Involvement of 2-arachidonoyl glycerol in the increased consumption of and preference for ethanol of mice treated with neurotoxic doses of methamphetamine

BACKGROUND AND PURPOSE

Methamphetamine (METH) is a psychostimulant amphetamine that causes long-term dopaminergic neurotoxicity in mice. Hypodopaminergic states have been demonstrated to increase voluntary ethanol (EtOH) consumption and preference. In addition, the endocannabinoid system has been demonstrated to modulate EtOH drinking behaviour. Thus, we investigated EtOH consumption in METH-lesioned animals and the role of cannabinoid (CB) signalling in this EtOH drinking.

EXPERIMENTAL APPROACH

Mice were treated with a neurotoxic regimen of METH, and 7 days later exposed to increasing concentrations of drinking solutions of EtOH (3, 6, 10 and 20%). Seven days after neurotoxic METH, the following biochemical determinations were carried out in limbic forebrain: CB(1) receptor density and stimulated activity, 2-arachidonoyl glycerol (2-AG) and monoacylglycerol lipase (MAGL) activity, dopamine levels and dopamine transporter density.

KEY RESULTS

EtOH consumption and preference were increased in METH-treated mice. Seven days after METH, a time at which both dopamine levels and density of dopamine transporters in limbic forebrain were decreased, CB(1) receptor density and activity were unaltered, but 2-AG levels were increased. At this same time-point, MAGL activity was reduced. The CB(1) receptor antagonist AM251 prevented the METH-induced increase in EtOH consumption and preference, while N-arachidonoyl maleimide, an inhibitor of MAGL, increased EtOH consumption and preference in both saline- and METH-treated mice.

CONCLUSIONS AND IMPLICATIONS

An increase in endocannabinoid tone may be involved in the increased consumption of and preference for EtOH displayed by METH-lesioned mice as blockade of the CB(1) receptor decreased EtOH-seeking behaviours, whereas the MAGL inhibitor increased EtOH consumption.

Genetic predisposition and environmental factors leading to the development of insulin-dependent diabetes mellitus in Chilean children

This study was designed to examine the hypothesis that some environmental factors increase the risk for insulin-dependent diabetes mellitus. Data on dietary history was collected from 80 diabetic children from the Santiago de Chile Registry and from 85 nondiabetic control subjects who were comparable in terms of age, sex, and ethnic characteristics. Early exposure was defined as the ingestion of food sources other than maternal milk before 3 months of age. To define genetic susceptibility to insulin-dependent diabetes mellitus each subject was typed in terms of HLA DQA1 and DQB1, and the possible conformation of susceptible heterodimers was considered as a risk marker. Fewer children were exclusively breast fed in the diabetic group than in the control group (21.55 +/- 15.05 vs 33.95 +/- 20.40 weeks, P<0.01). In addition, exposure to cow's milk and solid foods occurred earlier in the diabetic group than in the control group (15.90 +/- 10.95 vs 21.15 13.65 and 16.85 +/- 10.25 vs 21.20 +/- 12.35 weeks, P<0.05). Our data show that a short duration of breast-feeding and early exposure to cow's milk and solid foods may be important factors in the development of insulin-dependent diabetes mellitus. The high relative risk observed in individuals genetically predisposed indicates an interaction effect between genetic and environmental components.

Lipoprotein (a) and other risk factors in children with insulin-dependent diabetes mellitus and children without diabetes

AIMS

To study serum Lp(a) levels and other metabolic cardiovascular risk factors in children with Type 1 diabetes mellitus (DM) compared to sex and age matched nondiabetic children. The correlation of Lp(a) serum levels and other lipid parameters with HbA1c concentrations in diabetic children was investigated.

DESIGN

Transversal observational study.

TARGET POPULATION

36 C-peptide negative Type 1 DM children without microalbuminuria and no macromicrovascular or neurological complications, aged 8 to 15 years; 17 boys, 19 girls. Mean duration of Type 1 DM was 4.99 +/- 3.04 years, daily insulin need were 32.79 +/- 12.64 Units. 41 healthy children with no family history of DM, aged from 8 to 15 years, 26 boys, 15 girls, were studied in parallel as the control group.

METHODS

Serum total cholesterol (TC) and triglycerides (TG) were assayed by enzymatic methods, high-density lipoprotein (HDL) cholesterol by enzymatic method after precipitation of very-low-density (VLDL) and low-density lipoprotein (LDL) fractions. The LDL fractions was estimated after serum precipitation as the difference between total cholesterol and supernatant cholesterol concentrations. Apo-AI, apo-AII and apo-B were measured by radial immunodiffusion assays. Serum Lp(a) was measured by monoclonal anti-Lp(a) antibody (ELISA) method and whole blood glycosylated hemoglobin A1c (HbA1c) by high resolution liquid chromatography.

RESULTS

HbA1c concentration in diabetic children was 7.51 +/- 54% vs 4.16 +/- 0.35% in non diabetic children. Lp(a) serum levels did not significantly differ among both groups (25 +/- 22 mg/dl in diabetics subjects, 22 +/- 22 mg/dl in controls). Significant correlation was found between HbA1c levels and each of TC, LDL and TG serum concentrations in the diabetic group. Lp(a) levels were correlated with glycated hemoglobin in the whole diabetic group. But, in the 2 patients with the poorest metabolic control (HbA1c 10.5%) were excluded, the correlation disappeared.

CONCLUSIONS

In 36 children aged 5-15 years with uncomplicated Type 1 DM lasting less than 15 years, Lp(a) serum levels did not differ from age-matched controls but highest Lp(a) values were associated with poorest metabolic control.

Susceptibility to type 1 (insulin-dependent) diabetes mellitus in Spanish patients correlates quantitatively with expression of HLA-DQ alpha Arg 52 and HLA-DQ beta non-Asp 57 alleles

HLA-DQ alpha and beta alleles were chosen as the most sensitive Type 1 (insulin-dependent) diabetes mellitus susceptibility markers for evaluating the disease associations and Type 1 diabetes risk in a population-based registry from Madrid. The absence of aspartic acid in position 57 of the DQ beta chain (non-Asp 57), and the presence of arginine in position 52 of the DQ alpha chain (Arg 52) were found to be reliable markers of Type 1 diabetes susceptibility among the Spanish population, with significantly higher frequencies among the cases of Type 1 diabetes compared to randomly selected non-diabetic control subjects from the general Madrid population. While non-Asp 57 homozygosity conferred an absolute risk of 32.3 per 100,000 per year and Arg 52 of 31.5 per 100,000 per year, the risk for double homozygotes for both non-Asp 57 and Arg 52 was estimated as 101.7 per 100,000 per year. Individuals homozygous for only one of these alleles, and heterozygous at the other locus, had a markedly lower Type 1 diabetes risk (12.8 per 100,000 per year), approximating the general population incidence for Madrid. Thus, susceptibility to Type 1 diabetes in Spanish patients is associated, quantitatively, with non-Asp 57 DQ beta and Arg 52 DQ alpha alleles.