| Nervous system,endocrine system and immune system are the three regulating systems in the body,they are interdependent and interrestricted each another. Recently it has been proved that there is an immune system in the brain,but which is still an immune-privileged organ relatively. Also it is an unsolved problem where and how the blood-carrying immune messengers enter into the brain. The circumventricular organs(CVOs) are miniorgans around the wall of the third and fourth ventricules and include organum vasculosum laminae terminalis(OVLT),subfornical organ(SFO),subcommissural organ(SCO),median eminence(ME),hind leaf of pituitary,area postrema(AP),choroid plexuses and so on. CVOs are lack of the blood-brain barrier(BBB)since they are short of the tight junction between the endothelial cells of the blood capillaries,some of which belong to the fenestrated capillaries. In retrospective history of CVOs studies they had been concentrated in the field of neuroendocrine modulations until 1990s. However Broadwell(1992)proposed a concept of the windows of the brain,which included CVOs and the leptomeninges, and considered CVOs as some leaky points in BBB,but actually homeostasis of the brain is still maintained in spite of existence of the windows of the brain. Quan(1999)found when LPS was injected into the peritoneal cavity,the cells of BBB in the rat brain could synthesize some molecules of the immune signals,which would enter into the central nervous system(CNS),activating the cells inside the brainï¼›also he suggested that the cerebrospinal fluid (CSF) might be a waterway for transportation of the immune signals. Then someresearchers have pointed out that there may be three ways for the immune signals to enter into the brain:one is through BBB,another is through CVOs,as well as by way of the afferent fibers of the vagus nerve below the diaphragm. However it is still not clear how the immune signals outside the brain enter into it by way of CVOs and what significance is for coexistence of BBB and the windows of the brain. In view of such unsolved problems our study group started a series of studies on neuroimmune modulations of CVOs and advocated a hypothesis that CVOs may be the preferential sites for the blood-carrying molecules of the immune signals to enter into the brain in a minimal amount. Since CVOs are lack of BBB,so that they are easier and faster for these molecules to enter into the brain than the brain regions which have BBB. It is reasonable for deduce that the brain may response to these immune signals immediately as a pre-stress reaction before large amount of the immune messengers come into brain,so that the whole functions of body may be regulated in time. Because CVOs are only 0.2% of the entire brain in weight, the immune signals entering into the brain via CVOs must be a minimal amount,so that they would not result in tense immune challenge within the brain. Experimental allergic encephalomyelitis(EAE)is an autoimmune disease,which is mediated by the T cells of myelin sheath -autoimmune and result in specific pathological conditions such as demyelination in the white matter,the "cuff-like" lesion foci around the blood vessels in the junction region between the white and gray matters,and so on. EAE is a generally accepted animal model for the multiple sclerosis(MS). Though pathogenesis of MS has been not clarified thoroughly,it has been generally admitted that some components of the myelin sheath proteins may activate the systemic immune reactions,the helper T lymphocytes-1 could proliferate,differentiate,and secrete large amount of theinflammatory factors,then all of which enter into the brain and result in the brain damages,inducing a specific clinical syndrome. Our previous work suggested that CVOs were also damaged in EAE,and their dynamic pathological changes were corresponded to the different clinical stages of EAE . However how to prove our hypothesis of CVOs with EAE model has to provide much more evidence. I...
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