Nevertheless, immune castration with recombinant GnRH inhibitor (GnRH-I) in boars did not alter testicular ghrelin expression [25]; thus, it needs to be further examined whether testicular ghrelin expression does indeed not depend on testosterone or if there are compensatory mechanisms under conditions of GnRH-I-induced hypogonadism ensuring ghrelin expression in the testis. Here, GNRH1 is linked to hypogonadism.