Department of Physiology, Universidade Federal de São Paulo São Paulo, SP, Brazil.
Department of Biochemistry, Universidade Federal de São Paulo São Paulo, SP, Brazil.
Front Cell Neurosci. 2015 Mar 12;9:72. doi: 10.3389/fncel.2015.00072. eCollection 2015.
Intense activation of neurons triggers the appearance of immediate expression genes, including c-Fos. This gene is related to various signal cascades involved in biochemical processes such as neuronal plasticity, cell growth and mitosis. Here we investigate the expression pattern and the refractory period of c-Fos in rats and monkey's brains after stimulation with pentylenetetrazol. Rats and monkeys were sacrificed at various times after PTZ-induced seizure. Here we show that rats and monkeys already showed c-Fos expression at 0.5 h after seizure. Yet, the pattern of protein expression was longer in monkeys than rats, and also was not uniform (relative intensity) across different brain regions in monkeys as opposed to rats. In addition monkeys had a regional brain variation with regard to the temporal profile of c-Fos expression, which was not seen in rats. The refractory period after a second PTZ stimulation was also markedly different between rats and monkeys with the latter even showing a summatory effect on c-Fos expression after a second stimulation. However, assessment of c-Fos mRNA in rats indicated a post-transcriptional control mechanism underlying the duration of the refractory period. The difference in the protein expression pattern in rodents and primates characterizes a functional aspect of brain biochemistry that differs between these mammalian orders and may contribute for the more developed primate cognitive complexity as compared to rodents given c-Fos involvement in cognitive and learning tasks.
神经元的强烈激活会触发即时表达基因的出现，包括 c-Fos。该基因与涉及神经元可塑性、细胞生长和有丝分裂等生化过程的各种信号级联有关。在这里，我们研究了戊四氮（PTZ）诱导癫痫发作后大鼠和猴子大脑中 c-Fos 的表达模式和不应期。在 PTZ 诱导的癫痫发作后，大鼠和猴子在不同时间被处死。结果显示，大鼠和猴子在癫痫发作后 0.5 小时就已经出现 c-Fos 表达。然而，与大鼠相比，猴子的蛋白表达模式更长，并且在不同脑区的相对强度（relative intensity）也不均匀。此外，猴子的大脑区域在 c-Fos 表达的时间分布上存在差异，而大鼠则没有。第二次 PTZ 刺激后的不应期在大鼠和猴子之间也有明显差异，后者在第二次刺激后甚至出现了 c-Fos 表达的总和效应。然而，对大鼠 c-Fos mRNA 的评估表明，转录后控制机制是不应期持续时间的基础。啮齿动物和灵长类动物之间在蛋白表达模式上的差异，是这些哺乳动物目之间大脑生物化学功能方面的一个特征，并且可能有助于与啮齿动物相比，灵长类动物具有更发达的认知复杂性，因为 c-Fos 参与了认知和学习任务。
