Morel G, Chabot J G, Enjalbert A, Priam M, Dubois P M
CNRS URA 559, Laboratoire d'Histologie-Embryologie, Faculté de Médecine Lyon-Sud, Oullins, Paris, France.
Acta Endocrinol (Copenh). 1989 May;120(5):682-8. doi: 10.1530/acta.0.1200682.
Classic concepts of calcitonin (CT) function have focused on the effects of CT on calcium homeostasis. More recently CT actions on brain and pituitary have been investigated. In order to evaluate the effects of CT on the anterior pituitary gland we studied the action(s) of CT in vitro and visualized endogenous CT in adult male rat pituitary gland by immunocytochemistry on ultrathin sections obtained by cryoultramicomy. In vitro study using dispersed anterior pituitary cells indicated that CT stimulated the secretion of PRL, whereas the secretion of GH, TSH and LH was not affected. CT-like immunoreactivity was observed in lactotropes only. The other pituitary cell types were not immunoreactive. In lactotropes, immunostaining was observed in the cytoplasm and in the nucleus. In the cytoplasm, CT-like immunoreactivity was visuzalized in the cytoplasmic matrix and in the secretory granules. In the nucleus, immunostaining was distributed primarily in the euchromatin, in the vincinity of heterochromatin region. CT-like immunoreactivity was also observed at the plasma membrane but was only scarce. No reaction product was found when anti-CT serum pre-incubated with CT was used. In conclusion, these results bring evidence for a direct action of CT on lactotrope regulation in vitro as well as in intact animals.
降钙素（CT）功能的经典概念主要集中在CT对钙稳态的影响上。最近，人们对CT在脑和垂体中的作用进行了研究。为了评估CT对垂体前叶的影响，我们在体外研究了CT的作用，并通过对冷冻超薄切片进行免疫细胞化学，在成年雄性大鼠垂体中观察内源性CT。使用分散的垂体前叶细胞进行的体外研究表明，CT刺激了催乳素（PRL）的分泌，而生长激素（GH）、促甲状腺激素（TSH）和促黄体生成素（LH）的分泌未受影响。仅在催乳细胞中观察到CT样免疫反应性。其他垂体细胞类型无免疫反应性。在催乳细胞中，在细胞质和细胞核中均观察到免疫染色。在细胞质中，CT样免疫反应性在细胞质基质和分泌颗粒中可见。在细胞核中，免疫染色主要分布在常染色质中，靠近异染色质区域。在质膜上也观察到CT样免疫反应性，但很少。当使用与CT预孵育的抗CT血清时，未发现反应产物。总之，这些结果为CT在体外以及完整动物中对催乳细胞调节的直接作用提供了证据。
