Dopamine changes in a rat model of intracerebral hemorrhage

A TSPO ligand attenuates brain injury after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating disease without effective treatment. After ICH, the immediate infiltration of leukocytes and activation of microglia are accompanied by a rapid up-regulation of the 18-kDa translocator protein (TSPO). TSPO ligands have shown anti-inflammatory and neuroprotective properties in models of CNS injury. In this study, we determined the impact of a TSPO ligand, etifoxine, on brain injury and inflammation in 2 mouse models of ICH. TSPO was up-regulated in Iba1⁺ cells from brains of patients with ICH and in CD11b⁺CD45^int cells from mice subjected to collagenase-induced ICH. Etifoxine significantly reduced neurodeficits and perihematomal brain edema after ICH induction by injection of either autologous blood or collagenase. In collagenase-induced ICH mice, the protection of etifoxine was associated with reduced leukocyte infiltration into the brain and microglial production of IL-6 and TNF-α. Etifoxine improved blood–brain barrier integrity and diminished cell death. Notably, the protective effect of etifoxine was abolished in mice depleted of microglia by using a colony-stimulating factor 1 receptor inhibitor. These results indicate that the TSPO ligand etifoxine attenuates brain injury and inflammation after ICH. TSPO may be a viable therapeutic target that requires further investigations in ICH.—Li, M., Ren, H., Sheth, K. N., Shi, F.-D., Liu, Q. A TSPO ligand attenuates brain injury after intracerebral hemorrhage.

Post-status epilepticus treatment with the cannabinoid agonist WIN 55,212-2 prevents chronic epileptic hippocampal damage in rats

Repeated seizures are often associated with development of refractory chronic epilepsy, the most common form of which is temporal lobe epilepsy. G-protein-coupled cannabinoid receptors (CB1 and CB2 receptors) regulate neuronal excitability and have been shown to mediate acute anticonvulsant effects of cannabinoids in animal models. However, the potential of cannabinoids to prevent chronic neuronal damage and development of epilepsy remains unexplored. We hypothesized that treatment with a CB receptor agonist after an episode of status epilepticus--but before development of spontaneous recurrent seizures--might prevent the development of functional changes that lead to chronic epilepsy. Using the rat pilocarpine model, a therapeutic approach was simulated by administering the CB agonist, WIN 55,212-2 after an episode of status epilepticus. Epileptic behavior was monitored during development of spontaneous recurrent seizures for up to 6 months. Histology, neurochemistry, redox status and NMDA receptor subunit expression were assessed at 6 months after pilocarpine-induced seizures. Sub-acute treatment with WIN 55,212-2 (for 15 days starting 24h after PILO injection) dramatically attenuated the severity, duration and frequency of spontaneous recurrent seizures. Further, in contrast to vehicle-treated animals, hippocampi from WIN 55,212-2-treated animals showed: normal thiol redox state, normal NR2A and NR2B subunit expression, preservation of GABAergic neurons and prevention of abnormal proliferation of GABAergic progenitors. This study shows for the first time that, after a known inciting event, treatment with a compound targeting CB receptors has the potential to prevent the epileptogenic events that result in chronic epileptic damage.

Subacute manganese exposure in rats is a neurochemical model of early manganese toxicity

Manganese (Mn) is an essential trace element, but excess exposure leads to accumulation in biological tissues, including the brain. Chronically high Mn levels in the brain are neurotoxic and can result in a progressive, irreversible neurological disorder known as manganism. Manganism has signs and symptoms similar to, but distinguishable from idiopathic Parkinson's disease, which include both psychological and motor disturbances. Evidence suggests that Mn exposure impacts neurotransmitter levels in the brain. However, it remains unclear if subacute, low-level Mn exposure resulted in alterations in neurotransmitter systems with concomitant behavioral deficits. The current study used high performance liquid chromatography to quantify neurotransmitter levels in rat striatum (STR), substantia nigra (SN), and hippocampus (HP). Subacute Mn exposure via i.p. injection of 15mg Mn/kg as MnCl2 caused significantly increased dopamine (DA) levels in the STR. The enhancement was accompanied by significantly elevated levels of the DA metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in the STR. In addition, levels of HVA were significantly increased in the SN and HP. These data indicate that subacute, low-level Mn exposure disrupts multiple neurotransmitter systems in the rat brain which may be responsible, in part, for observed locomotor deficits.

Recent research on changes in genomic regulation and protein expression in intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is a devastating form of stroke that accounts for roughly 10% of all strokes and the effects on those that survive are often debilitating. To date, no suitable therapy exists. Recent work has examined alterations in gene and protein expression after ICH. The focus of this review is to outline the current knowledge of changes in genetic and protein expression after ICH and how those changes may affect the course of brain injury. Both animal and human data are reviewed.