Hypoxia/ischemia a key player in early post stroke seizures: modulation by opioidergic and nitrergic systems.

Stroke is a leading cause of death, disability, and socioeconomic loss worldwide. All attempts at pharmacological reduction of the complications of stroke (e.g. post-stroke seizure, and brain׳s vulnerability to hypoxic/ischemic injury) have failed. Endogenous opioids and nitric oxide (NO) overproduction has been documented in brain hypoxia/ischemia (H/I), which can exert pro-convulsive effects. In this study, we aimed to examine the possible involvement of opioidergic and nitrergic pathways in the pathogenesis of post-stroke seizure. H/I was induced by right common carotid ligation and sham-operated mice served as controls. We demonstrated that right common carotid ligation decreases the threshold for clonic seizures induced by pentylenetetrazole (PTZ), a GABA antagonist. Furthermore, pro-convulsive effect of H/I following right common carotid ligation was blocked by naltrexone (NTX) (3mg/kg), NG-Nitro-l-arginine methyl ester (l-NAME) (10mg/kg), and aminoguanidine (AG) (100mg/kg) administration (P<0.001). Interestingly, co-administration of non-effective doses of NTX and l-NAME (1 and 0.5mg/kg, respectively) reverses epileptogenesis of H/I (P<0.001). In the same way, co-administration of non-effective doses of NTX and AG (1 and 5mg/kg, respectively), reverses epileptogenesis of H/I (P<0.001). Indeed, the histological studies performed on mice exposed to H/I confirmed our previous data. These findings suggest hyper-susceptibility to PTZ induced seizure following H/I is mediated by interaction of opioidergic, and iNOS/NO pathways. Therefore, our results identify new pharmacological targets and provide the rationale for a novel strategy to promote recovery after stroke and possibly other brain injuries.

Hippocampal DHCR24 down regulation in a rat model of streptozotocin-induced cognitive decline.

The DHCR24 (24-dehydrocholesterol reductase) gene codes a multifunctional protein which consists of enzymatic, antioxidant, and anti-apoptotic activities. It exists in almost all neurons and protects the neural cells against amyloid ß toxicity. Several studies have shown the down regulation of DHCR24 in Alzheimer's disease. We examined the time profile of DHCR24-mRNA alteration in an animal model of streptozotocin (STZ)-induced cognitive impairment. The DHCR24 mRNA levels of hippocampus and cognitive impairment were evaluated at 7, 14, and 21 days after intracerebroventricular (ICV)-STZ/Saline administration. DHCR24 expression was down regulated at 14 and 21 days after ICV-STZ administration. The decrease in expression of DHCR24 preceded the onset of the cognitive impairment. These results suggest the potential relation between DHCR24 expression and cognitive impairment.

Elevated CSF and plasma microparticles in a rat model of streptozotocin-induced cognitive impairment.

Alzheimer's disease (AD), can be described as a vascular disorder, is characterized by endothelial and platelet activation. One feature of activated cells is loss of lipid asymmetry, and membrane blebbing which cause microparticle (MP) formation. MPs increased under many pathological states and little information is available relating to their changes in AD. The purpose of this work was to characterize the time course of the endothelial-derived microparticles (EMPs) and platelet-derived microparticles (PMPs) alteration after intracerebroventricular (ICV) injection of streptozotocin (STZ). Rats were injected bilaterally with ICV-STZ/Saline, cerebrospinal fluid (CSF) and plasma EMPs (Annexin V(+) CD61(-)CD144(+)) and PMPs (Annexin V(+) CD61(+)CD144(-)) were analyzed with flow cytometry at 2 h, 4 h, 24 h, 4 days, 7 days, 14 days and 21 days after ICV-STZ/Saline administration. Cognitive impairment, malondialdehyde (MDA) level of hippocampus, plasma serotonin, and serum S100B were also assessed. We showed the elevation of CSF and plasma level of EMPs and PMPs, which may represent a proinflammatory and prothrombotic status. These alterations were simultaneous with the hippocampal MDA rise, plasma serotonin increment, and S100B decrement, 7 days after ICV-STZ administration and precede the onset of cognitive impairment. Understanding the profile of MP changes in CSF or plasma as biomarkers from tissues undergoing activation or damage, may be helpful in prediction or early diagnosis of AD.

Acute and subacute toxicity of novel biogenic selenium nanoparticles in mice.

CONTEXT: In the present investigation, acute and subacute toxicity of the biogenic Se nanoparticles (Se NPs) has been reported. OBJECTIVE: To characterize the Se NPs produced by a bacterium species and to evaluate their toxicity and impact on clinical chemistry and hematological parameters of NMRI mice. MATERIALS AND METHODS: The Se NPs were prepared by Bacillus sp. MSh-1 in a culture medium containing SeO(2) (1.26 mM) and their physiochemical properties investigated using TEM, XRD and FT-IR. The LD(50) of Se NPs and SeO(2) were determined and the subacute toxicity evaluated by orally administration of 0, 2.5, 5, 10 and 20 mg kg(-1) of Se NPs to male mice for 14 consecutive days. Parameters of blood cells, AST, ALT, ALP, creatinine, BUN, cholesterol, bilirubin, triglyceride and CPK were experimentally measured. RESULTS: The XRD and TEM analyses showed that the spherical NPs were amorphous, in the size range of 80-220 nm. The toxicological evaluation showed that the LD(50) values of SeO(2) and Se NPs were 7.3 and 198.1 mg kg(-1), respectively. No biochemical changes were observed from the administration of 2.5, 5 and 10 mg kg(-1) of Se NPs, but a dose of 20 mg kg(-1) was accompanied with signs of toxicity including lower body weight and changes in clinical chemistry and hematological parameters. CONCLUSION: The biogenic Se NPs were less toxic than synthetic Se NPs and much less (26-fold) toxic than the SeO(2), which demonstrates the important role of Bacillus sp. MSh-1 in conversion of a highly toxic Se compound to the less toxic Se NPs.

Anticonvulsant and neuroprotective effects of Pimpinella anisum in rat brain.

BACKGROUND: Essential oil of Pimpinella anisum L. Apiaceae (anise oil) has been widely used in traditional Persian medicine to treat a variety of diseases, including some neurological disorders. This study was aimed to test the possible anti-seizure and anti-hypoxia effects of anise oil. METHODS: The effects of different concentrations of anise oil were tested on seizure attacks induced by pentylenetetrazol (PTZ) injection and neuronal hypoxia induced by oxygen withdrawal as well as on production of dark neurons and induction of long-term potentiation (LTP) in in vivo and in vitro experimental models of rat brain. RESULTS: Anise oil significantly prolonged the latency of seizure attacks and reduced the amplitude and duration of epileptiform burst discharges induced by injection of intraperitoneal PTZ. In addition, anise oil significantly inhibited production of dark neurons in different regions of the brain in epileptic rats. Anise oil also significantly enhanced the duration of the appearance of anoxic terminal negativity induced by oxygen withdrawal and inhibited induction of LTP in hippocampal slices. CONCLUSIONS: Our data indicate the anticonvulsant and neuroprotective effects of anise oil, likely via inhibition of synaptic plasticity. Further evaluation of anise oil to use in the treatment of neurological disorders is suggested.