A chemical compound of formula (I), wherein R1 to R3 are independently selected from hydrogen and alkyl; R4 is selected from hydrogen, alkyl, alkoxy, formyl and cyano; X1 is selected from N and C—R7; X2 is selected from N and C—R8; X3 is selected from N and C—R9; X4 is selected from N and C—R10; wherein at least one of X1, X2, X3 and X4 is N; and R5 to R10 are independently selected from hydrogen, halogen, hydroxy, alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, alkylsulfoxyl, alkylsulfonyl, arylsulfoxyl, arylsulfonyl, amino, monoalkylamino, dialkylamino, nitro, cyano, carboxaldehyde, alkylcarbonyl, arylcarbonyl, aminocarbonyl, monoalkylaminocarbonyl, dialkylaminocarbonyl, alkoxycarbonylamino, aminocarbonyloxy, monoalkylaminocarbonyloxy, dialkylaminocarbonyloxy, monoalkylaminocarbonylamino and dialkylaminocarbonylamino, and the use thereof in therapy, particularly for the treatment of disorders of the central nervous system; damage to the central nervous system; cardiovascular disorders; gastrointestinal disorders; diabetes insipidus; and sleep apnea, and particularly for the treatment of obesity.