Incorporation of Ethyl Glucuronide into rat hair: influence of hair h pigmentation and ethanol dose

Transcription

1 Incorporation of Ethyl Glucuronide into rat hair: influence of hair h pigmentation and ethanol dose Hicham Kharbouche University Center of Legal Medicine, Lausanne-Geneva ICADTS, Oslo 24 August 2010 Reference: Hicham Kharbouche, Nadia Steiner, Marie Morelato, Christian Staub, Benjamin Boutrel, Patrice Mangin, Frank Sporkert, Marc Augsburger. Influence of ethanol dose and pigmentation on the incorporation of ethyl glucuronide into rat hair. Alcohol doi: /j.alcohol

2 Ethyl glucuronide: detection of alcohol consumption H HOOC Ethyl glucuronide (EtG) HO HO H H O O H OH H Minor and specific metabolite of ethanol Advantage to be accumulated into growing hair large retrospective time window marker for long term alcohol consumption Increasingly used as marker of alcohol consumption 2/12

3 Predict dose of consumed ethanol based on EtG concentration in hair Evaluate relationship between EtG concentration in rat hair and ethanol doses administered Improve knowledge about incorporation of EtG in hair Investigate influence of hair pigmentation on EtG hair incorporation Study incorporation pathway of EtG into rat hair 3/12

4 Experimental design Animal model: Long Evans rats 4 groups: 0 (control), 1, 2, 3 g ethanol/kg Gavage solution prepared daily according to rat weight First ethanol administration D-1 D0 D4 D7 D11 D14 D18 D21 D28 Hair sampling Week 1 Week 2 Week 3 Newly grown hair sampling Blood sampling EtG determination in hair EtG + EtOH determination in blood Force-feeding step 4/12

5 Effect of hair pigmentation on EtG incorporation (1) EtG at D-1: - (all groups) EtG at D28: - (control group), + (other groups) EtG concentration: pg/mg hair EtG concentration: pg/mg hair [EtG pigmented ] = [EtG non-pigmented ] (Wilcoxon-Mann-Whitney test, P>0.05) 5/12

6 Effect of hair pigmentation on EtG incorporation (2) EtG concentration (pg/mg) in pigmented hair y = 0.90x-8.19 EtG concentration (pg/mg) in nonpigmented hair EtG concentration between non-pigmented / pigmented hair is correlated (Spearman s rho = 0.95, P<0.001) 6/12

7 Influence of ethanol dose on EtG incorporation Median = 189 ( pg/mg) * Wilcoxon-Mann-Whitney test 3 Dose of ethanol (g/kg) 2 1 Median = 104 ( pg/mg) Median = 21 (14-46 pg/mg) P<0.001* P<0.01* P<0.001* EtG concentration (pg/mg) in hair EtG concentration when ethanol dose 7/12

8 Kinetic profiles of ethanol and EtG in blood Blood EtG and blood EtOH before ethanol administration: - (all groups) * Area under curve EtOH concentration (g/kg) AUC EtOH * AUC EtG * EtG concentration (mg/kg) Time (hours) Example: concentration of EtOH and EtG in blood after ethanol administration by oral gavage at 3g/kg versus time Total EtG / EtOH exposure in rats for a 12-h period AUC EtG / AUC EtOH 8/12

9 Influence of ethanol dose on EtG/EtOH concentrations in blood Higher doses of EtOH administered: blood EtG AUC and blood EtOH AUC EtG AUC (mg/kg*h) EtOH AUC (g/kg*h) Dose of EtOH (g/kg) EtOH AUC correlated with EtG AUC (Spearman s rho = 0.84, P<0.001) 9/12

10 Relationship between EtG in blood and EtG in hair Log10 hair EtG concentration (pg/mg) Log10 EtG AUC (mg/kg*h) Blood EtG AUC proportional to hair EtG concentration (Pearson s r = 0.89, P<0.001) 10/12

11 EtG incorporation into rat hair Theoretically, 3 EtG incorporation pathways: sweat sebum Sweat No sweat glands in rats Sebum Nonpolar composition of sebum unlikely Blood Most probable route for EtG incorporation blood 11/12

12 Hair pigmentation has no effect on EtG incorporation rate in hair Hair EtG concentration increases with dose of ethanol administered EtG concentration in hair reflects EtG concentration in blood EtG likely to be incorporated into hair from bloodstream 12/12

13 Thank you for your attention Hicham Kharbouche Research Assistant Unit of Forensic Toxicology and Chemistry Switzerland Thank you to Benjamin Boutrel and Nadia Steiner, Center for Psychiatric Neurosciences, for their contribution in this project