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ÓSCAR ESCRIBANO Y COLS. AN. R. ACAD. NAC. FARM.

ma insulin increased by 2.5-fold in 1-year-old mice as compared with
their controls (Figure 6, panel D), however, this increase was much
lower than those at 6 months of age (3-fold, panel D), suggesting a
failure in insulin secretion with aging.

Figure 5. Progressive Insulin Resistance and Glucose Intolerance in iLIRKO
mice. A) Insulin tolerance tests were performed on random-fed, 2-, 4-, 6-month-
and 1-year-old male Control (white circles) and iLIRKO (black circles) mice. Animals
were injected intraperitoneally with 1 U/kg body weight of human insulin. Blood
glucose was measured immediately before injection and 15, 30, and 60 min after the
injection. Results expressed as percentage of initial blood glucose concentration are
means +/– SEM (n = 10-20). B) Glucose tolerance tests were performed on 2-, 4-, 6-
month- and 1-year-old Control (white circles) and iLIRKO (black circles) mice that
had been fasted for 16 h. Animals were injected intraperitoneally with 2 g/kg body
weight of glucose. Blood glucose was measured immediately before injection and
30, 60, 90 and 120 min after the injection. Results are expressed as mean +/– SEM
(n = 10–20). **P < 0.005; *P < 0.05; iLIRKO vs. Control.

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