TSPO pain

Neuropathic pain is a frequent complication of spinal cord injury (SCI), still refractory to conventional treatment. The presence and biological activity of steroidogenic regulatory proteins and enzymes in the spinal cord suggests that neurosteroids locally generated could modulate pain messages. In this study we explored temporal changes in the spinal expression of the 18kDa translocator protein TSPO, the steroidogenic acute regulatory protein (StAr) and the steroidogenic enzyme 5α-reductase (5α-RI/II) in an experimental model of central chronic pain...

Neuroinflammation is implicated in the pathophysiology of a growing number of human disorders, including multiple sclerosis, chronic pain, traumatic brain injury, and amyotrophic lateral sclerosis. As a result, interest in the development of novel methods to investigate neuroinflammatory processes, for the purpose of diagnosis, development of new therapies, and treatment monitoring, has surged over the past 15 years. Neuroimaging offers a wide array of non- or minimally invasive techniques to characterize neuroinflammatory processes...

Diazepam binds with the same high affinity to the central benzodiazepine receptor (CBR) and the peripheral benzodiazepine receptor, which has been renamed translocator protein (TSPO). Both receptors could promote neurosteroid synthesis. In the present study, we investigated whether a single dose of diazepam could inhibit neuropathic pain induced by L5 spinal nerve ligation (L5 SNL), and whether CBR and TSPO mediated this effect. We found that a single intraperitoneal injection of diazepam 9 d after L5 SNL significantly depressed the established mechanical allodynia and thermal hyperalgesia, which persisted until the end of the experiments...

Recent studies reported the translocator protein (TSPO) to play critical roles in several kinds of neurological diseases including the inflammatory and neuropathic pain. However, the precise mechanism remains unclear. This study was undertaken to explore the distribution and possible mechanism of spinal TSPO against chronic neuropathic pain (CNP) in a rat model of L5 spinal nerve ligation (SNL). Our results showed that TSPO was upregulated in a time-related manner in the spinal dorsal horn after SNL. Spinal TSPO was predominately expressed in astrocytes...

The activation of Translocator protein (18 kDa) (TSPO) has been demonstrated to mediate rapid anxiolytic efficacy in stress response and stress-related disorders. This protein is involved in the synthesis of endogenous neurosteroids that promote γ-aminobutyric acid (GABA)-mediated neurotransmission in the central neural system. However, little is known about the functions and the underlying mechanisms of TSPO in chronic pain-induced anxiety-like behaviors. The novel TSPO ligand N-benzyl-N-ethyl-2-(7,8-dihydro-7-benzyl-8-oxo-2-phenyl-9H-purin-9-yl) acetamide (ZBD-2) was used in the present study...

Etifoxine (etafenoxine, Stresam®) is a non-benzodiazepine anxiolytic with an anticonvulsant effect. It was developed in the 1960s for anxiety disorders and is currently being studied for its ability to promote peripheral nerve healing and to treat chemotherapy-induced pain. In addition to being mediated by GABAAα2 receptors like benzodiazepines, etifoxine appears to produce anxiolytic effects directly by binding to β2 or β3 subunits of the GABAA receptor complex. It also modulates GABAA receptors indirectly via stimulation of neurosteroid production after etifoxine binds to the 18 kDa translocator protein (TSPO) of the outer mitochondrial membrane in the central and peripheral nervous systems, previously known as the peripheral benzodiazepine receptor (PBR)...

Although substantial evidence has established that microglia and astrocytes play a key role in the establishment and maintenance of persistent pain in animal models, the role of glial cells in human pain disorders remains unknown. Here, using the novel technology of integrated positron emission tomography-magnetic resonance imaging and the recently developed radioligand (11)C-PBR28, we show increased brain levels of the translocator protein (TSPO), a marker of glial activation, in patients with chronic low back pain...

Although progesterone was reported to be a neuroprotective agent against injuries to the nervous system, including the peripheral neuropathy, the mechanisms of its dose or timing-related effects remain unclear. Translocator protein (TSPO) is predominantly located in the mitochondrial outer membrane and has been recently implicated in modulation of several brain injuries and nociception. This experiment was conducted using a rat model of L5 spinal nerve ligation (SNL) to observe the effects of progesterone against allodynia development in an 84-day period and to explore the spinal TSPO expression after treatment...

Inflammatory and degenerative diseases of the joint are major causes of chronic pain. Long-lasting pain symptoms are thought to result from a central sensitization of nociceptive circuits. These processes include activation of microglia and spinal disinhibition. Using a monoarthritic rat model of pain, we tried to potentiate neural inhibition by using etifoxine (EFX), a nonbenzodiazepine anxiolytic that acts as an allosteric-positive modulator of gamma-aminobutyric acid type A (GABAA) receptor function. Interestingly, EFX also can bind to the mitochondrial translocator protein (TSPO) complex and stimulate the synthesis of 3α-reduced neurosteroids, the most potent positive allosteric modulator of GABAA receptor function...

The role of glial activation has been implicated in the development and persistence of neuropathic pain after nerve injury by recent studies. PK11195 binding to the translocator protein 18kDa (TSPO) has been shown to be enhanced in activated microglia. This study was designed to assess PK11195 imaging in spinal microglia during activation after nerve injury. The development of neuropathic pain was induced by partial sciatic nerve ligation (PSL). PSL rats on days 7 and 14 after nerve injury were subjected to imaging with a small-animal positron emission tomography/computed tomography (PET/CT) scanner using [(11)C]PK11195 to detect spinal microglial activation by means of noninvasive in vivo imaging...

At present, effective drug for treatment of neuropathic pain is still lacking. Recent studies have shown that the ligands of translocator protein (TSPO, 18 kDa), a peripheral receptor for benzodiazepine, modulate inflammatory pain. Here, we report that TSPO was upregulated in astrocytes and microglia in the ipsilateral spinal dorsal horn of rats following L5 spinal nerve ligation (L5 SNL), lasting until the vanishing of the behavioral signs of neuropathic pain (∼50 d). Importantly, a single intrathecal injection of specific TSPO agonists Ro5-4864 or FGIN-1-27 at 7 and 21 d after L5 SNL depressed the established mechanical allodynia and thermal hyperalgesia dramatically, and the effect was abolished by pretreatment with AMG, a neurosteroid synthesis inhibitor...

BACKGROUND: Microglia serve as macrophage-like cells in the central nervous system, and activation of microglial cells in the spinal cord may contribute to ongoing pain following peripheral trauma or nerve injury. Following pronociceptive stimulation, activated microglia exhibit increased expression of the peripheral benzodiazepine receptor (PBR)/translocator protein 18 kDa (TSPO). METHODS: Using radioligand binding autoradiography and filtration assays, we examined the specific binding of the PBR/TSPO ligand [(3)H]PK11195 in spinal cords from the following rat experimental pain models: neuropathic pain induced by spinal nerve ligation (SNL), osteoarthritic pain induced by intraarticular injection of monosodium iodoacetate in the knee joint (MIA-OA), and subchronic inflammatory pain induced by intraplantar injection of complete Freund's adjuvant (CFA)...

The central processing of peripheral nociceptive messages is highly controlled by the activity of local inhibitory networks in the spinal cord and supraspinal centers. Recently, it has been shown that endogenous 3alpha-reduced neurosteroids (3alphaNS) exert a significant spinal antinociception by potentiating GABA(A) receptor function. Because endogenous 3alphaNS can be produced in many relay structures of the nociceptive system, we tested the potential analgesic efficacy of promoting the production of neurosteroids by using etifoxine (ETX, 50mg/kg i...

Translocator protein 18 kDa (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), is predominantly located in the mitochondrial outer membrane and plays an important role in steroidogenesis, immunomodulation, cell survival and proliferation. Previous studies have shown an increased expression of TSPO centrally in neuropathology, as well as in injured nerves. TSPO has also been implicated in modulation of nociception. In the present study, we examined the hypothesis that TSPO is involved in the initiation and maintenance of inflammatory pain using a rat model of Complete Freund's Adjuvant (CFA)-induced monoarthritis of the tibio-tarsal joint...