Investigating the Pathogenic Interplay of Alpha-Synuclein, Tau, and Amyloid Beta in Lewy Body Dementia: Insights from Viral-Mediated Overexpression in Transgenic Mouse Models

Lewy body dementia (LBD) is an often misdiagnosed and mistreated neurodegenerative disorder clinically characterized by the emergence of neuropsychiatric symptoms followed by motor impairment. LBD falls within an undefined range between Alzheimer's disease (AD) and Parkinson's disease (PD) due to the potential pathogenic synergistic effects of tau, beta-amyloid (Aβ), and alpha-synuclein (αsyn). A lack of reliable and relevant animal models hinders the elucidation of the molecular characteristics and phenotypic consequences of these interactions. Here, the goal was to evaluate whether the viral-mediated overexpression of αsyn in adult hTau and APP/PS1 mice or the overexpression of tau in Line 61 hThy1-αsyn mice resulted in pathology and behavior resembling LBD. The transgenes were injected intravenously via the tail vein using AAV-PHP.eB in 3-month-old hThy1-αsyn, hTau, or APP/PS1 mice that were then aged to 6-, 9-, and 12-months-old for subsequent phenotypic and histological characterization. Although we achieved the widespread expression of αsyn in hTau and tau in hThy1-αsyn mice, no αsyn pathology in hTau mice and only mild tau pathology in hThy1-αsyn mice was observed. Additionally, cognitive, motor, and limbic behavior phenotypes were not affected by overexpression of the transgenes. Furthermore, our APP/PS1 mice experienced premature deaths starting at 3 months post-injection (MPI), therefore precluding further analyses at later time points. An evaluation of the remaining 3-MPI indicated no αsyn pathology or cognitive and motor behavioral changes. Taken together, we conclude that the overexpression of αsyn in hTau and APP/PS1 mice and tau in hThy1-αsyn mice does not recapitulate the behavioral and neuropathological phenotypes observed in LBD.

Capillary microsampling in mice: effective way to move from sparse sampling to serial sampling in pharmacokinetics profiling

Pharmacokinetic studies are an integral part of drug discovery and development. Mice are the commonly used species for pharmacokinetics studies during early discovery studies. Conventionally, composite PK profiles are obtained from mice studies due to the physiological limitations of the total blood volume that can be drawn over a certain period.With advancements in bioanalytical instrumentation and in blood sampling techniques, analysis with small volume (<50 µL) became feasible enabling serial blood sampling from the mouse for PK studies. The objective of the current study was to develop and establish a serial blood sampling technique in mouse and compare it with the conventional sparse sampling method (composite PK) following oral administration of widely used NSAIDs, diclofenac, celecoxib and tenoxicam, into Swiss Albino mice.The pharmacokinetic parameters of all three probe drugs by serial blood sampling were comparable with that of sparse sampling method. There was no significant difference between the whole blood concentration time profiles of all three drugs between serial sampling and sparse sampling suggesting serial blood sampling method can be easily implemented for mice PK studies.Serial blood sampling technique requires use of fewer number of animals, less quantity of test compound and reduces the possible dosing errors as fewer number of animals need to be dosed resulting in quality PK data and enabling comparison of inter-animal differences in PK profile.

Does the mouse tail vein injection method provide a good model of lung cancer?

Lung cancer drug development requires screening in animal models. We aimed to develop orthotopic models of human non-small lung cancer using A549 and H3122 cells delivered by tail vein injection. This procedure has been used previously for a mouse lung cancer (Lewis lung carcinoma) and as a model of human breast cancer metastasis to lung. We report that the procedure led to poor animal condition 7-8 weeks after injection, and produced lesions in the lungs visible at necropsy but we were unable identify individual cancer cells using immunohistochemistry. We conclude that if this method is to produce a model that can be used in drug experiments, improvements are required for cancer cell detection post mortem, such as by using of a fluorescently tagged human lung cancer cell line.

Validation of a refined technique for taking repeated blood samples from juvenile and adult mice

Repeated blood sampling from laboratory animals is desirable in certain experimental designs and also for reducing the number of animals used in research. Biochemical methods for analysing blood samples require only small blood volumes to be collected (typically 20-40 µL). In juvenile mice, the small blood volume of the animals also requires only small samples to be taken. Furthermore, for behavioural studies it is desirable to have a method that does not require anaesthesia or the use of invasive indwelling cannulae. We report the validation of a refined method for repeated blood sampling (up to 3 times at 24 h intervals) in juvenile and adult mice using the tail incision method to sample from the lateral tail vein. This method is not stressful, as assessed by low basal levels of the stress hormone corticosterone. Since repeated blood samples can be collected from the same animal at multiple time points, it is not necessary to increase group size for terminal sample collection. Thus, in addition to being a refined method requiring no warming of the tail, no anaesthesia and only gentle restraint, this method also reduces the numbers of mice used for experiments.

Gender dimorphism in differential peripheral blood leukocyte counts in mice using cardiac, tail, foot, and saphenous vein puncture methods

BACKGROUND: In many animal models that investigate the pathology of various diseases, there is a need to monitor leukocyte counts and differentials. However, various researchers use a range of different techniques in male and female laboratory animals to collect such blood variable information. These studies are then compared to one another without consideration of the possibility that different bleeding sites or techniques as well as gender may produce varying results. In light of this, the peripheral blood leukocyte counts and differentials of C57BL/6 male and female mice were determined using four blood-sampling techniques: cardiac, tail, foot, and saphenous vein punctures. METHODS: Blood smears were prepared and stained with Wright-stain for differential cell analysis. The total number of peripheral blood leukocytes was determined with the aid of a hemocytometer. Applying ANOVA and Student t-test analysis made comparisons between groups. RESULTS: The total leukocyte counts obtained using the cardiac puncture method were significantly lower as compared to the other three blood sources; saphenous, tail and foot. There were no significant differences between leukocyte counts of blood samples collected from the tail, saphenous, and foot. Additionally, no significant differences were observed in total leukocyte counts between male and female mice. Differential analysis showed lymphocytes as the predominant cell type present in the peripheral blood of both male and female mice, comprising 75-90% of the total leukocytes. While no significant differences were observed between male and female differential counts of blood collected from saphenous and tail veins, a significant difference in differential counts of blood obtained via cardiac puncture was observed between the male and female groups, suggesting the role of sex hormones. Further, of the four methods, cardiac puncture appeared to be the fastest and more reliable technique, yielding the maximum blood volume with the least amount of stress being exerted on the sampling site. CONCLUSIONS: This information suggests that in studies concerning leukocyte counts and differentials, the animal gender and the sampling site of blood collection should be kept consistent as to avoid introducing any misleading experimental variation, and that cardiac puncture is the best method of blood collection in mice.