Enhanced lithogenicity of bile following chronic morphine administration to female guinea pigs.

Acute and chronic opiate exposure impairs the emptying of bile from the gallbladder. In this study, the effects of a 4-day morphine regimen on bile composition were examined. Bile acids and phospholipids concentration of bile obtained from the gallbladder of female morphine-treated (MT) guinea pigs were reduced by 60% and 80% respectively, resulting in a highly lithogenic bile.

Stress- and morphine-induced elevations of plasma and tissue cholesterol in mice: reversal by naltrexone.

Our earlier studies indicated that stress-induced facilitation of gallstone formation could be prevented by the opiate antagonist naltrexone. In view of the possible link between gallstone formation and atherosclerosis, the present study examined the possibility that endogenous opioids might also mediate stress-induced hypercholesterolemia. A 28-day immobilization stress schedule was used to induce increases in plasma, aortic and liver cholesterol of mice maintained on a high cholesterol diet.

Modification of drug action by hyperammonemia.

Pretreatment with ammonium acetate (NH4Ac) (6 mmol/kg s.c.) approximately doubled the time morphine-treated mice remained on a hot surface and similarly increased muscular incoordination by diazepam, but NH4Ac treatment alone had no effect.

Stress, endogenous opioids and salt intake.

The effect of stress on NaCl intake was examined in mice given a choice of water and 1.5% NaCl to drink. Immobilization of mice for 15-min and 24-h food deprivation resulted in a 2.