HCRT and obesity due to melanocortin 4 receptor deficiency: Injection of orexin-A into the third cerebral ventricle selectively increased a preference for high-fat diet (Clegg et al., 2002), whereas SB-334867, a selective OX1 receptor antagonist, blocked orexin-A-induced orexigenic effects and induced anorectic and anti-obesity activities in obese animals (Rodgers et al., 2001).