Functional changes of rostral ventrolateral medulla by nitric oxide from iNOS in conscious obese rats

The literature shows that obese animals present changes in the production of nitric oxide (NO). NO plays an important role in cardiovascular function, and the production via the inducible NO‐synthase (iNOS) is linked to inflammatory processes. In the rostral ventrolateral medulla (RVLM), glutamate is an important neurotransmitter and is modulated by NO. We aimed to evaluate the effects of L‐glutamate microinjection in RVLM on mean arterial pressure (MAP) and heart rate (HR) before and after microinjection of iNOS inhibitors and to asses NO (nitrite) in punchs of RVLM. The protocols were approved by our institutional ethic committee (process number: 33645/2010‐29). Neonatal Wistar rats received subcutaneous administration of 4 mg/g body weight of monosodium glutamate (MSG) or saline in the first 5 days of life. At 90 days were implanted cannulas guide to RVLM and after after 5 days, we performed catheterization of the femoral artery. After 24 hours the MAP and HR were recorded. The cardiovascular effects of glutamate (5nmol/100 ml) were evaluated before and after microinjection of aminoguanidine (AG) (250pmol/100NL) or S‐methylisothiourea (SMT) (250 pmol/100 ml) or physiological saline (100 ml) at RVLM. The increased MAP by L‐glutamate was higher in the obese group after AG (before: 40 mmHg ± 8; after: 61 ± 4 mmHg, n = 5) and SMT (before: 45± 8 mmHg; after: 65 ± 2 mmHg, n = 5). NO contend in the RVLM, showed a trend of MSG group is increased compared to the CTR (CTR 1.24 ± 0.33 uM/mg, n = 6; MSG 2.7 ± 1 uM/mg, n = 5). The data suggest that NO, probable derived from iNOS seems to be increased in RVLM of obese rats, and may have a role in the RVLM‐mediated cardiovascular responses. Support or Funding Information CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior)