---

Psychoneuroimmunology (PNI)

PNI offers an overall perspective on the link between distinct processes that explain how mental processes, such as stress, influence physical responses.  It is first cousin to psych-neuro-endocrinology.   PNI covers the interaction between mental processes (such as the perception of a stressful situation), central nervous system responses, and immune and endocrine function. How plausible are these various influences?The nervous, immune and endocrine systems mutually influence one another in numerous and complex ways. The CNS influences hormone outputs and, in reverse, hormones of various types act as neurotransmitters. The nervous system can also influence immune functioning; lesions in the brain can reduce the production of lymphocytes. There is extensive information on the influence of hormones on the immune system. Glucocorticoids regulate immune function in many ways, generally suppressing it following stressful events. The effect, however, is not linear and depends on when the hormone is released in relation to the introduction of the antigen. Epinephrine and androgens also suppress immune response; estrogens and progestins may stimulate or inhibit immune function; hormones such as prolactin or insulin generally stimulate immune function. There is also some, more limited, evidence for an effect of immune function on the endocrine system; some immune system cells appear to secrete ACTH. A common model for study is the link between stress and diseases such as cancers. From the discussions of the immune system, we would anticipate that the relations between stress and disease would be complex, and this appears to be true. Just as Selye distinguished good from bad stresses, stress can increase susceptibility, but it can also be protective. Numerous animal studies show associations between stress and immune function, but these emphasize that factors such as the meaning of the stressor is important. For example, the level of predictability and controllability of the stress influence its impact, but so does the type of tumor.

Links to   PNI  resources;    
- Lecture notes on PNI from Dr. JL Jarry at U of Toronto
- PPT slides on PNI by Fabiola Tatone (class presentation, December 2006)
- PPT slides from Margot Shields (class presentation, December 2006)
- PPT slides by Martha Louzada (class of 2008)
- Two introductory pages from Bryn Mawr on PNI: Wachterman and Kinser
- Other PNI links (this one is worth clicking on; it includes stuff on getting onto list servs, etc.);
- A pdf by David Reilly & Tansy Harrison on the historical origins of PNI. 
- The links between stress and immune responses, and the way in which the immune system sends information to the brain in the immune-brain loop.
- The placebo effect

 

---

Course Outline || Index of Course Notes || Reading list