Angiotensin II, dopamine and nitric oxide. An asymmetrical neurovisceral interaction between brain and plasma to regulate blood pressure

Vital functions, such as blood pressure, are regulated within a framework of neurovisceral integration in which various factors are involved under normal conditions maintaining a delicate balance. Imbalance of any of these factors can lead to various pathologies. Blood pressure control is the result of the balanced action of central and peripheral factors that increase or decrease. Special attention for blood pressure control was put on the neurovisceral interaction between Angiotensin II and the enzymes that regulate its activity as well as on nitric oxide and dopamine. Several studies have shown that such interaction is asymmetrically organized. These studies suggest that the neuronal activity related to the production of nitric oxide in plasma is also lateralized and, consequently, changes in plasma nitric oxide influence neuronal function. This observation provides a new aspect revealing the complexity of the blood pressure regulation and, undoubtedly, makes such study more motivating as it may affect the approach for treatment.

Enkephalinase regulation

After millennia of knowledge of opium, it was only recently that endogenous substances called opioids with similar properties to opium and derivatives were discovered. The first to be discovered were enkephalins. In addition to the regulation of their synthesis and expression of receptors, an important mechanism for the regulation of their functions carried out by multiple proteolytic enzymes acting at all levels of their structure is described. The action of such enzymes, known as enkephalinases, is also regulated by endogenous and exogenous factors which ultimately affect the control of the enkephalins's action. For therapeutic purposes, it is not only necessary to develop specific inhibitors but also to acquire a deep knowledge of the influence that such factors exert on their activities. This knowledge could help us to establish adapted therapeutic strategies in the treatment of pain or other processes in which enkephalinases are involved. In this chapter, some of these regulatory factors are discussed, such as regional and subcellular distribution, developmental changes, diurnal variations, hormonal influences, stress, dietary factors or interactions with other neurotransmitters.