左旋千金藤立定加强尾核脑片多巴胺释放(英文)

Augmentation of dopamine release by (-)-stepholidine from rabbit and rat caudate slices

观察左旋千金藤立定((-)-stepholidine,SPD)对家兔尾核脑片多巴胺(DA)释放的影响.方法:以[~3H]DA预孵脑片,测定DA放射性.结果:选择性D_2受体激动剂LY171555以剂量依赖方式抑制电诱发的兔尾核脑片[~3H]DA释放.SPD可翻转LY 171555对[~3H]DA释放的抑制作用,并以剂量依赖方式加强[~3H]DA释放,在无电刺激条件下,SPD诱发大鼠尾核[~3H]DA释放被蛋白激酶C(protein kinase C,PKC)激活剂咐波酯所加强.结论:SPD对突触前D_2自身受体是阻滞剂.

To study the effect of (-)-stepholidine (SPD) on dopamine (DA) release evoked by electric stimulation on slices of rabbit caudate nucleus. METHODS: Slices of rabbit caudate nucleus were preincubated with [3H]DA and then perfused and stimulated electrically. RESULTS: Quinpirole (Qui), a selective DA D2 receptor agonist, reduced [3H]DA overflow elicited by 24 mA electric stimulation (IC50 = 0.12, 95 % confidence limits 0.09 - 0.17 umol.L-1). SPD markedly increased the potential of the stimulation-evoked [3H ] DA overflow in a dose-dependent manner and reversed Qui (1umol.L-1)-induced attenuation of [3H]DA release. The pA2 value calculated from the data of [3H]DA overflow for SPD was 7.495. In the experiments with rat caudate nucleus slices, SPD (0. 1 mmol.L^1) increased the [3H ] DA outflow from 3. 3 ±0. 2 % to 6.5±0. 5 % of the tissue [3H]DA content, which was further enhanced by the protein kinase C (PKC) activator phorbol 12,13-dibutyrate (PDB, 1umol.L-1) to 10. 1 ±1.0 % of the total [3H]DA in the tissue. CONCLUSION: SPD is a presynaptic D2 au-toreceptor antagonist and induces a synergic effect on [3H]DA release process with PKC.