Author:
Okuda K.,Uenoyama Y.,Naito C.,Sakabe Y.,Kawate N.
Abstract
The concentration and affinity of luteinizing hormone (LH) receptors in bovine
luteal tissues during the oestrous cycle and pregnancy were investigated by
Scatchard analysis of the binding of 125I-labeled human
chorionic gonadotropin. Corpora lutea (CL) were classified into five stages of
the oestrous cycle and three stages of pregnancy. The concentration of LH
receptors sharply increased from the early I stage of the oestrous cycle (Days
2–3; 3.09 fmol mg-1 protein) to the early II stage
(Days 5–6; 9.44 fmol mg-1 protein) and then
remained constant until the late luteal stage (Days 15–17;
8.14–9.56 fmol mg-1 protein). The LH receptors
could not be analysed in the regressed luteal tissue due to the small amounts
of binding. There was no significant difference in the concentrations of LH
receptors (5.63–9.64 fmol mg-1 protein) among the
three stages of pregnancy. Moreover, the concentrations of the receptors in
the CL of pregnancy were comparable to those in the mid-cycle CL. The binding
affinity did not change significantly during the oestrous cycle and pregnancy.
Based on these results, it is assumed that the luteal function during the
entire period of pregnancy might be regulated, at least in part, by LH, which
is mediated via its specific receptors, and that the luteal function during
pregnancy seems not to be regulated by changes in the binding capacity and
affinity of LH receptors. To understand the physiological roles of LH in
regulating luteal function in pregnant cows, further studies are required.
Subject
Developmental Biology,Endocrinology,Genetics,Molecular Biology,Animal Science and Zoology,Reproductive Medicine,Biotechnology