Attenuation of gastric lesions by psychological aspects of aggression in rats.

Rats that fought with each other in response to electric shock showed reduced gastric lesions in comparison with animals that received the same shocks alone so that fighting behavior did not occur. Also, gastric lesions were similarly reduced in animals that fought even though they could not physically contact one another because of a barrier between them, so that the "protective" effect of fighting derived from release of, or display of, fighting behavior and did not require physical combat. A second experiment showed that animals that received shock together but did not engage in fighting behavior showed no reduction of gastric lesions, so that the protective effect of fighting was not an artifact of animals receiving shock together. Possible explanations for why fighting behavior reduces gastric lesions are discussed.