary hair follicle density at the age of 120 days in Rex rabbits were greater than those at the other ages ( p  < 0.05), and the major hair follicles were in the growing period at 15 days and 30 days of age. Some of them had already entered the degeneration period at 60 days of age, and most of them had entered the degeneration period at 90 days of age. The presence of quiescent hair follicles and the enlargement of primary hair follicles were also observed. At 120 and 150 days of age, the back hair follicles entered the growing period, and the secondary hair follicles had clearly differentiated. Furthermore, the expression levels of the Wnt10b , CTNNB1 , adenomatosis polyposis protein (APC) , disheveled 2 (DVL2) , glycogen synthase kinase 3β (GSK-3β) , Lymphoid enhancer-binding factor 1 (LEF1) , dickkopf-1 (DKK1) and transforming growth factor beta 1 (TGFβ-1) genes in the skin tissue of Rex rabbits at different age was significantly different ( p  < 0.05), and the expression of the Wnt10b , CTNNB1 , DVL2 , GSK-3β , and TGFβ-1 genes at 90 days were greater than those at the other days. The expression levels of the LEF1 and DKK1 genes at 60 days were greater than those at the other days. As indicated by western blotting, the β-catenin protein phosphorylation (P-CTNNB1) levels in the skin tissue of Rex rabbits first tended to increase, then decreased and then increased, and the levels at 60, 120 and 150 days were significantly greater than those at 15, 30 and 90 days ( p  < 0.05). With increasing age, the GSK-3β protein phosphorylation (P-GSK-3β) level in the skin tissue of Rex rabbits increased, reaching a maximum at 120 days of age ( p  < 0.05). These results show that age could influence the fur quality and hair follicle traits of Rex rabbits and that the Wnt signaling pathway is involved in the biological process of periodic hair follicle development in Rex rabbits. Considering the rules of fur growth, the slaughter age of Rex rabbits should not be earlier than 120 days.