N-acetylcysteine increases dopamine release and prevents the deleterious effects of 6-OHDA on the expression of VMAT2, α-synuclein, and tyrosine hydroxylase.

OBJECTIVES: Current treatments for Parkinson's disease using pharmacological approaches alleviate motor symptoms but do not prevent neuronal loss or dysregulation of dopamine neurotransmission. In this article, we have explored the molecular mechanisms underlying the neuroprotective effect of the antioxidant N-acetylcysteine (NAC) on the damaged dopamine system. METHODS: SH-SY5Y cells were differentiated towards a dopaminergic phenotype and exposed to 6-hydroxydopamine (6-OHDA) to establish an in vitro model of Parkinson's disease. We examined the potential of NAC to restore the pathological effects of 6-OHDA on cell survival, dopamine synthesis as well as on key proteins regulating dopamine metabolism. Specifically, we evaluated gene- and protein expression of tyrosine hydroxylase (TH), vesicle monoamine transporter 2 (VMAT2), and α-synuclein, by using qPCR and Western blot techniques. Moreover, we quantified the effect of NAC on total dopamine levels using a dopamine ELISA assay. RESULTS: Our results indicate that NAC has a neuroprotective role in SH-SY5Y cells exposed to 6-OHDA by maintaining cell proliferation and decreasing apoptosis. Additionally, we demonstrated that NAC treatment increases dopamine release and protects SH-SY5Y cells against 6-OHDA dysregulations on the proteins TH, VMAT2, and α-synuclein. CONCLUSIONS: Our findings contribute to the validation of compounds capable to restore dopamine homeostasis and shed light on the metabolic pathways that could be targeted to normalize dopamine turnover. Furthermore, our results highlight the effectiveness of the antioxidant NAC in the prevention of dopaminergic neurodegeneration in the present model. ABBREVIATIONS: DAT, dopamine transporter; 6-OHDA, 6-hydroxydopamine; NAC, N-acetylcysteine; PARP, poly (ADP-ribose) polymerase; RA; retinoic acid; ROS, reactive oxygen species; TH, tyrosine hydroxylase; TPA, 12-O-tetradecanoyl-phorbol-13-acetate; VMAT2, vesicle monoamine transporter 2.

Tendinosis-like changes in denervated rat Achilles tendon.

BACKGROUND: Tendon disorders are common and lead to significant disability and pain. Our knowledge of the 'tennis elbow', the 'jumpers knee', and Achilles tendinosis has increased over the years, but changes in denervated tendons is yet to be described in detail. The aim of the present study was to investigate the morphological and biochemical changes in tendon tissue following two weeks of denervation using a unilateral sciatic nerve transection model in rat Achilles tendons. METHODS: Tendons were compared with respect to cell number, nuclear roundness, and fiber structure. The non-denervated contralateral tendon served as a control. Also, the expression of neuromodulators such as substance P and its preferred receptor neurokinin-1 receptor, NK-1R, was evaluated using real-time qRT-PCR. RESULTS: Our results showed that denervated tendons expressed morphological changes such as hypercellularity; disfigured cells; disorganization of the collagen network; increased production of type III collagen; and increased expression of NK-1R. CONCLUSION: Taken together these data provide new insights into the histopathology of denervated tendons showing that denervation causes somewhat similar changes in the Achilles tendon as does tendinosis in rats.

Adipose stem cells enhance myoblast proliferation via acetylcholine and extracellular signal-regulated kinase 1/2 signaling.

INTRODUCTION: In this study we investigated the interaction between adipose tissue-derived stem cells (ASCs) and myoblasts in co-culture experiments. METHODS: Specific inductive media were used to differentiate ASCs in vitro into a Schwann cell-like phenotype (differentiated adipose tissue-derived stem cells, or dASCs) and, subsequently, the expression of acetylcholine (ACh)-related machinery was determined. In addition, the expression of muscarinic ACh receptors was examined in denervated rat gastrocnemius muscles. RESULTS: In contrast to undifferentiated ASCs, dASCs expressed more choline acetyltransferase and vesicular acetylcholine transporter. When co-cultured with myoblasts, dASCs enhanced the proliferation rate, as did ACh administration alone. Western blotting and pharmacological inhibitor studies showed that phosphorylated extracellular signal-regulated kinase 1/2 signaling mediated these effects. In addition, denervated muscle showed higher expression of muscarinic ACh receptors than control muscle. DISCUSSION: Our findings suggest that dASCs promote proliferation of myoblasts through paracrine secretion of ACh, which could explain some of their regenerative capacity in vivo. Muscle Nerve 57: 305-311, 2018.