Gonadal Steroid Action on the Brain: Neurochemistry and Neuropharmacology

Steroid hormones of the gonads and adrenals influence the brain and alter the affective state as well as· overt behavior and neuroendocrine function. These actions are manifested in various ways and at various levels of obser­ vation and experimentation. For example, in female vertebrates of many species, estrogens prime the brain and pituitary gland and make possible the occurrence of ovulation and sexual receptivity. Androgens, On the other hand, facilitate male reproductive behavior including vocalizations (e.g. song in passerine birds, mate-calling in frogs), defense of territory and related aggressive displays, and copulatory behavior. At another level of analysis, estrogen treatment counteracts tardive diskinesia and L-DOPA­ induced diskinesia (1) and has antidepressant effects in women resistant to other kinds of antidepressant drug therapy (2). Moreover, changes in estro­ gen and progestin levels are often linked to the emotional lability associated with the premenstrual and postpartum periods (3, 4). Studies of the action of steroid honnones on the brain have progressed to a point where specific mechanisms and brain sites of action are now recognized. Especially important to the neurophannacologist are those aspects of mechanism which have begun to deal with hormonal modifica­ tion of properties and functions of synapses. Synaptic function and neuro­ transmission are indeed the common currency for the analysis of neuroendocrine events and honnone-regulated behaviors, as well as other aspects of brain function; and the study of drugs which modify neurotrans­ mission through blockade of synthesis, degradation, reuptake, and recep-