Training-Induced Pressure Fall in Spontaneously Hypertensive Rats Is Associated With Reduced Angiotensinogen mRNA Expression Within the Nucleus Tractus Solitarii

• Published in: Hypertension (Dallas, Tex. 1979) Vol. 50; no. 4; pp. 780 - 785
• Main Authors: Felix, Jorge Vinicius Cestari, Michelini, Lisete Compagno
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Philadelphia, PA American Heart Association, Inc 01.10.2007; Hagerstown, MD Lippincott
• Subjects: Angiotensinogen - metabolism; Animals; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Blood Pressure - physiology; Cardiology. Vascular system; Clinical manifestations. Epidemiology. Investigative techniques. Etiology; Experimental diseases; Heart Rate - physiology; Hypertension - pathology; Hypertension - physiopathology; Male; Medical sciences; Physical Conditioning, Animal - physiology; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, Angiotensin, Type 1 - metabolism; Renin-Angiotensin System - physiology; RNA, Messenger - genetics; RNA, Messenger - metabolism; Solitary Nucleus - metabolism; Solitary Nucleus - pathology; Physical exercise; Arrhythmia; Rat; Brain stem; Peptide hormone; Cardiovascular disease; experimental; angiotensin receptors; Encephalon; Octapeptide; Renin; Heart disease; Angiotensinogen; Arterial pressure; Aspartic endopeptidases; Blood pressure; rats; Angiotensin II; Sedentary; Hypertension; Enzyme; Rodentia; Excitability disorder; Heart rate; Peptidases; Autoradiography; Vertebrata; Bradycardia; Renin angiotensin system; Mammalia; Animal; Hydrolases; Comparative study
• ISSN: 0194-911X; 1524-4563; 1524-4563
• DOI: 10.1161/HYPERTENSIONAHA.107.094474

Knowing that exercise training reduces arterial pressure in hypertensive individuals and that pressure fall is accompanied by blockade of brain renin-angiotensin system, we sought to investigate whether training (T) affects central renin-angiotensin system. Spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto controls (WKY) were submitted to training or kept sedentary (S) for 3 months. After functional recordings, brain was removed and processed for autoradiography (brain stem sequential slices hybridized with S-oligodeoxynucleotide probes for angiotensinogen [Aogen] and angiotensin II type 1 [AT1A] receptors). Resting arterial pressure and heart rate were higher in SHRS (177±2 mm Hg, 357±12 bpm versus 121±1 mm Hg, 320±9 bpm in WKYS; P<0.05). Training was equally effective to enhance treadmill performance and to cause resting bradycardia (−10%) in both groups. Training-induced blood pressure fall (−6.3%) was observed only in SHRT. In SHRS (versus WKYS) AT1A and Aogen mRNA expression were significantly increased within the NTS and area postrema (average of +67% and +41% for AT1A and Aogen, respectively; P<0.05) but unchanged in the gracilis nucleus. Training did not change AT1A expression but reduced NTS and area postrema Aogen mRNA densities specifically in SHRT (P<0.05 versus SHRS, with values within the range of WKY groups). In SHRs, NTS Aogen mRNA expression was correlated with resting pressure (y=5.95x +41; r=0.55; P<0.05), with no significant correlation in the WKY group. Concurrent training-induced reductions of both Aogen mRNA expression in brain stem cardiovascular-controlling areas and mean arterial pressure only in SHRs suggest that training is as efficient as the renin-angiotensin blockers to reduce brain renin-angiotensin system overactivity and to decrease arterial pressure.