Nitric oxide as regulator of adrenal function

Abstract

One of the main adrenal functions is the synthesis and release of glucocorticoids. Although glucocorticoids were originally so called because of their influence on glucose metabolism, they are currently defined as steroids that exert their effect in virtually all tissues including liver, adipose, skeletal muscle, kidney, hypothalamus, pituitary, skin, breast, lung and also in the immune and the cardiovascular systems, and in the gastrointestinal tract. Their effects include the regulation signal, degradation of ibrillar muscle proteins, decrease of reabsorption of calcium, inhibition of collagen synthesis, inhibition of insulin secretion, age-related involution of the thymus, inhibition of monocyte proliferation and antigen presentation and they also influence memory, among other effects. These broad effects of the glucocorticoids require a fine regulation of the adrenal function to maintain a wide range of physiological responses and a high capacity to respond to a variety of stimulus. Nitric oxide is one of the modulators of the adrenal function. The adrenal gland expresses the neuronal and the endothelial isoforms of nitric oxide synthase and the nitric oxide produced into the adrenal cells modulates negatively the production of glucocorticoids. In this chapter, we will describe the effect and the mechanism of action of nitric oxide in the regulation of adrenal zona fasciculata function.