NLX-112 is anti-inflammatory, upregulates GDNF and is neuroprotective against MPTP-induced nigrostriatal dopaminergic degeneration in mice

NLX-112 is a potent and selective 5-HT1A agonist that has successfully completed phase 2A clinical trial for treatment of L-DOPA-induced dyskinesia in Parkinsons disease (PD). We investigated the neuroprotective activity of NLX-112 in a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD. Four groups of mice received either saline (1ml/kg) daily for 15 days, MPTP (21.4 mg/kg for 5 days, preceded and followed by 5 days saline, NLX-112 (1mg/kg/day for 15 days) or combined MPTP + NLX-112. Two weeks following cessation of treatments, NLX-112-treated mice showed increased locomotor activity and reduced anxiety-like behaviour in an open-field test, consistent with sustained effects of 5-HT1A receptor activation. MPTP-treated male mice showed a significant reduction of dopaminergic (i.e., tyrosine hydroxylase immunoreactive; TH-ir) neurones in the substantia nigra (SN) and the striatum by 40 and 55%, respectively. NLX-112 treatment elicited a significant protection against MPTP-induced loss of TH-ir neurones and nerve terminals. MPTP also a markedly increased the levels of GFAP-ir astrocytes and Iba1-ir microglia in the SN, and co-expression of glial-derived neurotrophic factor (GDNF) in the GFAP-ir astrocytes in both the SN and the striatum. However, in MPTP treated mice, NLX-112, markedly reversed microglial expression in the SN, and upregulated GFAP/GDNF co-localisation in both the striatum and the SN. Overall, the present study demonstrates a robust neuroprotective effect of NLX-112 in a mouse model of PD by preventing microgliosis, upregulating GDNF and favouring sustained pro-locomotor activity.