Immunohistochemical detection of calcium/calmodulin‐dependent protein kinase II in the spinal cord of the rat and monkey with special reference to the corticospinal tract

Abstract

Calcium/calmodulin-dependent protein kinase II is a prominent enzyme in the mammalian brain that phosphorylates a variety of substrate proteins. In the present study, monoclonal antibodies that specifically recognize either the alpha or the beta isoforms of this enzyme were used to determine the distribution of these isoforms within the rat and monkey spinal cord. In the rat, the corticospinal tract consists of two components: the dorsal corticospinal tract, which occupies the ventralmost aspect of the dorsal funiculus; and the ventral corticospinal tract, which occupies an area adjacent to the ventral median fissure. Both dorsal and ventral corticospinal tract fibers were strongly immunopositive for the alpha-antibody. Unilateral ablation of the sensorimotor cortex of the rat eliminated the alpha-immunoreactive staining in the contralateral dorsal corticospinal tract. The neuropil in the superficial laminae of the dorsal horn (Rexed's laminae I and II) was densely stained with the alpha-antibody, whereas the neuropil in laminae IV-X was immunonegative. Dense alpha-immunopositive neurons were also distributed in the head of the dorsal horn (laminae I-IV). In contrast to the strong alpha-immunoreactivity seen in the dorsal corticospinal tract fibers, only very weak beta-immunoreactivity was observed in this tract. Moderate beta-immunoreactive products were distributed homogenously throughout the neuropil of the gray matter, although the neuropil of the superficial laminae of the dorsal horn (laminae I and II) was stained more strongly than the other regions of the gray matter (laminae III-X). Neuronal components in all laminae were immunopositive for the beta-antibody. Thus, motoneurons in the ventral horn, which were immunonegative for the alpha-antibody, were immunopositive for the beta-antibody. This selective distribution pattern of immunoreactivity of alpha- and beta-antibodies in the rat was also present in the monkey spinal cord, although the alpha-immunopositive corticospinal tract fibers in the monkey descended in the lateral funiculus as the lateral corticospinal tract instead of passing through the dorsal funiculus, as is the case in the rat. The differential distribution of immunoreactivity in the spinal cord suggests that these two isoforms of calcium/calmodulin-dependent protein kinase II may have different functional roles in the spinal cord.

Localization of the calcium/calmodulin-dependent protein phosphatase, calcineurin, in the hindbrain and spinal cord of the rat

“…The results suggest that CaN is not simply an enzyme involved in general cell physiology but, rather, has cell-specific roles in calcium signaling. Interestingly, other calcium-activated enzymes, such as Cah4 kinase I1 (Terashima et al, 1994; this study) and pand y-isoforms of protein kinase C (Mori et al, 1990) are much more widely expressed in the spinal cord. Insofar as the antibody used in this study recognizes the a-isoform of the CaN catalytic subunit, it is possible that unstained structures contain high levels of other isoforms of the phosphatase.…”

In VivoTracing of Neural Tracts in the Intact and Injured Spinal Cord of Marmosets by Diffusion Tensor Tractography

“…As primates, they are closely related to humans in terms of neurofunctional anatomy of the spinal cord. For example, the CST fibers localize mainly in the dorsal funiculus in rodents, whereas in primates they are mainly located in the lateral funiculus (Qiu et al, 1991;Terashima et al, 1994;Lacroix et al, 2004;Lemon et al, 2004;Iwanami et al, 2005a). From a practical standpoint, common marmosets are easy to handle, breed effectively, and are small enough to fit into the narrow MRI coil.…”

“…The direction of diffusion anisotropy was followed until tracking was terminated when it reached a voxel with a fractional anisotropy of Ͻ0.25. To delineate the motor tracts, the seed was placed on the area histologically known to contain CaMKII-␣-positive fibers in the upper cervical cord, which corresponds to the CST (Terashima et al, 1994;Iwanami et al, 2005a). To delineate the afferent pathways of the spinal cord, we placed the seed at the anterolateral and posterior funiculi of the lower cervical cord, which correspond to the spinothalamic tract and the gracile fasciculus, respectively.…”

“…Analysis of histological sections stained for calmodulindependent protein kinase II-␣ (CaMKII-␣) determined the location of the CST (Terashima et al, 1994;Iwanami et al, 2005a) within the medulla, and DTT of the CST was performed by setting the ROI, which is a manually selected area based on anatomical knowledge from which DTT fiber tracking was initiated, in the pyramid of the medulla and tracing caudally (Fig. 3A).…”

Neuronal Ca2+/Calmodulin-Dependent Protein Kinase II-Discovery, Progress in a Quarter of a Century, and Perspective: Implication for Learning and Memory

“…64) A different distribution of a and b isoforms is also examined in spinal cord of rat and monkey. 65) Both dorsal and ventral corticospinal tract fibers are strongly immunoreactive for the a-antibody. In these regions, very weak immunoreactivity is observed for the b-antibody.…”