Carbofuran, a widely used carbamate pesticide, has been reported to cause neurotoxicity. However, the underlying mechanisms involved in carbofuran neurotoxicity are not well understood. The present study was envisaged to investigate the possible role of oxidative stress in carbofuran neurotoxicity and to evaluate the protective effects of N-acetylcysteine (NAC). Acetylcholinesterase activity was significantly inhibited in all the regions of brain after carbofuran exposure (1 mg/kg body weight, orally, for 28 days). NAC, on the other hand, was found to partially restore the activity of acetylcholinesterase in carbofuran treated animals. Carbofuran exposure resulted in increased lipid peroxidation (LPO) in brain regions accompanied by decreased levels of glutathione. NAC administration to the carbofuran exposed animals lowered LPO along with partial repletion in glutathione levels. Concomitantly, the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase were significantly decreased after carbofuran exposure, while no significant change in the activity of glutathione-S-transferase was observed. NAC treatment to carbofuran treated rats resulted in protective effect on the activities of these enzymes. Marked impairment in the motor function was seen following carbofuran exposure, which is evident by significant decrease in the retention time of the rats on rotating rods. Cognitive deficits were also seen after carbofuran exposure as indicated by the significant decrease in active avoidance response. NAC treatment significantly improved the carbofuran-induced neurobehavioral deficits. The results clearly demonstrate that carbofuran exerts its neurotoxic effects by accentuating oxidative stress and suggest neuroprotective role of NAC in carbofuran neurotoxicity.

The present work investigates the protective effects of N-acetylcysteine (NAC) on carbofuran-induced alterations in lipid composition and activity of membrane bound enzymes (Na+-K+-ATPase and Ca2+-ATPase) in the rat brain. Animals were exposed to carbofuran at a dose of 1 mg/kg body weight, orally, for a period of 28 days. A significant increase in lipid peroxidation in terms of TBARS was observed in brain after carbofuran exposure. NAC administration (200 mg/kg body weight) on the other hand lowered the carbofuran-induced lipid peroxidation to near normal. The increased lipid peroxidation following carbofuran exposure was accompanied by a significant decrease in the levels of total lipids, which is attributed to the reduction in phospholipid levels. Furthermore, NAC administration had a beneficial effect on carbofuran-induced alterations in lipid composition. The ratio of cholesterol to phospholipid, a major determinant of membrane fluidity, was increased in response to carbofuran exposure. This was associated with decreased activity of Na+-K+-ATPase and Ca2+-ATPase. NAC was observed to offer protection by restoring the cholesterol to phospholipid ratio along with the activity of Na+-K+-ATPase and Ca2+-ATPase. The results clearly suggest that carbofuran exerts its neurotoxic effects by increasing lipid peroxidation, altering lipid composition and activity of membrane bound enzymes. NAC administration ameliorated the effects of carbofuran suggesting its potential therapeutic effects in carbofuran neurotoxicity.

Excessive pathophysiological activity of the nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP1) causes neuron death in brain hypoxia/ischemia by inducing mitochondrial permeability transition and nuclear translocation of apoptosis-inducing factor (AIF). Bcl-2/adenovirus E1B 19 kDa-interacting protein (Bnip3) is a prodeath BH3-only Bcl-2 protein family member that is induced in hypoxia, and has effects on mitochondrial permeability and neuronal survival similar to those caused by PARP1 activation. We hypothesized that Bnip3 is a critical mediator of PARP1-induced mitochondrial dysfunction and neuron death. Hypoxic death of mouse cortical neuron cultures was mitigated by deletion of either PARP1 or Bnip3, indicating that both factors are involved. Direct normoxic PARP1 activation by a DNA alkylating agent enhanced Bnip3 expression, and caused Bnip3-dependent mitochondrial membrane permeability, AIF translocation, and neuron death. Hypoxia produced PARP1-dependent depletion of nicotinamide adenine dinucleotide (NAD ϩ ) and inhibition of the NAD ϩ -dependent class III histone deactelyase (HDAC) sirtuin-1 (SIRT1). This, in turn, led to hyperacetylation and nuclear localization of the forkhead box (Fox) protein FoxO3a, followed by enhanced association of FoxO3a with the Bnip3 upstream promoter region, increased levels of Bnip3 transcript, and elevated mitochondrial Bnip3 immunoreactivity. Finally, FoxO3a silencing using a lentiviral short hairpin RNA approach significantly reduced hypoxic Bnip3 expression, mitochondrial damage, and neuron death. Together, these data illustrate a direct PARP1-mediated hypoxic signaling pathway involving NAD ϩ depletion, SIRT1 inhibition, FoxO3a-driven Bnip3 generation, and mitochondrial AIF release.Key words: apoptosis-inducing factor; Bnip3; ischemia; mitochondrial permeability; PARP; sirtuin IntroductionPoly(ADP-ribose) polymerase-1 (PARP1) is a genomic stability enzyme that responds to DNA damage by using nicotinamide adenine dinucleotide (NAD ϩ ) as a substrate to synthesize protein-conjugated chains of ADP-ribose polymers (PARs; Rouleau et al., 2010). PARP1 plays a paradoxically destructive role in pathological DNA damage, causing detrimental cytosolic NAD ϩ consumption, glycolytic inhibition, ATP depletion, and cell death (Cohen and Barankiewicz, 1987). Accordingly, blocking PARP1 activity enhances cell survival in brain trauma (LaPlaca et al., 2001) and ischemia (Eliasson et al., 1997). In brain hypoxia/ ischemia, PARP1 causes mitochondrial permeability transition (MPT), leading to caspase-independent neuron death initiated by nuclear translocation of mitochondrial apoptosis-inducing factor (AIF; Yu et al., 2002;Culmsee et al., 2005). The mechanism by which nuclear PARP1 causes mitochondrial damage is the subject of continued study. There is a line of evidence that PAR binds directly to AIF, causing nuclear translocation (Andrabi et al., 2006). There are also reports that NAD ϩ depletion is a requisite step for AIF release (Alano et al., 2010; Won et al., 2012).Bcl-2/adenovi...

Patients with chronic liver disease are referred late to hospice or never referred. There are several barriers to timely referral. First, liver transplantation (LT) and hospice care have always been perceived as mutually exclusive. Yet the criteria for hospice referral and for LT are more similar than different (for example, advanced liver disease and imminent death). Second, physicians, patients, and families have not had a reliable metric to guide referral. However, many patients wait for transplantation but never receive an organ. We hypothesized that the Model for End-Stage Liver Disease (MELD) score already in use to prioritize LT could be used in selected patients for concurrent hospice referral. Furthermore, we hypothesized that patients awaiting LT can receive hospice care and remain eligible for transplantation. Patients with advanced or end-stage liver disease were referred to the University of California Davis Health System hospice program. We correlated the MELD score at admission to length of stay (LOS) in hospice. A total of 157 end-stage liver disease patients were admitted to the hospice service. At the time of hospice admission the mean MELD score was 21 (range, 6-45). The mean length of hospice stay was 38 days (range, 1-329 days). A significant correlation was observed between hospice LOS and MELD score at hospice admission (P Ͻ 0.01). Six patients were offered a liver graft while on the combined (LT and hospice) program. MELD can be used to guide clinician recommendation to families about hospice care, achieving one of the national benchmark goals of increasing hospice care duration beyond the current median of 2-3 weeks. A higher MELD score might augment physician judgment as to hospice referral. Hospice care for selected patients may be an effective strategy to improve the care of end-stage liver disease patients waiting for LT.