Background: Amyotrophic Lateral Sclerosis (ALS) is a degenerative disease of unknown origin characterized by the progressive loss of motor neurons of the anterior horns in the cortex, bulb and spinal cord. Among the several pathogenetic mechanisms considered in the attempt to explain motor neuron death in ALS, the hypothesis of the occurrence of mitochondrial dysfunction has received a considerable interest. Permeabilization of mitochondrial membranes, due to the opening of the mitochondrial permeability transition pore (MPTP), is considered an important step in the apoptotic or necrotic cell death cascade. MPTP is a multiprotein complex in which the peripheral benzodiazepine receptor (PBR) represents a core structural protein. PBR has been recently reported to play an important role in the regulation of MPT and in the control of apoptotic cell death. Objectives: to evaluate the kinetic binding parameters of the specific PBR ligand, PK 11195, in platelets obtained from patients affected by ALS. Methods: 16 ALS patients (mean 64.1 ± 2.39 years) and 18 control healthy volunteers (mean, 40.3 ± 3.06 years) were recruited for the study. Platelets obtained from each ALS patient and healthy volunteer were centrifuged and stored at –80°C. Aliquots of platelet membrane suspensions were incubated with increasing concentrations of [3H] PK 11195, either in the absence (total binding) or in the presence (non-specific binding) of PK 11195. After incubation, the samples were filtered, washed and the radioactivity was counted, using a liquid-phase scintillation counter. Results: The PBR kinetic binding parameters in platelet membranes from ALS and controls were saturable and with high affinity. Scatchard plots were linear for all analysed subjects, suggesting the presence of an homogeneous population of binding sites. A significant decrease in PBR Bmax values was observed in platelets of ALS patient as compared to controls (p=0.002), whereas the Kd values did not differ significantly. The relationship between the reduction of platelet PBR Bmax and the disease progression showed a significant correlation (r=0.62, p <0.01) Conclusion: The present data are consistent with an alteration of PBR density in ALS patients. This indicates a possible role of PBR in the pathogenesis of ALS and, at the same time suggests a perspective use of it as candidate biomarker to trace disease severity and progression.
Mitochondrial peripheral benzodiazepine receptor in amyotrophic lateral sclerosis
MANCUSO, MICHELANGELO;MARTINI, CLAUDIA;SICILIANO, GABRIELE
2007-01-01
Abstract
Background: Amyotrophic Lateral Sclerosis (ALS) is a degenerative disease of unknown origin characterized by the progressive loss of motor neurons of the anterior horns in the cortex, bulb and spinal cord. Among the several pathogenetic mechanisms considered in the attempt to explain motor neuron death in ALS, the hypothesis of the occurrence of mitochondrial dysfunction has received a considerable interest. Permeabilization of mitochondrial membranes, due to the opening of the mitochondrial permeability transition pore (MPTP), is considered an important step in the apoptotic or necrotic cell death cascade. MPTP is a multiprotein complex in which the peripheral benzodiazepine receptor (PBR) represents a core structural protein. PBR has been recently reported to play an important role in the regulation of MPT and in the control of apoptotic cell death. Objectives: to evaluate the kinetic binding parameters of the specific PBR ligand, PK 11195, in platelets obtained from patients affected by ALS. Methods: 16 ALS patients (mean 64.1 ± 2.39 years) and 18 control healthy volunteers (mean, 40.3 ± 3.06 years) were recruited for the study. Platelets obtained from each ALS patient and healthy volunteer were centrifuged and stored at –80°C. Aliquots of platelet membrane suspensions were incubated with increasing concentrations of [3H] PK 11195, either in the absence (total binding) or in the presence (non-specific binding) of PK 11195. After incubation, the samples were filtered, washed and the radioactivity was counted, using a liquid-phase scintillation counter. Results: The PBR kinetic binding parameters in platelet membranes from ALS and controls were saturable and with high affinity. Scatchard plots were linear for all analysed subjects, suggesting the presence of an homogeneous population of binding sites. A significant decrease in PBR Bmax values was observed in platelets of ALS patient as compared to controls (p=0.002), whereas the Kd values did not differ significantly. The relationship between the reduction of platelet PBR Bmax and the disease progression showed a significant correlation (r=0.62, p <0.01) Conclusion: The present data are consistent with an alteration of PBR density in ALS patients. This indicates a possible role of PBR in the pathogenesis of ALS and, at the same time suggests a perspective use of it as candidate biomarker to trace disease severity and progression.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
