The presence of LH components having different ratios of bioactivity to immunoreactivity in the rat pituitary glands.

Publisher Website
Google Scholar
Abstract
The isoelectric components of LH [luteinizing hormone] were isolated from the male rat pituitary glands by preparative isoelectric focusing. The biological activities of these components were measured in vitro from testosterone production in rat Leydig cells at equal doses and expressed as the equivalent of National Institutes of Health-LH-S1 immunoreactivity. There were significant differences in the bioactivities among the components. The bioactivities of the components decreased with decreasing pI [isoelectric point]; components E (pI = 9.6) and F (pI = 9.8) showed .apprx. 5- to 6-fold higher activities than component A'' (pI = 7.9). When the rat pituitary extracts were measured for LH by radioimmunoassay, and then measured for the ratio of biological activity to immunoreactivity (B:I), the order was as follows; intact female rats > intact male rats > orchidectomized rats. This phenomenon could be explained by the differences in the relative amounts of the LH components which changed according to the physiological states. The lH components with different pI and B:1 ratio are related to the different estimation of total LH in the rat pituitary glands by bioassay and radioimmunoassay.