Chapter 55 - Endocrine Effects on the Brain and Their Relationship to Behavior

Abstract

Publisher Summary This chapter focuses on the neurochemical and molecular aspects of the influences of hormones on the nervous system. The brain undergoes changes in its chemistry and struc­ture in response to changes in the environment. Circulating hormones of the adrenals, thyroid, and gonads play an impor­tant role in this adaptation because the brain controls the endocrine system through the pituitary gland. This control allows environmental signals to regulate hormonal secretion. Hormonal actions occur during sensitive periods of the devel­opment in adult life as natural endocrine cycles, and in response to experience as well as during the aging process. As a result of their fundamental actions on cel­lular processes, genomic activity, and of the control of their secretion by environmental signals, steroid and thyroid hormone actions on the brain provide unique insights into the plasticity of the brain and behavior. Similar to steroid hormones, thyroid hormones interact with receptors to alter genomic activity and affect the synthesis of specific proteins during the development. As with testosterone and progesterone, metabolic transformation of thyroxine (T4) is critical to its action. Moreover, as with steroid hormones, thyroid hormones alter brain functions in adult life in ways that both resemble and differ from their action in the period of devel­opment.