AGE, GENDER, AND VASOPRESSIN AFFECT SURVIVAL AND BRAIN ADAPTATION IN RATS WITH METABOLIC ENCEPHALOPATHY

Children and menstruant women are far more likely than men to develop metabolic brain damage from hyponatremia. We evaluated brain adaptatio n and mortality from hyponatremia in male and female rats of three dif ferent age groups. With acute hyponatremia, the mortality was 84% in p repubertal rats vs. 15% in adults and 0% in elderly rats. With chronic hyponatremia, mortality was 13% in adult males vs. 62% in females. Te stosterone pretreatment significantly decreased mortality (from 62 to 9% in adult females, and from 100% to zero in prepubertal rats), but e strogen significantly increased mortality (from 13 to 44% in adult mal es). With acute hyponatremia in adult rats, brain sodium was significa ntly decreased (-17%), but in prepubertal rats it was actually increas ed (+37%). Cerebral perfusion during chronic hyponatremia was signific antly impaired in adult females vs. males or controls (P < 0.01). Neit her vasopressin administration nor chronic hyponatremia induced with d esmopressin resulted in any mortality or decrement of cerebral perfusi on. Thus age, gender, and the cerebral effects of vasopressin are majo r determinants of mortality in experimental metabolic encephalopathy.