Angiotensin II stimulates sympathetic neurotransmission to adipose tissue

• Published in: Physiological reports 2013-07, Vol.1 (2), p.np-n/a
• Main Authors: King, Victoria L., English, Victoria L., Bharadwaj, Kalyani, Cassis, Lisa A.
• Format: Article
• Language: English
• Subjects: Adipocytes; Adipose tissue (brown); Angiotensin; Angiotensin II; Blood pressure; Body fat; Body weight; Cardiovascular system; catecholamine turnover; Food; Food intake; Heart failure; Hypertension; Hypotheses; Kidneys; Laboratories; Lipids; Localization; Metabolism; Nervous system; Neurotransmission; Norepinephrine; Original Research; Peptides; Physiology; Propranolol; Tyrosine; Ventricle; Ventricles (cerebral); Water intake
• ISSN: 2051-817X; 2051-817X
• DOI: 10.1002/phy2.14

Angiotensin II (AngII) facilitates sympathetic neurotransmission by regulating norepinephrine (NE) synthesis, release, and uptake. These effects of AngII contribute to cardiovascular control. Previous studies in our laboratory demonstrated that chronic AngII infusion decreased body weight of rats. We hypothesized that AngII facilitates sympathetic neurotransmission to adipose tissue and may thereby decrease body weight. The effect of chronic AngII infusion on the NE uptake transporter and NE turnover was examined in metabolic (interscapular brown adipose tissue, ISBAT; epididymal fat, EF) and cardiovascular tissues (left ventricle, LV; kidney) of rats. To examine the uptake transporter saturation isotherms were performed using [3H]nisoxetine (NIS). At doses that lowered body weight, AngII significantly increased ISBAT [3H]NIS binding density. To quantify NE turnover, alpha‐methyl‐para‐tyrosine (AMPT) was injected in saline‐infused, AngII‐infused, or saline‐infused rats that were pair‐fed to food intake of AngII‐infused rats. AngII significantly increased the rate of NE decline in all tissues compared to saline. The rate of NE decline in EF was increased to a similar extent by AngII and by pair feeding. In rats administered AngII and propranolol, reductions in food and water intake and body weight were eliminated. These data support the hypothesis that AngII facilitates sympathetic neurotransmission to adipose tissue. Increased sympathetic neurotransmission to adipose tissue following AngII exposure is suggested to contribute to reductions in body weight. e00014 We demonstrate that infusion doses of angiotensin II in rats that lower body weight result in an increase in levels of the norepinephrine uptake transporter and elevated catcholamine turnover in adipose tissue. Angiotensin II‐induced regulation of body weight was abolished by the beta‐adrenergic receptor antagonist, propranolol. Heightened activity of the renin–angiotensin system in certain disease states not only regulates the cardiovascular system, but also may regulate body weight.