Another face of VitB6 is that it inhibits prolactin secretion. Prolactin is a pituitary immunity stimulating hormone normally secreted during sleep or lactation but often overproduced in chronic inflammatory diseases and allergies.
Endocrinology. 2006 Aug;147(8):3936-42. Epub 2006 May 11.
Pyridoxal phosphate inhibits pituitary cell proliferation and hormone secretion.
Ren SG, Melmed S.
Department of Medicine, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Room 2015, Los Angeles, California 90048, USA.
Pyridoxal phosphate (PLP), a bioactive form of pyridoxine, dose-dependently (10-1000 microm) inhibited cell proliferation in rat pituitary MMQ and GH3 cells and in mouse AtT-20 cells. After 4 d, MMQ cell numbers were reduced by up to 81%, GH3 cell numbers were reduced by up to 64% (P < 0.05), and AtT-20 cell numbers were reduced by up to 90%. Cell proliferation rates recovered and dose-dependently reverted to control levels after PLP withdrawal. After 4 d, PLP (400 and 1000 microm) decreased [3H]thymidine incorporation by up to 71% (P < 0.05). PLP (400-1000 microm) reduced GH3 cell GH and prolactin secretion and AtT-20 cell ACTH secretion (adjusted for cell number) by approximately 70% after 2 d. The 100 microm PLP also inhibited prolactin secretion (65%, P < 0.05) in primary rat pituitary cells treated for 2 d. PLP decreased the percentage of AtT-20 and GH3 cells in S phase and increased those in G0-G1 phase. Furthermore, PLP induced AtT-20 and GH3 cell apoptosis (28 vs. 6, P < 0.05; 26 vs. 3, P < 0.05, respectively) and dose-dependently reduced content of the antiapoptosis gene Bcl-2. These results indicate that pharmacological doses of PLP inhibit pituitary cell proliferation and hormone secretion, in part mediated through PLP-induced cell-cycle arrest and apoptosis. Pyridoxine may therefore be appropriate for testing as a relatively safe drug for adjuvant treatment of hormone-secreting pituitary adenomas.
PMID: 16690808
Boll Soc Ital Biol Sper. 1984 Feb 28;60(2):273-8.
[Influence of administration of pyridoxine on circadian rhythm of plasma ACTH, cortisol prolactin and somatotropin in normal subjects]
Barletta C, Sellini M, Bartoli A, Bigi C, Buzzetti R, Giovannini C.
The influence of vitamin B6 in a dosage of 300 mg X 2 in 24 hrs, on circadian rhythm of plasmatic ACTH, cortisol, prolactin and somatotropin have been studied in 10 normal women. After vitamin B6 24 hrs pattern of ACTH and cortisol is unchanged; prolactin levels are slightly lower, in a statistically unsignificant proportion the night peak of growth hormone is higher in a statistically significant proportion (p. 0.05). The effect of vitamin B6 is likely to me mediated by dopaminergic receptors at hypothalamic level as previous studies by other Authors appear to prove.
PMID: 6324828
N Engl J Med. 1982 Aug 12;307(7):444-5.
Pyridoxine (B6) suppresses the rise in prolactin and increases the rise in growth hormone induced by exercise.
Moretti C, Fabbri A, Gnessi L, Bonifacio V, Fraioli F, Isidori A.
PMID: 7088124
Horm Metab Res. 1985 Jan;17(1):46-7.
Pyridoxine (Vit. B6) decreases opioids-induced hyperprolactinemia.
Vescovi PP, Gerra G, Rastelli G, Ceresini G, Moccia G.
PMID: 3967846
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