Although it is well known that both nucleus accumbens (Acb) adenosine A2A receptor (A2AR) and hypothalamic orexin neurons are involved in regulating the sleep-arousal, the reciprocally neural connection remains uncertain.In the present study, after adeno-associated virus (AAV) vector encoding humanized Rcnilla green fluorescent protein (hrGFP) was injected into Acb ofA2AR Cre mouse, the brain sections contain Acb and hypothalamus were immunohistochemically examined.