α-synuclein antibody 5G4 identifies idiopathic REM-sleep behavior disorder in abdominal skin biopsies.

INTRODUCTION: Idiopathic REM-sleep behavior disorder (iRBD) is considered the most specific prodromal marker of Parkinson's disease (PD). With the need to improve early detection of prodromal α-synucleinopathies, several methods to identify peripheral α-synuclein (α-syn) pathology have been exploited in manifest and prodromal PD with varying diagnostic accuracy. Recently, a disease specific 5G4 antibody has been evaluated in skin biopsies of manifest PD patients. The aim of our study was to analyze the 5G4 α-syn immunoreactivity in skin biopsies of deeply phenotyped subjects with iRBD and controls. METHODS: The study cohort consisted of 28 patients with PD, 24 subjects with iRBD and 27 healthy controls, recruited from the CEGEMOD, PDBIOM and PARCAS cohorts. All subjects were deeply phenotyped and assessed for prodromal PD (pPD) probability based on MDS research criteria. Abdominal skin punch biopsies were processed and stained using a conformation specific 5G4 α-syn antibody as well as axonal markers SMI-31 and S100. RESULTS: 5G4-positivity was identified in 23/28 PD patients, 20/24 iRBD subjects and 8/27 healthy controls. Compared to healthy controls, sensitivity and specificity reached 83.33 % and 70.37 % for iRBD; and 82.14 % and 70.37 % for PD, respectively. 5G4-positivity rate in our study was irrespective of the calculated pPD probability of iRBD subjects. CONCLUSIONS: This work establishes the diagnostic yield of conformation specific 5G4 α-syn antibody testing in skin biopsies of subjects with pPD, specifically iRBD. The diagnostic accuracy for this method seems to be similar for both manifest and prodromal PD and is not dependent on the pPD probability ratios.

Bradykinin and noradrenaline preconditioning influences level of antioxidant enzymes SOD, CuZn-SOD, Mn-SOD and catalase in the white matter of spinal cord in rabbits after ischemia/reperfusion.

The aim of present work is to assess the effects of bradykinin (Br) or noradrenaline (Nor) preconditioning to the levels of antioxidant enzymes: superoxide dismutase (SOD), copper, zinc superoxide dismutase (CuZn-SOD), manganese superoxide dismutase (Mn-SOD) and catalase in ischemia/reperfusion (I/R) model in the rabbit spinal cord white matter as well as effect on glial fibrillary acidic protein (GFAP) and ubiquitin immunoreaction in glial cells. Rabbits were preconditioned by intraperitoneal single dose of Br or Nor 48 h prior to 20 min of ischemia followed by 24 or 48 h of reperfusion. White matter of L3-L6 spinal cord segments was used for comparison of antioxidant enzyme levels in sham control, ischemic groups and four preconditioned groups. The total SOD level in the Br or Nor preconditioned groups after 48 h of reperfusion was increased vs Br or Nor preconditioned groups after 24 h of reperfusion. The comparison among the ischemic group vs Br preconditioned (P<0.05), and Nor preconditioned (P<0.001) groups after 48 h of reperfusion, showed statistically significant decrease of Mn-SOD activity. Tissue catalase level activity was significantly decreased in the Br preconditioned group after 48 h of reperfusion (P<0.05) and Nor preconditioned groups after 24 h of reperfusion (P<0.001) and also after 48 h of reperfusion (P<0.001), in comparison to ischemic group after 48 h of reperfusion. Significantly decreased tissue catalase activity (P<0.05) in both Nor preconditioned groups after 24 or 48 h of reperfusion was measured vs Br preconditioned group after 48 h of reperfusion. According to our results, in the white matter, activation of stress proteins in glial cells, as well as antioxidant enzymes levels, were influenced by pharmacological preconditioning followed by 20 min of ischemia and 24 or 48 h of reperfusion. These changes contribute to ischemic tolerance acquisition and tissue protection from oxidative stress during reperfusion period.

Ubiquitin and endogenous antioxidant enzymes participate in neuroprotection of the rabbit spinal cord after ischemia and bradykinin postconditioning.

The aim of this study was to investigate neuroprotective effect of bradykinin postconditioning on the rabbit spinal cord after 20 min of ischemia and 3 days of reperfusion. Bradykinin was administered by single i.p. application at 1, 6, 12 or 24 h after ischemia. Assessment of neurological function of hind limbs (Tarlov score) was estimated. Quantitative analysis was evaluated by Fluoro Jade B method, NeuN and ubiquitin immunohistochemistry in anterior horn neurons of the spinal cord. Histomorphologically distribution of ubiquitin and endogenous antioxidant enzymes (SOD1, SOD2, catalase) immunoreaction was described. Bradykinin postconditioning showed decreased number of degenerated neurons, increased number of surviving neurons and increase in number of ubiquitin positive neurons in all bradykinin postconditioned groups versus ischemia/reperfusion group. According to our results bradykinin postconditioning applied 24 h after ischemia significantly decreased (p < 0.001) number of degenerated neurons versus ischemia/reperfusion group. The least effective time window for bradykinin postconditioning was at 12 h after ischemia. Tarlov score was significantly improved (p < 0.05) in groups with bradykinin postconditioning applied 1, 6 or 24 h after ischemia versus ischemia/reperfusion group. Tarlov score in group with bradykinin application 12 h after ischemia was significantly decreased (p < 0.05) versus sham control group. Neuronal immunoreaction of ubiquitin, SOD1, SOD2 and catalase influenced by bradykinin postconditioning was dependent on neuronal survival or degeneration. In conclusion, bradykinin postconditioning showed protective effect on neurons in anterior horns of the rabbit spinal cord and improved motor function of hind limbs.