FIGURE 5.

Western blot analysis of pineal gland and brain cortex protein content showing nocturnal up-regulation of FRA-2 and p-CREB in pineal glands. Representative chemiluminescent images of Fra-2, CREB-1, p-CREB, and p-ATF-1 expression in pineal glands sampled at either 12.00 or 24.00 h (P12/P24) or brain cortex (Cx). The image labeled Fra-2++ is an extended film exposure of the same blot in the upper FRA-2 image, and the CREB-1 image is a re-probe of the same Western blot indicating relatively invariant CREB-1 expression (within the two sample groups) and consequently equal gel loading/transfer. A similar CREB-1 re-probe was obtained for the lower p-CREB/p-ATF-1 blot (not shown). Note that FRA-2 expression is increased at 24.00 versus 12.00 h and that FRA-2 expression in cortex is minimal. The amounts of protein extract loaded in each lane were as follows: 6 μg, pineal nuclear; 15 μg, cortex nuclear; 20 μg, pineal whole cell; 35 μg, cortex whole cell). Horizontal bars represent positions of molecular weight markers.