Antiobesity Effect of a Short-Length Peptide YY Analogue after Continuous Administration in Mice

Gastrointestinal peptides such as peptide YY (PYY) can regulate appetite, which is relevant to the study of obesity. The intraperitoneal bolus administration of PYY<sub>3–36</sub> and a 12-amino acid PYY analogue, benzoyl-[Cha<sup>27,28,36</sup>,Aib<sup>31</sup>]­PYY<sub>25–36</sub> (<b>1</b>), showed similar anorectic activity by activating the Y2 receptor (Y2R). However, food intake inhibition and body weight loss were not observed upon continuous subcutaneous administration of <b>1</b> with osmotic pumps in diet-induced obese (DIO) mice. N-Terminal elongation of <b>1</b>, together with amino acid substitution at position 24, led to a hydrophilic 14-amino acid peptide, Ac-[d-Hyp<sup>24</sup>,Cha<sup>27,28,36</sup>,Aib<sup>31</sup>]­PYY<sub>23–36</sub> (<b>18</b>), that showed higher affinity and more potent agonist activity for Y2R and a robust anorectic activity with potency similar to that of PYY<sub>3–36</sub>. In addition, the continuous subcutaneous administration of <b>18</b> at 0.3 mg/(kg·day) induced significant body weight loss in DIO mice. These results suggest that a short-length PYY analogue can be a lead compound for antiobesity therapy in a sustained-release formulation.