Using transgenic mice expressing the receptor for diphtheria toxin in ghrelin-secreting cells, it was shown that targeted ablation of ghrelin-secreting cells in adult mice with diphtheria toxin injections had no effect, not even transiently, on food intake, body weight or susceptibility to diet-induced obesity, despite reducing circulating ghrelin levels by 85–90% [289]. This evidence concerns the gene GHRL and obesity due to melanocortin 4 receptor deficiency.