XXXX induced by swim stress: interaction between analgesic and thermoregulatory mechanisms.

@entity19 @entity26 @entity1337 @entity519 @entity158 @entity2332
Exposure of an animal to stressful stimuli, perceived by the animal as a threatening, emergency condition, elicits a transient @entity158 sensitivity, which often affects thermoregulatory mechanisms in the threatened organism. We studied the interaction between emergency and thermoregulatory components of swim stress in developing swim stress-induced @entity1337 (SSIA). The subjects were @entity19 selectively bred for high @entity1337 (HA) induced by swimming in 20 degrees C water, and displaying profound swim @entity2332 . The @entity19 were acclimated to one of the following conditions: (1) ambient cold (5 degrees C, mimicking the thermal component of swim stress); (2) daily 3-min swimming at 32 degrees C (mimicking the emergency, emotional in nature, component of swim stress), or (3) daily swimming at 20 degrees C (a combination of both emergency and thermal component of swim stress). Following each of the procedures the @entity1337 induced by swimming in 20 degrees C water and by acute exposure to -2.5 degrees C in helium/ @entity26 (Helox) atmosphere was measured. @entity1337 was also assessed in a group of naive @entity19 immersed in 20 degrees C shallow water with the purpose of eliminating the emergency condition, but assuring the animal's contact with the cold water environment. Cold acclimation markedly attenuated @entity519 ( @entity519 ) without affecting SSIA, whereas repeated swims attenuated SSIA without affecting @entity519 . The results suggest that @entity2332 is the only stimulus eliciting @entity519 , while the emergency condition of swimming is essential for inducing SSIA. The significantly lower magnitude of SSIA in @entity19 acclimated to repeated swims in 20 degrees C than in 32 degrees C water suggests that SSIA develops due to an interaction between the emergency and hypothermic components of swim stress. This is further supported by a greater @entity2332 and greater @entity1337 in freely swimming than in immersed naive @entity19 .
