title: A specific taurine recognition site in the rabbit brain is responsible for taurine effects on thermoregulation.
abstract: (1) Taurine and GABA are recognized as endogenous cryogens. In a previous study, some structural analogues of taurine, namely 6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine 1,1-dioxide (TAG), 2-aminoethylarsonic (AEA), 2-hydroxyethanesulfonic (ISE) and (+/-)cis-2-aminocyclohexane sulfonic acids (CAHS) have been shown to displace [(3)H]taurine binding from rabbit brain synaptic membrane preparations, without interacting either with GABA-ergic systems, nor with taurine uptake mechanism, thus behaving like direct taurinergic agents. (2) To answer the question whether the role of taurine as an endogenous cryogen depends on the activation of GABA receptors or that of specific taurine receptor(s), taurine or the above structural analogues were injected intracerebroventricularly in conscious, restrained rabbits singularly or in combination and their effects on rectal (RT)- and ear-skin temperature and gross motor behavior (GMB) were monitored. (3) Taurine (1.2 x 10(-6)-4.8 x 10(-5) mol) induced a dose-related hypothermia, vasodilation at ear vascular bed and inhibition of GMB. CAHS, at the highest dose tested (4.8 x 10(-5) mol) induced a taurine-like effect either on RT or GMB. On the contrary ISE, injected at the same doses of taurine, induced a dose-related hyperthermia, vasoconstriction and excitation of GMB. AEA and TAG caused a dose-related hyperthermia, but at doses higher than 1.2 x 10(-7) mol caused death within 24 h after treatment. (4) CAHS (4.8 x 10(-5) mol) antagonized the hyperthermic effect induced by TAG (1.2 x 10(-6) mol), AEA (1.2 x 10(-8) mol) or ISE (4.8 x 10(-5) mol). (5) In conclusion, these findings may indicate the existence of a recognition site specific for taurine, responsible for its effects on thermoregulation.
authors.affiliation: Istituto di Scienze Farmacologiche, Università di Siena, Nuovo Polo Scientifico, Viale A. Moro 2, lotto C, Siena 53100, Italy. frosinim@unisi.it
authors.forename: Maria
authors.initials: M
authors.lastname: Frosini
authors.forename: Casilde
authors.initials: C
authors.lastname: Sesti
authors.forename: Simona
authors.initials: S
authors.lastname: Saponara
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Ricci
authors.forename: Massimo
authors.initials: M
authors.lastname: Valoti
authors.forename: Mitri
authors.initials: M
authors.lastname: Palmi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Machetti
authors.forename: Giampietro
authors.initials: G
authors.lastname: Sgaragli
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D001833:Body Temperature Regulation / Q000187:drug effects* / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D007276:Injections, Intraventricular; D008297:Male; D011817:Rabbits; D013654:Taurine / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D013654:Taurine