Malendowicz L K, Tretjer M, de Caro R, Jedrzejczak N, Brelinska R, Markowska A, Nussdorfer G G, Nowak M
Department of Histology and Embryology, School of Medicine, Poznan, Poland.
Histol Histopathol. 1999 Apr;14(2):439-43. doi: 10.14670/HH-14.439.
Cholecystokinin (CCK) is a multifunctional regulatory peptide, which acts through two main subtypes of receptors, named CCK-A and CCK-B. Evidence indicates that CCK modulates cell proliferation in various tissues in a paracrine manner, and proofs are available of the presence of CCK in both adrenal glands and thymus. Hence, we have investigated the possible mitogenic action of this peptide on these two tissues, by evaluating the /1000 of metaphase-arrested cells after vincristin injection (mitotic index). The systemic administration of CCK (three subcutaneous injections of 20 nmol/kg, 28, 16 and 4 h before the sacrifice) increased the mitotic index in both the outer adrenal and thymus cortexes of immature (20-day-old) rats and the enucleated adrenal gland of adult (2-month-old) animals at day 5 and 8 of regeneration. The simultaneous administration of equimolar doses of a selective CCK-A receptor antagonist blocked the effect of CCK, while a CCK-B antagonist was ineffective. These findings indicate that CCK exerts a marked CCK-A-mediated proliferogenic effect on both adrenal cortex and thymus in the rat, the physiological relevance of which, however, remains to be demonstrated. In fact, the administration of the CCK-A antagonist alone was ineffective, thereby casting doubts on the role played by endogenous CCK in the maintenance and stimulation of adrenal and thymus growth.
胆囊收缩素（CCK）是一种多功能调节肽，它通过两种主要的受体亚型发挥作用，即CCK-A和CCK-B。有证据表明，CCK以旁分泌方式调节各种组织中的细胞增殖，并且在肾上腺和胸腺中均已证实存在CCK。因此，我们通过评估注射长春新碱后中期停滞细胞的千分率（有丝分裂指数），研究了该肽对这两种组织可能的促有丝分裂作用。全身性给予CCK（在处死前28、16和4小时皮下注射三次，每次20 nmol/kg）可增加未成熟（20日龄）大鼠的肾上腺外层和胸腺皮质以及成年（2月龄）动物再生第5天和第8天摘除肾上腺后的有丝分裂指数。同时给予等摩尔剂量的选择性CCK-A受体拮抗剂可阻断CCK的作用，而CCK-B拮抗剂则无效。这些发现表明，CCK对大鼠的肾上腺皮质和胸腺均发挥明显的CCK-A介导的增殖作用，然而，其生理相关性仍有待证实。实际上，单独给予CCK-A拮抗剂无效，从而使人对内源性CCK在维持和刺激肾上腺及胸腺生长中所起的作用产生怀疑。
