title: Homeostasis and the concept of 'interstitial fluids hierarchy': Relevance of cerebrospinal fluid sodium concentrations and brain temperature control (Review).
abstract: In this review, the aspects and further developments of the concept of homeostasis are discussed also in the perspective of their possible impact in the clinical practice, particularly as far as psychic homeostasis is concerned. A brief historical survey and comments on the concept of homeostasis and allostasis are presented to introduce our proposal that is based on the classical assumption of the interstitial fluid (ISF) as the internal medium for multicellular organisms. However, the new concept of a hierarchic role of ISF of the various organs is introduced. Additionally, it is suggested that particularly for some chemico‑physical parameters, oscillatory rhythms within their proper set‑ranges should be considered a fundamental component of homeostasis. Against this background, we propose that the brain ISF has the highest hierarchic role in human beings, providing the optimal environment, not simply for brain cell survival, but also for brain complex functions and the oscillatory rhythms of some parameters, such as cerebrospinal fluid sodium and brain ISF pressure waves, which may play a crucial role in brain physio‑pathological states. Thus, according to this proposal, the brain ISF represents the real internal medium since the maintenance of its dynamic intra-set-range homeostasis is the main factor for a free and independent life of higher vertebrates. Furthermore, the evolutionary links between brain and kidney and their synergistic role in H2O/Na balance and brain temperature control are discussed. Finally, it is surmised that these two interrelated parameters have deep effects on the Central Nervous System (CNS) higher integrative actions such those linked to psychic homeostasis.
authors.affiliation: Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41121 Modena, Italy.
authors.forename: Luigi F
authors.initials: LF
authors.lastname: Agnati
authors.affiliation: Department of Pharmacy, Unit of Pharmacology and Toxicology, and Center of Excellence for Biomedical Research, University of Genova, 16126 Genova, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Marcoli
authors.affiliation: Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41121 Modena, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Leo
authors.affiliation: Department of Pharmacy, Unit of Pharmacology and Toxicology, and Center of Excellence for Biomedical Research, University of Genova, 16126 Genova, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Maura
authors.affiliation: Department of Molecular Medicine, University of Padova, 35121 Padova, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Guidolin
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001833:Body Temperature Regulation; D001921:Brain / Q000502:physiology*; D002555:Cerebrospinal Fluid / Q000378:metabolism; D045604:Extracellular Fluid / Q000378:metabolism*; D025461:Feedback, Physiological; D006706:Homeostasis; D006801:Humans; D007668:Kidney / Q000502:physiology; D012964:Sodium / Q000378:metabolism
chemical_list: D012964:Sodium