Heat acclimation affects the neuromodulatory role of AngII and nitric oxide during combined heat and hypohydration stress.
We studied the effect of heat acclimation on the neuromodulatory role of angiotensin (AngII) and nitric oxide during combined heat (39 degrees C) and hypohydration (water deprivation, -10% body weight) stress. Rats were divided into control (C), short (2d-STHA) or long (30d-LTHA) acclimation (34 degrees C) groups. AngII, 7-nitroindazole (7NI)-nNOS blocker, or both were centrally administered (5 mul, bolus) under light chloroform anesthesia prior to each experimental paradigms: (1) In vivo: measurements of skin-vasodilatation (VTsh) and salivation-cooling (STsh) thresholds, and heat endurance in conscious heat/hypohydrated stressed rats; (2) expression of AT(1) and AT(2) AngII receptors and nNOS were measured in the hypothalamus (Western blot); (3) transcript levels of the coding genes were measured using real-time PCR. A synthesis of the results shows a biphasic acclimatory profile of VTsh, STsh, and transcript levels of all studied genes, with transient up/down-regulatory changes on STHA. AngII affected the physiological integrative outcome primarily during euhydration, although AT membranal changes (except in LTHA) were confined to hypohydration. 7NI had an impact during hypohydration. Evidence is provided that AngII and 7NI modulate thermoregulation primarily via AT(1) and AT(2) receptors, with predominance of AT(2) signaling following LTHA and/or hypohydration, opposing a drop in AT(1)-mediated thresholds. The final shaping of AngII signaling depends on cross-talk between nNOS and AngII receptors at both molecular and protein levels. Hypohydration induces transcriptional responses but desensitizes AngII receptors signaling, attenuating their effect on VTsh and STsh, and abolishing the beneficial thermoregulatory effects achieved by heat acclimation. nNOS, AngII receptor-independent pathway is also implicated.[1]References
- Heat acclimation affects the neuromodulatory role of AngII and nitric oxide during combined heat and hypohydration stress. Schwimmer, H., Gerstberger, R., Horowitz, M. Brain Res. Mol. Brain Res. (2004) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
