Effect of specific opioid-receptor antagonist naloxone on rats with hereditary hypothalamic diabetes insipidus (Brattleboro strain) during acute hemorrhagic shock.

The development of an acute hemorrhagic shock in rats with hereditary diabetes insipidus (DI), lacking vasopressin, is very dramatic, compared to rats of the parent strain Long Evans (LE). After removal of 50% of the circulating blood for LE, and 30% for DI, the mortality for both LE and DI groups was 50%, the shock index being 0.049 and 0.028, respectively. Infusion of either vasopressin (107 mU/100 g) or naloxone (0.2 mg/100 g) in DI rats, prevented the progression of hemorrhagic shock into irreversible stage, and augmented survival up to 66% and 57%, respectively. The specific opioid antagonist naloxone exerted a therapeutic effect on rats with hemorrhagic shock by antagonism of opioid receptors, without influencing ACTH and aldosterone secretion in DI rats. This is another evidence for the role of beta-endorphin in the pathogenesis of hemorrhagic shock.