Abstract
Many of the influences of estrogens and progestins on the brain and behavior are mediated
by estrogen receptors and progestin receptors, acting as transcriptional regulators.
The homologous and heterologous regulation of the concentrations of these receptors
by cognate hormones is well established. However, although they were discovered and
characterized based on their binding to cognate hormone and their role in transcriptional
regulation, steroid hormone receptors have a more complex role and serve many more
functions than originally suspected. First, besides being regulated by steroid hormones,
the intracellular concentrations of brain steroid hormone receptors are regulated
by neurotransmitters, a pathway by which stimuli from the environment, including from
conspecific animals, can modulate the concentration of particular steroid hormone
receptors in subsets of cells. Further, besides being activated by cognate steroid
hormones, the receptors can be activated by a variety of neurotransmitters and phosphorylation
pathways, providing a route through which environmental stimulation can activate steroid-receptor-dependent
functions in specific cells. In addition, the transcription factor, estrogen receptor-α,
produced from the estrogen receptor-α gene, can be modified to be targeted to membranes,
where it can signal via kinase pathways. Finally, developmental experiences, such
as particular stressors during the pubertal period, can permanently remodel the brain’s
response to ovarian hormones, most likely by long-term changes in regulation of the
receptors mediating those responses. In addition to their function in responding to
cognate ligand, it is now more appropriate to think of steroid hormone receptors as
integrators of a wide variety of signaling pathways.
Key words
estradiol - progesterone - behavior - neuroendocrinology - estrogen receptor - progestin
receptor
