Molecular Distribution and Localization of Calcium-sensing Receptor and Vitamin D Receptor in Laying Hens

Calcium-sensing receptor (CaSR) and vitamin D receptor (VDR) play important roles in regulating calcium mobilization, calcium absorption and maintaining calcium homeostasis, which could be potential therapeutic targets for osteoporosis in laying hens. The present study was to investigate the molecular distribution of CaSR and VDR, and the localization of CaSR in the kidney, proventriculus, duodenum, jejunum, ileum, colon, cecum, shell gland and tibia of laying hens at three different laying stages (19, 40 and 55 weeks). The RT-qPCR results showed that at the laying peak (40-week age), the relative mRNA abundance of CaSR in the kidney, ileum, proventriculus, duodenum, and colon was significantly higher than other tissues (P < 0.05). The variation trend of 55-week age was consistent with that of 40-week age. In the tibia, the relative mRNA abundance of CaSR at 55 weeks of age was significantly higher than that at 40 weeks of age (P < 0.05). However, western-blotting results showed that no significant difference of relative CaSR expression was found in the different tissues at the laying peak, or in each tissue at three different laying stages (P > 0.05). The relative mRNA abundance of VDR was significantly higher in the small intestine (duodenum, jejunum, and ileum) when compared with other tissues at three different laying stages. Western blotting results showed that the expression of VDR in the duodenum was significantly higher than that in the proventriculus, colon, and cecum, respectively (P < 0.05). Different laying stages did not affect the VDR expression in each tissue (P > 0.05). From IHC results, we detected that the positive brown staining can be found widely in each tissue, and different laying stages did not affect the localization of CaSR except for the tibia tissue. In conclusion, CaSR and VDR are widely expressed in the gut, bone and shell gland of laying hens, but their expressions are rarely affected by the different laying stages in each tissue.

Published in the proceedings of the Animal Nutrition Conference of Canada 2020. For information on the event, past and future editions, check out https://animalnutritionconference.ca/.