| Popis: |
Estrogens act in diverse brain regions to regulate reproductive and nonreproductive behaviors and neuronal functions, including mood, cognition, pain, seizures, sensorimotor integration, energy homeostasis, and neural degeneration due to aging, ischemia, and other insults. This chapter reviews evidence that estrogens act at multiple levels in many brain regions to modify synaptic neurotransmission. Identified targets of estrogen action include classical neurotransmitters and diverse peptides that function as neuromodulators. Estrogens act both presynaptically, regulating transmitter availability and/or release, and postsynaptically, governing cellular responses to released transmitter. Hormone-dependent alterations in neural responses to transmitters involve regulation of transmitter receptor expression and the efficacy of transmembrane signal transduction. Estrogens also determine which intracellular signal transduction pathways are activated when neurotransmitters bind their receptors. Emerging evidence suggests that estrogens can activate downstream molecules associated with growth factors and modify the crosstalk between growth factor and neurotransmitter receptor signaling pathways. Therefore, we also summarize findings indicating that physiologically relevant cross talk occurs among estrogen receptor, neurotransmitter receptor, and growth factor receptor signal transduction pathways. The data show that estrogens act throughout the brain to modulate neuronal excitability, synaptic efficacy, and neurogenesis, suggesting that these are fundamental mechanisms of steroid hormone action in the brain. |
