Gotoh J, Kuang T Y, Nakao Y, Cohen D M, Melzer P, Itoh Y, Pak H, Pettigrew K, Sokoloff L
Laboratory of Cerebral Metabolism, National Institute of Mental Health, Bethesda, Maryland 20892-4030, USA.
Am J Physiol Heart Circ Physiol. 2001 Feb;280(2):H821-9. doi: 10.1152/ajpheart.2001.280.2.H821.
Vibrissal stimulation raises cerebral blood flow (CBF) in the ipsilateral spinal and principal sensory trigeminal nuclei and contralateral ventroposteromedial (VPM) thalamic nucleus and barrel cortex. To investigate possible roles of adenosine and nitric oxide (NO) in these increases, local CBF was determined during unilateral vibrissal stimulation in unanesthetized rats after adenosine receptor blockade with caffeine or NO synthase inhibition with N(G)-nitro-L-arginine methyl ester (L-NAME) or 7-nitroindazole (7-NI). Caffeine lowered baseline CBF in all structures but reduced the percent increase during stimulation only in the two trigeminal nuclei. L-NAME and 7-NI lowered baseline CBF but reduced the percent increase during stimulation only in the higher stations of this sensory pathway, i.e., L-NAME in the VPM nucleus and 7-NI in both the VPM nucleus and barrel cortex. Combinations of caffeine with 7-NI or L-NAME did not have additive effects, and none alone or in combination completely eliminated functional activation of CBF. These results suggest that caffeine-sensitive and NO-dependent mechanisms are involved but with different regional distributions, and neither fully accounts for the functional activation of CBF.
触须刺激可增加同侧脊髓和三叉神经主感觉核、对侧腹后内侧（VPM）丘脑核以及桶状皮质的脑血流量（CBF）。为了研究腺苷和一氧化氮（NO）在这些增加过程中可能发挥的作用，在用咖啡因阻断腺苷受体或用N（G）-硝基-L-精氨酸甲酯（L-NAME）或7-硝基吲唑（7-NI）抑制一氧化氮合酶后，在未麻醉大鼠单侧触须刺激期间测定局部脑血流量。咖啡因降低了所有结构中的基线脑血流量，但仅在两个三叉神经核中降低了刺激期间的增加百分比。L-NAME和7-NI降低了基线脑血流量，但仅在该感觉通路的较高部位降低了刺激期间的增加百分比，即L-NAME作用于VPM核，7-NI作用于VPM核和桶状皮质。咖啡因与7-NI或L-NAME的组合没有相加作用，单独或联合使用均未完全消除脑血流量的功能激活。这些结果表明，涉及对咖啡因敏感和依赖NO的机制，但具有不同的区域分布，且两者均不能完全解释脑血流量的功能激活。
