Progesterone is a steroid hormone that regulates the menstrual cycle and is essential for pregnancy. It is also commonly used to induce melasma models.

Progesterone drives a series of events in which luminal cells may furnish basal cells with Wnt4 and RANKL signals, which in turn respond by upregulating homologous receptors, transcriptional targets, and markers of the cell cycle. Progesterone exhibits a biphasic effect on the proliferation of breast cancer cells; it stimulates growth during the initial cell cycle and subsequently impedes cell progression at the G1/S phase.

Twenty-one days after dorsal medial thalamic nuclei damage, rats treated with progesterone exhibited reduced neuronal degeneration. In female 3xTg-AD mice, progesterone negated the advantageous effects against Abeta accumulation, yet it did not affect behavioral performance. During the Morris water maze spatial navigation task, progesterone-treated rats demonstrated less impairment compared to control rats.