Effects on Behavior by Different Exposure Durations of Predator Scent Stress / Efectos Conductuales por Exposición a Diferentes Duraciones de Estrés por Olor de Depredador

Abstract Stress is conceptualized as a systemic response triggered by a stimulus potentially harmful to an organism. Instead of an adaptive outcome, life-threatening experiences may contribute to the development of anxiety disorders and depression. Predator scent stress (PSS) is one of the most utilized rodent models of stress-induced psychopathology, in which rodents are exposed to a volatile predator cue that signifies imminent danger. It is unclear if the duration of a life-threatening experience could have differential consequences on the expression of anxiety-like and depression-like behaviors. For this reason, the goal of this present study was to evaluate the effect of different exposure durations (3 min., 10 min., or 20 min.) to the scent of bobcat urine. Wistar rats housed under 12/12 dark cycle in standard laboratory conditions were exposed to the PSS model and 24 hrs. after the stressor, behavioral consequences were evaluated in the open field test, saccharin preference test, and forced swim test. The results obtained show that a 10-minute exposure is sufficient to induce an anxiety-like and a depression-like behavioral profile. We conclude that the time exposure could be a major variable to obtain clear and trustable results and to avoid overexposure to stressor.

Resumen El estrés es una respuesta sistémica desencadenada por un estímulo potencialmente peligroso para el organismo. Esta respuesta permite al organismo adaptarse a la condición estresante, sin embargo, experiencias que amenazan a la vida pueden incrementar el riesgo de desarrollar trastornos de ansiedad y depresión. La exposición al olor de depredador (EOD) es el modelo animal de patología inducida por estrés más utilizado. Consta de la exposición a una pista olfativa que significa peligro inminente. Aún no está claro si la duración a una experiencia que amenaza la vida puede generar diferencias en la expresión conductas tipo-ansiedad o tipo-depresión. Por esta razón, el objetivo de este estudio fue evaluar el efecto de diferentes duraciones de exposición (3 min., 10 min. o 20 min.) al aroma de lince. Se utilizaron ratas hembra de la cepa Wistar en un ciclo luz oscuridad 12/12 en condiciones estándar de laboratorio, los sujetos fueron evaluados en la prueba de campo abierto, preferencia de sacarina y nado forzado 24 hrs. después de terminado el estresor. Los resultados indican que la exposición a 10 min. es suficiente para inducir el perfil conductual tipo-depresión y tipo-ansiedad. Concluimos que el tiempo de exposición puede ser una variable de mayor importancia para obtener resultados confiables y prevenir exposiciones innecesarias al estrés.

Lrrk2 R1441G-related Parkinson's disease: evidence of a common founding event in the seventh century in Northern Spain.

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene together represent the most common genetic determinant of Parkinson's disease (PD) identified to date. The vast majority of patients with LRRK2-related PD reported in the literature carry one of three pathogenic substitutions: G2019S, R1441C, or R1441G. While G2019S and R1441C are geographically widespread, R1441G is most prevalent in the Basque Country and is rare outside of Northern Spain. We sought to better understand the processes that have shaped the current distribution of R1441G. We performed a haplotype analysis of 29 unrelated PD patients heterozygous for R1441G and 85 wild-type controls using 20 markers that spanned 15.1 Mb across the LRRK2 region. Nine of the patients were of Basque origin and 20 were non-Basques. We inferred haplotypes using a Bayesian approach and utilized a maximum-likelihood method to estimate the age of the most recent common ancestor. Significant but incomplete allele sharing was observed over a distance of 6.0 Mb and a single, rare ten-marker haplotype 5.8 Mb in length was seen in all mutation carriers. We estimate that the most recent common ancestor lived 1,350 (95% CI, 1,020-1,740) years ago in approximately the seventh century. We hypothesize that R1441G originated in the Basque population and that dispersion of the mutation then occurred through short-range gene flow that was largely limited to nearby regions in Spain.

Mitochondrial transcription factor A (TFAM) gene variation in Parkinson's disease.

Mitochondrial function is necessary to supply the energy required for cell metabolism. Mutations/polymorphisms in mitochondrial DNA (mtDNA) have been implicated in Parkinson's disease (PD). The mitochondrial transcription factor A (TFAM) controls the transcription of mtDNA and regulates the mtDNA-copy number, thus being important for maintaining ATP production. TFAM dysfunction may also be involved in PD, and TFAM gene mutations/polymorphisms could contribute to the risk of developing PD. We searched for gene variants in the seven TFAM-exons in a total of 250 PD-patients. We found five common polymorphisms, and only one was a missense change (S12T in exon 1). Genotype and allele frequencies did not differ between patients and healthy controls (n=225) for the five polymorphisms. Our work suggests that TFAM-variants did not contribute to the risk of developing PD.

No association between Parkinson's disease and three polymorphisms in the eNOS, nNOS, and iNOS genes.

Nitric oxide synthases (NOS) and mitochondrial DNA-polymorphisms have been associated with the risk of developing Parkinson's disease (PD). In this report, we genotyped 450 PD-patients and 200 controls for three polymorphisms in the endothelial, inducible and neuronal NOS-genes, and for the T4336C and A10398G mitochondrial DNA-polymorphisms. None of the eNOS (intron 4 VNTR), iNOS (exon 22 A/G), or nNOS (exon 29T/C) were significantly associated with PD. Mitochondrial 4336C increased the PD-risk among women (OR=6.13), while the 10398G had a protective effect (OR=0.52). We did not find significantly interactions between the NOS and mitochondrial polymorphisms in the risk for PD in our population.

Digenic parkinsonism: investigation of the synergistic effects of PRKN and LRRK2.

The complex genetic etiology of Parkinson's disease (PD) is indicative of a multifactorial syndrome. A combination of gene-gene and gene-environment interactions may determine a variable phenotypic outcome. Recently a direct gene/protein interaction between two of the most common genetic causes of parkinsonism PRKN and LRRK2 has been postulated. We have identified three Spanish patients simultaneously harboring mutations in PRKN and LRRK2. In comparison to other Spanish patients with a single LRRK2 or PRKN mutation, the three double-mutation patients reported here do not present with an earlier age-at-onset or a faster progression of disease. Although the clinical findings do not support a synergistic effect of LRRK2 and PRKN, a potential genetic interplay might be concealed by the modulating effects of other genes. Nevertheless, this work demonstrates that the presence of mutations in one familial gene should not serve as exclusion criteria in a screen for further genetic variation. Direct interaction of Lrrk2 and parkin proteins was not observed in co-immunoprecipitation pull down experiments. However, in vivo studies are required to assess whether there is an indirect link between Lrrk2 and parkin in disease pathogenesis.

Mitochondrial DNA haplogroups in Spanish patients with hypertrophic cardiomyopathy.

Mutations in mtDNA have been implicated in the development of hypertrophic cardiomyopathy (HCM), including cases from families with a maternal transmission. Alleles at several polymorphic sites in mtDNA define different haplogroups and some of these haplogroups have been involved in the risk of developing several diseases in which mitochondria should be involved. We analysed the association between the nine common European haplogroups and HCM. A total of 130 Spanish patients and 300 healthy controls were genotyped for eight mitochondrial single nucleotide polymorphisms (SNPs) through polymerase chain reaction followed by digestion with a restriction enzyme (PCR-RFLP). We compared the frequencies of these polymorphisms and mitochondrial haplogroups between patients and controls. Haplogroup T, specifically defined by 13368A, was significantly involved in the risk of developing HCM in our population (p=0.007; OR=2.42; 95% CI=1.25-4.67). Our data suggest that the genetic variation at the mitochondrial genome could significantly contribute to the risk for HCM.

Mitochondrial DNA polymorphisms and risk of Parkinson's disease in Spanish population.

Mutations in mitochondrial DNA (mtDNA) have been implicated in the development of Parkinson's disease (PD). Mitochondrial function is necessary to supply the energy required for cell metabolism, and mutations in mitochondrial genes should have a deleterious effect in neuronal function. An association between several common mtDNA-polymorphisms and the risk of PD has been described. To test this association among Spanish patients, we genotyped 271 PD-patients and 230 healthy controls for 13 single-nucleotide polymorphisms (SNPs) through polymerase chain reaction (PCR) followed by digestion with a restriction enzyme. Alleles at eight of these SNPs define nine common European haplotypes, the mitochondrial haplogroups. In our population, no haplogroup showed significantly different frequencies between patients and controls. A significant association was found for the 4336T/C SNP (a polymorphism in the tRNA gln gene), with allele 4336C having a significantly increased frequency in PD-women compared to controls (OR=4.45; 95%CI=1.23-15.96; p=0.011). We also sequenced five of the complex I genes (ND1 to ND5) in the patients who were 4336C, and no mutation in these genes was found. We also found a significantly reduced frequency of 10398G in patients (p=0.009; OR=0.53), confirming a previously described protective effect for this allele in PD. In conclusion, we provided further evidence of the involvement of mitochondrial DNA variation in PD. In agreement with previous reports, we described a higher risk for PD among women with the mitochondrial 4336C allele in our population, and a protective effect for 10398G.

LRRK2 R1441G in Spanish patients with Parkinson's disease.

Pathogenic mutations in leucine-rich repeat kinase 2 (LRRK2; PARK8) have been implicated in autosomal dominant, late-onset Parkinson's disease (PD). The LRRK2 4321C>G (R1441G) mutation was originally identified in Spanish families originating from the Basque region. Within this ethnicity, Lrrk2 R1441G substitutions have been suggested as a frequent cause of disease. Herein we have assessed another referral-based series of 225 patients with PD from the neighboring region of Asturias, Northern Spain. The LRRK2 4321C>G mutation was found in 5 (2.7%) of sporadic, late-onset patients and was not present in control subjects. Although patients with a Lrrk2 R1441G substitution are apparently unrelated, they share a chromosome 12q12 haplotype not found in controls and indicative of a common founder.

Chemokines (RANTES and MCP-1) and chemokine-receptors (CCR2 and CCR5) gene polymorphisms in Alzheimer's and Parkinson's disease.

Parkinson's disease (PD) is a complex disorder characterized by the progressive degeneration of dopaminergic neurons in the midbrain. Late-onset Alzheimer's disease (LOAD) is the most common cause of dementia in the elderly, affecting about 5% of the population older than 65 years. Several works have demonstrated the involvement of inflammation in the pathogenesis of both, PD and LOAD. Genetic susceptibility to develop PD and LOAD has also been widely recognised. Thus, functional polymorphisms at the genes encoding inflammatory proteins could influence the overall risk of developing these neurodegenerative disorders. We examined whether DNA-polymorphisms at the genes encoding chemokines MCP-1 (-2518 A/G) and RANTES (-403 A/G), and chemokine receptors 5 (CCR5, Delta32) and 2 (CCR2,V64I), were associated with the risk and/or the clinical outcome of LOAD and PD. A total of 200 PD, 326 LOAD, and 370 healthy controls were genotyped for the four polymorphisms, and genotype frequencies statistically compared. We did not find significant differences in the frequencies of the different genotypes between both groups of patients and controls. We conclude that the four DNA polymorphisms, which have been associated with several immuno-modulated diseases, did not contribute to the risk of PD or LOAD.