Neuroendocrine Studies in Psychiatric Disorders

This chapter describes the basic principles behind neuroendocrine challenge studies, and reviews the evidence for the role of 5-HT in hormone secretion. It presents critique clinical studies of the effects of various serotonergic challenge drugs on hormone secretion in normal volunteers and psychiatric patients, and discusses the potential contribution of neuroendocrine studies with regard to understanding biological abnormalities in psychiatric disorders and the mechanisms by which thymoleptic drugs may correct or influence these mechanisms. Neuroendocrinology is the study of the neural mechanisms involved in hormone secretion. The lack of specificity of many drugs for a given subtype of 5-HT receptor, as well as effects on non-5-HT systems that may influence hormone secretion, makes it hazardous to draw conclusions concerning 5-HT-receptor-mediated processes. The hypothalamic-pituitary-adrenocortical axis is generally considered the prototypical stress-responsive system in the mammalian organism. Serotonin is synthesized in neurons from the essential amino acid L-tryptophan.