The insect molting hormone 20-hydroxyecdysone protects dopaminergic neurons against MPTP-induced neurotoxicity in a mouse model of Parkinson's disease
FREE RADICAL BIOLOGY AND MEDICINE
Authors: Lim, Hye-Sun; Moon, Byeong Cheol; Lee, Jun; Choi, Goya; Park, Gunhyuk
Abstract
20-hydroxyecdysone (20E), a steroidal prohormone, is secreted from the prothoracic glands. While 20E has been shown to have neuroprotective effects in Parkinson's disease (PD) models in vitro, its effects have not yet been examined in vivo. We sought to assess the behavioral and mechanistic effects of 20E on MPTP-induced toxicity in mice. To this end, we used behavioral tests, stereological analyses of dopaminergic neurons by tyrosine hydroxylase immunohistochemistry, and assessments of apoptotic mechanisms, focusing on Nrf2 signaling through Western blotting and ELISA assays. A 20E treatment protected against MPTP-induced motor incoordination, postural imbalance, and bradykinesia, and significantly reduced dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc) and the striatum (ST). It also attenuated dopamine deficiency in the ST, modulated levels of antioxidative enzymes superoxide dismutase, catalase, and glutathione in the SNpc, increased the Bcl-2/Box ratio, and inhibited cytosolic cytochrome c release and caspase-9, -7, and -3 activity in the SNpc. These results indicated that 20E inhibited the apoptotic cascade. Furthermore, the attenuation of MPTP neurotoxicity was associated with inhibited cleaved-caspase signaling pathways, along with upregulated Nrf2 pathways in the SNpc, suggesting that 20E mitigates MPTP-induced neurotoxicity via mitochondria-mediated apoptosis by modulating anti-oxidative activities. Our results suggest that 20E can inhibit MPTP-induced behavioral and neurotoxic effects in mice. This lays the foundation for further research on 20E as a potential target for therapeutic use.
Yohimbine Ameliorates Temporomandibular Joint Chondrocyte Inflammation with Suppression of NF-kappa B Pathway
INFLAMMATION
Authors: Ou, Farong; Huang, Yihuan; Sun, Jiadong; Su, Kai; He, Yiqing; Zeng, Rongsheng; Tang, Dongxiao; Liao, Guiqing
Abstract
Local joint inflammation plays an important role in the pathogenesis of temporomandibular joint (TMJ) osteoarthrosis (TMJOA). Yohimbine, an alpha-2 adrenergic receptor antagonist, possesses anti-inflammatory properties; however, the ability of Yohimbine to protect against TMJOA-associated chondrocyte inflammation remains unclear. We conductedin vitroandin vivoanalyses to investigate whether Yohimbine could ameliorate TMJOA-induced chondrocyte inflammation and to elucidate the mechanisms involved. Chondrocytes of TMJOA mice were stimulated with interleukin (IL)-1 beta or noradrenaline (NE), and the resulting production of inflammation-related factors was evaluated in the presence or absence of Yohimbine. Furthermore, two TMJOA mouse models were treated with Yohimbine and the therapeutic effect was quantified. NE (10(-6)M) triggered inflammatory cytokine secretion by TMJ chondrocytes, and Yohimbine suppressed IL-1 beta- or NE-induced IL-6 upregulation in TMJ chondrocytes with the nuclear factor (NF)-kappa B pathway inhibition. Yohimbine also ameliorated cartilage destruction in the TMJOA models. Interestingly, alpha mpT, a tyrosine hydroxylase inhibitor, reversed the effects of Yohimbine by activating the NF-kappa B pathway. Collectively, these findings show that Yohimbine ameliorated TMJ chondrocyte inflammation and the suppression of NF-kappa B pathway contributes to this effect.