The relationship between serum neuropeptide Y levels and coronary collateral development

Purpose: Neuropeptide Y (NPY) is a co-transmitter released from sympathetic nerve terminals. NPY stimulates endothelial cell activation, proliferation, migration, and tube formation. It has been demonstrated that NPY produces angiogenic activity in a variety of in vitro models. The aim of this study was to evaluate relationship of serum NPY levels with coronary collateral vessel development in patients with coronary artery disease (CAD). Methods: The study consisted of 81 patients with ≥1 coronary stenosis with ≥80% narrowing in coronary angiography. Collateral vessels were graded according to the Rentrop classification. The study patients were divided into two groups, namely, patients with well developed collaterals and patients with poorly developed collaterals. Well developed collaterals were defined as Rentrop collateral score 2. Serum levels of NPY, vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and noradrenalin (NA) were measured. Results: Of the 81 patients included in the study, 33 (41%) had well developed collaterals. Patient profiles with respect to age, gender, diabetes, hypertension, hyperlipidemia, previous history of a myocardial infarction, and left ventricular ejection fraction are similar between groups. Extent of coronary artery disease (Gensini socre) was significantly higher in patients with well developed collaterals (65.4±24.4 vs 45.3±23.7, p<0.001). Mean level of serum NPY in patients with well developed collaterals was significantly higher than those patients with poorly developed collaterals (0.85±0.0.43 ng/mL versus 0.66±0.34 ng/mL, p=0.026). In contrast, NA was significantly lower in patients with well developed collaterals (4.34±2.58 ng/mL vs 6.60±5.1 ng/mL, p=0.022). There was no statistically significant difference in levels of VEGF and FGF between groups. The NPY level was negatively correlated with the level of the FGF (r=-0.232, p=0.037) and with the level of the LDL (r=-0.278, p=0.012), and positively correlated with the presence of diabetes (r=0.528, p<0.001). After confounding variables were controlled for, the NPY level in patients with well developed collaterals was significantly higher from those patients with poorly developed collaterals. Conclusions: We found that NPY levels are significantly higher in patients with well developed coronary collaterals compared to patients with poorly developed collaterals. New studies are needed to show whether this relationship is causal.