Altered expression of dopaminergic cell fate regulating genes prior to manifestation of symptoms in a transgenic rat model of Huntington's disease

Striatal ZBTB16 Is Associated With Cognitive Deficits in Alzheimer Disease Mice

PURPOSE

In Alzheimer disease (AD), brain regions such as the cortex and the hippocampus show abundant amyloid load which correlates with cognitive function decline. Prior to the significant development of AD pathophysiology, patients report the manifestation of neuropsychiatric symptoms, indicating a functional interplay between basal ganglia structures and hippocampal regions. Zinc finger and BTB domain-containing protein 16 (ZBTB16) is a transcription factor that controls the expression of downstream genes and the involvement of ZBTB16 in the striatum undergoing pathological aging in AD and the resulting behavioral phenotypes has not yet been explored.

METHODS

To study molecular alterations in AD pathogenesis, we analyzed the brain from amyloid precursor protein (APP)/ presenilin 1 (PS1) transgenic mice. The molecular changes in the striatal region of the brain were analyzed via the immunoblotting, and the quantitative RNA sequencing. The cognitive impairments of APP/PS1 mice were assessed via 3 behavioral tests: 3-chamber test, Y-maze test, and noble object recognition test. And multielectrode array experiments for the analysis of the neuronal activity of the striatum in APP/PS1 mice was performed.

RESULTS

We found that the alteration in ZBTB16 levels that occurred in the early ages of the pathologically aging striatum coalesces with the disruption of transcriptional dysregulation while causing social memory deficits, anxiety-like behavior. The early ZBTB16 knockdown treatment in the striatum of APP/PS1 mice rescued cognition that continued into later age.

CONCLUSION

This study demonstrates that perturbation of transcriptional regulation of ZBTB16 during pathological aging may influence cognitive impairments and reveals a potent approach to targeting the transcriptional regulation of the striatum for the treatment of AD.

Liraglutide Improves Cognitive and Neuronal Function in 3-NP Rat Model of Huntington's Disease

Huntington’s disease (HD) is an autosomal dominant inherited neurodegenerative disease characterized by progressive motor, psychiatric, and cognitive abnormalities. The antidiabetic drug liraglutide possesses a neuroprotective potential against several neurodegenerative disorders; however, its role in Huntington’s disease (HD) and the possible mechanisms/trajectories remain elusive, which is the aim of this work. Liraglutide (200 μg/kg, s.c) was administered to rats intoxicated with 3-nitropropionic acid (3-NP) for 4 weeks post HD model induction. Liraglutide abated the 3-NP-induced neurobehavioral deficits (open field and elevated plus maze tests) and histopathological changes. Liraglutide downregulated the striatal mRNA expression of HSP 27, PBR, and GFAP, while it upregulated that of DARPP32. On the molecular level, liraglutide enhanced striatal miR-130a gene expression and TrKB protein expression and its ligand BDNF, while it reduced the striatal protein content and mRNA expression of the death receptors sortilin and p75NTR, respectively. It enhanced the neuroprotective molecules cAMP, p-PI3K, p-Akt, and p-CREB, besides modulating the p-GSK-3β/p-β-catenin axis. Liraglutide enhanced the antioxidant transcription factor Nrf2, abrogated TBARS, upregulated both Bcl2 and Bcl-XL, and downregulated Bax along with decreasing caspase-3 activity. Therefore, liraglutide exerts a neurotherapeutic effect on 3-NP-treated rats that is, besides the upturn of behavioral and structural findings, it at least partially, increased miR-130a and modulated PI3K/Akt/CREB/BDNF/TrKB, sortilin, and p75NTR, and Akt/GSK-3β/p-β-catenin trajectories besides its capacity to decrease apoptosis and oxidative stress, as well as its neurotrophic activity.

The Role of Hypothalamic Pathology for Non-Motor Features of Huntington's Disease

 Huntington’s disease (HD) is a fatal genetic neurodegenerative disorder. It has mainly been considered a movement disorder with cognitive symptoms and these features have been associated with pathology of the striatum and cerebral cortex. Importantly, individuals with the mutant huntingtin gene suffer from a spectrum of non-motor features often decades before the motor disorder manifests. These symptoms and signs include a range of psychiatric symptoms, sleep problems and metabolic changes with weight loss particularly in later stages. A higher body mass index at diagnosis is associated with slower disease progression. The common psychiatric symptom of apathy progresses with the disease. The fact that non-motor features are present early in the disease and that they show an association to disease progression suggest that unravelling the underlying neurobiological mechanisms may uncover novel targets for early disease intervention and better symptomatic treatment. The hypothalamus and the limbic system are important brain regions that regulate emotion, social cognition, sleep and metabolism. A number of studies using neuroimaging, postmortem human tissue and genetic manipulation in animal models of the disease has collectively shown that the hypothalamus and the limbic system are affected in HD. These findings include the loss of neuropeptide-expressing neurons such as orexin (hypocretin), oxytocin, vasopressin, somatostatin and VIP, and increased levels of SIRT1 in distinct nuclei of the hypothalamus. This review provides a summary of the results obtained so far and highlights the potential importance of these changes for the understanding of non-motor features in HD.