Gorewit R C, Tucker H A
J Dairy Sci. 1976 Nov;59(11):1890-6. doi: 10.3168/jds.S0022-0302(76)84458-X.
Unlabeled cortisol and dexamethasone reduced tritiated cortisol and tritiated dexamethasone binding to 700 X g supernatant and precipitate fractions of mammary tissue slices from virgin heifers and from multiparous cows that were 1-mo prepartum (nonlactating), lactating (non-pregnant), or dry (nonpregnant, nonlactating). Unlabeled progesterone, testosterone, and 17beta-estradiol had no effect on tritiated glucocorticoid binding in 700 X g supernatant and precipitate fractions from these mammary tissue slices. The 700 X g fractions in mammary tissue slices from all cattle bound cortisol and dexamethasone with high affinity (Kd 10-10M). There were 1263 and 1955 molecules of cortisol and dexamethasone bound per mammary cell, respectively, in mammary tissue slices from lactating non-pregnant cows; in comparison virgin heifers bound 413 and 651 molecules of cortisol and dexamethasone; dry, non-pregnant cows bound 336 and 536 molecules of cortisol and dexamethasone; and 1-mo prepartum nonlactating cows bound 532 molecules of cortisol. Mammary tissue slices from cattle in reproductive states examined contained a major non-specific component which bound cortisol in both 700 X g tissue fractions. Since mammary tissue slices from lactating cattle bound more molecules of glucocorticoids than mammary slices from cattle in other reproductive states, we speculate specific glucorticoid binding may be associated with lactation.
未标记的皮质醇和地塞米松可降低来自初产小母牛以及经产奶牛（产前1个月，非泌乳期；泌乳期，非妊娠期；干奶期，非妊娠非泌乳期）乳腺组织切片的700×g上清液和沉淀组分中氚化皮质醇和氚化地塞米松的结合。未标记的孕酮、睾酮和17β-雌二醇对这些乳腺组织切片的700×g上清液和沉淀组分中氚化糖皮质激素的结合没有影响。所有牛的乳腺组织切片中的700×g组分都以高亲和力（解离常数Kd为10⁻¹⁰M）结合皮质醇和地塞米松。在非妊娠泌乳奶牛的乳腺组织切片中，每个乳腺细胞分别结合1263个和1955个皮质醇和地塞米松分子；相比之下，初产小母牛结合413个和651个皮质醇和地塞米松分子；干奶期非妊娠奶牛结合336个和536个皮质醇和地塞米松分子；产前1个月的非泌乳奶牛结合532个皮质醇分子。所检测的处于不同生殖状态的牛的乳腺组织切片含有一种主要的非特异性成分，该成分在700×g组织组分中均能结合皮质醇。由于泌乳奶牛的乳腺组织切片比处于其他生殖状态的奶牛的乳腺切片结合更多的糖皮质激素分子，我们推测特异性糖皮质激素结合可能与泌乳有关。
