Sex steroid hormone binding globulin levels and free 17 beta-estradiol and testosterone in cynomolgus monkeys during different reproductive states.
The effect of differences in sex hormone binding globulin (SHBG) levels associated with reproductive status on free 17 beta-estradiol (E2) and testosterone (T) was characterized in cynomolgus monkeys. Cycling female cynomolgus monkeys had higher SHBG levels than males, pregnant and lactating females (P less than 0.05). Ovariectomized females were not different than control females, suggesting no hypoestrogenic effect. The percentage of free T was elevated in pregnant animals (P less than 0.05) compared to normal males and females, but the percentage of free E2 was similar between these groups. Although a gender difference in the percentages of free E2 and T was not detected, there was a gender difference in the free T and E2 concentrations due to endogenous secretion. Increased free E2 concentrations during pregnancy were the result of endogenous secretion rather than the decreased binding capacity of SHBG; the increased percentage of free T during pregnancy significantly increased free T concentrations. These data suggest that the gender difference in SHBG levels in cynomolgus monkeys is due to androgenic influences and that estrogens have minimal influence. Furthermore, the decrease in SHBG levels during pregnancy and lactation may not be entirely dependent on these androgenic influences.
D000818:Animals; D004958:Estradiol / Q000097:blood*; D005260:Female; D007774:Lactation; D008252:Macaca fascicularis; D008297:Male; D011247:Pregnancy; D012098:Reproduction; D012737:Sex Factors; D012738:Sex Hormone-Binding Globulin / Q000032:analysis* / Q000378:metabolism; D013739:Testosterone / Q000097:blood*
D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol