Casticin, a flavonoid isolated from Vitex rotundifolia, inhibits prolactin release in vivo and in vitro.
OBJECTIVE
to investigate the anti-hyperprolactinemia activity of casticin, a flavonoid isolated from Vitex rotundifolia, and elucidate its molecular mechanism.


METHODS
hyperprolactinemia (MIHP) was induced by administration of metoclopramide dihydrochloride (50 mg/kg, tid, ip, for 10 d) in SD rats and the primary pituitary cells were prepared from the pituitary glands of the SD rats. Prolactin concentrations were measured using a radioimmunoassay. Cell viability was measured using an MTT assay. The mRNA expression of estrogen receptor alpha and beta in rat pituitary cells was measured using semi-quantitative RT-PCR analysis.


RESULTS
the level of serum prolactin in the MIHP model group was 2.1 fold higher than that in the untreated control group (P<0.01). Casticin (10, 20, and 40 mg/kg, ip, for 7 d) reduced serum prolactin levels by 33.9%, 54.3%, and 64.7%, respectively (P<0.01). The positive control drug bromocriptine 1 mg/kg decreased the serum prolactin concentration in MIHP rats by 44.9%. 17β-Estradiol (E2) significantly increased the proliferation of pituitary cells and casticin (1 and 10 micromol/L) markedly inhibited E2-induced pituitary cell proliferation by 27.7% and 42.1%, respectively. Stimulation of pituitary cells with E2 increased prolactin secretion into the cell culture supernatants, and casticin (0.1, 1, and 10 micromol/L) significantly inhibited the prolactin release stimulated by E2 in a concentration-dependent manner. Casticin (1 and 10 micromol/L) significantly inhibited ERα mRNA expression in pituitary cells stimulated with E2 (P<0.01) but increased ERβ mRNA expression at a concentration of 10 micromol/L (P<0.01). However, casticin had no effects on proliferation and prolectin release of the unstimulated primary pituitary cells in vitro.


CONCLUSIONS
casticin inhibited the release of prolactin from pituitary cells of SD rats stimulated with E2 in vivo and in vitro. These effects might be related with inhibiting the ERα mRNA expression and increasing the ERβ mRNA expression.
Department of Pharmacognosy, School of Pharmacy, Second Military Medical University, Shanghai 200433, China.
Qi
Q
YE
Qiao-yan
QY
ZHANG
Cheng-jian
CJ
ZHENG
Yang
Y
WANG
Lu-ping
LP
QIN
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000378:metabolism; D005260:Female; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D005638:Fruit / Q000737:chemistry; D006966:Hyperprolactinemia / Q000139:chemically induced / Q000503:physiopathology / Q000517:prevention & control*; D008787:Metoclopramide; D008517:Phytotherapy; D010902:Pituitary Gland / Q000378:metabolism; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020950:Vitex / Q000737:chemistry*
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D005419:Flavonoids; D010936:Plant Extracts; D004958:Estradiol; C054133:casticin; D011388:Prolactin; D008787:Metoclopramide