Ollivier-Bousquet M, Aubourg A
INRA, Laboratoire de Biologie Cellulaire et Moléculaire, Jouy-en-Josas, France.
Reprod Nutr Dev. 1992;32(5-6):441-51. doi: 10.1051/rnd:19920504.
The secretagogue effect of prolactin (PRL) on casein release by epithelial mammary cells has been previously related to stimulation of the phospholipase A2-arachidonic acid cascade. In order to determine whether other intracellular pathways are implicated in this secretagogue effect, different agents acting on protein kinase C (PKC) and phospholipase C (PLC) activity have been assessed in vitro in lactating rabbit mammary gland fragments. Phorbol ester (20 nm TPA and 1-oleoyl-2-acetyl-sn-glycerol (10 microM (OAG) stimulated newly synthesized casein secretion and potentiated the PRL secretatogue effect. However, 100 microM quercetin, 100 microM H-7 and 5 and 20 nM staurosporine did not inhibit the latter effect. Exogenous PLC did not stimulate casein secretion. PRL did not affect production of inositol phosphates (IPs) during 10 or 60 min exposure. These results show that PKC activation may increase basal levels of casein secretion, and demonstrate that PRL does not act primarily via PKC activation or by PLC activation to stimulate casein secretion.
催乳素（PRL）对乳腺上皮细胞酪蛋白释放的促分泌作用先前已被认为与磷脂酶A2-花生四烯酸级联反应的刺激有关。为了确定其他细胞内途径是否参与这种促分泌作用，已在体外对泌乳兔乳腺组织块中作用于蛋白激酶C（PKC）和磷脂酶C（PLC）活性的不同试剂进行了评估。佛波酯（20 nM TPA和1-油酰基-2-乙酰基-sn-甘油（10 μM OAG）刺激新合成的酪蛋白分泌，并增强PRL的促分泌作用。然而，100 μM槲皮素、100 μM H-7以及5和20 nM星形孢菌素并未抑制后者的作用。外源性PLC并未刺激酪蛋白分泌。在暴露10分钟或60分钟期间，PRL并未影响肌醇磷酸（IPs）的产生。这些结果表明，PKC激活可能会增加酪蛋白分泌的基础水平，并证明PRL主要不是通过PKC激活或PLC激活来刺激酪蛋白分泌的。
