The peripheral benzodiazepine receptor (Translocator protein 18 kDa) in microglia: From pathology to imaging
Section snippets
Microglia: origin and function
Microglia constitute up to 10% of the total cell population of the brain. As resident macrophages (histiocytes), microglia phagocytose cellular debris, present foreign antigens and presumably serve many other vital functions in the brain (Minghetti and Levi, 1998). Del Rio Hortega first recognized the pathological importance of microglia in the central nervous system (CNS), and he also coined their name (Del Rio Hortega, 1932). Microglia are derived from cells of the monocyte lineage. During
The peripheral benzodiazepine receptor: structure and function
Evidence indicating that diazepam bound with high affinity in the rat kidney led to the postulation and later characterization of the peripheral benzodiazepine receptor (PBR) (Braestrup et al., 1977), named to differentiate it from the previously described diazepam binding sites in the CNS (central benzodiazepine receptor). Within the CNS, two pharmacologically distinct benzodiazepine receptors exist: the central and the peripheral benzodiazepine receptors. The central benzodiazepine receptor
Summary
The low levels of mitochondrial PBR present in the normal CNS increase dramatically with injury and neurodegeneration, and predominantly in microglia, as suggested by several studies using animal models and human postmortem tissues. The mechanisms of PBR regulation and its functions in microglia are not known. In this review, we discuss the evidence supporting preferential increases in PBR in microglia. We also discuss hypothesized mechanisms of PBR regulation at the cellular level as well as
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2024, Applied Radiation and IsotopesExercise protects synaptic density in a rat model of Parkinson's disease
2021, Experimental NeurologyCitation Excerpt :The lack of an effect of exercise on striatal dopamine levels is consistent with our findings of no treadmill exercise-induced preservation or restoration of the level of TH immunopositive nigral loss, nor reversal of the increased [3H]Raclopride binding which occurred in response to reduced synaptic striatal dopamine content, in the ipsilateral 6-OHDA injected brain. At post-mortem, PD subjects show microglial activation in the substantia nigra, striatum, and frontal association cortex (Marinova-Mutafchieva et al., 2009; Venneti et al., 2006; McGeer et al., 1988). Activated microglia express TSPO which can be detected in vivo using [11C]PK11195 or [11C]PBR28 PET.