Interspecies variation of clopidogrel hydrolysis in liver microsomes from various mammals.

Clopidogrel, a clinically used antiplatelet agent, can be readily hydrolyzed by human carboxylesterase 1A (CES1A) to release an inactive metabolite clopidogrel carboxylic acid (CCA). In this study, clopidogrel was used as a tool substrate to investigate the interspecies variation of clopidogrel hydrolysis in hepatic microsomes from various mammals including human and six laboratory animals (such as mouse, rat, rabbit, beagle dog, minipig and cynomolgus monkey). The results demonstrated that clopidogrel could be hydrolyzed into CCA by all tested hepatic microsomes from human or other mammals, but the hydrolytic rates greatly varied among species. Inhibition assays demonstrated that BNPP (an inactivator of mammalian CES) strongly inactivated clopidogrel hydrolytic activity in all tested hepatic microsomes, suggested that mammalian CES were major contributor(s) responsible for clopidogrel hydrolysis in hepatic preparations from all above-mentioned species. By contrast, the response of a reversible inhibitor of human CES1A on clopidogrel hydrolysis in these liver preparations varied significantly among different species. Moreover, the enzymatic kinetics and the apparent kinetic parameters of clopidogrel hydrolysis in hepatic microsomes from various animal species were evaluated and compared to each other. These findings provide crucial information for deeply understanding the differences in catalytic behaviors of mammalian CES, which will be very helpful for choosing suitable laboratory animal(s) for whole tests of CES1A substrate-drugs.

Chronic caffeine treatment protects against experimental autoimmune encephalomyelitis in mice: therapeutic window and receptor subtype mechanism.

Chronic treatment with caffeine, the most widely consumed psychoactive drug and a non-selective antagonist of adenosine receptors, can protection against myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). In this study, we investigated the mechanism underlying caffeine-mediated neuroprotection against EAE by determining the effective therapeutic time-window of caffeine and the involvement of adenosine A2A and A1 receptor. We found that administration of caffeine during the effector phase (10 â†’ 20 days post-immunization, d.p.i., corresponding to appearance of neurological deficits) but not the induction phase (0 â†’ 10 d.p.i., before the appearance of ascending flaccid paralysis) significantly ameliorated EAE-induced neurobehavioral deficits, reduced the infiltration of inflammatory cells into the spinal cord and reduced the demyelination of spinal cord. Furthermore, genetic deletion of the A2AR exacerbated MOG-induced brain damage and caffeine administering to A2AR knockout mice reversed this EAE pathology by acting at non-A2AR target. The protective effect of chronic caffeine treatment was associated with up-regulation of brain A1R (but not A2AR). The identification of the effective therapeutic window of caffeine at the effector phase and clarification of non-A2AR target (likely A1R) in caffeine action in EAE models advance the therapeutic prospective that chronic caffeine consumption may attenuate brain damage in MS.

[The change of periphery and centra CD4(+);CD25(+);Treg, CD8(+);CD28(-);Treg in the MOG induced model of experimental autoimmune encephalomyelitis].

AIM: To observe the change of periphery and centra CD4(+); CD25(+); Treg, CD8(+); CD28(-); Treg of MOG35₋55; induced EAE disease in mouse, and to explore the potential mechanism of cellular immunity in the process of EAE. METHODS: MOG35₋55; were used to establish EAE model on femina C57BL/6 mice.The behavioral changes and the histological scores were recorded. The changes of CD4(+); CD25(+); Treg, CD8(+); CD28(-); Treg on periphery and centra lymphocyte in spleen , brain were analyzed by flow cytometry. RESULTS: MOG35₋55;-induced EAE group Showed the typical clinical behavior and pathological manifestations, CD4(+); CD25(+); Treg, CD8(+); CD28(-); Treg lymphocytes were detected in the brain and spinal cord of EAE group mice, but they were not detected in the brain of control group. CD8(+); CD28(-); Treg in the spleen of EAE group were lower than those in control group (P < 0.01). CD4(+); CD25(+); Treg lymphocytes were slight higher than the control group. CONCLUSION: CD4(+); CD25(+); Treg, CD8(+); CD28(-); Treg lymphocytes all play important roles in the pathogenesy of EAE. The distribution of CD4(+); CD25(+); Treg, CD8(+); CD28(-); Treg in the CNS and peripheral of EAE is different, suggesting that their entry into the CNS and regulate of local inflammation.

Neonatal endotoxin exposure suppresses experimental autoimmune encephalomyelitis through regulating the immune cells responsivity in the central nervous system of adult rats.

Early-life exposure to bacterial endotoxin (lipopolysaccharide, LPS) affects the susceptibility to a variety of systemic organic inflammation in adulthood. To determine the long-term effects of neonatal LPS exposure on inflammatory responses in the central nervous system (CNS) in adulthood, we examined the effects on the development of experimental autoimmune encephalomyelitis (EAE) in adult rats as well as the potential regulatory immune mechanisms involved. The results showed that neonatal LPS exposure significantly reduced the morbidity (p<0.01) and severity (p<0.05) of EAE in adult rats, and decreased inflammatory cell infiltration and demyelination in the CNS compared with neonatal saline controls (p<0.05). Neonatal LPS-treated animals showed reduced activation of microglia and astrocytes, as detected by immunocytochemistry, accompanied by down-regulation of the pro-inflammatory cytokines interleukin-17 and interferon-gamma but up-regulation of anti-inflammatory cytokine interleukin-10 in the CNS (p<0.05). At the same time, cerebrum mRNA levels of the transcription factors T-bet and RORgammat were lower in neonatal LPS-compared with saline- treated animals (p<0.05) accompanied with increased STAT-6 and Foxp3 levels in the neonatal LPS-treated group (p<0.05). These findings suggest that early-life exposure to LPS could provide an important neuroprotective effect on the development of EAE in adult rats due to modulation of inflammatory responses in the CNS.

Idazoxan attenuates spinal cord injury by enhanced astrocytic activation and reduced microglial activation in rat experimental autoimmune encephalomyelitis.

Idazoxan, an imidazoline 2 receptor (I(2)R) ligand, has been shown to protect against brain injury in several animal models of neurological disorders. In the present study we investigated the effect of idazoxan on experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. EAE was induced by immunizing Wistar rats with guinea pig spinal cord homogenates emulsified in CFA, followed by daily treatment of idazoxan (0, 0.5 mg/kg, 1.5 mg/kg, 4.5 mg/kg, i.p, bid) for 10 days. The results showed that the treatment of idazoxan (1.5 mg/kg and 4.5 mg/kg) significantly decreased the incidence and alleviated inflammatory cell infiltration and demyelination in spinal cords and cerebral cortex. Furthermore, the protective effect of idazoxan on EAE was associated with the enhanced astrocytic activation and attenuated microglial activation and with the subsequent down-regulated expression of proinflammatory cytokines IL-12p40 and IFN-gamma and up-regulated expression of anti-inflammatory cytokines IL-10 and TGF-beta(1). Thus, the daily treatment of the I(2)R ligand idazoxan for 10 days attenuates EAE pathology by differential modulation of astrocytic and microglial activations, raising a possibility that the I(2)R ligand may be a novel strategy for treating EAE.