RESUMEN
Objective: To study the role of dopamine D2 receptor (D2R) on the regulation of prolactin (PRL) secretion by malt total alkaloids. Methods: MMQ and GH3 cells of pituitary adenoma were divided into control group, bromocriptine (5 μg/mL), malt total alkaloids (4.4, 8.8, 35.2, 70.4 μg/mL), haloperidol (10, 20, 40 μg/mL), and combined administration group of total malt alkaloids and haloperidol. Cell viability was detected by CCK-8; The expressions of PRL and D2R were detected by western blotting; The level of PRL was detected by ELISA; The level of PRL and D2R mRNA were detected by qRT-PCR. Results: Compared with control group, malt alkaloids (35.2, 70.4 μg/mL) significantly reduced the expression levels of PRL protein and mRNA, and the level of PRL in the supernatant of MMQ cells (P < 0.05). Malt alkaloids (35.2, 70.4 μg/mL) significantly increased the expression levels of D2R protein and mRNA in MMQ cells. Haloperidol significantly inhibited the downregulation of malt alkaloids on the expression levels of PRL protein and mRNA, and the expression level of PRL in supernatant of MMQ cells (P < 0.05). Haloperidol significantly inhibited the upregulation of malt alkaloids on the levels of D2R protein and mRNA (P < 0.05). The level of PRL in GH3 cells had no change by malt alkaloids. Conclusion: Malt alkaloids could inhibit the expression and secretion of PRL in MMQ cell by upregulating D2R.