C57BL/6 mice are widely used in metabolic research as a model of dietinduced obesity. However, due to their availability from many different vendors, phenotypic differences have arisen, as a result of both genetic and environmental variability. This adds a level of complexity to the interpretation of metabolic parameters, especially when comparing studies using mice from different vendors.

To shed further light on this issue, Hull et al. performed a comprehensive analysis of in vitro and in vivo insulin secretory responses following low or high fat feeding in six C57BL/6 substrains obtained from different vendors within the USA and Australia. The authors found that the in vitro but not the in vivo insulin response was different in low fat fed mice between C57BL/6J and C57BL/6N substrains. In contrast, the in vivo insulin response following high fat feeding was different among C57BL/6N but not C57BL/6J substrains. This variability was not due to differences in body weight, adiposity, food intake or the area of insulin-secreting pancreatic β-cells.

The authors advise caution in extrapolating findings from in vitro studies to the in vivo situation and call for care in selecting the appropriate C57BL/6 substrain for studies in metabolic research.

Read the full article in Journal of Endocrinology 233 53–64