Kukulski Filip, Sévigny Jean, Komoszyński Michał
Department of Biochemistry, Institute of General and Molecular Biology, N. Copernicus University of Toruń, Toruń, Poland.
Brain Res. 2004 Dec 24;1030(1):49-56. doi: 10.1016/j.brainres.2004.09.044.
We have investigated the metabolism of extracellular adenine nucleotides and adenosine in porcine brain. The cortex synaptic plasma membranes hydrolyzed ATP to ADP, AMP and adenosine. We also observed a slow hydrolysis of adenosine with the concomitant accumulation of inosine. These results indicate that NTPDase1, NTPDase2, ecto-5'-nucleotidase, and adenosine deaminase are present in cortex synaptic membranes from porcine brain. We further showed that all these enzymes are also abundant in synaptic membranes from hippocampus, cerebellum, and medulla oblongata and compared their specific activities. Brain cortex and hippocampus exhibited higher activities of NTPDase1 and NTPDase2 than cerebellum and medulla oblongata. It was consistent with the high level of the expression of NTPDases in the two first structures. Adenosine deaminase activity was found in all brain structures analyzed; however, it was lower than the activity of ecto-nucleotidases. Taken together, our data suggest that investigated enzymes have a ubiquitous abundance in porcine brain, and observed differences in their activities in cortex, hippocampus, cerebellum, and medulla oblongata may correlate with the pattern of P2 receptor expression in these brain areas. In addition, low activity of adenosine deaminase may indicate that nonenzymatic mechanism(s) are responsible for the termination of P1 receptor signaling in porcine brain.
我们研究了猪脑中细胞外腺嘌呤核苷酸和腺苷的代谢。大脑皮质突触质膜可将ATP水解为ADP、AMP和腺苷。我们还观察到腺苷的缓慢水解以及肌苷的伴随积累。这些结果表明，NTPDase1、NTPDase2、胞外5'-核苷酸酶和腺苷脱氨酶存在于猪脑皮质突触膜中。我们进一步表明，所有这些酶在海马体、小脑和延髓的突触膜中也很丰富，并比较了它们的比活性。大脑皮质和海马体中NTPDase1和NTPDase2的活性高于小脑和延髓。这与前两个结构中NTPDases的高表达水平一致。在所分析的所有脑结构中均发现了腺苷脱氨酶活性；然而，它低于胞外核苷酸酶的活性。综上所述，我们的数据表明，所研究的酶在猪脑中普遍存在，并且在皮质、海马体、小脑和延髓中观察到的它们活性的差异可能与这些脑区中P2受体的表达模式相关。此外，腺苷脱氨酶的低活性可能表明非酶机制负责猪脑中P1受体信号的终止。
