[Ala17]-MCH, a MCH analogue (HY-P1525A), is a selective ligand for MCHR1 (Ki=0.16 nM) over MCHR2 (Ki=34 nM). [Eu3+ chelate-labeled [Ala17]-MCH shows high affnity for MCHR1 (Kd=0.37 nM) while has little demonstrable binding affnity for MCHR2.