In this study, parathyroid hormone (PTH) receptor binding was examined in the membrane fraction of the endometrium of the shell gland of laying and nonlaying hens by the use of 125I-PTH-related peptide (PTHrP) binding assays. Specific 125I-PTHrP binding was found in the endometrium of the shell gland and increased during the first 1 h of incubation and then reached a plateau. Specific 125I-PTHrP binding increased in line with an increase in protein concentration from 10 to 80 μg. The membrane fraction had specific binding to 125I-PTHrP. The Scatchard plot analysis revealed a linear profile that indicated the presence of one type of receptor. The equilibrium dissociation constant (K(d)) and the maximum binding capacity (B(max)) in the shell gland decreased 19 h before oviposition in egg-laying hens and remained low for about 20 h during the period of calcification. In contrast, the K(d) and the B(max) in nonlaying hens were constant throughout a 24-h period. These results suggest that PTH acts on the endometrium of the shell gland during the eggshell calcification. (C) 2000 Academic Press.
ASJC Scopus subject areas
- Animal Science and Zoology