| الوصف: |
Almost 30 years ago, the circulating effector hormone of the reninangiotensin system (RAS), the octapeptide angiotensin II (ANG II), was first reported to act not only on peripheral vascular structures but also on the central nervous system (CNS) (Bickerton and Buckley, 1961). In the following years, evidence has accumulated that the brain, in addition to possessing ANG II-sensitive sites, contains the precursor molecule as well as the enzymatic apparatus to generate its own angiotensin peptides, suggesting a local synthesis of ANG II in the brain (Brosnihan et al., 1988; Ganten et al., 1971; Unger et al., 1988). In addition, the protein genes of the RAS are expressed in the CNS and mRNAs have been localized in specific brain areas (Hellmann et al., 1988; Jin et al., 1988), although not all components of the RAS were demonstrated within the same neuron. ANG II receptors were found in the rat brain mainly in the thalamus, hypothalamus, midbrain, septum, and medulla (Bennett and Snyder, 1976; Mendelsohn et al., 1984; Sirett et al., 1977), with higher concentrations in the lateral septum, superior colliculus, and area postrema and very high concentrations in the subfornical organ (SFO), median preoptic area (MnPO), organum vasculosum of the lamina terminalis (OVLT), medial preoptic area (MPO), paraventricular nucleus (PVN), supraoptic nucleus (SON), and nucleus tractus solitarii (NTS). |
