In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.

 Internal controls over the volume of milk suckled do not appear until infant rats are about 2 weeks of age at which time gastric distension , milk , systemic dehydration , and intestinal hormone cholecystokinin suppress milk intake derived through suckling .
intestinal hormone cholecystokinin