The role of vasopressin and prolactin in abnormal salt and water metabolism of obese patients before and after fasting and during refeeding.
Arginine vasopressin (AVP) and prolactin (PRL) concentrations were measured in the plasma of grossly obese subjects to determine if abnormalities in salt and water homeostasis could be related to these hormones. Acute oral water loads and hypertonic saline infusions were administered during baseline obesity, after prolonged fasting, and after hypocaloric refeeding. Only 64.7%, 46.1%, and 70.1% of a water load was excreted during the respective three stages. Pre-water load plasma AVP levels were normal, but after the water load the obese failed to suppress AVP secretion in a normal fashion; this defect was corrected after fasting and with refeeding. Salt loading resulted in appropriate osmolality and AVP responses. Serum prolactin levels, normal at baseline during all phases, rose slightly after water loading during fasting. Hypertonic.saline produced no changes in prolactin levels in the obese or in the normal controls. In the disordered salt and water metabolism of the obese, persistently high AVP values during water loading appeared to be a factor in the delay of water excretion. In the observed water retentionduring dietary restriction and refeeding, secretion of AVP and PRL did not appear to have a major regulatory function.
D000328:Adult; D002986:Clinical Trials as Topic; D004435:Eating; D005215:Fasting; D006801:Humans; D008297:Male; D009765:Obesity / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism; D014667:Vasopressins / Q000378:metabolism*; D014867:Water / Q000378:metabolism; D014882:Water-Electrolyte Balance
D014867:Water; D014667:Vasopressins; D012965:Sodium Chloride; D011388:Prolactin