Neural, hormonal and genetic mechanisms for the activation of brain and behavior.

Underlying all motivated behavior is the concept of brain arousal, the generalized activation of forebrain and behavior. A concrete expression of this would be sexual arousal and behavior. The sex behavior whose mechanisms are best understood is the lordosis response, a vertebral dorsiflexion by the female permitting fertilization. Estrogenic facilitation of this behavior requires new transcription and protein synthesis. The genes which are turned on by estrogens and whose products facilitate the behavior are organized in modules. Some exert direct effects, e.g. genes coding for neurotransmitter receptors in hypothalamic neurons. Other modules exert indirect effects: through neuronal growth, through facilitation of transcription from the progesterone receptor gene, and even through other preparative behaviors. An unexpected result deriving from a microarray study was the estrogenic effect on prostaglandin-D synthetase, important because of the marked actions of prostaglandin-D on arousal and sleep.