Basu S, Sinha SK, Shao Q, Ganguly PK, Dhalla NS. Neuropeptide Y modulation of sympathetic activity in myocardial infarction.
J Am Coll Cardiol 1996;
27:1796-803. [PMID:
8636570 DOI:
10.1016/0735-1097(96)00063-0]
[Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES
We examined the possible effect of neuropeptide Y in modulating central sympathetic activity after myocardial infarction in rats.
BACKGROUND
Previous studies have shown the coexistence of neuropeptide Y and norepinephrine in the brain and a possible functional interaction between the two. Neuropeptide Y inhibits the release of norepinephrine at the presynaptic level and can be considered to act as a neuromodulator.
METHODS
Two groups of rats were examined in this study-an experimental group, defined as those rats undergoing left coronary artery ligation, and a sham group without coronary artery ligation, serving as the control group. The animal in both groups underwent microdialysis in the paraventricular nucleus at 2, 4 and 8 weeks after operation. Microdialysis samples were collected with and without injecting neuropeptide Y in the paraventricular nucleus. The concentration of norepinephrine was determined by injecting purified microdialysate samples during high performance liquid chromatography. To explore the receptor's possible role, autoradiographic localization of neuropeptide Y receptors in the paraventricular nucleus was also carried out in the experimental and sham groups.
RESULTS
The concentration of norepinephrine measured in the samples was decreased by 50% with neuropeptide Y in 2- and 4-week old rats after infarction, but by only 20% (p < 0.05) in 8-week old rats after infraction. The diminished inhibitory effects of neuropeptide Y on norepinephrine release was associated with increased sympathetic activity, as reflected by plasma norepinephrine; 8-week old rats after infarction had almost a 100% (p < 0.05) increase in their plasma norepinephrine level compared with the sham group. Autoradiography revealed a significant decrease in density of neuropeptide Y receptors in the paraventricular nucleus in 8-week old rats after infarction (p < 0.05).
CONCLUSIONS
The data presented in this report suggest that the reduction of the inhibitory activation of neuropeptide Y on sympathetic release may contribute to elevated norepinephrine levels after myocardial infarction.
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