Lapchak P A, Jenden D J, Hefti F
Division of Neurogerontology, Andrus Gerontology Center, University of Southern California, Los Angeles 90089.
Neuroscience. 1992 Oct;50(4):847-56. doi: 10.1016/0306-4522(92)90208-j.
The present study determined the effects of chronic recombinant human nerve growth factor administration [1 microgram given intracerebroventricularly q.i.d. (every other day) for three weeks] on in vivo hippocampal cholinergic function in adult rats with unilateral partial fimbrial transections. Partial fimbrial transections did not significantly alter the levels of endogenous acetylcholine or [2H4]acetylcholine in the hippocampus due to functional compensation by surviving cholinergic terminals. In animals chronically treated with nerve growth factor, the levels of endogenous choline, endogenous acetylcholine, [2H4]choline and [2H4]acetylcholine accumulated in the hippocampus on the lesioned side were not significantly different from those on the contralateral unlesioned side or from values measured in animals treated with cytochrome c, a control protein. However, changes in cholinergic parameters induced by the partial lesions or recombinant human nerve growth factor treatment became manifest when animals were challenged using pharmacological agents such as pentylenetetrazole or pilocarpine given after lithium chloride pretreatment. First, in nerve growth factor-treated animals administered the general stimulant pentylenetetrazole (10 mg/kg) 2 min prior to measuring in vivo cholinergic parameters, we observed a significant increase in the hippocampal content of [2H4]choline in both lesioned and unlesioned hippocampi. The magnitude of the increase was significantly higher on the lesioned compared to the unlesioned side. Although chronic recombinant human nerve growth factor treatment induced increases of hippocampal [2H4]choline levels, there were no concomitant increases in the level of [2H4]acetylcholine. Second, in nerve growth factor-treated animals administered lithium chloride (3 mmol/kg) 20 h prior to pilocarpine (30 mg/kg), we observed a significant enhancement of the content of endogenous acetylcholine in the hippocampus of the lesioned side. Partial fimbrial transections also reduced in vitro cholinergic parameters reflecting endogenous acetylcholine levels in hippocampal slices. The content of endogenous acetylcholine in the slices was decreased by approximately 50% and chronic nerve growth factor treatment significantly elevated this value to approximately non-lesioned control values. Similarly, reductions in spontaneous and veratridine-evoked release of endogenous acetylcholine induced by partial fimbrial transections were counteracted by recombinant human nerve growth factor treatment. These findings demonstrate that chronic recombinant human nerve growth factor treatment effectively enhances the in vivo and in vitro synthesis, storage and release of endogenous acetylcholine. The results from the in vivo studies suggest that recombinant human nerve growth factor-induced differences in functional performance of hippocampal neurons may only be manifest during behavioral and/or pharmacological stimulation.
本研究确定了慢性给予重组人神经生长因子[1微克，经脑室内注射，每日4次（每隔一天一次），持续三周]对单侧部分海马伞横断的成年大鼠体内海马胆碱能功能的影响。部分海马伞横断并未因存活的胆碱能终末的功能代偿而显著改变海马中内源性乙酰胆碱或[2H4]乙酰胆碱的水平。在长期接受神经生长因子治疗的动物中，损伤侧海马中内源性胆碱、内源性乙酰胆碱、[2H4]胆碱和[2H4]乙酰胆碱的积累水平与对侧未损伤侧或用细胞色素c（一种对照蛋白）治疗的动物所测值相比，无显著差异。然而，当动物在氯化锂预处理后使用诸如戊四氮或毛果芸香碱等药理学试剂进行激发时，部分损伤或重组人神经生长因子治疗所诱导的胆碱能参数变化就会显现出来。首先，在测量体内胆碱能参数前2分钟给接受神经生长因子治疗的动物注射一般兴奋剂戊四氮（10毫克/千克），我们观察到损伤和未损伤海马中[2H4]胆碱的海马含量均显著增加。损伤侧的增加幅度显著高于未损伤侧。尽管慢性重组人神经生长因子治疗导致海马[2H4]胆碱水平升高，但[2H4]乙酰胆碱水平并未随之增加。其次，在给接受神经生长因子治疗的动物注射毛果芸香碱（30毫克/千克）前20小时注射氯化锂（3毫摩尔/千克），我们观察到损伤侧海马中内源性乙酰胆碱含量显著增加。部分海马伞横断也降低了反映海马切片中内源性乙酰胆碱水平的体外胆碱能参数。切片中内源性乙酰胆碱含量降低了约50%，而慢性神经生长因子治疗显著将该值提高到接近未损伤对照值。同样，重组人神经生长因子治疗抵消了部分海马伞横断所诱导的内源性乙酰胆碱自发释放和藜芦碱诱发释放的减少。这些发现表明，慢性重组人神经生长因子治疗有效地增强了体内和体外内源性乙酰胆碱的合成、储存和释放。体内研究结果表明，重组人神经生长因子诱导的海马神经元功能表现差异可能仅在行为和/或药理学刺激期间显现。
