The placebo effect and relaxation response: neural processes and their coupling to constitutive nitric oxide

The placebo effect appears to be a real phenomenon as is the scientifically demonstrated and examined relaxation response. Given this, we attempt to understand how these phenomena work in light of our current understanding of central and peripheral nervous system mechanisms. Central to our hypothesis is the significance of norepinephrine, nitric oxide and opioid signaling both in the central and peripheral nervous system. In this regard, we find that nitric oxide controls norepinephrine processes on many levels, including synthesis, release and actions. In closing, we conclude that enough scientific information exists to support these phenomena as actual physical processes that can be harnessed to provide better patient care. (C) 2001 Elsevier Science B.V. All rights reserved.