Effect of ascorbic acid on pituitary prolactin secretion in the non-ascorbate synthesizing osteogenic disorder shionogi (ODS) rat

We examined the secretion of prolactin (PRL) in the hereditary scurvy-prone Osteogenic Disorder Shionogi (ODS) rat to investigate the role of ascorbic acid (AsA) in pituitary lactotroph and hypothalamic function. Plasma PRL concentrations of conscious AsA-deficient or control ODS rats were measured before and after the administration of metoclopramide (MCP), 5- hydroxy-L-tryptophan (5-HTP) or saline. The basal plasma PRL levels did not differ between the two groups. However, the AsA-deficient rats exhibited significantly larger changes in plasma prolactin concentration in response to MCP or 5-HTP than the control ODS rats. Thus, AsA deficiency enhanced the stimulated, but not the basal, secretion of PRL in ODS rats. Our findings suggest that AsA may have an inhibitory effect on PRL secretion.