Intravenous CCK-8, but not GLP-1, suppresses ghrelin and stimulates PYY release in healthy men

We have investigated the effects of exogenous CCK-8 and GLP-1, alone and in combination, on ghrelin and PYY secretion. Nine healthy males were studied on four occasions. Plasma ghrelin and PYY concentrations were measured during 150 min intravenous infusions of: (i) isotonic saline, (ii) CCK-8 at 1.8 pmol/kg/min, (iii) GLP-1 at 0.9 pmol/kg/min or (iv) CCK-8 and GLP-1 combined. CCK-8 markedly suppressed ghrelin and stimulated PYY when compared with control between t = 0–120 min (P < 0.001 for both). GLP-1 had no effect on ghrelin, but decreased PYY slightly at 120 min (P < 0.05). During infusion of CCK-8 + GLP-1, there was comparable suppression of ghrelin (P < 0.001), but the stimulation of PYY was less (P < 0.001), than that induced by CCK-8, between t = 20–120 min. In conclusion, in healthy subjects, in the doses evaluated, exogenous CCK-8 suppresses ghrelin and stimulates PYY, and exogenous GLP-1 has no effect on ghrelin and attenuates the effect of CCK-8 on PYY.