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Inhibition of prolactin secretion by American ginseng is mediated by ginseng polysaccharide‐induced nitric oxide production
Author(s) -
Murphy Laura L,
Arbogast Lydia A,
King Mandy L
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1195.7
Subject(s) - ginseng , prolactin , nitric oxide , polysaccharide , chemistry , endocrinology , ginsenoside , medicine , nitric oxide synthase , pharmacology , biology , biochemistry , hormone , alternative medicine , pathology
Rats treated with American ginseng exhibit an approximate 50% reduction in serum prolactin levels and a compensatory decrease in hypothalamic dopamine activity. To investigate whether ginseng has direct pituitary effects, anterior pituitaries collected from random cycling female rats were dispersed and cultured for 1 week prior to treatment with water soluble ginseng extract (0 – 2 mg/ml) for 24 hr. Ginseng produced a dose‐dependent decrease in prolactin with maximum suppression (∼50%) within 6 hr at ≥1mg/ml; there was no change in media LH levels. When the ginsenoside and polysaccharide components in ginseng were examined, ginseng polysaccharides (12.5μg/ml) inhibited prolactin whereas ginsenosides had no effect in the pituitary cultures. Ginseng and its polysaccharides both stimulated nitric oxide (NO) production from cultured cells at 24 hr and induced iNOS gene and protein expression at 12 and 24 hr, respectively. The specific iNOS inhibitor 1400W blocked the ginseng/polysaccharide effects on NO production and prolactin release, whereas eNOS and nNOS inhibitors had no effect. Together, these results suggest that the reduction in circulating prolactin levels following ginseng ingestion is due to polysaccharide‐induced pituitary iNOS and NO production and subsequent prolactin suppression.