Muscarinic receptors in the rat ovary are involved in follicular development but not in steroid secretion.

Acetylcholine (ACh) may be involved in the regulation of ovarian functions. A previous systemic study in rats showed that a 4-week, intrabursal local delivery of the ACh-esterase blocker Huperzine-A increased intraovarian ACh levels and changed ovarian follicular development, as evidenced by increased healthy antral follicle numbers and corpora lutea, as well as enhanced fertility. To further characterize the ovarian cholinergic system in the rat, we studied whether innervation may contribute to intraovarian ACh. We explored the cellular distribution of three muscarinic receptors (MRs; M1, M3, and M5), analyzed the involvement of MRs in ovarian steroidogenesis, and examined their roles in ovarian follicular development in normal conditions and in animals exposed to stressful conditions by employing the muscarinic antagonist, atropine. Denervation studies decreased ovarian norepinephrine, but ovarian ACh was not affected, evidencing a local, nonneuronal source of ACh. M1 was located on granulosa cells (GCs), especially in large antral follicles. M5 was associated with the ovarian vascular system and only traces of M3 were found. Ex vivo ovary organo-typic incubations showed that the MR agonist Carbachol did not modify steroid production or expression of steroid biosynthetic enzymes. Intrabursal, in vivo application of atropine (an MR antagonist) for 4 weeks, however, increased atresia of the secondary follicles. The results support the existence of an intraovarian cholinergic system in the rat ovary, located mainly in follicular GCs, which is not involved in steroid production but rather via MRs exerts trophic functions and regulates follicular atresia.

Frequencies of 23 functionally significant variant alleles related with metabolism of antineoplastic drugs in the chilean population: comparison with caucasian and asian populations.

Cancer is a leading cause of death worldwide. The cancer incidence rate in Chile is 133.7/100,000 inhabitants and it is the second cause of death, after cardiovascular diseases. Most of the antineoplastic drugs are metabolized to be detoxified, and some of them to be activated. Genetic polymorphisms of drug-metabolizing enzymes can induce deep changes in enzyme activity, leading to individual variability in drug efficacy and/or toxicity. The present research describes the presence of genetic polymorphisms in the Chilean population, which might be useful in public health programs for personalized treatment of cancer, and compares these frequencies with those reported for Asian and Caucasian populations, as a contribution to the evaluation of ethnic differences in the response to chemotherapy. We analyzed 23 polymorphisms in a group of 253 unrelated Chilean volunteers from the general population. The results showed that CYP2A6*2, CYP2A6*3, CYP2D6*3, CYP2C19*3, and CYP3A4*17 variant alleles are virtually absent in Chileans. CYP1A1*2A allele frequency (0.37) is similar to that of Caucasians and higher than that reported for Japanese people. Allele frequencies for CYP3A5*3(0.76) and CYP2C9*3(0.04) are similar to those observed in Japanese people. CYP1A1*2C(0.32), CYP1A2*1F(0.77), CYP3A4*1B(0.06), CYP2D6*2(0.41), and MTHFR T(0.52) allele frequencies are higher than the observed either in Caucasian or in Japanese populations. Conversely, CYP2C19*2 allelic frequency (0.12), and genotype frequencies for GSTT1 null (0.11) and GSTM1 null (0.36) are lower than those observed in both populations. Finally, allele frequencies for CYP2A6*4(0.04), CYP2C8*3(0.06), CYP2C9*2(0.06), CYP2D6*4(0.12), CYP2E1*5B(0.14), CYP2E1*6(0.19), and UGT2B7*2(0.40) are intermediate in relation to those described in Caucasian and in Japanese populations, as expected according to the ethnic origin of the Chilean population. In conclusion, our findings support the idea that ethnic variability must be considered in the pharmacogenomic assessment of cancer pharmacotherapy, especially in mixed populations and for drugs with a narrow safety range.

Determinación del polimorfismo de CYP2C9*2 y su relación con la farmacocinética de acenocumarol en voluntarios sanos / Relation of cy2c9*2 polymorphism and acenocumarol pharmacokynetics in healthy volunteers

Antecedentes: La mayoría de los pacientes que reciben tratamientos con anticoagulantes orales por periodos prolongados presentan variabilidad en la respuesta. El acenocumarol es el anticoagulante oral más prescrito en nuestro país, es biotransformado principalmente por CYP2C9 e investigaciones recientes demuestran que la variante CYP2C9*2 es una de las responsables de la variabilidad de respuesta a acenocumarol. Objetivo: Determinar las diferencias en los parámetros farmacocinéticos de acenocumarol en voluntarios que presentan la variante alélica CYP2C9*2. Métodos: Se estudiaron 24 voluntarios sanos. La detección de genotipos se realizó mediante PCR-RFLP y los parámetros farmacocinéticos se obtuvieron mediante la concentración plasmática de acenocumarol usando un método validado para UPLC-MS/MS. Resultados: Del total de 24 voluntarios, 19 tenían el genotipo CYP2C9*1/*1 (wt/wt), 4 tenían genotipo CYP2C9*1/*2 (heterocigoto) y 1 voluntario tenía genotipo de CYP2C9*2/*2 (homocigoto recesivo). Los parámetros farmacocinéticos del acenocumarol no fueron significativamente diferentes entre los individuos con genotipo CYP2C9*2 y CYP2C9*1. Sin embargo, la farmacocinética de acenocumarol del individuo CYP2C9*2/*2 mostró diferencias relevantes con respecto a la observada en el grupo CYP2C9*1/*1 (tmáx aumentó 1,4 veces, ke disminuyó 1,8 veces y t1/2 aumentó 1,7 veces). Conclusión: La farmacocinética de acenocumarol en el individuo con el genotipo CYP2C9*2/*2 refleja una potencial relevancia de este polimorfismo en el tratamiento con acenocumarol.

Background: Most of the patients receiving anticoagulant therapy for extended periods show variability in their clinical response. Acenocumarol, the most commonly prescribed oral anticoagulant in our country, is biotransformed mainly through CYP2C9 and recent research shows that CYP2C9*2 variant is partly responsible for the variable response to ace-nocumarol. Aim: to determine pharmacokinetics parameters of acenocumarol in volunteers exhibiting the CYP2C9*2 polymorphic variant. Methods: Genotype detection was performed using PCR-RFLP and pharmacokinetics parameters were obtained from the acenocumarol concentrations, using a UPLC-MS/MS validated method. The project was approved by the institutional Ethics Committee of the University of Chile's Faculty of Medicine. Results: 19 out of 24 volunteers had the CYP2C9*1/*1 genotype, 4 the CYP2C9*1/*2 genotype (heterozygous) and 1 subject had the CYP2C9*2/*2 genotype (recessive homozygous). No statistically significant differences between acenocumarol pharmacokinetics parameters of CYP2C9*2 compared to those with normal variant, CYP2C9*1were observed.. However, a single individual with the CYP2C9*2/*2 genotype showed different phar-macokinetics parameters: tmáx and t1/2 were increased 1.4 and 1.7 times, respectively, and kc was 1.8 times lower compared to the group with the CYP2C9*1/*1 genotype. Conclusion: There are clear differences in genotype-dependent acenocoumarol pharmacokinetics in individuals with the CYP2C9*2/*2 genotype, reflecting a potential relevance of this polymorphism in anticoagulation with acenocumarol.

Oral cancer susceptibility associated with the CYP1A1 and GSTM1 genotypes in Chilean individuals.

Polycyclic aromatic hydrocarbons (PAHs) contained in tobacco smoke acquire carcinogenicity following their activation by xenobiotic-metabolizing enzymes to highly reactive metabolites. The cytochrome P4501A1 (CYP1A1) enzyme is central to the metabolic activation of these PAHs, and GSTM1 is the main enzyme responsible for its detoxification. CYP1A1 and GSTM1 polymorphisms were evaluated in 124 Chilean healthy controls and 48 oral cancer patients through PCR-based restriction fragment length polymorphism. In the healthy controls, frequencies of the CYP1A1 variant alleles for m1 (CYP1A1(*)2A) and the GSTM1null genotype were found to be 0.25 and 0.19, respectively. In the oral cancer patients, these frequencies were 0.33 and 0.50, respectively. Thus, the GSTM1 and m1 rare alleles were significantly more frequent in the oral cancer patients compared to the controls. The estimated relative risk for oral cancer associated with the single genotype CYP1A1 or GSTM1 was 2.08 for wt/m1, 1.04 for m1/m1 and 4.16 for the GSTM1null genotype. For smokers, the estimated relative risk (adjusted by age and gender) was higher in the individuals carrying the m1 allele of CYP1A1 [wt/m1: odds ratio (OR)=5.68, P=0.0080; m1/m1: OR=7.77, P=0.0420] or GSTM1null genotype (OR=20.81, P<0.0001). Combined genotypes CYP1A1 and GSTM1 increased the risk significantly (wt/m1/GSTM1null: OR=19.14, P=0.0030; m1/m1/GSTM1null: OR=21.39, P=0.0130). Taken together, these findings suggest that Chilean individuals carrying single or combined GSTM1 and CYP1A1 polymorphisms may be more susceptible to oral cancer induced by environmental tobacco smoking.