Abstract
The Philippine wild-caught castaneus mouse (Mus musculus castaneus) and laboratory mouse (C57BL/6J: B6) were used to develop a new non-insulin dependent diabetes mellitus (NIDDM) model. Offspring from the cross between a wild male and B6 female were backcrossed to the sire. One male which exhibited highest fasting hyperglycemia (190 mg/dl) among eighty-seven backcross offspring was selected at 10 weeks of age, and crossed with a B6 female to comprise the fundamental stock (F0). Thereafter, full-sib mating was performed to develop a new inbred strain named CBD (Castaneus-B6 diabetic) mouse. Mice with relatively higher fasting hyperglycemia among F0 and F1 generations were selected for breeding. From the F2 generation, mice were defined as diabetic when blood glucose levels exceeded 200 mg/dl at 120 min in intraperitoneal glucose tolerance test (IPGTT) at 10 weeks of age, and have been selectively bred. The incidence of diabetic males from the F3-F6 generation fluctuated 45-75% at 10 weeks of age and 59-72% at 20 weeks of age. Diabetic males had about two-fold higher fasting glucose and insulin levels than B6 males. Glucose-stimulated insulin secretion was impaired in diabetic CBD mice compared to B6 males at 20 weeks. Moreover, diabetic mice had slight obesity compared to B6 mice. These facts indicated that diabetic features of CBD mice resemble NIDDM in humans. The CBD strain, characterized by high incidence and early onset of diabetes with mild obesity would be of value as a new NIDDM model. The method, utilizing wild castaneus mouse of different origin from laboratory mice, maybe useful in the development of other animal models.
