Metabolic responses in discrete regions of rat brain following acute administration of glutamate

Chronic pretreatment with acetyl-L-carnitine and ±DL-α-lipoic acid protects against acute glutamate-induced neurotoxicity in rat brain by altering mitochondrial function

Cellular oxidative stress and energy failure were shown to be involved in Glutamate (L-Glu) neurotoxicity, whereas, acetyl-L-carnitine (ALCAR) and ±DL-α-lipoic acid (LA) are known to be key players in the mitochondrial energy production. To evaluate the effects of the above antioxidants, adult rats were pretreated with ALCAR (100 mg/kg i.p for 21 days) and both ALCAR and LA (100 mg/kg i.p + 50 mg/kg i.p for 21 days), before stereotactically administering L-Glu bolus (1 μmole/1 μl) in the cerebral cortex. Results showed that acute L-Glu increased ROS (P < 0.001), LPO (P < 0.001), Ca(2+) (P < 0.001), TNF-α (P < 0.001), IFN-γ (P < 0.001), NO (P < 0.001) levels and mRNA expression of Caspase-3, Casapase-9, iNOS, and nNOS genes with respect to saline-injected control group. Key antioxidant parameters such as SOD, CAT, GSH, GR along with mitochondrial transmembrane potential (Ψ∆m) were decreased (P < 0.05), while ALCAR pretreatment prevented these effects by significantly inhibiting ROS (P < 0.001), LPO (P < 0.001), Ca(2+) (P < 0.05), TNF-α (P < 0.05), IFN-γ (P < 0.001), NO (P < 0.01) levels and expression of the above genes. This chronic pretreatment of ALCAR also increased SOD, CAT, GSH, GR, and Ψ∆m (P < 0.0.01, P < 0.0.01, P < 0.05, P < 0.05, and P < 0.001, respectively) with respect to L: -Glu group. The addition of LA to ALCAR resulted in further increases in CAT (P < 0.05), GSH (P < 0.01), GR (P < 0.05), Ψ∆m (P < 0.05) and additional decreases in ROS (P < 0.001), LPO (P < 0.05), Ca(2+) (P < 0.05), TNF-α (P < 0.05) and mRNA expression of iNOS and nNOS genes with respect to ALCAR group. Hence, this "one-two punch" of ALCAR + LA may help in ameliorating the deleterious cellular events that occur after L-Glu.

In vivo neuroprotective effects of peripheral kynurenine on acute neurotoxicity induced by glutamate in rat cerebral cortex

N-methyl-D-aspartate (NMDA) receptors play a crucial role in Glutamate (L-Glu) neurotoxicity. To evaluate the effects of astrocyte-derived tryptophan metabolite kynurenic acid (KYNA), on L-Glu neurotoxicity, adult male rats were pretreated with Kynurenine (KYN) which is a precursor of KYNA, at a dose of 30 mg or 300 mg/kg bw i.p., 2 h before stereotactic L-Glu bolus (1 micromole/1 microl) administration in cerebral cortex. Results showed that acute L-Glu increased reactive oxygen species, rate of lipid peroxidation, calcium, nitric oxide and neuroinflammatory markers viz. TNF-alpha, IFN-gamma levels and decreased key antioxidant parameters such as SOD, catalase, total glutathione and glutathione reductase along with mitochondrial membrane potential. While peripheral loading of 30 mg/kg dose of KYN had no protective effects on L-Glu induced neurotoxicity, 300 mg/kg dose prevented the above toxic effects following intracortical L-Glu. KYN apparently crossed blood brain barrier to elevate astrocytic-KYNA level, which seems to protect neurons through several interactive mechanisms.

Elevated inflammatory markers in a group of amyotrophic lateral sclerosis patients from northern India

The role of cytokines in the pathophysiology of amyotrophic lateral sclerosis (ALS) and its relation to clinical outcome has not been clearly defined. We evaluated tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and nitric oxide (NO) levels in the serum of 22 ALS patients and 20 controls. Serum TNF-alpha levels and IFN-gamma levels were significantly (P < 0.001) elevated in ALS patients. We also observed NO levels to be significantly (P < 0.05) increased with respect to normal subjects. We further noticed positive correlation between the duration of ALS and these proinflammatory molecule levels. Exitotoxicity and oxidative stress are known to play a crucial role in the neurodegeneration observed in ALS. Since high levels of TNF-alpha are known to be cytotoxic, it could be that a complex interplay of these effectors may be one of the factors underlying the progression of ALS. This study confirms the involvement of inflammation in ALS and the need to develop surrogate markers to check the progression of this disease.