title: Persistent GHRH-induced PRL secretion in Cushing's syndrome, obesity and exogenous hypercortisolism.
abstract: Endogenous Cushing's syndrome, obesity and chronic glucocorticod treatment are characterized by blunted GH secretion. The administration of GHRH is capable of stimulating a small but significant PRL increase in normal subjects. The current study was designed to determine plasma PRL levels in response to GHRH, studied in three different situations characterized by a blunted GH secretion. Obese patients (n = 6) with a weight over 30% of ideal body weight, patients with active Cushing's syndrome, and normal volunteers treated with dexamethasone 22 mg per os over two days before the pituitary challenge were studied. As a control group 18 normal subjects of similar age and sex were studied. GH and PRL was determined at intervals after GHRH (1 microgram/kg). GHRH-induced GH secretion was markedly reduced in patients with obesity, patients with endogenous Cushing's syndrome and volunteers treated with dexamethasone. In contrast, GHRH-induced PRL secretion was not affected in these three clinical situations. In summary, in three situations characterized for an impairment of the somatotroph cell, due to a primary intrinsic defect or to a functional hypothalamic alteration, there is a persistent GHRH-induced PRL secretion, suggesting that prolactin could be released by mammosomatotrophs that function normally in spite of hyposomatotropism.
authors.affiliation: Unidad de Endocrinología, Hospital Juan Canalejo, La Coruña, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Cordido
authors.forename: R
authors.initials: R
authors.lastname: Peino
authors.forename: T
authors.initials: T
authors.lastname: Martínez-Ramonde
mesh_terms: D000328:Adult; D003480:Cushing Syndrome / Q000503:physiopathology*; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D007987:Gonadotropin-Releasing Hormone; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood* / Q000378:metabolism; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000503:physiopathology*; D011388:Prolactin / Q000378:metabolism*; D012636:Secretory Rate / Q000187:drug effects; D013268:Stimulation, Chemical
chemical_list: D007987:Gonadotropin-Releasing Hormone; D003907:Dexamethasone; D011388:Prolactin; D013006:Growth Hormone; D006854:Hydrocortisone