Immortalized Mouse Dopaminergic Neuronal Cells (MN9D)

Effects of Propofol alone or Combined with Curcumin on the Cell Viability of MN9D Cells

Propofol abuse can cause neurotoxicity and cognitive deficits. Autophagy dysregulation contributes to neuronal injury. Curcumin is a natural polyphenol derived from the turmeric plant, and it has neuroprotective and cognition-enhancing properties. He's team investigated whether curcumin protects MN9D dopaminergic cells against propofol-induced neurotoxicity by modulating autophagy via the Akt/mTOR/p70S6K signaling pathway.

They first evaluated MN9D cell cytotoxicity using CCK-8 assays. Methanol was used as a solvent and a negative control due to the hydrophobicity of curcumin. Cells were treated with 1-80 μM curcumin or 5-80 μg/mL propofol for 24 h (Fig.1c and d). Curcumin had low toxicity, even at 80 μM. Propofol was dose-dependently cytotoxic (viability was reduced to about 80% at 40 μg/mL) and decreased cell density. Therefore, 40 μg/mL propofol was used with 10-40 μM curcumin to explore neuroprotection (Fig. 1e and f). After 24 h, propofol-treated cells were smaller in size with decreased nodules, but curcumin co-treated cells had an almost 90% viability and exhibited protection from propofol-induced senescence with spindle-like morphology.

Fig. 1. Impact of propofol alone or in combination with curcumin on MN9D cell growth (He H X, Han Y P, et al., 2024).

Rotenone and Antimycin A Significantly Reduced ATP Production and Disrupt Catecholamine Biosynthesis in MN9D Cells

Mitochondrial dysfunction is central to Parkinson's disease (PD), as dopaminergic neurons are highly susceptible to oxidative stress and energy depletion. Rotenone (Complex I inhibitor) and antimycin A (Complex III inhibitor) disrupt mitochondrial function, but their comparative effects on dopaminergic neurons remain unclear.

Adetuyi et al. investigated how rotenone and antimycin A induce energy depletion, oxidative stress, and neuronal death in MN9D dopaminergic cells to elucidate their roles in PD pathogenesis. Figure 2 demonstrates ATP levels in MN9D cells treated with mitochondrial toxins. Cells exposed to rotenone (1.5 µM) or antimycin A (10 µM) for 1 hour showed significantly reduced ATP production compared to control (KRB-HEPES buffer, pH 7.5), measured via colorimetric/fluorometric assays. To assess catecholamine biosynthesis, cells were treated with rotenone (1.5 µM), antimycin A (10 µM), or tetrabenazine (1 µM) for 1 hour. Figure 3a-c reveals that all three toxins markedly decreased dopamine levels versus control, as quantified by HPLC.

Fig. 2. Effect of Toxins treatment on ATP level (Adetuyi OA, Wimalasena K, et al., 2025).

Fig. 3. Rotenone and Antimycin A disrupt catecholamine biosynthesis (Adetuyi OA, Wimalasena K, et al., 2025).