Beas-Zárate C, Morales-Villagran A, Tapia-Arizmendi G, Feria-Velasco A
Laboratorio de Neuroquímica, Facultad de Ciencias Biológicas, Universidad de Guadalajara, Jalisco, México.
Eur J Pharmacol. 1991 May 30;198(1):7-14. doi: 10.1016/0014-2999(91)90555-5.
The cerebellum receives indolaminergic fibers influencing Purkinje cell discharges. Data from our laboratories have demonstrated an endogenous release of serotonin (5-HT) and a Na(+)-dependent uptake and Ca(2+)-dependent release of [3H]5-HT from slices, homogenates and synaptosomal fractions of the rat cerebellar molecular layer. While the neurotransmitter produced by climbing fibers has been sought for in several studies and some of the classical transmitters have been ruled out, as yet this neurotransmitter is unknown. The aim of this work was to measure the 5-HT uptake and release from rat cerebellar slices, 6 h and 15 days after intraperitoneal injection of 3-acetylpyridine (3-AP) (75 mg/kg), harmaline (15 mg/kg) and nicotinamide (300 mg/kg). A histological study of medulla and cerebellar cortex in these animals showed destruction of neurons in the inferior olivary nuclei and changes in the granulation of the cortical molecular layer in the cerebellum. A significant reduction of the 5-HT content (100%), 5-HT uptake (60%) and its Vmax (60%) was seen on the 5th day, in cerebellar preparations obtained from rats injected with 3-AP. The Ca(2+)-dependent release of 5-HT from these preparations was found to be similar to the basal values, in spite of depolarizing stimuli with 53 mM KCl or veratrine (60 micrograms/ml). The results suggest that 5-HT could play an important role as neurotransmitter produced by some climbing fibers.
小脑接受影响浦肯野细胞放电的吲哚胺能纤维。我们实验室的数据表明，大鼠小脑分子层切片、匀浆和突触体组分中存在内源性5-羟色胺（5-HT）释放以及Na⁺依赖性摄取和Ca²⁺依赖性[³H]5-HT释放。虽然在多项研究中寻找了攀缘纤维产生的神经递质，并且一些经典递质已被排除，但这种神经递质至今仍未知。这项工作的目的是测量腹腔注射3-乙酰吡啶（3-AP）（75mg/kg）、槟榔碱（15mg/kg）和烟酰胺（300mg/kg）6小时和15天后大鼠小脑切片中5-HT的摄取和释放。对这些动物延髓和小脑皮质的组织学研究显示下橄榄核神经元破坏以及小脑皮质分子层颗粒变化。在注射3-AP的大鼠获得的小脑制剂中，第5天观察到5-HT含量（100%）、5-HT摄取（60%）及其Vmax（60%）显著降低。尽管用53mM KCl或藜芦碱（60μg/ml）进行去极化刺激，但发现这些制剂中5-HT的Ca²⁺依赖性释放与基础值相似。结果表明5-HT可能作为某些攀缘纤维产生的神经递质发挥重要作用。
