Anti-inflammatory and anti-apoptotic effects of (RS)-glucoraphanin bioactivated with myrosinase in murine sub-acute and acute MPTP-induced Parkinson's disease

Abstract

This study was focused on the possible neuroprotective role of (RS)-glucoraphanin, bioactivated with myrosinase enzyme (bioactive RS-GRA), in an experimental mouse model of Parkinson's disease (PD). RS-GRA is one of the most important glucosinolates, a thiosaccharidic compound found in Brassicaceae, notably in Tuscan black kale seeds. RS-GRA was extracted by one-step anion exchange chromatography, further purified by gel-filtration and analyzed by HPLC. Following, pure RS-GRA was characterized by (1)H and (13)C NMR spectrometry and the purity was assayed by HPLC analysis of the desulfo-derivative according to the ISO 9167-1 method. The obtained purity has been of 99%. To evaluate the possible pharmacological efficacy of bioactive RS-GRA (administrated at the dose of 10mg/kg, ip +5μl/mouse myrosinase enzyme), C57BL/6 mice were used in two different sets of experiment (in order to evaluate the neuroprotective effects in different phases of the disease), according to an acute (2 injections·40mg/kg MPTP) and a sub-acute (5 injections·20mg/kg MPTP) model of PD. Behavioural test, body weight changes measures and immunohistochemical localization of the main PD markers were performed and post-hoc analysis has shown as bioactive RS-GRA is able to reduce dopamine transporter degradation, tyrosine hydroxylase expression, IL-1β release, as well as the triggering of neuronal apoptotic death pathway (data about Bax/Bcl-2 balance and dendrite spines loss) and the generation of radicalic species by oxidative stress (results focused on nitrotyrosine, Nrf2 and GFAP immunolocalization). These effects have been correlated with the release of neurotrophic factors, such as GAP-43, NGF and BDNF, that, probably, play a supporting role in the neuroprotective action of bioactive RS-GRA. Moreover, after PD-induction mice treated with bioactive RS-GRA are appeared more in health than animals that did not received the treatment both for phenotypic behaviour and for general condition (movement coordination, presence of tremors, nutrition). Overall, our results suggest that bioactive RS-GRA can protect neurons against the neurotoxicity involved in PD via an anti-apoptotic/anti-inflammatory action.

Keywords: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; DA; DAT; GL; Glucosinolates; IHC; IL-1β; ITC; Inflammation; MPTP; Myr; Myrosinase; Nitrosative stress; PD; Parkinson’s disease; R(S)-Glucoraphanin; SNpc; Substantia Nigra pars compacta; TH; dopamine transporter; dopaminergic; glucosinolate; immunohistochemical; interleukin-1beta; isothiocyanates; myrosinase; tyrosine hydroxilase.