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Methylcobalamin (MeCbl) is a vitamin B12 analog that has some positive effects on peripheral nervous disorders. Although some previous studies revealed the effects of MeCbl on neurons, its effect on the muscle, which is the final target of motoneuron axons, remains to be elucidated. This study aimed to determine the effect of MeCbl on the muscle. We found that MeCbl promoted the proliferation and migration of C2C12 myoblasts in vitro and that these effects are mediated by the Erk1/2 signaling pathway without affecting the activity of the Akt signaling pathway. We also demonstrated that MeCbl inhibits C2C12 cell apoptosis during differentiation. Our results suggest that MeCbl has beneficial effects on the muscle in vitro. MeCbl administration may provide a novel therapeutic approach for muscle injury or degenerating muscle after denervation.

It has been suggested that interleukin-6 (IL-6) plays a key role in the pathogenesis of rheumatoid arthritis (RA), including osteoporosis not only in inflamed joints but also in the whole body. However, previous in vitro studies regarding the effects of IL-6 on osteoblast differentiation are inconsistent. The aim of this study was to examine the effects and signal transduction of IL-6 on osteoblast differentiation in MC3T3-E1 cells and primary murine calvarial osteoblasts. IL-6 and its soluble receptor significantly reduced alkaline phosphatase (ALP) activity, the expression of osteoblastic genes (Runx2, osterix, and osteocalcin), and mineralization in a dose-dependent manner, which indicates negative effects of IL-6 on osteoblast differentiation. Signal transduction studies demonstrated that IL-6 activated not only two major signaling pathways, SHP2/MEK/ERK and JAK/STAT3, but also the SHP2/PI3K/Akt2 signaling pathway. The negative effect of IL-6 on osteoblast differentiation was restored by inhibition of MEK as well as PI3K, while it was enhanced by inhibition of STAT3. Knockdown of MEK2 and Akt2 transfected with siRNA enhanced ALP activity and gene expression of Runx2. These results indicate that IL-6 negatively regulates osteoblast differentiation through SHP2/MEK2/ERK and SHP2/PI3K/Akt2 pathways, while affecting it positively through JAK/STAT3. Inhibition of MEK2 and Akt2 signaling in osteoblasts might be of potential use in the treatment of osteoporosis in RA.

Neuropathic pain caused by nerve damage in the central and/or peripheral nervous systems is a refractory disorder and the management of such chronic pain has become a major issue. Neurotropin is a drug widely used in Japan and China to treat chronic pain. Although Neurotropin has been demonstrated to suppress chronic pain through the descending pain inhibitory system, the mechanism of analgesic action in the peripheral nervous system remains to be elucidated. In this study, we investigated the local effects of Neurotropin on peripheral nerve damage in a chronic constriction injury (CCI) model. Neurotropin reduced mRNA expressions of IL-1β, IL-6, and TNF-α in the sciatic nerve 1 day after the injury. Activation of Erk was also inhibited locally in the Neurotropin treatment group. Since Erk activation results in demyelination along with dedifferentiation of Schwann cells, we investigated the expression level of myelin basic protein. Five days after the injury, Neurotropin attenuated the downregulation of myelin basic protein in the sciatic nerve in the CCI model. Local effects of Neurotropin around the injury site may result in discovery of new treatments for not only neuropathic pain but also demyelinating diseases and peripheral nervous system injury.

Methylcobalamin (MeCbl), a vitamin B12 analog, promotes neurite outgrowth by activating Akt in neurons. However, Akt is involved in many cellular functions, and the downstream signal of Akt that promotes neurite outgrowth in neurons in the presence of MeCbl remains obscure. Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that regulates multiple cellular functions including neurite outgrowth. mTOR is regarded as important for the regeneration of injured nerves. In this study, we examined the relationship between MeCbl and mTOR activity and found that MeCbl increases mTOR activity via the activation of Akt and promotes neurite outgrowth in cerebellar granule neurons via the activation of mTOR.

In the course of study on the dynamic morphology of astrocytes grown in vitro, special attention was paid to the acclimatizing features of processes of astrocytes, to the astrocytes with highly flattened cytoplasm and to the pinocytotic process of unusually large droplets observed in these astrocytes.In the series of mulifarious features observed in the processes of cultured astrocytes, there can be recognized two morphological ‘extremes’; 1. a wide, thin, membrane-like ‘flattened process’, and 2. a fibrous, slender, wire-like ‘condensed process’. Both seem to be highly acclimatized expressions of usual protoplasmic processes to enviromental conditions.The acclimatizing astrocytes with highly flattened processes were named ‘flattened astrocytes’.In the flattened astrocyte, pinocytic granules of unusual size (5-10μ) are occasionally found. These large granules are contacted by several minute phase-dense granules (0.3-1.5μ) with acid phosphatase activity. They may possibly correspond to the microkinetoshere (ROSE 1957a, b) or the lysosome (de DUVE et al. 1955).As a result of interplay between a large pinocytic granule and the minute phasedense granules, there is produced a medium-sized phase-dense granule (2.0-3.5μ). The possible relation of the medium-sized granules to the segresome (TANAKA 1960) or the cytolysome (NOVIKOFF 1959) was discussed.From the information at hand, the pinocytosis in cultured astrocytes per se can not be considered a degenerative process, although it is not an indispensable activity of the cell.

The area of the reticular formation of the brain stem of several newborn and young manmals was cultivated in vitro. Neurons were observed for a period up to 54 days. At the end of this period in many preparations they still exhibited signs of chromatolysis as judged by the eccentric position of the nuclei and the peripheral location of the Nissl material. It has been impossible thus far to identify particular neurons as belonging to a particular nucleus of the reticular formation, probably due to slight morphological and structural changes of these cells in vitro. Although the oldest neurons observed were kept only 54 days in vitro it seems likely that they could have been maintained for a longer time since their appearance indicated more regenerative rather than degenerative features.

1. The fate of the embryonal granule cells have been the object of the strenuous study and opinion is still divided. In order to pursue this problem by means of tissue culture, identification was attempted as the first step in this present report.2. The most striking feature of the tissue culture of the cerebellar cortex of the kitten and pnppy younger than 3 weeks after birth is the tremendous migration of the small cells. Among the small cells in the cerebellar cortex of the animals in this stage, the internal granule cells, glial cells and the small cells of the cortex are considered besides the embryonal granule cells.But from the facts as follows the majority of the small cells are considered to belong to the embryonal granular layer.a) The embryonal granule cells which are observed in the cerebellar cortex pressed between the cover glass and slide glass look very much like the small cells migrated in the tissue culture of cerebellar cortex of young animals.b) These small cells do not appear in the tissue culture of the cerebellar cortex of the animals mature enough to lose the embryonal granular layer.c) The small cells which appear in the tissue culture of parts of the brain other than the cerebellar cortex can be identified with the oligodendroglia, immature oligodendroglia and indifferentiated cells. Some of them remain difficult to differentiate from the embryonal granule cells, but this is rather natural considering the entity of the embryonal granule cells.d) The embryonal granule cells seen in the tissue culture correspond well to the cells which have been reported so far by several authors in silver impregnated preparations.3. Discussion was made about the differentiation of the small cells from the oligodendroglia and other indifferentiated cells. Mention was made also on the internal granule cells cultivated in vitro.

Based on the normal histological findings and the organization of the spinal afferents revealed by the Nauta and the Marchi methods, a cell group corresponding to the lateral cervical nucleus (NCL) of the cat was identified in the first and the second cervical segments of the spinal cord of the Japanese monkey (Macaca fuscata). The nucleus begins to appear at the level of the caudal end of the gracile nucleus and gradually disappears within the caudal half of the second cervical segment of the cord. The nucleus consists of medium-sized and small-sized nerve cells and receives spinal afferents ascending through the lateral funiculus, probably chiefly through the posterior spino-cerebellar tract, from lower levels of the spinal cord. The spinal afferents seem to take origin entirely, or at least chiefly, from the ipsilateral spinal gray and to terminate in the nucleus without any localization. Some problems concerning the lateral cervical nucleus as the site of the spino-thalamic tract have also been discussed from the point of view of comparative anatomy.

Attempts were made to identify the living granule cells in the cultures of the mouse cerebellar cortex.1. When 10 days or more old mice are used as culture materials, thousands of small cells with scanty cytoplasm can be identified as granule cells on the basis of a) their size, b) their nuclear morphology, c) their vast numbers in cultures, d) their characteristic processes depicted by the silver impregnation, e) absence of cells in the embryonal granular layer in impregnated cultures, and f) the fact that they are discernible even in cultures from 20 days old mice in which the embryonal granular layer has already disappeared.2. When newborn mice are cultivated, granule cell neurons cannot be distinguished in the living state from cells in the embryonal granular layer.3. Oligodendrocytes situated in the explant cannot generally be differentiated from granule cells in the living state.4. These granule cells are more vulnerable to various unfavorable conditions, e. g. the acidic or hypertonic state of the culture media.5. Small myelinated perikarya are frequently noted among these granule cells. They are often apposed to myelinated axons.

In order to study the frequency of occurrence of Barnes' ventrolateral pyramidal tract, the lower parts of the medulla oblongata and the upper three cervical segments of the spinal cords of 210 adult Japanese were examined histologically. The tracts were encountered in 43 out of 210 cases (20.5 ± 2.8%); bilaterally in (7.6 ± 1.8%), and unilaterally in 27 (12.9 ± 2.3%) cases. Consequently the tracts were found to be present in 59 out of 420 sides (14.0 ± 1.7%). Sex diffierence was not statistically significant (χ2 = 0.6, d.f. = 1, p > 0.25).