DNA damage and oxidative stress induced by seizures are decreased by anticonvulsant and neuroprotective effects of lobeline, a candidate to treat alcoholism.

The alkaloid lobeline (Lob) has been studied due to its potential use in treatment of drug abuse. This study evaluates the possible anticonvulsant and neuroprotective activities of Lob to obtain new information on its properties that could confirm it as a candidate in the treatment of alcohol addiction. The anticonvulsant effect of Lob was evaluated using a pilocarpine-induced seizure model. In addition, possible neuroprotective effects were investigated measuring DNA damage using the comet assay, assessing free radical levels by dichlorofluorescein diacetate (DCF) oxidation, and measuring the antioxidant potential using the α, α-diphenyl-ß-picrylhydrazyl (DPPH) scavenging assay, besides measuring superoxide dismutase (SOD) and catalase (CAT) enzyme activities in brain tissues. Lobeline increased the latency to the first seizure and decreased the percentage of seizures in a similar way as diazepam, used as control. DNA damage induced by Pil and hydrogen peroxide were decreased in hippocampus and cerebral cortex from mice treated with Lob. The levels of free radicals and CAT activity increased in cortex and hippocampus, respectively, in mice treated with Pil. Lobeline decreased CAT in hippocampus, leading to similar values as in the saline negative control. In conclusion, Lob has anticonvulsant and neuroprotective actions that may be mediated by antioxidant-like mechanisms, indicating its potential as candidate drug in alcoholism therapy.

Evaluation of mutagenic and genotoxic activities of lobeline and its modulation on genomic instability induced by ethanol.

AIM: Lobeline is a natural alkaloid derived from Lobelia inflata that has been investigated as a clinical candidate for the treatment of alcoholism. In a pre-clinical trial, lobeline decreased the preference for and consumption of ethanol, due to the modulation of the nicotinic acetylcholine receptor. However, the interaction between lobeline and ethanol is poorly known and thus there are safety concerns. The present study was conducted to evaluate the mutagenic and genotoxic effects of lobeline and assess its modulation of ethanol-induced toxicological effects. MAIN METHODS: CF-1 male mice were divided into five groups. Groups received an intraperitoneal injection of saline solution, lobeline (5 or 10mg/kg), ethanol (2.5 g/kg), or lobeline plus ethanol, once a day for three consecutive days. Genotoxicity was evaluated in peripheral blood using the alkaline comet assay. The mutagenicity was evaluated using both Salmonella/microsome assay in TA1535, TA97a, TA98, TA100, and TA102 Salmonella typhimurium strains and the micronucleus test in bone marrow. Possible liver and kidney injuries were evaluated using biochemical analysis. KEY FINDINGS: Lobeline did not show genotoxic or mutagenic effects and did not increase the ethanol-induced genotoxic effects in blood. Lobeline also protected blood cells against oxidative damage induced by hydrogen peroxide. Biochemical parameters were not altered, indicating no liver or kidney injuries or alterations in lipid and carbohydrate metabolisms. SIGNIFICANCE: These findings suggest that lobeline does not induce gene or chromosomal mutations, and that this lack of genetic toxicity is maintained in the presence of ethanol, providing further evidence of the safety of this drug to treat alcohol dependence.

Neurotoxicological profile assessment of lobeline after acute treatment in mice.

Lobeline is a natural alkaloid with high affinity for nicotinic acetylcholine receptors, and it is a promising candidate for addiction treatment in human beings. This work evaluated the toxicological profile of lobeline with different behavioural models and investigated its effect on DNA damage (comet assay and micronucleus test) in mice. Acute administration of lobeline (5 or 10 mg/kg; i.p.) did not impair the parameters measured in the habituation and inhibitory avoidance test, suggesting that it has no effect on memory acquisition in these tasks. Lobeline did not affect the number or the latency to the first head-dip in the hole board test, indicating that it was not anxiolytic/anxiogenic in this model. No genotoxic effects were observed in blood, liver and brain tissues collected 24 hr after the single injection of lobeline (both doses). There was no increase in micronucleus frequency in mice treated with lobeline, indicating the absence of toxicity in bone marrow of the animals. Therefore, the acute treatment with high doses of lobeline did not impair the behavioural parameters measured in this work. Additionally, the drug was not able to produce DNA damage.

Overexpression of VMAT-2 and DT-diaphorase protects substantia nigra-derived cells against aminochrome neurotoxicity.

We tested the hypothesis that both VMAT-2 and DT-diaphorase are an important cellular defense against aminochrome-dependent neurotoxicity during dopamine oxidation. A cell line with VMAT-2 and DT-diaphorase over-expressed was created. The transfection of RCSN-3 cells with a bicistronic plasmid coding for VMAT-2 fused with GFP-IRES-DT-diaphorase cDNA induced a significant increase in protein expression of VMAT-2 (7-fold; P<0.001) and DT-diaphorase (9-fold; P<0.001), accompanied by a 4- and 5.5-fold significant increase in transport and enzyme activity, respectively. Studies with synaptic vesicles from rat substantia nigra revealed that VMAT-2 uptake of ³H-aminochrome 6.3 ± 0.4nmol/min/mg was similar to dopamine uptake 6.2 ± 0.3nmol/min/mg that which were dependent on ATP. Interestingly, aminochrome uptake was inhibited by 2µM lobeline but not reserpine (1 and 10µM). Incubation of cells overexpressing VMAT-2 and DT-diaphorase with 20µM aminochrome resulted in (i) a significant decrease in cell death (6-fold, P<0.001); (ii) normal ultra structure determined by transmission electron microscopy contrasting with a significant increase of autophagosome and a dramatic remodeling of the mitochondrial inner membrane in wild type cells; (iii) normal level of ATP (256 ± 11µM) contrasting with a significant decrease in wild type cells (121±11µM, P<0.001); and (iv) a significant decrease in DNA laddering (21 ± 8pixels, P<0.001) cells in comparison with wild type cells treated with 20µM aminochrome (269 ± 9). These results support our hypothesis that VMAT-2 and DT-diaphorase are an important defense system against aminochrome formed during dopamine oxidation.

Nuevas estrategias en el tratamiento farmacológico del tabaquismo / News strategies in the pharmacological treatment of tobac adiction

La adicción a la nicotina es uno de los problemas de salud pública más importantes en todos los países del mundo. Se piensa que el potencial adictivo de la nicotina es similar en intensidad al que genera la cocaína. Las tasas esperadas de muerte relacionadas al uso del tabaco para el 2020 será aproximadamente de 10 millones de personas. Las estrategias farmacológicas actuales para el tratamiento del tabaquismo incluyen la terapia sustitutiva por vías no inhalables, el bloqueo de los receptores nicotínicos y el desarrollo de una vacuna. Se ha demostrado que el bupropión es un antagonista de la nicotina. En los próximos años se tendrá una vacuna para uso clínico (Nic Vax ) que bloquea a la nicotina circulante antes que acceda al sistema nervioso central.