FIGURE 3.

Alterations in glucose homeostasis in the iPLA₂γ^−/− mouse. A, glucose tolerance test of mice on the standard diet (left panel) or HF (right panel) diets. As described under “Experimental Procedures,” d-glucose (2 mg/g) was administered by intraperitoneal injection to WT (solid lines) or iPLA₂γ^−/− (dotted lines) male mice after 8–10 months fed on either a standard (left panel) or HF (right panel) diet. Blood was collected at base line and at 30, 60, and 120 min after injection for measurement of serum glucose concentrations. Glucose intolerance with an enhanced rate of glucose uptake was observed in the iPLA₂γ^−/− mice fed a HF diet (*, p < 0.05). Values are displayed as means ± S.E. (n = 10–16 per group). B, increased insulin sensitivity of iPLA₂γ^−/− mice on a HF diet. An insulin tolerance test was performed as described under “Experimental Procedures” with iPLA₂γ^−/− (square symbols and dotted lines) and WT (diamond symbols and solid lines) mice. Human regular insulin (0.75 unit/kg) was administered by intraperitoneal injection to a 1-h fasted male mice after 8 months on the HF diet, and blood was collected at base line and at 30, 60, and 90 min after injection to measure glucose concentration as described under “Experimental Procedures.” Values are displayed as means ± S.E. (n = 10–16). *, p < 0.05 by the Student's t test. C, serum blood insulin levels in mice on either the standard or the HF diet. Insulin levels were determined as described under “Experimental Procedures” with measurements taken at time 0 after an overnight fast (pre) and at 10 min following intraperitoneal glucose injection (post). n = 3 per group. WT, solid line; KO, dashed line. All experiments were performed with four WT and iPLA₂γ^−/− mice between the ages of 8–10 months of age. D, box-and-whisker analysis as described under “Experimental Procedures” of nonfasted (NF) blood insulin of wild-type (WT) and iPLA₂γ^−/− (KO) mice on the HF diet. Statistical significance was performed using the Student's t test, and significant differences are indicated by brackets. n = 4 WT and 11 KO.