@entity836 antagonizes the biobehavioral adaptation to cold water stress in XXXX .

@entity836 @entity11896 @entity1337 @entity458 @entity35 @entity2332
The reported studies on the development of tolerance to the analgesic effects of stress have been mostly concerned with the involvement of opioid or non-opioid substances in stress-induced @entity1337 (SIA). To further investigate the processes involved in SIA tolerance, @entity35 were exposed to forced @entity11896 ( @entity11896 , 18 exposures, 3/min, 10 sec each) on 16 consecutive days. On days 15 and 16, they were injected prior to swim with saline and @entity836 (10 mg/kg), respectively. During swim, three types of readily identifiable behaviors were observed. They may be characterized by immobility and horizontal floating (Type I), intensive activity and escape attempts (Type II), and passivity and "behavioral despair" (Type III). In the acute condition, only Type II and Type III appear in sequence. In the chronic condition, the sequence of behaviors is: Type I, Type II, and Type III. Thirty minutes after swim, @entity1337 , core temperature, and degree of inactivity were measured. With chronic exposure, tolerance developed to the @entity1337 , @entity2332 and @entity458 induced by the @entity11896 . Type I behavior appeared on day 3 or 4 and persisted throughout the chronic treatment. Type II behavior did not adapt. @entity836 (10 mg/kg) antagonized the adaptive aspect of all those variables where adaptation or tolerance were found ( @entity1337 , @entity458 , @entity2332 , and Type I behavior) but had no effect on Type II behavior where no adaptation was observed. It is suggested that the endorphins have a functional role in the behavioral and and physiological adaptation to aversive stressful environmental situations.
