In the long history of biomedical research, animals are always the non-replaceable parts. During the last four decades, 99% of the laureates of Noble Prize in Physiology and Medicine won the honor referring to their animal-based research. For human diseases study specifically, although the non-human primates, such as rhesus monkey, do have their undeniable advantages, the disadvantages are also quite obvious, such as high cost, long reproducing cycle, and ethic issue. Under this circumstance, to find new model animals for human diseases research has been written in scientists’ agenda.
Tree shrews are small mammals native to the tropical forests of Southeast Asia. Many of their characteristics could right compensate the shortcomings of large non-human primate animals, such as short life span and propagation cycle, low cost, easy to handle as well as their unique high brain to body mass ratio. But, although as a good candidate of model animals, lots of evidence have indicated that they could be applied in the study of human myopia, depression, hepatitis, etc, still, many physical and genetic details about tree shrews need to be clarified.
During the past few years, in order to standardize tree shrews as a model animal, Kunming Institute of Zoology, the CAS, has gathered lots of strength to work on this project. On December 2012, KIZ obtained accreditation, became the first normalized tree shrew breeding center in China, Now, it provides over 1000 tree shrews annually to dozens of academic facilities and the inbred stain 5 has been derived.
Besides of this, one important breakthrough is the successful annotation of Chinese tree shrew genome (KIZ, the CAS, Nature communication,February 2013). This phylogenomic analysis highly supports tree shrews’ close affinity to primates. By characterizing key factors and signaling pathways in nervous and immune systems, it also demonstrate that tree shrews possess both shared common and unique features, and provide a genetic basis for the use of this animal as a potential model for biomedical research.
Now, the tree shrew has drawn more attention than ever in many aspects of biomedical research. Most recently, Dr. WU Xiaoyun and her colleagues (KIZ, the CAS) have conducted a study about its potential application in the research of metabolic syndromes (MetS), for example, obesity, type 2 diabetes, cardiovascular diseases, and non-alcoholic fatty liver disease. In order to figure out the key questions in understanding normal metabolism and disease, the relationships between body weight, fasting blood glucose concentration, age and sex of the tree shrew have been analyzed over 992 individuals aged between 4 months and 4 years old.
The results show that male tree shrews have significantly higher body weight and fasting blood glucose concentration than female tree shrews. The concentration of fasting blood glucose slightly increased with body weight in males. Meanwhile, in females, the body weight, concentration of fasting blood glucose and waist circumference positively increased with age. Additionally, 17 obese tree shrews significantly higher body weight, waist circumference and glycated haemoglobin A1C than non-obese ones.
This study provides the first clear relationships between body weight, fasting blood glucose concentration, sex and age in tree shrews, further improving our understanding of this relationship in MetS. Given the similarity of tree shrews to humans and non-human primates, this finding supports their potential use as an animal model in the research of MetS.
Taken together, with the completing of our knowledge about the tree shrew, it is promising for it to be applied in biomedical research as a standard lab animal model.
The main findings of WU’s study have been published on Journal of Animal Physiology and Animal Nutrition (http://onlinelibrary.wiley.com/doi/10.1111/jpn.12036/pdf).
(By Su-Qing Liu)
