Integrative Immunology and Behavior Program, Department of Animal Sciences, College of ACES and Department of Pathology, College of Medicine, University of Illinois at Urbana-Champaign, 250 Edward R. Madigan Lab, 1201 W. Gregory Drive, Urbana, IL 61801-3873, USA.
Humans and animals use the classical five senses of sight, sound, touch, smell and taste to monitor their environment. The very survival of feral animals depends on these sensory perception systems, which is a central theme in scholarly research on comparative aspects of anatomy and physiology. But how do all of us sense and respond to an infection? We cannot see, hear, feel, smell or taste bacterial and viral pathogens, but humans and animals alike are fully aware of symptoms of sickness that are caused by these microbes. Pain, fatigue, altered sleep pattern, anorexia and fever are common symptoms in both sick animals and humans.
Many of these physiological changes represent adaptive responses that are considered to promote animal survival, and this constellation of events results in sickness behavior. Infectious agents display a variety of pathogen-associated molecular patterns (PAMPs) that are recognized by pattern recognition receptors (PRRs). These PRR are expressed on both the surface [e.g. Toll-like receptor (TLR)-4] and in the cytoplasm [e.g. nucleotide-binding oligomerization domain (Nod)-like receptors] of cells of the innate immune system, primarily macrophages and dendritic cells. These cells initiate and propagate an inflammatory response by stimulating the synthesis and release of a variety of cytokines.
Once an infection has occurred in the periphery, both cytokines and bacterial toxins deliver this information to the brain using both humoral and neuronal routes of communication. For example, binding of PRR can lead to activation of the afferent vagus nerve, which communicates neuronal signals via the lower brain stem (nucleus tractus solitarius) to higher brain centers such as the hypothalamus and amygdala.
Blood-borne cytokines initiate a cytokine response from vascularendothelial cells that form the blood-brain barrier (BBB). Cytokines can also reach the brain directly by leakage through the BBB via circumventricular organs or by being synthesized within the brain, thus forming a mirror image of the cytokine milieu in the periphery. Although all cells within the brain are capable of initiating cytokine secretion, microglia have an early response to incoming neuronal and humoral stimuli. Inhibition of proinflammatory cytokines that are induced following bacterial infection blocks the appearance of sickness behaviors.
Collectively, these data are consistent with the notion that the immune system communicates with the brain to regulate behavior in a way that is consistent with animal survival.
Am old enough to understand the difference between the Bay of Pigs - and roasting a pig at a epicurian feast. Been thru the hippy, yippie and yuppie years - always remaining who I am.
Very much believe in "Sing your own song - weave your own tapestry"
Am young enough to still know the thrill of new discoveries, the beauty of the evening, to celebrate the joy of another tommorow.
Survived these many decades with a severe medical problems. Sorting out the maze of now having two lymphomas and all their nasty little companions, but I continue.
Besides, being a simple iconoclastic eclectic, have been called many things. An incurable romanticist - with a strong touch of reality. Thinker, intellectual (God, how I hate that term) - been told I am a lion with the heart of the poet.
Know how to wage war and conquer my foes - but would rather be known as one who brings hope and life. To bring hope into anothers life is the ultimate of joys.
Life should be about bringing hope, peace, vision... a sense of purpose beyond yourself.