Effect of pyridoxine on human hypophyseal trophic hormone release: a possible stimulation of hypothalamic dopaminergic pathway.

A single dose of pyridoxine (300 mg iv) produced significant rises in peak levels of immunoreactive growth hormone GH and significant decrease of plasma prolactin PRL in 8 hospitalized healthy subjects. Serum glucose, luteinizing hormone LH, follicle stimulating hormone FSH and thyrotropin TSH were not altered significantly. In addition, in 5 acromegalic patients who were studied with both L-dopa and pyridoxine, inhibition of GH secretion followed either agent in a similar pattern. These data suggest a hypothalamic dopaminergic effect of pyridoxine.