Stimulation of NPY Y 2 receptors by PYY 3-36 reveals divergent cardiovascular effects of endogenous NPY in rats on different dietary regimens

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2004-01, Vol.286 (1), p.R138-R142
• Main Authors: Nordheim, Ulrich, Hofbauer, Karl G.
• Format: Article
• Language: English
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00374.2003

In the present experiments the gut hormone peptide YY 3-36 (PYY 3-36 ), which inhibits neuropeptide Y (NPY) release, was used as a tool to study the cardiovascular effects of endogenous NPY under different dietary regimens in rats instrumented with a telemetry transmitter. In a first experiment, rats were placed on a standard chow diet ad libitum and in a second experiment on a high-fat diet ad libitum. After 6 wk, PYY 3-36 (300 μg/kg) or vehicle was injected intraperitoneally. In a third experiment, PYY 3-36 or vehicle was administered after 14 days of 50% restriction of a standard chow diet. In food-restricted rats, PYY 3-36 increased mean arterial pressure (7 ± 1 mmHg, mean ± SE, P < 0.001 vs. saline, 1-way repeated-measures ANOVA with Bonferroni t-test) and heart rate (22 ± 4 beats/min, P < 0.001) during 3 h after administration. Conversely, PYY 3-36 did not influence mean arterial pressure (0 ± 1 mmHg) and heart rate (-8 ± 5 beats/min) significantly in rats on a high-fat diet. Rats fed standard chow diet ad libitum showed an intermediate response (mean arterial pressure 4 ± 1 mmHg, P < 0.05, and heart rate 5 ± 2 beats/min, not significant). Thus, in our studies, divergent cardiovascular responses to PYY 3-36 were observed in rats on different dietary regimens. These findings suggest that the cardiovascular effects of PYY 3-36 depend on the hypothalamic NPY release, which is increased after chronic food restriction and decreased during a high-fat diet.