Behavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors
Behavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors
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DOI：
10.1073/pnas.0608310104
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发表时间：
2007-04-10
影响因子：
11.1
通讯作者：
Sapolsky, Robert M.
中科院分区：
文献类型：
--
作者：
Vyas, Ajai;Kim, Seon-Kyeong;Sapolsky, Robert M.
原生动物寄生虫刚地弓形虫（Toxoplasma gondii）会阻止老鼠对猫尿的先天厌恶，转而产生对信息素的吸引力；这可能会增加猫先于老鼠的可能性。这被认为反映了弓形虫的适应性行为操纵，因为寄生虫虽然能够感染老鼠，但只在猫的肠道中有性繁殖。“行为操纵”假说认为，寄生虫会专门操纵宿主的行为，以增强其自身的传播。然而，涉及先天恐惧、焦虑和习得恐惧的神经回路都有相当大的重叠，这增加了弓形虫可能非特异性地破坏所有这些神经回路的可能性。我们调查了这些相互矛盾的预测。在小鼠和大鼠身上，潜伏的弓形虫感染将对猫气味的厌恶转化为吸引力。这种恐惧的丧失是非常特殊的，因为感染并没有减少习得性恐惧、焦虑样行为、嗅觉或非厌恶学习。这些影响与杏仁核结构中寄生虫囊肿比大脑其他区域中发现的更丰富的趋势有关。通过仔细检查其他被预测会改变的行为模式，我们发现慢性弓形虫感染的行为影响是高度特异性的。总的来说，这项研究为行为操纵假说提供了强有力的支持。这种行为操纵的近似机制尚不清楚，尽管部分寄生虫的微妙倾向仍然是一种强有力的可能性。
The protozoan parasite Toxoplasma gondii blocks the innate aversion of rats for cat urine, instead producing an attraction to the pheromone; this may increase the likelihood of a cat predating a rat. This is thought to reflect adaptive, behavioral manipulation by Toxoplasma in that the parasite, although capable of infecting rats, reproduces sexually only in the gut of the cat. The "behavioral manipulation" hypothesis postulates that a parasite will specifically manipulate host behaviors essential for enhancing its own transmission. However, the neural circuits implicated in innate fear, anxiety, and learned fear all overlap considerably, raising the possibility that Toxoplasma may disrupt all of these nonspecifically. We investigated these conflicting predictions. In mice and rats, latent Toxoplasma infection converted the aversion to feline odors into attraction. Such loss of fear is remarkably specific, because infection did not diminish learned fear, anxiety-like behavior, olfaction, or nonaversive learning. These effects are associated with a tendency for parasite cysts to be more abundant in amygdalar structures than those found in other regions of the brain. By closely examining other types of behavioral patterns that were predicted to be altered we show that the behavioral effect of chronic Toxoplasma infection is highly specific. Overall, this study provides a strong argument in support of the behavioral manipulation hypothesis. Proximate mechanisms of such behavioral manipulations remain unknown, although a subtle tropism on part of the parasite remains a potent possibility.