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Age, gender, and vasopressin affect survival and brain adaptation in rats with metabolic encephalopathy
A I Arieff1, E Kozniewska, T P Roberts
1Department of Medicine, Baylor College of Medicine, Houston, Texas 77024, USA.
Insights
Hyponatremia poses a higher risk of brain damage in children and menstruant women. This study reveals age, sex, and hormones significantly impact mortality and brain adaptation in experimental hyponatremia.
Area of Science:
- Neuroscience
- Endocrinology
- Toxicology
Background:
- Hyponatremia (low sodium levels) can cause metabolic encephalopathy, with higher risks observed in children and menstruant women.
- The influence of age, sex, and hormonal factors on hyponatremia-induced brain damage and mortality requires further investigation.
Purpose of the Study:
- To evaluate the impact of age and sex on mortality and brain adaptation during acute and chronic hyponatremia in a rat model.
- To investigate the protective or detrimental effects of testosterone and estrogen on hyponatremia outcomes.
Main Methods:
- Experimental induction of acute and chronic hyponatremia in male and female rats across three age groups (prepubertal, adult, elderly).
- Assessment of mortality rates, brain sodium levels, and cerebral perfusion under different hyponatremia conditions.
- Administration of testosterone and estrogen to evaluate their effects on hyponatremia-induced mortality.
Main Results:
- Mortality from acute hyponatremia was highest in prepubertal rats (84%) and lowest in elderly rats (0%).
- Chronic hyponatremia resulted in significantly higher mortality in adult females (62%) compared to adult males (13%).
- Testosterone pretreatment reduced mortality, while estrogen administration increased it, particularly in adult males.
Conclusions:
- Age, sex, and sex hormones are critical determinants of mortality and brain adaptation in experimental hyponatremia.
- Cerebral perfusion impairment was more pronounced in adult female rats during chronic hyponatremia.
- Vasopressin's role in hyponatremia-induced mortality appears minimal under the tested conditions.
Abstract:
Children and menstruant women are far more likely than men to develop metabolic brain damage from hyponatremia. We evaluated brain adaptation and mortality from hyponatremia in male and female rats of three different age groups. With acute hyponatremia, the mortality was 84% in prepubertal rats vs. 15% in adults and 0% in elderly rats. With chronic hyponatremia, mortality was 13% in adult males vs. 62% in females. Testosterone pretreatment significantly decreased mortality (from 62 to 9% in adult females, and from 100% to zero in prepubertal rats), but estrogen significantly increased mortality (from 13 to 44% in adult males). With acute hyponatremia in adult rats, brain sodium was significantly decreased (-17%), but in prepubertal rats it was actually increased (+ 37%). Cerebral perfusion during chronic hyponatremia was significantly impaired in adult females vs. males or controls (P < 0.01). Neither vasopressin administration nor chronic hyponatremia induced with desmopressin resulted in any mortality or decrement of cerebral perfusion. Thus age, gender, and the cerebral effects of vasopressin are major determinants of mortality in experimental metabolic encephalopathy.