Striatal dopamine level after i. v. injection of d -phenylglycine- l -dopa. Values represent the group mean ± s.e.m. (n = 4). Single dose d-phenylglycine-l-dopa (50 mg/kg in 2.5 mL of normal saline) was administered i.v. via femoral vein to anesthetized male Sprague-Dawley rats (280 - 320 g). The dialysates collected from the brain microdialysis probe was subjected to HPLC to measure the striatal dopamine concentration at 10 min interval.