Tirassa Paola, Costa Nicola
Institute of Neurobiology and Molecular Medicine (CNR), Italy.
Neurochem Int. 2007 Jan;50(1):130-8. doi: 10.1016/j.neuint.2006.07.008. Epub 2006 Sep 11.
In our previous studies, we demonstrated that intraperitoneal (i.p.) injections with the neurotransmitter/neuromodulatory peptide Cholecystokinin-8 (CCK-8) stimulate the synthesis of the neurotrophin nerve growth factor (NGF) resulting in the structural and functional recovery of neuronal damage. This neurotrophin-mediated neuroprotective action of CCK-8 has opened a new perspective for a better understanding of the CCK neurobiological and pharmacological properties. To explore the possible beneficial effects of the CCK-induced increase of neurotrophin availability in brain, we compared the effects of i.p. CCK-8 in healthy rats and in a chemical kindling model using a subconvulsive dose of pentylenetetrazol (PTZ). Behavioural changes were monitored during treatment and classified according to a six-point scale. After 3 weeks of treatment (12 trials), the PTZ group of rats manifested generalized clonic-tonic seizures (Class 5 behaviour). For this reason, this time point was chosen to compare the effects of CCK-8 treatment on the expression of NGF, the brain derived neurotrophin factor (BDNF) and their receptors in the septum and hippocampus. We found that repeated i.p. injections with CCK-8 in adult rats result in: (1) an increase of NGF and BDNF protein and mRNA levels in the septum and hippocampus; (2) a down-regulation of TrkA and p75NTR and an up-regulation of TrkB; (3) reduced susceptibility to develop chemical kindling; (4) recovery of the PTZ-induced changes in the expression of neurotrophin receptors in the septal and hippocampal tissues. This data clearly indicates that CCK-induced variation of neurotrophin synthesis in brain is able to influence the susceptibility to develop seizures in adult rats most probably by counteracting the progressive neuronal dysfunction and/or damage.
在我们之前的研究中,我们证明腹腔注射神经递质/神经调节肽胆囊收缩素-8(CCK-8)可刺激神经营养因子神经生长因子(NGF)的合成,从而导致神经元损伤的结构和功能恢复。CCK-8这种神经营养因子介导的神经保护作用为更好地理解CCK的神经生物学和药理学特性开辟了新的视角。为了探究CCK诱导的脑内神经营养因子可用性增加可能产生的有益作用,我们比较了腹腔注射CCK-8对健康大鼠和使用亚惊厥剂量戊四氮(PTZ)的化学点燃模型的影响。在治疗期间监测行为变化,并根据六点量表进行分类。治疗3周(12次试验)后,PTZ组大鼠出现全身性阵挛-强直发作(5级行为)。因此,选择这个时间点来比较CCK-8治疗对隔区和海马中NGF、脑源性神经营养因子(BDNF)及其受体表达的影响。我们发现,成年大鼠反复腹腔注射CCK-8会导致:(1)隔区和海马中NGF和BDNF蛋白及mRNA水平增加;(2)TrkA和p75NTR下调,TrkB上调;(3)对化学点燃的易感性降低;(4)PTZ诱导的隔区和海马组织中神经营养因子受体表达变化得到恢复。这些数据清楚地表明,CCK诱导的脑内神经营养因子合成变化能够影响成年大鼠发生癫痫的易感性,很可能是通过抵消渐进性神经元功能障碍和/或损伤来实现的。