Laboratory of Behavioral Neuroscience, Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892-3730, USA.
Physiol Behav. 2012 Dec 5;107(5):649-62. doi: 10.1016/j.physbeh.2011.12.025. Epub 2012 Jan 8.
Inbred mouse strains differ greatly in social behaviors, making them a valuable resource to study genetic and non-genetic mechanisms underlying social deficits relevant to autism spectrum disorders. A hallmark symptom of autism is a lack of ability to understand other people's thoughts and intentions, which leads to impairments in adjusting behaviors in response to ever-changing social situations in daily life. We compared the ability of BTBR T+tf/J (BTBR), a strain with low sociability, and C57BL/6J (B6), a strain with high sociability, for their abilities to modulate responses to social cues from different partners in the reciprocal social interaction test. Results indicate that BTBR exhibited low sociability toward different partners and displayed minimal ability to modify behaviors toward different partners. In contrast, B6 showed high sociability toward different partners and was able to modify social behaviors toward different partners. Consistent results were found in two independent cohorts of different ages, and in both sexes. In the three-chambered test, high sociability in B6 and low sociability in BTBR were independent of strain of the novel mouse. Since social deficits in BTBR could potentially be caused by physical disabilities in detecting social olfactory cues, or in cognitive abilities, we tested BTBR and B6 mice on measures of olfaction and cognition. BTBR mice displayed more sniffing of social odors emitted by soiled bedding than of an odorless novel object, but failed to show a preference for a live novel mouse over a novel object. On olfactory habituation/dishabituation to a sequence of odors, BTBR displayed discrimination abilities across three non-social and two social odors. However, as compared to B6, BTBR displayed less sniff time for both non-social and social odors, and no significant dishabituation between cage odors from two different novel mouse strains, findings that will be important to investigate further. BTBR was generally normal in spatial acquisition on the Morris water maze test, but showed deficits in reversal learning. Time spent freezing on contextual and cued fear conditioning was lower in BTBR than in B6. Our findings suggest that BTBR has poor abilities to modulate its responses to different social partners, which may be analogous to social cognition deficits in autism, adding to the value of this strain as a mouse model of autism.
近交系小鼠在社交行为方面存在很大差异,因此成为研究与自闭症谱系障碍相关的社交缺陷的遗传和非遗传机制的宝贵资源。自闭症的一个标志性症状是缺乏理解他人思想和意图的能力,这导致他们在日常生活中应对不断变化的社交情况时,调整行为的能力受损。我们比较了社交能力较低的 BTBR T+tf/J(BTBR)和社交能力较高的 C57BL/6J(B6)两种品系的小鼠调节对不同社交对象的社交线索的反应的能力。结果表明,BTBR 对不同的社交对象表现出较低的社交性,并且对不同的社交对象表现出最小的行为调节能力。相比之下,B6 对不同的社交对象表现出较高的社交性,并且能够调节对不同社交对象的社交行为。在不同年龄的两个独立队列中,以及在两个性别中,都得到了一致的结果。在三箱测试中,B6 的高社交性和 BTBR 的低社交性与新小鼠的品系无关。由于 BTBR 的社交缺陷可能是由于检测社交嗅觉线索或认知能力的身体残疾引起的,我们测试了 BTBR 和 B6 小鼠在嗅觉和认知方面的表现。BTBR 小鼠对脏垫料散发的社交气味的嗅探次数多于对无味的新物体的嗅探次数,但对活的新小鼠没有表现出比对新物体的偏好。在对一系列气味的嗅觉习惯化/去习惯化测试中,BTBR 对三个非社交气味和两个社交气味表现出了辨别能力。然而,与 B6 相比,BTBR 对非社交和社交气味的嗅探时间都较少,并且在来自两个不同新小鼠品系的笼气味之间没有明显的去习惯化,这些发现将有助于进一步研究。BTBR 在莫里斯水迷宫测试中的空间获取方面通常正常,但在反转学习中存在缺陷。在上下文和线索恐惧条件反射中,BTBR 的冻结时间低于 B6。我们的研究结果表明,BTBR 调节其对不同社交对象的反应的能力较差,这可能类似于自闭症的社交认知缺陷,增加了该品系作为自闭症小鼠模型的价值。