ABSTRACT
The immune system is considered to be self-contained, being regulated by a variety of intrinsic processes. Modulation of the immune response by the endocrine, central, and peripheral nervous systems has been suggested to occur via specific effects of neuropeptides on immunocompetent cells. Capsaicin, 8-methyl-N-vanillyl-6-nonenamide, has been very useful as a selective neurotoxin in studying the multiple functions of the afferent nervous system. The sensory nervous system can exert its influence on the immune system indirectly via the endocrine system or more directly via locally released neurotransmitters. The endocrine system can be activated by orthodromic transmission of various sensory modalities to the central nervous system. Adrenocorticotropin (ACTH) release from the pituitary gland and subsequent glucocorticoid secretion from the adrenal cortex represent the uniform hormonal response to a variety of physical and psychological stressors. The predominant trigger for ACTH release is corticotropin-releasing factor (CRF) release from hypothalamic neurons. Other mediators involved in this process include vasopressin, oxytocin, angiotensin, and catecholamines.
