ABSTRACT
Many psychotropic drugs act on the neurotransmitters, and neuroendocrine challenge tests can also be used to assess both acute and chronic effect of drug treatment on neurotransmitter function. Most neuroendocrine challenge tests in humans have measured the secretion of anterior pituitary hormones such as prolactin, growth hormone and corticotropin. Neuroendocrine challenge studies in humans require careful methodological control. Clearly hormonal responses to drug challenge can be altered by fundamental demographic factors such as age, gender and body weight. Methodological issues are also important in interpretation of neuroendcrine challenge data. Thus a difference in neuroendocrine response to a selective drug challenge between patients and controls could reflect an abnormality in the neurotransmitter regulating the hormone concerned. Clomipramine is a selective 5-HT re-uptake inhibitor but is metabolised in vivo to desmethylclomipramine, a noradrenaline re-uptake inhibitor. The studies outlined demonstrate that the use of neuroendocrine tests provides good evidence that certain aspects of brain 5-HT function are impaired in major depression.
