de Gortari Patricia, Vargas Miguel Angel, Martínez Adrián, García-Vázquez Arlene I, Uribe Rosa María, Chávez-Gutiérrez Lucía, Magdaleno Víctor, Boileau Guy, Charlí Jean-Louis, Joseph-Bravo Patricia
Div. Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñíz, México D.F., México.
J Mol Neurosci. 2007;33(3):252-61. doi: 10.1007/s12031-007-0020-9. Epub 2007 Apr 17.
Aminopeptidase N (APN) and neprilysin (NEP) inactivate neuropeptides released into the brain extracellular fluid. We previously showed that the expression of pyroglutamyl peptidase II (PPII), the TRH degrading ecto-enzyme, is regulated in rat brain by amygdaline kindling, a paradigm that activates neuronal pathways in the limbic system increasing the expression of several neuropeptides including TRH and opioids. To understand the specificity of this phenomenon, we studied APN and NEP expression in brains of partially or fully kindled rats (stage II and V), sacrificed 6 h after last stimulus, compared with sham-operated animals. In situ hybridization analysis of NEP mRNA levels showed decreased expression at stage II in CA1, CA2, olfactory tubercle and medial mammillary nucleus, and increased at stage V in CA1 and CA2 cells. These changes were specific for the ipsilateral side. APN mRNA levels, semi-quantified by RT-PCR, were decreased at stage II and increased at stage V, in frontal cortex-olfactory tubercle, and hippocampus. NEP and APN enzymatic activities, determined by fluorometric assays, followed similar variations to their respective mRNA levels. The coordinated changes (in some regions) of NEP and APN expression were opposite to those previously observed for PPII mRNA and activity levels in limbic regions. These results demonstrate that expression of ectopeptidases can be regulated when peptide neurons are activated and, that regulation is enzyme-, region-, and stage-specific.
氨肽酶N（APN）和中性内肽酶（NEP）可使释放到脑细胞外液中的神经肽失活。我们之前发现，焦谷氨酸肽酶II（PPII），即TRH降解外切酶的表达，在大鼠脑中受杏仁核点燃调节，这是一种激活边缘系统神经元通路的模式，会增加包括TRH和阿片类物质在内的多种神经肽的表达。为了解这种现象的特异性，我们研究了部分或完全点燃大鼠（II期和V期）在末次刺激6小时后处死的大脑中APN和NEP的表达，并与假手术动物进行比较。NEP mRNA水平的原位杂交分析显示，在II期，CA1、CA2、嗅结节和内侧乳头体核中的表达降低，而在V期，CA1和CA2细胞中的表达增加。这些变化在同侧具有特异性。通过RT-PCR半定量分析的APN mRNA水平，在II期降低，在V期，在额叶皮质-嗅结节和海马中升高。通过荧光测定法测定的NEP和APN酶活性，与其各自的mRNA水平呈现相似的变化。NEP和APN表达的协同变化（在某些区域）与之前在边缘区域观察到的PPII mRNA和活性水平的变化相反。这些结果表明，当肽能神经元被激活时，外肽酶的表达可以受到调节，而且这种调节具有酶、区域和阶段特异性。
