The LepRNull/Null model develops diabetes at a very early age.32 Higher blood glucose and low insulin levels are associated with oxidative stress, decreases in synaptic density and cell death.80-82 Therefore, although the two mouse models used in the current study had similar reductions in brain weight and similar body weights, different levels of circulating glucose and insulin may be associated with our divergent findings in brain cellular composition when comparing Lepob/ob and LepRNull/Null mice and with the higher variability observed in the LepRNull/Null group. The gene discussed is INS; the disease is diabetes mellitus.