Strack S, Wadzinski B E, Ebner F F
Institute for Developmental Neuroscience, Vanderbilt University, Nashville, Tennessee 37203, USA.
J Comp Neurol. 1996 Nov 4;375(1):66-76. doi: 10.1002/(SICI)1096-9861(19961104)375:1<66::AID-CNE4>3.0.CO;2-M.
The calcium/calmodulin-dependent protein phosphatase calcineurin was localized at the light microscopic level in the rat hindbrain and spinal cord by using an antibody against the alpha-isoform of the catalytic subunit. Calcineurin was highly concentrated in axons, dendrites, and cell bodies of a subpopulation of alpha-motoneurons in hindbrain motor nuclei and the lateral motor column along the length of the spinal cord. These calcineurin-positive alpha-motoneurons appeared to be randomly distributed and represented approximately 25% of the total alpha-motoneuron pool in the motor trigeminal nucleus and the spinal cord lateral motor column. Within the facial nucleus, calcineurin-containing motoneurons were present in the medial and dorsal subdivision but not in the lateral and intermediate subdivision. In addition to the enrichment in motoneurons, calcineurin was enriched in cells of the superficial laminae of the spinal cord dorsal horn and its extension into the medulla, the caudal spinal trigeminal nucleus. Axonal staining in the white matter of the spinal cord was generally weak, except in the dorsolateral funiculus, where strongly calcineurin-positive axons formed a putative ascending tract that appeared to terminate uncrossed in the caudal lateral reticular nucleus of the medulla. This tract may originate from calcineurin-positive cells in the dorsolateral funiculus. We also compared the distribution of calcineurin with calcium/calmodulin-dependent kinase II in the spinal cord and found that the kinase is more widely expressed. Thus, calcineurin is highly restricted to a few locations in the hindbrain and spinal cord. Selective staining in facial subnuclei that innervate phasically active muscles suggests that calcineurin-positive motoneurons represent a subset of alpha-motoneurons innervating a metabolic subtype of muscle fibers, possibly fast-twitch fibers.
利用针对催化亚基α-异构体的抗体，在光学显微镜水平上对大鼠后脑和脊髓中的钙/钙调蛋白依赖性蛋白磷酸酶钙调神经磷酸酶进行了定位。钙调神经磷酸酶高度集中于后脑运动核和沿脊髓全长的外侧运动柱中α运动神经元亚群的轴突、树突和细胞体中。这些钙调神经磷酸酶阳性的α运动神经元似乎是随机分布的，约占三叉神经运动核和脊髓外侧运动柱中α运动神经元总数的25%。在面神经核内，含钙调神经磷酸酶的运动神经元存在于内侧和背侧亚核，而外侧和中间亚核中则没有。除了在运动神经元中富集外，钙调神经磷酸酶还富集于脊髓背角浅层及其向延髓延伸部分（尾侧脊髓三叉神经核）的细胞中。脊髓白质中的轴突染色通常较弱，但在背外侧索中除外，在背外侧索中，钙调神经磷酸酶强阳性的轴突形成一条假定的上行束，似乎不交叉地终止于延髓尾侧外侧网状核。这条束可能起源于背外侧索中的钙调神经磷酸酶阳性细胞。我们还比较了钙调神经磷酸酶与钙/钙调蛋白依赖性激酶II在脊髓中的分布，发现该激酶表达更为广泛。因此，钙调神经磷酸酶高度局限于后脑和脊髓中的少数位置。对面部支配相位性活动肌肉的亚核进行的选择性染色表明，钙调神经磷酸酶阳性运动神经元代表支配肌肉纤维代谢亚型（可能是快肌纤维）的α运动神经元的一个子集。
