Abstract
Endogenous dopamine (DA) released from slices of rat striatum and n. accumbens into the superfusate was quantified with high performance liquid chromatography (HPLC) combined with an electrohemical detector (ECD). The basal efflux of DA from slices of rat striatum and n. accumbens were 600 pg/mg protein/10 min and 400 pg/mg protein/10 min, respectively. Compared with normal K+ Krebs-Ringer solution, 25 mM K+ Krebs-Ringer solution significantly incleased (about 20 times) the DA efflux. This stimulant effect of high K+ did not occur in Ca2+ deficient Krebs - Ringer solution. Methamphetamine (10-7 -10-3M) caused significant increases in DA efflux in a dose dependent manner. This system may be quite useful to investigate endogenous DA releasing mechanisms in slices of rat brain. Thyrotropin releasing hormone (10-5 -10-3M) did not increase the DA release from either the n. accumbens or the striatum. On the other hand, DN -1417, γ-butyrolactone-γ-histidyl-prolinamide citrate, caused a significant increase in DA efflux from both regions. Removal of Ca2+ from the Krebs-Ringer solution abolished the effect of DN-1417. The stimulant effect of DN -1417 seemed to be greater in the n. accumbens than in the striatum.
