Neuroprotective role for RORA in Parkinson’s disease revealed by analysis of post-mortem brain and a dopaminergic cell line

Parkinson's disease (PD) is almost twice as prevalent in men, which has largely been attributed to neuroprotective effect of oestradiol in women. RORA (retinoic acid receptor-related orphan receptor alpha) regulates the transcription of central aromatase, the enzyme responsible for local oestradiol synthesis, simultaneously, RORA expression is regulated by sex hormones. Moreover, RORA protects neurones against oxidative stress, a key mechanism contributing to the loss of dopaminergic neurones in PD. Therefore, we hypothesized that there would be sex differences in RORA expression in the substantia nigra pars compacta (SNpc), which could contribute to sex differences observed in PD prevalence and pathogenesis. In a case control study, qPCR and western blot analyses were used to quantify gene and protein expression in the SNpc of post-mortem brains (n = 14 late-stage PD and 11 age and sex matched controls). The neuroprotective properties of a RORA agonist were then investigated directly using a cell culture toxin-based model of PD coupled with measures of viability, mitochondrial function and apoptosis. RORA was expressed at significantly higher levels in the SNpc from control females' brains compared to males. In PD, we found a significant increase in SNpc RORA expression in male PD compared to female PD. Treatment with a RORA agonist showed a significant neuroprotection in our cell culture model of PD and revealed significant effects on intracellular factors involved in neuronal survival and demise. This study is the first to demonstrate a sex specific pattern of RORA protein and gene expression in the SNpc of controls post-mortem human brains, and to show that this is differentially altered in male and female PD subjects, thus supporting a role for RORA in sex-specific aspects of PD. Furthermore, our in vitro PD model indicates mechanisms whereby a RORA agonist exerts its neuroprotective effect, thereby highlighting the translational potential for RORA ligands in PD

Accumulation and dissemination of prion protein in experimental sheep scrapie in the natural host

<p>Abstract</p> <p>Background</p> <p>In order to study the sites of uptake and mechanisms of dissemination of scrapie prions in the natural host under controlled conditions, lambs aged 14 days and homozygous for the VRQ allele of the PrP gene were infected by the oral route. Infection occurred in all lambs with a remarkably short and highly consistent incubation period of approximately 6 months. Challenge of lambs at approximately eight months of age resulted in disease in all animals, but with more variable incubation periods averaging significantly longer than those challenged at 14 days.</p> <p>This model provides an excellent system in which to study the disease in the natural host by virtue of the relatively short incubation period and close resemblance to natural infection.</p> <p>Results</p> <p>Multiple sites of prion uptake were identified, of which the most important was the Peyer's patch of the distal ileum.</p> <p>Neuroinvasion was detected initially in the enteric nervous system prior to infection of the central nervous system. At end stage disease prion accumulation was widespread throughout the entire neuraxis, but vacuolar pathology was absent in most animals that developed disease at 6–7 months of age.</p> <p>Conclusion</p> <p>Initial spread of detectable PrP was consistent with drainage in afferent lymph to dependent lymph nodes. Subsequent accumulation of prions in lymphoid tissue not associated with the gut is consistent with haematogenous spread. In addition to macrophages and follicular dendritic cells, prion containing cells consistent with afferent lymph dendritic cells were identified and are suggested as a likely vehicle for carriage of prions from initial site of uptake to the lymphoreticular system, and as potential carriers of prion protein in blood. It is apparent that spongiform change, the characteristic lesion of scrapie and other prion diseases, is not responsible for the clinical signs in sheep, but may develop in an age dependent manner.</p

The evaluation of exposure risks for natural transmission of scrapie within an infected flock

Background: Although the epidemiology of scrapie has been broadly understood for many years, attempts to introduce voluntary or compulsory controls to eradicate the disease have frequently failed. Lack of precision in defining the risk factors on farm has been one of the challenges to designing control strategies. This study attempted to define which parts of the annual flock management cycle represented the greatest risk of infection to naive lambs exposed to the farm environment at different times.Results: In VRQ/VRQ lambs exposed to infected sheep at pasture or during lambing, and exposed to the buildings in which lambing took place, the attack rate was high and survival times were short. Where exposure was to pasture alone the number of sheep affected in each experimental group was reduced, and survival times were longer and related to length of exposure.Conclusion: At the flock level, eradication and control strategies for scrapie must take into account the need to decontaminate buildings used for lambing, and to reduce (or prevent) the exposure of lambs to infected sheep, especially in the later stages of incubation, and at lambing. The potential for environmental contamination from pasture should also be considered. Genotype selection may still prove to be the only viable tool to prevent infection from contaminated pasture, reduce environmental contamination and limit direct transmission from sheep to sheep

Mentors and protégés: The impact of the mentoring relationship on beginning teachers and mentor teachers

The ordeals and challenges of the first year teacher have often been cited as reasons why up to one-third of new teachers become discouraged and even abandon their teaching careers within the first two years. This extraordinary turnover among new teachers should give us an indication that the induction process into the teaching profession needs to change. The threat of teacher shortages has prompted many districts across the nation to turn to formal induction in an effort to support new teachers in the classroom and keep them from leaving the profession. Mentoring programs are now being implemented as a professional development strategy for beginning teachers. Acclimating new teachers and easing their transition from the world of education theory to the world of education practice is a lofty goal of mentoring programs. The state of Connecticut established a mentoring program in 1989 entitled BEST (Beginning Educator Support and Training). This study examined the effects this formalized mentoring program had on mentors and protégés and also identified the qualities of successful mentor/protégé relationships. Focus groups were conducted in three different districts in Connecticut. The groups were comprised of beginning teachers and mentor teachers who have participated or are presently participating in the BEST Program. Interviews were employed as a means of studying individual perceptions. The results of the study will assist in documenting the impact of mentoring and make recommendations for a successful mentoring relationship

Sex dependent influences of dexamethasone exposure in utero and stress and stress hormones in adulthood on a rat model of Parkinson's disease

Stress is increasingly identified as a risk factor for brain disease, but the underlying processes are unkown. This thesis examines the influence of raised levels of the glucocorticoid (GC) stress hormone at different stages of life (during late gestation and/or in adulthood) on pathways known to be altered in parkinson’s disease (PD), and compares this with the effects of repeated adult stress. Adult stress or GC treatment produced complex, differential sex and region specific changes in these pathways. Notably, adult stress or GC treatment increased markers of nirosative stress in the male but not female rat substantia nigra (SN). Prenatal GC treatment produced long term effects on both dopamineric (DA) and noradrenergic (NA) nuclei, increasing the number of DA neurons in the SN and ventral tegmental area, and reducing the number of NA neurons in the locus coeruleus of adult rats. Furthermore microglial and astrocyte populations were increased and decreased respectively in these nuclei. Interestingly prenatal GC treatment rendered the male midbrain susceptible to a down regulation of DA measures in response to adult challenge, whereby the number of SN DA neurons and striatal and accumbal DA levels were attenuated. Fascinatingly adult stress or GC treatment, but not prenatal GC treatment exacerbated 6-hydroxydopamine-induced neurotoxicity, that was associated with increased microglial activation and protein nitration in the SN, in males, but afforded neuroprotection in females, neither of which were substantially altered by prenatal treatment. This is the first study to demonstrate that prenatal GC treatment can permanentlty alter the response of the midbrain DA pathways to adult challenge. Furthermore this is one of very few studies looking at male and female responses in parallel and thus highlights some striking sex differences in the response to stress and GCs. Together these novel data strongly support the premise that stress and GCs influence the functional integrity of pathways involved in PD, thereby potentially contributing to PD pathogenesis. The data also highlight the complex sexually dimorphic nature of their actions. Although further work is required to determine the functional consequences of these stress/GC related changes, these findings may have considerable implications for the use of GCs in clinical practice.EThOS - Electronic Theses Online ServiceUK Parkinson?s Disease SocietyGBUnited Kingdo

Neuroprotective role for RORA in Parkinson’s disease revealed by analysis of post-mortem brain and a dopaminergic cell line

Abstract Parkinson’s disease (PD) is almost twice as prevalent in men, which has largely been attributed to neuroprotective effect of oestradiol in women. RORA (retinoic acid receptor-related orphan receptor alpha) regulates the transcription of central aromatase, the enzyme responsible for local oestradiol synthesis, simultaneously, RORA expression is regulated by sex hormones. Moreover, RORA protects neurones against oxidative stress, a key mechanism contributing to the loss of dopaminergic neurones in PD. Therefore, we hypothesized that there would be sex differences in RORA expression in the substantia nigra pars compacta (SNpc), which could contribute to sex differences observed in PD prevalence and pathogenesis. In a case control study, qPCR and western blot analyses were used to quantify gene and protein expression in the SNpc of post-mortem brains (n = 14 late-stage PD and 11 age and sex matched controls). The neuroprotective properties of a RORA agonist were then investigated directly using a cell culture toxin-based model of PD coupled with measures of viability, mitochondrial function and apoptosis. RORA was expressed at significantly higher levels in the SNpc from control females’ brains compared to males. In PD, we found a significant increase in SNpc RORA expression in male PD compared to female PD. Treatment with a RORA agonist showed a significant neuroprotection in our cell culture model of PD and revealed significant effects on intracellular factors involved in neuronal survival and demise. This study is the first to demonstrate a sex specific pattern of RORA protein and gene expression in the SNpc of controls post-mortem human brains, and to show that this is differentially altered in male and female PD subjects, thus supporting a role for RORA in sex-specific aspects of PD. Furthermore, our in vitro PD model indicates mechanisms whereby a RORA agonist exerts its neuroprotective effect, thereby highlighting the translational potential for RORA ligands in PD

Minimum Effective Dose of Cattle and Sheep BSE for Oral Sheep Infection.

The minimum dose required to cause infection of Romney and Suffolk sheep of the ARQ/ARQ or ARQ/ARR prion protein gene genotypes following oral inoculation with Romney or Suffolk a sheep Bovine spongiform encephalopathy (BSE)-derived or cattle BSE-derived agent was investigated using doses ranging from 0.0005g to 5g. ARQ/ARQ sheep which were methionine (M) / threonine (T) heterozygous or T/T homozygous at codon 112 of the Prnp gene, dosed ARQ/ARR sheep and undosed controls did not show any evidence of infection. Within groups of susceptible sheep, the minimum effective oral dose of BSE was found to be 0.05g, with higher attack rates following inoculation with the 5g dose. Surprisingly, this study found no effect of dose on survival time suggesting a possible lack of homogeneity within the inoculum. All clinical BSE cases showed PrPd accumulation in brain; however, following cattle BSE inoculation, LRS involvement within Romney recipients was found to be significantly lower than within the Suffolk sheep inoculated group which is in agreement with previous reports

Pruritus is a common feature in sheep infected with the BSE agent

Background: The variability in the clinical or pathological presentation of transmissible spongiform encephalopathies (TSEs) in sheep, such as scrapie and bovine spongiform encephalopathy (BSE), has been attributed to prion protein genotype, strain, breed, clinical duration, dose, route and type of inoculum and the age at infection. The study aimed to describe the clinical signs in sheep infected with the BSE agent throughout its clinical course to determine whether the clinical signs were as variable as described for classical scrapie in sheep. The clinical signs were compared to BSE-negative sheep to assess if disease-specific clinical markers exist. Results: Forty-seven (34%) of 139 sheep, which comprised 123 challenged sheep and 16 undosed controls, were positive for BSE. Affected sheep belonged to five different breeds and three different genotypes (ARQ/ARQ, VRQ/VRQ and AHQ/AHQ). None of the controls or BSE exposed sheep with ARR alleles were positive. Pruritus was present in 41 (87%) BSE positive sheep; the remaining six were judged to be pre-clinically infected. Testing of the response to scratching along the dorsum of a sheep proved to be a good indicator of clinical disease with a test sensitivity of 85% and specificity of 98% and usually coincided with weight loss. Clinical signs that were displayed significantly earlier in BSE positive cases compared to negative cases were behavioural changes, pruritic behaviour, a positive scratch test, alopecia, skin lesions, teeth grinding, tremor, ataxia, loss of weight and loss of body condition. The frequency and severity of each specific clinical sign usually increased with the progression of disease over a period of 16-20 weeks. Conclusion: Our results suggest that BSE in sheep presents with relatively uniform clinical signs, with pruritus of increased severity and abnormalities in behaviour or movement as the disease progressed. Based on the studied sheep, these clinical features appear to be independent of breed, affected genotype, dose, route of inoculation and whether BSE was passed into sheep from cattle or from other sheep, suggesting that the clinical phenotype of BSE is influenced by the TSE strain more than by other factors. The clinical phenotype of BSE in the genotypes and breed studied was indistinguishable from that described for classical scrapie cases

Frequency of accumulation of PrP^d in the LRS tissues of BSE positive sheep.

<p>Frequency of accumulation of PrP^d in the LRS tissues of BSE positive sheep.</p