Amphetamine-induced release of diadenosine polyphosphates - Ap4A and Ap5A - from caudate putamen of conscious rat

The release of diadenosine polyphosphates - diadenosine tetraphosphate (Ap 4 A) and diadenosine pentaphosphate (Ap 5 A) - was measured by intracerebral push-pull perfusion in conscious rats after systemic amphetamine injection. Samples were collected from the caudate putamen, and nucleotide compounds were analyzed by HPLC. The presence of Ap 4 A and Ap 5 A was demonstrated by their retention times and phosphodiesterase digestion. Dinucleotides were not detectable before amphetamine injection (5 mg/kg). The maximal levels were reached 20 min after the injection with values of 12.9 ± 0.9 and 11.5 ± 0.9 pmol/fraction for Ap 4 A and Ap 5 A, respectively. A slow and progressive decrease in their concentration followed. This study shows for the first time the amphetamine-induced release of diadenosine polyphosphates in conscious rats, and a role for Ap 4 A and Ap 5 A in the central nervous system is therefore suggested.