The present invention is related to a nucleic acid, preferably binding to ghrelin, whereby the nucleic acid comprisesa first stretch Box A, anda second stretch Box B,wherebythe first stretch Box A comprises about 25 consecutive nucleotides,the second stretch Box B comprises about six to eight consecutive nucleotides,wherebya 3′-terminal stretch of nucleotides of the first stretch Box A hybridises with the second stretch Box B, whereby upon hybridisation a first double-stranded structure is formed, whereby such first double-stranded structure comprises a bulge.
