| There are the same set of messenger molecules (e.g. neropeptide, hormone and cytokines) and their receptors in the nervous system, endocrine system and immune system. These messenger molecules combine with their receptors in the identical system or in other systems, and they also can act on the receptors of other ligands across. It makes the three systems or the inside of one of systems to contact together and coadjust, and forms the complicated immune-neuroendocrine network. The research headway of neuroimmunoendocrinology provides the new clue for acquainting hypertension. The process of coming on a hypertension is always shown the abnormal function of the complicated immune-neuroendocrine network, in which the information is mainly transferred by neropeptide, hormones and cytokines.The hypothalamus is a senior nerve center to modulate visceral activities, endocrine functions and emotional behaviors. These functions and activities include the changes of corresponding cardiovascular activities, so the hypothalamus is also a cardiovascular nerve center above of the medulla. The peptidergic neurons within the hypophysiotrophic area secrete many types of hypothalamus regulatory peptide (HRP), and been adjusted by other neurotransmitters or cytokines.The present researches make it clear that nitric oxide (NO), an active free radical formed during the conversion of L-arginine (L-Arg) to L-citrulline by the enzyme NO synthase (NOS), is a critical neurotransmitter and biological mediator of the cardiovascular system and neuroendocrine axis. However, NO distributes widely in the central nervous system and the role of NO in the different regions is different, so its exact function is not completely unclear. Thyrotropin-releasing hormone (TRH) is a tripeptide that has a multiplicity of functions including some control of the blood pressure. Although the thalamus and cerebellum contain greater overall quantities, the highest concentration of TRH in the rat brain is found in the hypothalamus. But the effects of TRH injected into the different hypothalamic nucleus on the blood pressure and heart rate are variant. NO may affect on the modulation of TRH in blood outflowand the TRH-induced secretion of some hormones. The role of interleukin-6 (IL-6) in immune-neuroendocrine network is important. The multiple roles of IL-6 rely on its membrane receptors, which are widely distributed throughout the central nervous system of rats. Cytokines in central nervous system can mediate the blood pressure, but the role of IL-6 is unclear. Therefore, we evaluated the role of the hypothalamic NO, TRH and IL-6 on cardiovascular activity and studied their interactions and mechanisms in order to establish the theoretical basic to a certain extent of immune-neuroendocrine network in the hypophysiotrophic area.In these studies, we investigated the effects of the injection into the hypophysiotrophic area of NO, TRH and IL-6 on cardiovascular activity and studied their interactions and possible mechanisms. The Sprague-Dawley rats were mounted in a stereotaxic apparatus and a guide cannula, through which all agents were microinjected, was placed in the left hypophysiotrophic area nearby the arcuate nucleus. The blood pressure (or left ventricular pressure), heart rate (HR), the speed and acceleration of cardiac muscle contraction and extension (dp/dtmax, -dp/dtmax, d2p/dt2max and -d2p/dt2max) were recorded. The results were as follows:1. The 0.9% normal saline (control) microinjected into the hypophysiotrophic area had no significant effects on the mean arterial pressure (MAP), left ventricular spike pressure (LVSP), HR, and dp/dtmax, -dp/dtmax, d2p/dt2max and -d2p/dt2max.2. L-arginine (50μg/0.5μl), a precursor of NO, induced a significant decrease of LVSP, while Na,-Nitro-L-arginine methyl este (L-NAME, 50μg/0.5μl), an inhibitor of NO synthase, increased LVSP significantly in the hypophysiotrophic area. Both of them had no effects on MAP, HR and dp/dtmax, -dp/dtmax, d2p/dt2max and -d2p/dt2max.3. TRH (0.5ug/0.5ul) microinjected...
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