Neurosciences Centre of Excellence for Drug Discovery, GlaxoSmithKline, 37135 Verona, Italy.
Eur J Pharmacol. 2012 Mar 15;679(1-3):16-23. doi: 10.1016/j.ejphar.2012.01.003. Epub 2012 Jan 20.
In the present study, adrenocorticotropic hormone (ACTH) release and intracellular calcium (Ca(2+)) increase induced by arginine vasopressin (AVP) were characterized in collagenase-dispersed and 3-day cultured rat anterior pituitary cells. AVP and the selective vasopressin V(1b) receptor agonist, [1-deamino-4-cyclohexylalanine]AVP (d[Cha(4)]AVP) induced ACTH release with nanomolar potencies in both cell preparations, and produced a maximal stimulation that was about 1.5 fold greater in the 3-day cultured cells, indicating that the vasopressin V(1b) receptor-ACTH release pathway is enhanced over time in culture. In dispersed cells, AVP, oxytocin and d[Cha(4)]AVP induced Ca(2+) increases with nanomolar potencies. The selective vasopressin V(1a) receptors antagonist, SR49059 (100 nM), together with the selective oxytocin receptors antagonist (d(CH(2))(5)(1)Tyr(Me)(2),Thr(4),Orn(8),Tyr-NH(2)(9)-vasotocin (100 nM), inhibited the maximal AVP response by ~70%, without affecting the response to d[Cha(4)]AVP, suggesting that the V(1b) receptor was only partially responsible for the AVP-induced Ca(2+) increase. In contrast, in 3-day cultures, AVP induced an increase in Ca(2+), while oxytocin and d[Cha(4)]AVP did not. The response to AVP was completely antagonized by SR49059, whereas the vasopressin V(1b) receptor antagonists, SSR149415 and (d(CH(2))(5)(1)Tyr(Me)(2),Thr(4),Orn(8),Tyr-NH(2)(9))-vasotocin had no effect, indicating that the Ca(2+) increase was mediated exclusively by vasopressin V(1a) receptors. In conclusion, the enhancement of vasopressin V(1b) receptor-mediated ACTH release and the lack of a detectable vasopressin V(1b) receptor coupling to Ca(2+) increase in cultured cells suggests the activation of a different/additional signaling pathway in the molecular mechanism of ACTH release.
在本研究中，我们对胶原酶分散和培养 3 天的大鼠垂体前叶细胞中精氨酸血管加压素 (AVP) 诱导的促肾上腺皮质激素释放 (ACTH) 和细胞内钙离子 (Ca(2+)) 增加进行了特征描述。AVP 和选择性血管加压素 V(1b) 受体激动剂 [1-脱氨基-4-环己基丙氨酸]AVP(d[Cha(4)]AVP) 在两种细胞制剂中均以纳摩尔效力诱导 ACTH 释放，并且在培养的 3 天细胞中产生约 1.5 倍的最大刺激，表明血管加压素 V(1b) 受体-ACTH 释放途径在培养过程中随着时间的推移而增强。在分散细胞中，AVP、催产素和 d[Cha(4)]AVP 以纳摩尔效力诱导 Ca(2+) 增加。选择性血管加压素 V(1a) 受体拮抗剂 SR49059(100 nM) 与选择性催产素受体拮抗剂 (d(CH(2))(5)(1)Tyr(Me)(2),Thr(4),Orn(8),Tyr-NH(2)(9)-vasotocin(100 nM)) 一起抑制 AVP 最大反应约 70%，而不影响对 d[Cha(4)]AVP 的反应，表明 V(1b) 受体仅部分负责 AVP 诱导的 Ca(2+) 增加。相比之下，在 3 天的培养物中，AVP 诱导 Ca(2+) 增加，而催产素和 d[Cha(4)]AVP 则没有。SR49059 完全拮抗 AVP 反应，而血管加压素 V(1b) 受体拮抗剂 SSR149415 和 (d(CH(2))(5)(1)Tyr(Me)(2),Thr(4),Orn(8),Tyr-NH(2)(9))-vasotocin 没有影响，表明 Ca(2+) 增加仅由血管加压素 V(1a) 受体介导。总之，培养细胞中血管加压素 V(1b) 受体介导的 ACTH 释放增强以及检测不到血管加压素 V(1b) 受体与 Ca(2+) 增加的偶联表明，在 ACTH 释放的分子机制中激活了不同/附加的信号通路。
