Esposito Giuseppe, Giovacchini Giampiero, Der Margaret, Liow Jeih-San, Bhattacharjee Abesh K, Ma Kaizong, Herscovitch Peter, Channing Michael, Eckelman William C, Hallett Mark, Carson Richard E, Rapoport Stanley I
Brain Physiology and Metabolism Section, Bldg. 9, Rm. 1S128, National Institute on Aging, National Institutes of Health, 9 Memorial Drive, Bethesda, MD 20892, USA.
Neuroimage. 2007 Feb 15;34(4):1342-51. doi: 10.1016/j.neuroimage.2006.11.018. Epub 2006 Dec 29.
Arachidonic acid (AA, 20:4n-6), an important second messenger, is released from membrane phospholipid following receptor mediated activation of phospholipase A(2) (PLA(2)). This signaling process can be imaged in brain as a regional brain AA incorporation coefficient K*.
K* will be increased in brain visual areas of subjects submitted to visual stimulation.
Regional values of K* were measured with positron emission tomography (PET), following the intravenous injection of [1-(11)C]AA, in 16 healthy volunteers subjected to visual stimulation at flash frequencies 2.9 Hz (8 subjects) or 7.8 Hz (8 subjects), compared with the dark (0 Hz) condition. Regional cerebral blood flow (rCBF) was measured with intravenous [(15)O]water under comparable conditions.
During flash stimulation at 2.9 Hz or 7.8 Hz vs. 0 Hz, K* was increased significantly by 2.3-8.9% in Brodmann areas 17, 18 and 19, and in additional frontal, parietal and temporal cortical regions. rCBF was increased significantly by 3.1-22%, often in comparable regions. Increments at 7.8 Hz often exceeded those at 2.9 Hz for both K* and rCBF. Decrements in both parameters also were produced, particularly in frontal brain regions.
AA plays a role in signaling processes provoked by visual stimulation, since visual stimulation at flash frequencies of 2.9 and 7.8 Hz compared to 0 Hz modifies both K* for AA and rCBF in visual and related areas of the human brain. The two-stimulus condition paradigm of this study might be used with PET to image effects of other functional activations and of drugs on brain signaling via AA.
花生四烯酸（AA，20:4n - 6）是一种重要的第二信使，在受体介导的磷脂酶A2（PLA2）激活后从膜磷脂中释放出来。这个信号传导过程在大脑中可作为区域脑AA掺入系数K*进行成像。
接受视觉刺激的受试者大脑视觉区域的K*会增加。
在16名健康志愿者静脉注射[1 - （11）C]AA后，采用正电子发射断层扫描（PET）测量K*的区域值，这些志愿者分别在闪光频率为2.9 Hz（8名受试者）或7.8 Hz（8名受试者）的条件下接受视觉刺激，并与黑暗（0 Hz）条件进行比较。在类似条件下，通过静脉注射[（15）O]水测量局部脑血流量（rCBF）。
与0 Hz相比，在2.9 Hz或7.8 Hz的闪光刺激期间，Brodmann区域17、18和19以及额外的额叶、顶叶和颞叶皮质区域的K显著增加2.3 - 8.9%。rCBF显著增加3.1 - 22%，通常在类似区域。对于K和rCBF，7.8 Hz时的增加通常超过2.9 Hz时的增加。这两个参数也出现了下降，特别是在额叶脑区。
AA在视觉刺激引发的信号传导过程中起作用，因为与0 Hz相比，2.9 Hz和7.8 Hz闪光频率的视觉刺激会改变人脑视觉及相关区域中AA的K*和rCBF。本研究的双刺激条件范式可与PET一起用于成像其他功能激活和药物对通过AA的脑信号传导的影响。
