牛ACTH受体和TGFβ1的调节作用

BOVING ACTH-RECEPTORS AND REGULATION OF TGFβ1

目的观察牛肾上腺皮质细胞ACTH受体的分布和转化生长因子β1（TGFβ1）对ACTH受体的调节作用。方法牛肾上腺皮质束、网带细胞（BAC细胞）的原代培养和(125)I－ACTH特异性受体结合标记等。结果在该培养条件下，BAC细胞的受体可分为高、低两种亲和力亚型。它们在每个细胞上的数目分别为3400（高）和15000（低）个。kD分别为4．90368×10(-11)和3．53974×10(－10)mol／L。TGFβ1可减少高亲和力受体至2000个，增加低亲和力受体到33000个。它们的kD也相应地发生了改变。结论TGFβ1对受体亚型具有不同的调节作用，TGFβ1对ACTH高亲和力受体的负性调节作用和ACTH对TGFβ1受体的正性调节作用可能构成对肾上腺皮质激素生成活动调节的角反馈机制。

Aim To observe the distributions of ACTH-receptors on bovine adrenocortical cells and the action oftrans forming growth factor 31 (TGF8l ) on ACTH-recptors. Metbod Primary culture of bovine adrenocortical fascilata-reticu-laris ce1l and '25I-ACTH specific receptor binding labeling. Result8 Under this culture condition,ACTH-receptors could be di-vided into two types(high affinity and low affinity). Their numbers were 34OO sites/cell for high affinity and 15OOO sites/cellfor low affinity. Their equilibrium dissociation constants (kD) were 4. 9O368 X lO-11 and 3. 53974 X 1O-'mol/L respectively.TGF91 treatment decreased high affinity receptors to 2OOo sites/cell and increased low affinity receptors to 33oOo sites/cell.Their kDs were changed correspondingly. Concluslon TGF61 expressed different effects on ACTH high and low affinity re-ceptors. Dewn regulation of TGF51 on high affinity ACTH-receBtors as well as Up regulation ACTH on TGF8l-receptorsmaybe constitute a negative feedback mechanism by which the steroidogenesis of BAC cells is controlled.