Figure 6.

Immunohistological staining of brain sections after intranasal administration of insulin with or without L-penetratin to mice. The brains were isolated 30 min after intranasal administration of PBS (negative control) or insulin in the absence or presence of L-penetratin. (A) Olfactory bulbs, (B) bottom part of the brain, (C) central part, and (D) cerebral cortex and hippocampus (CA2) at 4.25, 0.85, 0.85, and −1.91 mm from bregma. Insulin was detected with an anti-insulin primary antibody and Alexa 488-conjugated secondary antibody (green). Blood vessels were stained with DyLight 594 conjugated tomato lectin (red). The images show a typical result obtained in one experiment. Separate experiments under the same conditions yielded similar results (n = 3 or 4).