Figure 1.

Seventy-two hours of culture of rat cortical neurons with 100 nm progesterone has opposite effects on neurite length [assessed after staining with microtubule associated protein-2 (MAP2)] in neurons from male and female animals. The top panel shows cortical neurons stained with MAP2 in male (top) and female (bottom) untreated control rats (left) and those treated with progesterone (right). The bottom panel is a bar graph showing neurite length in male (blue) and female (red) untreated control rats (solid) and those treated with progesterone (striped). Neurite length is greater in female animals compared with males in the absence of progesterone, whereas the opposite is true following exposure to progesterone (L. Zhang et al., unpublished data). ∗∗∗P < 0.001.