Differentiation of NSC-34 cells is characterized by expression of NGF receptor p75, glutaminase and NCAM L1, activation of mitochondria, and sensitivity to fatty acid intervention

Ca2+ signaling-mediated low-intensity pulsed ultrasound-induced proliferation and activation of motor neuron cells

Motor neuron diseases (MND) including amyotrophic lateral sclerosis and Parkinson disease are commonly neurodegenerative, causing a gradual loss of nerve cells and affecting the mechanisms underlying changes in calcium (Ca²⁺)-regulated dendritic growth. In this study, the NSC-34 cell line, a population of hybridomas generated using mouse spinal cord cells with neuroblastoma, was used to investigate the effect of low-intensity pulsed ultrasound (LIPUS) as part of an MND treatment model. After NSC-34 cells were seeded for 24 h, LIPUS stimulation was performed on the cells at days 1 and 3 using a non-focused transducer at 1.15 MHz for 8 min. NSC-34 cell proliferation and morphological changes were observed at various LIPUS intensities and different combinations of Ca²⁺ channel blockers. The nuclear translocation of Ca²⁺-dependent transcription factors was also examined. We observed that the neurite outgrowth and cell number of NSC-34 significantly increased with LIPUS stimulation at days 2 and 4, which may be associated with the treatment's positive effect on the activation of Ca²⁺-dependent transcription factors, such as nuclear factor of activated T cells and nuclear factor-kappa B. Our findings suggest that the LIPUS-induced Ca²⁺ signaling and transcription factor activation facilitate the morphological maturation and proliferation of NSC-34 cells, presenting a promising noninvasive method to improve stimulation therapy for MNDs in the future.

Cannabis terpenes display variable protective and anti-aggregatory actions against neurotoxic β amyloid in vitro: highlighting the protective bioactivity of α-bisabolol in motorneuronal-like NSC-34 cells

BACKGROUND

Terpenes form a diverse class of naturally occurring chemicals ascribed various biological activities. Cannabis contains over 400 different terpenes of varying chemical complexity which may add to the known biological activities of phytocannabinoids of relevance to the increasing use of medical cannabis; however, to date have been incompletely characterized. We assessed three terpenes predominant in cannabis: α-bisabolol, myrcene and β-caryophyllene for neuroprotective and anti-aggregative properties in both undifferentiated and differentiated NSC-34 motorneuronal-like cells as a sensitive model for neurotoxicity to oxidative stress and amyloid β (Aβ_1-42) protein exposure.

METHODS

Cell viability was assessed biochemically using the MTT assay in the presence of either α-bisabolol, myrcene and β-caryophyllene (1-1000µM) for 48hr. Sub-toxic threshold test concentrations of each terpene were then applied to cells, alone or with concomitant incubation with the lipid peroxidant tert-butyl hyrdroperoxide (t-BHP) or amyloid β (Aβ_1-42; 0-1µM) to assess neuroprotective effects. Direct effects of each terpene on Aβ fibril formation and aggregation were also evaluated using the Thioflavin T (ThT) fluorometric kinetic assay, circular dichroism and transmission electron microscopy (TEM) to visualise fibril and aggregate morphology.

RESULTS

Terpenes were intrinsically benign to NSC-34 cells up to 100µM. No significant antioxidant effects were observed following t-BHP administration with myrcene and β-caryophyllene, however α-bisabolol provided a modest but significant increase in cell viability in undifferentiated cells. α-bisabolol also demonstrated a significant neuroprotective effect against amyloid β exposure, with β-caryophyllene also providing a lesser, but significant increase in cell viability. Protective effects of terpenes were more pronounced in undifferentiated versus differentiated cells, attributable more so to an attenuated loss of cell viability in response to Aβ_1-42 following NSC-34 cell differentiation. Neuroprotection was associated with a direct inhibition of Aβ_1-42 fibril and aggregate density, evidenced by both attenuated ThT fluorescence kinetics and both spectral and microscopic evidence of altered and diminished density of Aβ aggregates. While myrcene and β-caryophyllene also elicited reductions in ThT fluorescence and alterations in Aβ aggregation, these were less well associated with neuroprotective capacity.

CONCLUSIONS

These findings highlight a neuroprotective role of α-bisabolol against Aβ-mediated neurotoxicity associated with an inhibition of Aβ fibrillization and modest antioxidant effect against lipid peroxidation, while β-caryophyllene also provided a small but significant measure of protection to Aβ-mediated neurotoxicity. Anti-aggregatory effects were not directly correlated with neuroprotective efficacy. This demonstrates that bioactivity of selected terpenes should be a consideration in the emergent use of medicinal cannabis formulations for the treatment of neurodegenerative diseases.

The Ryanodine receptor stabilizer S107 fails to support motor neuronal neuritogenesis in vitro

Calcium homeostasis is essential for neuronal cell survival/differentiation. Imbalance of the Ca2+ homeostasis due to excessive Ca2+ overload is essential for spinal cord injury (SCI). The overload resulted from Ca2+ flux across the plasma membrane and from internal Ca2+ store release (mitochondria, endoplasmic reticulum, ER). Inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) are involved in releasing Ca2+ from ER contributing to axonal degeneration following SCI. In turn, block of both receptors is axoprotective. The calstabin RyR subunit, stabilizing the channel in a state of reduced activity, prevents pathological Ca2+ release too. We investigated whether S107, a RyR-stabilizing compound (Rycal), is beneficial for survival and neuritogenesis of spinal cord motor neurons in vitro. We used a spinal cord slice model and the motor neuron-like NSC-34 cell line. Effects of S107 were tested by propidium iodide/fluorescein diacetate vital staining, mitotic index determination via BrdU-incorporation, and neurite sprouting parameters. Results showed that S107 (i) had no effect on gliosis resulting from slices preparation; (ii) had no effect on motor neuronal survival and proliferation; and (iii) impaired neurite sprouting, no matter whether it was a differentiation (NSC-34 cells) or regeneration (spinal cord slices) process. The results underline the need for a flexible Ca2+homeostasis provided by the ER for re-initiation of neuritogenesis.