Brown R E, Schellinck H M, West A M
Department of Psychology, Dalhousie University, Halifax, Nova Scotia, Canada.
Physiol Behav. 1996 Aug;60(2):365-72.
This study directly compared the role of genetic and dietary factors in the production of individual urinary odors in mice by investigating the ability of male Long-Evans hooded rats to discriminate between urine samples from two strains of mice (C57BL/6-H-2Kb/J and C57BL/6-H-2Kbml/ByJ), which differ at only one locus of the major histocompatibility complex (MHC) and which were maintained on two different diets. Groups of rats were trained in an olfactometer on a go/no-go operant task with water as reinforcement to discriminate between one of the following four pairs of mouse urinary odors: individual mice differing at the MHC and maintained on the same diet (task 1), individual mice differing at the MHC and maintained on different diets (task 2), individual mice of the same MHC type maintained on the same diet (task 3), or individual mice of the same MHC type maintained on different diets (task 4). The urinary odors of mice on different diets (task 2 and 4) were more readily discriminable than those of mice maintained on the same diet (tasks 1 and 3), irrespective of genetic differences at the MHC. It was more difficult to discriminate between urinary odors of mice on the same diet whether they were genetically identical (task 4) or differed at the MHC (task 1). A second experiment revealed that it was no less difficult for rats to discriminate between the urinary odors of mice that differed at three MHC loci than it was for rats to discriminate between two mice that differed at one MHC locus. Thus, the results from Experiment 1 were not caused by the degree of genetic difference at the MHC. Overall, these results provide further evidence that dietary as well as genetic cues contribute to individual odors in rodents, and demonstrate the ability of rats to make very subtle discriminations between odors when trained in an olfactometer.
本研究通过调查雄性长-伊斯特曼有帽大鼠区分两种小鼠品系（C57BL/6-H-2Kb/J和C57BL/6-H-2Kbml/ByJ）尿液样本的能力，直接比较了遗传和饮食因素在小鼠个体尿液气味产生中的作用。这两种小鼠品系仅在主要组织相容性复合体（MHC）的一个位点上存在差异，且饲养在两种不同的饮食条件下。将大鼠分组，在嗅觉计中进行有/无操作任务训练，以水作为强化物，来区分以下四对小鼠尿液气味中的一对：在MHC上存在差异且饲养在相同饮食条件下的个体小鼠（任务1）、在MHC上存在差异且饲养在不同饮食条件下的个体小鼠（任务2）、相同MHC类型且饲养在相同饮食条件下的个体小鼠（任务3）、或相同MHC类型且饲养在不同饮食条件下的个体小鼠（任务4）。无论MHC上的遗传差异如何，饲养在不同饮食条件下的小鼠尿液气味（任务2和4）比饲养在相同饮食条件下的小鼠尿液气味（任务1和3）更容易区分。区分相同饮食条件下的小鼠尿液气味更为困难，无论它们在基因上是相同的（任务4）还是在MHC上存在差异（任务1）。第二项实验表明，大鼠区分在三个MHC位点上存在差异的小鼠尿液气味的难度，并不低于区分在一个MHC位点上存在差异的两只小鼠尿液气味的难度。因此，实验1的结果并非由MHC上的遗传差异程度所致。总体而言，这些结果进一步证明饮食线索以及遗传线索都对啮齿动物的个体气味有影响，并证明了大鼠在嗅觉计中训练后能够对气味进行非常细微的区分。
