Different Responses to Two Hypothalamic Hormones in Acromegalics

It is now well established that hypothalamic hormones stimulate the release of all the known hormones from the anterior pituitary gland except prolactin which is primarily under an inhibitory influence.1The hypothalamus also inhibits the release of melanocyte-stimulating hormone (MSH) from the intermediate lobe of the pituitary.2,3The structure and synthesis of thyrotropin-releasing hormone (TRH) was recently announced,4,5and it is probable that this will be accomplished soon for other hypothalamic hormones. When available, these materials should be of value both for diagnosis and therapy. The hypothalamic hormones will theoretically provide a means of differentiating primary hypothalamic from pituitary disorders, a distinction which until now has been difficult or impossible to make. It would be expected that release of pituitary hormones by the stimulatory hypothalamic hormones would only occur when sufficient pituitary reserve remained. Clinical tests have already been performed with synthetic TRH6-11and