Albert D J, Dyson E M, Walsh M L
Psychology Department, University of British Columbia, Vancouver, Canada.
Physiol Behav. 1987;40(6):695-701. doi: 10.1016/0031-9384(87)90270-8.
Castrated male hooded rats were given electrolytic lesions of the medial hypothalamus or sham lesions. Another group of castrated rats was implanted subcutaneously with bilateral testosterone-filled Silastic capsules or empty capsules. Lesioned animals with a high defensiveness (reactivity) score toward the experimenter were each placed in a cage with a sham-lesioned animal of a similar weight. Animals with testosterone implants were likewise housed with an animal of similar weight without a testosterone implant. Following a period of adaptation to a 23-hr water deprivation schedule, each pair of rats was given daily competition tests on each of 6 days. During the tests, a single water spout was placed in the cage for a 4-min period. The spout was surrounded by a plastic ring which prevented more than one animal from drinking at any time. Access to an unencumbered water spout was present following the competition test for 1-hr each day. Rats with medial hypothalamic lesions displayed more aggression than sham-lesioned rats during the competition tests and were able to spend more time drinking. Rats with testosterone implants were more successful in maintaining access to the spout but did not consistently display more aggression than their cagemates without testosterone implants. The aggression of the lesioned rats was defensive while that of animals with testosterone implants corresponded to intermale social aggression. These results demonstrate that a competitive situation can elicit intermale social aggression mediated by testosterone and defensiveness induced by medial hypothalamic lesions.
对去势雄性有帽大鼠进行下丘脑内侧的电解损伤或假损伤。另一组去势大鼠皮下植入双侧填充睾酮的硅橡胶胶囊或空胶囊。对实验者具有高防御性（反应性）评分的损伤动物，每只与一只体重相似的假损伤动物放在一个笼子里。植入睾酮的动物同样与一只体重相似但未植入睾酮的动物饲养在一起。在适应23小时禁水时间表一段时间后，每对大鼠在6天中的每一天都进行每日竞争测试。测试期间，在笼子里放置一个单一的饮水口，持续4分钟。饮水口被一个塑料环包围，防止任何时候有超过一只动物饮水。每天竞争测试后，有1小时时间可以使用不受阻碍的饮水口。在下丘脑内侧损伤的大鼠在竞争测试中比假损伤大鼠表现出更多的攻击性，并且能够花更多时间饮水。植入睾酮的大鼠在保持使用饮水口方面更成功，但与未植入睾酮的同笼伙伴相比，并没有持续表现出更多的攻击性。损伤大鼠的攻击行为是防御性的，而植入睾酮的动物的攻击行为则相当于雄性间的社会攻击。这些结果表明，竞争情境可以引发由睾酮介导的雄性间社会攻击和下丘脑内侧损伤诱导的防御性。
