Browsing by Subject "Acetylcholinesterase"

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Open Access
Age and gender alter synaptic proteins in zebrafish (Danio Rerio) models of normal and delayed aging
(2017-07) Karoğlu, Elif Tuğçe
Cognitive decline occurs during normal aging in some specific domains of cognitive abilities including but not limited to episodic memory, divided attention and executive functions, however, it is not a unitary decline since some cognitive domains, including vocabulary and implicit memory tend to be preserved and even improved at older ages. Normal aging is not associated with global and significant neuronal and synapse loss, yet subtle molecular alterations occurring in gene expression patterns, protein homeostasis, mitochondrial dynamics and hypofunction in the cholinergic system may account for the age related decline in some cognitive abilities. Additionally, males and females showed differential vulnerabilities against age-related alterations in the cognitive abilities, physiological integrity and subtle molecular dynamics. More direct relationships can be established between the age-related cognitive decline and subtle molecular changes by analyzing the elements of synaptic integrity, which could alter synaptic plasticity and result in the changes in learning and memory abilities. Post-synaptic 95 (PSD-95), gephyrin (GEP) and synaptophysin (SYP) are integral synaptic proteins and they could be attributed as indicators of excitatory post-synaptic, inhibitory post-synaptic and pre-synaptic integrities, respectively. The first aim of this study was to show effects of age and gender on the expression levels of PSD-95, GEP and SYP in young, middle-aged and old, female and male zebrafish cohorts. Significant age by gender interactions were revealed in the levels of PSD-95 and SYP. It was shown that PSD-95 and SYP levels tend to be preserved and increased in the female groups throughout the aging process, whereas, in male groups, expression levels of these proteins tend to be reduced at older ages. The second aim was to investigate whether ameliorating the cholinergic hypofunction might have beneficial effects on the aging-related protein expression alterations and check for sexually dimorphic patterns. For this aim old male and female zebrafish from a mutant line (ache), which has decreased levels of acetylcholinesterase and increased levels of acetylcholine, were compared with old male and female wildtype animals. In the ache old groups, significant increases in the expression levels of SYP and GEP were revealed compared to the wildtype, and also in the old ache females SYP expression was higher than the other groups. These studies emphasized the importance of gender and sexually dimorphic patterns in the context of aging andcholinergic manipulations could be a promising target of intervention to attenuate the effects of age-related synaptic alterations, which could have possible contributions to age-related cognitive decline. .
Open Access
Identification of preclinical implications for novel indole-benzimidazoles and phenothiazines using in vitro cancer cell line and in vivo zebrafish models
(2020-09) Yaman, Murat
Breast cancer (BC) and hepatocellular carcinoma (HCC) are two major health problems with significant mortality rates. Although drug therapies are available, therapeutic success remains limited. Because of low bioavailability, high toxicity and recurring drug resistance, novel therapeutic options are essential. In the present thesis, a multitude of in vitro, in silico and in vivo approaches were executed to test anti-cancer effects and preclinical potentials of novel indole-benzimidazoles and phenothiazines in BC and HCC, respectively. In the first component of the thesis, I evaluated BC cell line toxicity and estrogen receptor (ER) relationship of novel indole-benzimidazole derivatives using in vitro cancer lines, in vivo zebrafish embryos/larvae, and in silico comparative transcriptomics analyses. In the second part, antipsychotic compounds phenothiazines (PTZ) were repurposed for HCC therapy. Therefore, generic PTZ derivatives alone or in combination with sorafenib (SFB) were tested using in vitro cancer lines followed by zebrafish developmental assays and embryonic stage xenografts. In addition, RNAseq analyses were performed on trifluoperazine (TFP), SFB, and TFP+SFB combination treated Hep3B cells to understand synergistic/antagonistic effects of the drugs at gene expression level. Lastly, anti-HCC potential of novel PTZ derivatives were explored by in vitro and in vivo screenings. Moreover, effects of the novel and generic derivatives on neural pathways were evaluated by cholinesterase assays and motor response measurements. The findings of the dissertation present potential leads for conducting further preclinical studies tailored towards novel BC and HCC therapies.
Open Access
Long-term acetylcholinesterase depletion alters the levels of key synaptic proteins while maintaining neuronal markers in the aging zebrafish (Danio rerio) Brain
(S. Karger AG, 2023-10-04) Karoğlu-Eravsar, Elif Tuğçe; Tüz-Şaşik, Melek Umay; Karaduman, Ayşenur; Keşküş, Ayse Gökçe; Arslan-Ergul, Ayça; Konu, Özlen; Kafalıgönül, Hulusi; Adams, Michelle M.
Introduction: Interventions targeting cholinergic neurotransmission like acetylcholinesterase (AChE) inhibition distinguish potential mechanisms to delay age-related impairments and attenuate deficits related to neurodegenerative diseases. However, the chronic effects of these interventions are not well described. Methods: In the current study, global levels of cholinergic, cellular, synaptic, and inflammation-mediating proteins were assessed within the context of aging and chronic reduction of AChE activity. Long-term depletion of AChE activity was induced by using a mutant zebrafish line, and they were compared with the wildtype group at young and old ages. Results: Results demonstrated that AChE activity was lower in both young and old mutants, and this decrease coincided with a reduction in ACh content. Additionally, an overall age-related reduction in AChE activity and the AChE/ACh ratio was observed, and this decline was more prominent in wildtype groups. The levels of an immature neuronal marker were upregulated in mutants, while a glial marker showed an overall reduction. Mutants had preserved levels of inhibitory and presynaptic elements with aging, whereas glutamate receptor subunit levels declined. Conclusion: Long-term AChE activity depletion induces synaptic and cellular alterations. These data provide further insights into molecular targets and adaptive responses following the long-term reduction of AChE activity that was also targeted pharmacologically to treat neurodegenerative diseases in human subjects.
Open Access
Tissue specific transcriptome of zebrafish in ache mutant embryos
(2019-06) Dinçaslan, Fatma Betül
Differential expression of specific genes in certain tissues provides information about tissue specificity which might define phenotypes of various tissues. It is possible to understand the tissue-specific effects of knockout or knockdown studies performed on zebrafish embryos, using such genes. In this study, publicly available RNA-seq datasets providing data on 15 of the tissues from 5-9 months old zebrafish were used to estimate tissue specificity for zebrafish genes. Three different normalizations (i.e SD, RPKM, TPM) of 15 tissues were performed to compare; and the results were used to understand whether a given zebrafish mutant has significant enrichments for tissue-specific genes, based on different metrics including Tau, TSI, Hg, Spm, Gini, Counts. Application of these pipelines to the publicly available acetylcholinesterase (ache) mutant vs. healthy zebrafish data (GSE74202) revealed that many retina- muscle-, and liver-specific genes were downregulated in ache mutants. The downregulation of retina and liver specific genes (such as arr3a, rpe65a, rom1b and fabp10a, respectively) were futher confirmed with qPCR on comparative study of ache (+/?) and ache (-/-) 3 days post fertilization (dpf) zebrafish embryos. In addition a pilot experiment testing the effects of constant light and constant dark exposure for 3-5 dpf ache mutant and healthy embryos were performed, suggesting that the expression of retina-specific genes were more prominently affected in 3 dpf mutant embryos regardless of light.
Open Access
Zebrafish optomotor response to second-order motion illustrates that age-related changes in motion detection depend on the activated motion system
(Elsevier Inc., 2023-06-10) Karaduman, Ayşenur; Karoğlu-Eravşar, Elif Tuğçe; Kaya, Utku; Aydın, Alaz; Adams, Michelle Marie; Kafalıgönül, Hulusi
Various aspects of visual functioning, including motion perception, change with age. Yet, there is a lack of comprehensive understanding of age-related alterations at different stages of motion processing and in each motion system. To understand the effects of aging on second-order motion processing, we investigated optomotor responses (OMR) in younger and older wild-type (AB-strain) and acetylcholinesterase (achesb55/+) mutant zebrafish. The mutant fish with decreased levels of acetylcholinesterase have been shown to have delayed age-related cognitive decline. Compared to previous results on first-order motion, we found distinct changes in OMR to second-order motion. The polarity of OMR was dependent on age, such that second-order stimulation led to mainly negative OMR in the younger group while older zebrafish had positive responses. Hence, these findings revealed an overall aging effect on the detection of second-order motion. Moreover, neither the genotype of zebrafish nor the spatial frequency of motion significantly changed the response magnitude. Our findings support the view that age-related changes in motion detection depend on the activated motion system. © 2023 Elsevier Inc.