“The behavior was … reduced by potent adenosine analogs, such as N6-cyclohexyl adenosine (CHA, 0.1 and 0.2 mg/kg IP) and …-(l-phenyl isopropyl) adenosine (l-PIA, 0.2 mg/kg IP), but conversely was potentiated by phentolamine (10 mg/kg IP) or … (10 mg/kg IP).”