The second consideration should be whether the ghrelin receptor antagonist shows selective effects on consumption of other rewarding substances. D-Lys3-GHRP-6 has been investigated in food intake studies and at doses similar to the dose we tested, decreased food intake in food-deprived rodents (Asakawa et al., 2003; Beck et al., 2004). In our preference studies, mice treated with D-Lys3-GHRP-6 did not show a decrease in the amount of water consumed suggesting that this drug shows at least some selectivity to ethanol consumption. However, Jerlhag and colleagues (2009a) showed that a GHSR 1a antagonist did decrease saccharin (a non-caloric reward) consumption. Of the two GHSR 1a antagonists tested by Jerlhag et al. (2009b), JMV2959 decreased food intake while BIM28163 increased it, indicating that the effect of ghrelin receptor antagonists on alcohol and saccharin are independent of their actions on food intake.
