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Angiotensin II Stimulates Sympathetic Neurotransmission to Adipose Tissue.

King VL, English VL, Bharadwaj K, Cassis LA - Physiol Rep (2013)

Bottom Line: These effects of AngII contribute to cardiovascular control.At doses that lowered body weight, AngII significantly increased ISBAT [(3)H]NIS binding density.AngII significantly increased the rate of NE decline in all tissues compared to saline.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, University of Kentucky, Lexington, KY 40536.

ABSTRACT
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 [(3)H]nisoxetine (NIS). At doses that lowered body weight, AngII significantly increased ISBAT [(3)H]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.

No MeSH data available.


Related in: MedlinePlus

Pair feeding demonstrates that reductions in food intake partially mediate body weight reductions of angiotensin II (AngII)-infused rats. Rats were administered saline, AngII (400 ng/kg per minute) or were pair-fed to food intake of AngII-infused rats for 14 days. Body weight (A), food intake (B), and water intake (C) of rats in each group. Data are mean ± SEM from n = 15 rats/group. *Denotes significantly different from saline-infused rats (P < 0.05).
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fig04: Pair feeding demonstrates that reductions in food intake partially mediate body weight reductions of angiotensin II (AngII)-infused rats. Rats were administered saline, AngII (400 ng/kg per minute) or were pair-fed to food intake of AngII-infused rats for 14 days. Body weight (A), food intake (B), and water intake (C) of rats in each group. Data are mean ± SEM from n = 15 rats/group. *Denotes significantly different from saline-infused rats (P < 0.05).

Mentions: Following 14 days of AngII infusion, blood pressure was significantly increased compared to saline and pair-fed rats (saline: 108 ± 9; pair-fed: 105 ± 4; AngII: 132 ± 5 mmHg; P < 0.05). Body weight was significantly decreased in AngII-infused and pair-fed rats compared to saline (Fig. 4A), with reductions in food intake (Fig. 4B) accounting for approximately 64% of the effect of AngII on body weight at 14 days. Water intake was significantly increased in AngII-infused rats compared to saline and pair-fed rats (Fig. 4C). The endogenous NE concentration in LV and kidney from AngII-infused rats was significantly decreased compared to saline and pair-fed rats (Table 2). In contrast, AngII infusion resulted in a significant increase in NE concentration in ISBAT and EF compared to saline and pair-fed rats. In tissues from rats in each group the log NE concentration was regressed against time after AMPT administration and covariance matrix analysis of regression curves was performed to determine significant differences between groups (Fig. 5). The rate of NE decline (k) was determined from the slope of regression lines (Fig. 5) and was significantly greater in LV, kidney, and ISBAT from AngII-infused rats compared to saline and pair-fed rats (Figs. 5 and 6A). In EF, the rate of NE decline was increased to a similar extent in AngII-infused and pair-fed rats. The NE turnover rate (K) was significantly increased in ISBAT from AngII-infused rats compared to saline and pair-fed rats; in contrast, in LV the NE turnover rate was decreased in pair-fed rats compared to saline and AngII-infused rats (Fig. 6B).


Angiotensin II Stimulates Sympathetic Neurotransmission to Adipose Tissue.

King VL, English VL, Bharadwaj K, Cassis LA - Physiol Rep (2013)

Pair feeding demonstrates that reductions in food intake partially mediate body weight reductions of angiotensin II (AngII)-infused rats. Rats were administered saline, AngII (400 ng/kg per minute) or were pair-fed to food intake of AngII-infused rats for 14 days. Body weight (A), food intake (B), and water intake (C) of rats in each group. Data are mean ± SEM from n = 15 rats/group. *Denotes significantly different from saline-infused rats (P < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3818081&req=5

fig04: Pair feeding demonstrates that reductions in food intake partially mediate body weight reductions of angiotensin II (AngII)-infused rats. Rats were administered saline, AngII (400 ng/kg per minute) or were pair-fed to food intake of AngII-infused rats for 14 days. Body weight (A), food intake (B), and water intake (C) of rats in each group. Data are mean ± SEM from n = 15 rats/group. *Denotes significantly different from saline-infused rats (P < 0.05).
Mentions: Following 14 days of AngII infusion, blood pressure was significantly increased compared to saline and pair-fed rats (saline: 108 ± 9; pair-fed: 105 ± 4; AngII: 132 ± 5 mmHg; P < 0.05). Body weight was significantly decreased in AngII-infused and pair-fed rats compared to saline (Fig. 4A), with reductions in food intake (Fig. 4B) accounting for approximately 64% of the effect of AngII on body weight at 14 days. Water intake was significantly increased in AngII-infused rats compared to saline and pair-fed rats (Fig. 4C). The endogenous NE concentration in LV and kidney from AngII-infused rats was significantly decreased compared to saline and pair-fed rats (Table 2). In contrast, AngII infusion resulted in a significant increase in NE concentration in ISBAT and EF compared to saline and pair-fed rats. In tissues from rats in each group the log NE concentration was regressed against time after AMPT administration and covariance matrix analysis of regression curves was performed to determine significant differences between groups (Fig. 5). The rate of NE decline (k) was determined from the slope of regression lines (Fig. 5) and was significantly greater in LV, kidney, and ISBAT from AngII-infused rats compared to saline and pair-fed rats (Figs. 5 and 6A). In EF, the rate of NE decline was increased to a similar extent in AngII-infused and pair-fed rats. The NE turnover rate (K) was significantly increased in ISBAT from AngII-infused rats compared to saline and pair-fed rats; in contrast, in LV the NE turnover rate was decreased in pair-fed rats compared to saline and AngII-infused rats (Fig. 6B).

Bottom Line: These effects of AngII contribute to cardiovascular control.At doses that lowered body weight, AngII significantly increased ISBAT [(3)H]NIS binding density.AngII significantly increased the rate of NE decline in all tissues compared to saline.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, University of Kentucky, Lexington, KY 40536.

ABSTRACT
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 [(3)H]nisoxetine (NIS). At doses that lowered body weight, AngII significantly increased ISBAT [(3)H]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.

No MeSH data available.


Related in: MedlinePlus