Responses of Growth Hormone to Metoclopramide in Normal Women and. Amenorrheic Women with or without Hyperprolactinemia

Abstract

Response of growth hormone (GH) release to metoclopramide (MCP), a dopamine antagonist, was evaluated in normal women, hyperprolactinemic-amenorrheic patients with pituitary microadenoma and normoprolactinemic-amenorrheic patients. Mean basal concentrations of serum GH and prolactin (PRL) in amenorrheic patients were not significantly different from those in normal women except PRL concentrations in hyperprolactinemic patients. Serum GH concentrations significantly increased after MCP administration in normal women and normoprolactinemic-amenorrheic patients, but not in hyperprolactinemic patients. Dopamine causes modest and transient GH secretion in some subjects. Therefore MCP is not likely to stimulate GH secretion through its effect as a dopamine antagonist, and the mechanism of action of MCP on GH secretion is not known. Although the cause of the absence of GH response to MCP in hyperprolactinemic patients is unclear, it may be related to the increased hypothalamic dopaminergic tone which is operative in such patients or it may reflect a direct action of PRL on hypothalamic-pituitary GH regulation. © 1986, The Japan Endocrine Society. All rights reserved.