New bioactive angiotensins formation pathways and functional involvements.

After a brief review of the actual knowledge concerning the circulating and tissue Renin-Angiotensin System (RAS) as a unitary hormonal system, the cognitive acquisitions regarding the formation and action mechanisms of the new biologically active angiotensins will be presented. The review of the enzymatic pathways for their synthesis and inactivation, as metabolism products of angiotensin II (1-8), will be followed by the presentation of the main physio-pharmacological actions of angiotensin III (2-8), angiotensin IV (3-8) and angiotensin (1-7). The functional involvements of the cerebral angiotensin IV in what concerns its possible participation in the normal neurochemical processes of memory and in the neurodegenerative processes of Alzheimer disease will be exposed, together with the vasodilating effects of angiotensin (1-7) as counteracting factor for the constricting effects of angiotensin II. The data concerning the bioactive fragments of angiotensin II will be accompanied by those regarding its implication in the cardiovascular modeling and the induction of oxidative stress, inflammation, atherogenesis, etc. In their turn, personal researches bring new experimental evidences in favor of interactions between angiotensin (1-7) and angiotensin II within the rat thoracic aorta. Biphasic, dose-dependent effects were observed for angiotensin (1-7), induced both through nitric oxide, kinins and prostaglandin release for counteracting the vasoconstricting effects of angiotensin II and the modulation of its own vasodilator action.

Actual data concerning the brain--immune system interface.

After a brief presentation of the immune system as sensorial and effector organ, which recognizes and defends against cellular aggressions, the main psycho-neuro-endocrine components of immune reaction regulation and modulation will be shown. Both central nervous structures that control the hormonal emissions, the vegetative innervation of the lymphoid organs as well as the afferent neurohumoral pathways involved in the making of the self-regulating and neuromodulating circuits of the humoral and cellular immune responses will be mentioned. An important position will be held by the interrelations between the hypothalamus-pituitary-corticoadrenal gland, the sympathetic-parasympathetic efferent pathways and the chemical messengers (hormones, neurotransmitters, interleukins, neurotrophins) which make possible the bi-directional neuroimmune communication for maintaining the homeostatic balances on this third effector pathway, too. Also will be presented experimental proof concerning the ability of central neurons to secrete neuromodulator cytokines and the presence of specific receptors for the various neuroactive molecules within lymphoid organs and circulating lymphocytes. To close, the psychoemotional components of the neuro-immunomodulator circuits will be mentioned, using as examples the changes induced by stress generally and oxidative stress in particular.