Figure 5
Systemic absorption and brain distribution of exendin-4 and insulin, and the subsequent hypoglycemic effect after long-term multiple administrations of exendin-4 with or without L-penetratin and additionally with insulin, to SAMP8 mice with progressive cognitive dysfunction. Panels A and B exendin-4 concentration in the plasma and the brain, respectively, at 15 min after the 30th administration. Panel C insulin concentration in the plasma and brain of mice intranasally receiving exendin-4, L-penetratin, and insulin at 15 min after the 30th administration. The concentration in mice not receiving insulin was not measured because of no cross reactivity between administered human insulin and endogenous mouse insulin in ELISA. Panel D time-dependent changes in the blood glucose levels after the 29th administration. Tests were conducted at 37 (blood glucose) or 38 (plasma exendin-4 and insulin) weeks of age. Each data point represents the mean ± SEM of n = 4–8. *p < 0.05 indicates significant difference from SAMP8 receiving exendin-4 solution.
