sentence: Striatal cholinergic and MSNs express several neurotransmitter receptors including the γ - aminobutyric acid ( GABA ) , glutamate , DA , adenosine , serotonin , opioids , and substance P ( NK1 ) receptors ( Lee et al ., 1997 ; Tzaferis and McGinty , 2001 ; Solbrig et al ., 2002 ; Lim et al ., 2014 ) .