Browsing by study line "Farmakologi"

Ischemic heart disease (IHD) and subsequent heart failure are caused by irreversible loss of contractile cardiomyocytes due to low oxygen supply to the heart. As the leading cause of death worldwide, IHD raises an urgent need for regenerative therapies that prevent or reverse loss of cardiomyocytes. The fetal mammalian heart grows by cardiomyocyte proliferation and utilizes glycolysis as main energy metabolism pathway, until it is introduced to increased oxygen and fatty acid supply at birth. Subsequently, cardiac energy metabolism shifts from glycolysis to β-oxidation of fatty acids and cardiomyocytes exit the mitotic cell cycle. Due to cessation of proliferation the heart can no longer regenerate after ischemic injury and responds to it by introduction of maladaptive pathological processes leading to heart failure. To gain deeper insight on the roles of cardiac metabolism pathways and hypoxia in cell cycle activation, we evaluated the effects of pharmacological metabolic modulation and oxygen supply on cardiomyocyte phenotype and hypoxia response. Furthermore, we studied the changes in the metabolic genotype of cardiomyocytes under alterations of oxygen supply. We utilized quantitative reverse transcription PCR (qRT-PCR) to evaluate the effects of hypoxia and metabolic maturation on the expression of genes involved in hypoxia signaling and metabolism of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs). Additionally, we investigated the effects of five metabolism-modulating compounds on cell cycle and phenotype of both metabolically matured and unmatured hiPSC-CMs, by utilizing high content analysis. We observed presence of hypoxia signaling as an increase in vascular endothelial growth factor A (VEGFA) expression following 3-hour hypoxic exposure. High expression of succinate dehydrogenase complex flavoprotein subunit A (SDHA) in hiPSC-CMs, which was downregulated at hypoxia, confirmed occurrence of oxidative metabolism induced by metabolic maturation. Surprisingly, metabolic maturation tended to increase proliferation and decrease stress response signaling of hiPSC-CMs. Introduction of the TCA cycle intermediate succinate decreased proliferation of metabolically unmatured hypoxic hiPSC-CMs by 8.2 %. Finally, inhibition of the mevalonate pathway and ketogenesis caused no alterations in hiPSC-CM phenotype or cell cycle, but introduction of the ketone body β-hydroxybutyrate tended to increase proliferation, supporting current evidence that ketogenesis plays a role in cardiomyocyte cell cycle regulation. Our observations suggest that hypoxic hiPSC-CMs can be useful in investigating gene expression and phenotype. Even so, additional methodologies are needed for in-depth evaluation of metabolic reprogramming and its effects on cardiomyocyte phenotype.

Parkinson’s disease (PD) is a progressive neurodegenerative disorder in which dopaminergic neurons in the substantia nigra (SN) degenerate and die. This causes multiple motor symptoms such as rigidity, bradykinesia and tremor and non-motor symptoms such as depression, hallucinations, and cognitive impairment. At the time of the diagnosis, approximately 60% of the dopaminergic cells can already be lost, which underlines the importance of neurorestorative treatments for PD. Currently used treatments are only symptomatic and mostly based on levodopa, which can lose its effectiveness as the disease progresses and additionally cause significant side effects such as dyskinesia. Neurotrophic factors (NTF) such as glial cell-line derived neurotrophic factor (GDNF) and neurturin (NRTN) have been studied in clinical trials with PD patients but have shown only modest effects on motor function. Additionally, they have been administered with invasive techniques such as intraputamenal or intracerebroventricular injections which includes many risks. Mesencephalic astrocyte-derived neurotrophic factor (MANF) belongs to unconventional NTF’s with unique molecular structure and mode of action. MANF has shown both neuroprotective and neurorestorative properties for nigrostriatal dopamine system in in vivo study in rat model of PD. To enable systemic administration of MANF, the molecule has been modified by retaining only the C-terminal domain to form C-terminal MANF fragment (C-MANF). C-MANF has shown neurorestorative effects when administered intrastriatally in 6-OHDA lesioned rats and when injected subcutaneously (s.c.) in an ALS animal model. The aim of this study was to assess the effect of daily and weekly s.c administered C-MANF in 6-OHDA mouse model of PD. Cylinder and amphetamine-induced rotation tests were performed as behavioural tests and thereafter morphological studies were done by analyzing tyrosine hydroxylase (TH)+ cells in the substantia nigra pars compacta (SNpc) and optical density from TH+ axons in the striatum. Interestingly, weekly C-MANF treatment decreased the number of TH+ cells in SNpc and the density of TH+ fibers in the striatum compared to PBS. However, it decreased ipsilateral rotations and showed some positive effects in the cylinder test. On the other hand, daily C-MANF treatment increased the number of TH+ cells in SNpc and the density of TH+ fibers in the striatum but had a modest effect on ipsilateral rotations and the cylinder test compared to PBS. Although no statistically significant effects were observed in behavioral and morphological studies, s.c administered C-MANF presents a promising treatment option for PD. Particularly, daily administration of C-MANF showed neurorestorative effects in morphological studies; however, further research is required for validation. Additionally, the investigation of higher doses of C-MANF should be considered.

Parkinson’s disease (PD) is a progressive chronic neurodegenerative disorder, which results in the selective loss of dopaminergic neurons in the substantia nigra (SN). The loss of these neurons results in the dysfunction of the nigrostriatal pathway bringing forth the characteristic motor symptoms seen in PD: postural instability, rigidity, slowness of movement and resting tremors. Non-motor symptoms, such as cognitive deficits, depression and impaired olfaction, typically emerge before motor symptoms. Currently available treatments only provide symptomatic relief with diminishing returns over time and no improvements on the overall outcome of the disease. Neurotrophic factors (NTF) have been of particular interest as a possible curative treatment for PD due to their potential for neuroprotection and neurorestoration. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an NTF that has shown promising results in numerous in vitro and in vivo studies of PD. However, therapy with MANF and other NTFs involves surgical intervention for local administration, as NTFs cannot cross the blood-brain barrier (BBB). Therefore, the therapeutic potential of a systemically administered NTF would be tremendous, as it would lead to a significantly more favorable risk-benefit ratio for the patient. The aim of the current investigation is to evaluate the efficacy of a next generation variant of MANF in the 6-hydroxydopamine toxin-induced unilateral lesion rat model of PD. Prior in vivo results suggested that subcutaneously injected MANF variant is able to penetrate the BBB. Amphetamine-induced rotational behavior (AMPH-ROTO) was used to evaluate the severity of the unilateral lesions during the experiment every other week until the end of the experiment at week eight. Animals were divided into treatment groups during week two based on their AMPH-ROTO results. Animals received MANF variant either subcutaneously through an implanted osmotic minipump at two different dosages or as a single dose divided into three separate intrastriatal injections. Tyrosine hydroxylase (TH) immunohistochemical staining was performed on brain sections collected from the striatum and SN for data analysis. In addition to AMPH-ROTO results, the efficacy of treatment was determined via the optical density of TH-positive striatal fibers and the number of TH-positive cells in the SN. Statistically significant differences (defined by p < 0.05 and a non-zero mean difference at a 95 % confidence interval) were observed only in the number of TH-positive cells in the SN favoring intrastriatal MANF variant treatment over both intrastriatal MANF and the vehicle treatment. The main concern regarding the validity of the results was related to the heterogeneous lesion sizes in different treatment groups possibly resulting in unsuccessful randomization due to excessive baseline differences. The inadvertent negative effects of this was further exacerbated by low a priori statistical power, which in the end had likely caused inflated effect sizes. Thus, assessment of the definitions of the used statistical parameters and the limitations of the experimental design suggest that presently, the efficacy of the MANF variant could not be evaluated reliably, in spite of the statistically significant result.

The ability to regulate release of noradrenaline, dopamine and GABA is one of the most important roles of the nicotinic receptors. The release of neurotransmitters following stimulation of nicotinic receptors is addressed in the thesis, with focus on dopamine and noradrenaline. Release of neurotransmitters, mediated through nicotinic receptors, has been researched using various methods, including brain slices, microdialysis and synaptosomes. Research using synaptosomes have provided valuable information regarding nicotinic receptors and their ability to regulate neurotransmitter release. Research using receptor specific antagonists have provided information regarding the stoichiometry of nicotinic receptor in different regions of the brain. The primary focus in the thesis, was the characterization of [3H]dopamine release following stimulation of nicotinic receptors with varenicline and acetylcholine, using synaptosomes from mouse striatum. Using a-conotoxin-MII, the [3H]dopamine release was divided into a-conotoxin- MII-resistant and -sensitive release. [3H]Dopamine release was mediated through a6b2*- and a4b2*-receptors from striatal synaptosomes. The involvement of other receptors could not be ruled out, but based on these results and results from previous studies, the involvement of other nicotinic receptors is supposedly low.

Current therapies for depression have limitations in efficacy and delayed onset of action. Rapid-acting antidepressants like ketamine, an N-methyl-D-aspartate receptor (NMDA-R) antagonist, have gathered attention as an improved treatment option. However, the neurobiological mechanism underlying their antidepressant effect remains uncertain. Integral mechanisms of action seem to be alterations in synaptic plasticity, global cortical excitation, and repair of neuronal dysfunctions prevalent in the pathophysiology of depression. Emerging evidence does suggest that antidepressant drugs act by facilitating brain derived neurotrophic factor (BDNF) mediated tropomyosin receptor kinase B (TrkB) signaling. Interestingly, rapid-acting antidepressants seem to increase TrkB-associated signaling after their acute pharmacological effect has dissipated, and when animals become sedated and show various physiological changes associated with deep sleep (e.g., slow wave EEG activity, SWA). Indeed, recently a close relationship between sedation and molecular signaling implicated in antidepressant effects has been discovered. The aim of this study was to explore the relationship between sedation and molecular signaling associated with antidepressant effect. This was carried out by assessing the localization of TrkB-associated phosphorylation signaling in the adult male mice medial prefrontal cortex (mPFC) using dexmedetomidine, a sedative. Key signaling molecules such as ribosomal protein S6 kinase (p70S6K), ribosomal protein S6 (rpS6), glycogen synthase kinase 3 (GSK3), mitogen activated protein kinases (MAPKs) and immediate early gene c-Fos, were examined through immunohistochemical (IHC) analysis. Two separate experiments were conducted using naïve adult 8-13-week-old (n=8 and n=10) male C57BL/6JRccHs mice. In the experiments mice were injected intraperitoneally with either dexmedetomidine (0,05 mg/kg, Dexdomitor®), or saline followed by a 30-minute recovery period whereafter mice were euthanized. In the first experiment, medial prefrontal cortex samples were collected immediately post decapitation for western blot (WB) analysis. The results showed that dexmedetomidine significantly activated TrkB-associated signaling in brain homogenates, consistent with expectations. In the second experiment, mice were perfused with 4% paraformaldehyde (PFA) before brain collection for IHC analysis. However in this experimental setting, no significant difference in the localization of TrkB-associated signaling induced by dexmedetomidine was observed compared to saline. Although, no significant results for signal localization were observed, the results provide insights into the neurobiological effect of sedation induced TrkB-signaling. Further research factoring in limitations is needed to uncover the involvement of physiological states in antidepressant mechanisms.

Left ventricular hypertrophy (LVH) takes place when cardiomyocytes respond to excessive stress by growing in size. Cardiomyocytes have a very marginal capability to proliferate, which is why hypertrophic growth is almost their only option to meet the requirements of increased workload. In the long run, however, LVH leads to further problems, such as cardiac failure and an increased risk of myocardial infarction. Hypertension is the most prevalent cause of LVH, and its current treatment relies on antihypertensive drugs. They decrease the workload of the heart and therefore alleviate symptoms but have very little effect on the built damage and remodeling. Understanding the details of cellular level signaling pathways and genetic expression in LVH is crucial for future drug development. Regulation of gene expression is a very complex process, which involves more than just DNA being translated into a protein. In this project, two types of factors participating in this regulation were in focus: long non-coding RNAs (lncRNA) and transcription factors GATA4 and FOG2. LncRNAs are RNA sequences of more than 200 nucleotides that do not code for any protein final products themselves but are involved in chromatin remodeling as well as transcriptional and post-transcriptional gene regulation. They are highly organ-selective, which makes them potential targets for drug development. Our group has previously found a selection of cardiomyocyte-selective lncRNAs, which share a similar expression pattern in neonatal mouse hearts. In this project, three of them were silenced in a primary cardiomyocyte culture while simultaneously hormonally inducing hypertrophy. The goal was to see whether these lncRNAs have an effect on the hypertrophic response and apoptosis in the cardiomyocytes. Transcription factors are proteins with partially similar activities to lncRNAs; they regulate, which genes are expressed under certain circumstances. GATA4 is an important transcription factor in the heart as it targets various developmental and functional genes in cardiomyocytes. FOG2 is a cofactor of GATA4; interaction between them regulates the activity of GATA4. Our group has recently developed a selection of compounds that affect protein-protein interaction between GATA4 and NKX2-5, another important transcription factor. The second part of the project was to set up and optimize a compound screening assay for GATA4-FOG2 interaction. The results showed no change in hypertrophic response when the lncRNAs were silenced. Other experimental designs could still reveal if they have effects that could not be seen with these protocols. The silencing had no effect on apoptosis. As for the GATA4-FOG2 interaction experiments, transfecting COS-1 with GATA4 and FOG2 plasmids in a ratio of 10:1 resulted in a signal suitable for compound screening. Initial compound screening results indicated the compounds may have an effect on GATA4-FOG2 interaction, but further studies are needed before drawing conclusions.

Ahmintahäiriö on epätyypillinen syömishäiriö, johon liittyy toistuvia ahmintakohtauksia, joiden aikana syödään hallitsemattomasti suuria määriä ruokaa, vaikka olo olisi jo epämiellyttävän täysi. Mantelitumake on ohimolohkon pohjukassa sijaitseva pelon ja tunteiden, mutta myös ruokahalun ei-homeostaattisen säätelyn, kannalta tärkeä rakenne. Mantelitumakkeen sentraalisen tumakkeen lateraalisen osan (CeL) solut säätelevät muun muassa ruoan palkitsevuutta ja tyydyttyneisyyden tunteen muodostumista ruokailun aikana. Suurin osa CeL:n kolinergisista hermoyhteyksistä on aivorungon pedunculopontisesta tegmentaalisesta tumakkeesta (PPT) projisoituvia hermoratoja. PPT:een kolinergisten hermopäätteiden in vivo optisen aktivaation on aikaisemmissa tutkimuksissa havaittu säätelevän opittua välttämiskäyttäytymistä, mutta optisen aktivaation vaikutusta ruoankulutukseen koe-eläimillä ei ole vielä tutkittu. Tämän pro gradu -tutkielman kokeellisen osan tavoite oli tutkia PPT:sta CeL:aan projisoituvan kolinergisen hermoradan in vivo optisen aktivaation vaikutusta ruoankulutukseen C57BL/6N -hiirillä. Optisen aktivaation vaikutusta tutkittiin sekä homeostaattiseen että ei-homeostaattiseen ruoankulutukseen. Ei-homeostaattisen ruoankulutuksen tutkimiseksi hiirille indusoitiin ahminnan kaltaista syömiskäyttäytymistä tarjoamalla hiirille rasvapitoista ruokaa viikoittain 24 tunnin jaksoissa. Tämän lisäksi tutkittiin ovatko optisen aktivaation vaikutukset kumottavissa asetyylikoliinireseptorien antagonistien mekamyyliamiinin tai skopolamiinin intraperitoneaalisella annostelulla. In vivo optisella aktivaatiolla ei havaittu olevan tilastollisesti merkitsevää vaikutusta ruoankulutukseen C57BL/6N -hiirillä. Tästä johtuen myöskään asetyylikoliinin antagonistien annostelun vaikutusta optisen aktivaation vaikutuksiin ei voitu arvioida. Tulokset viittaavat siihen, että PPT:een ja CeL:n välinen kolinerginen hermorata säätelee koe-eläimillä opittua välttämiskäyttäytymistä, mutta ei ruokahalua. Näin ollen on myös epätodennäköistä, että optisen aktivaation vaikutukset edellyttävät CeL:n proteiinikinaasi C deltaa ilmentäviä soluja. PPT:een kolinergisten hermosolujen vaikutus CeL:n toimintaa hermosolutasolla tulee kuitenkin varmistaa tarkemmissa jatkotutkimuksissa. Vaikka tutkimuksessa ei havaittu tilastollisesti merkitsevää vaikutusta, havaintoihin on kuitenkin suhtauduttava varauksella, sillä tutkimuksen toteuttamiseen liittyneet haasteet voivat rajoittaa havaittujen tuloksien luotettavuutta.

Cardiovascular diseases are the most common causes of mortality worldwide. More adequate human-based models would be needed for the purposes of disease modeling and drug development. One of the most promising fields of in vitro modeling is the use of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). A central problem of hPSC-CMs is their immature or fetal-like phenotype compared to adult human cardiomyocytes regarding many structural, functional, and metabolic properties. The development of metabolic properties is considered to be a central driver of cardiomyocyte maturation. One practicable way to promote the metabolic maturation of hPSC-CMs in vitro is the use of various biochemical cues in the cell culturing media. The topic of this study was the metabolic maturation of hPSC-CMs. The research questions were: What biochemical cues have been suggested to be involved in the hPSC-CM maturation in vitro? What signaling pathways connected to the biochemical cues have been explored in the context of the maturation of hPSC-CM? What experimental results have been achieved on the effects of the biochemical cues and the involvement of the signaling pathways? The study was conducted as a systematic review with the database Scopus (Elsevier). The final set of materials consisted of 46 original research articles published in peer-reviewed journals in English in the years 2013–2022. Out of the materials, 11 articles (24%) were characteristically longitudinal studies. They indicated that the pathways leading to metabolic changes such as PPARs (peroxisome proliferator-activated receptors) and PGC-1α (peroxisome proliferator-activated receptor γ coactivator 1α) are activated already in early stages. In 12 articles (26%), pharmacological agents were used to target the metabolic pathways, and in 8 articles (17%) techniques affecting the gene expression were utilized. The most recent studies involved ever more frequently combinations of different techniques. Considering the use of biochemical cues, the trend has been to favor fatty acids, thyroid hormone and dexamethasone over glucose, insulin and insulin-like growth factor. Some cues such as retinoic acid and neuregulin 1 have been tested only in single experiments. In addition to the nuclear receptor mediated pathways, the energy sensors AMPK (AMP-activated protein kinase) and mTOR (mechanistic target of rapamycin), the oxygen sensor HIF-1α (hypoxia-inducible factor 1α), and the microRNAs turned out to be central.

Left ventricular noncompaction cardiomyopathy (LVNC) is a unique form of cardiomyopathy, which is believed to arise from arrest in the compaction process during cardiac development. Dysfunctions in cell cycle regulation and increased or decreased proliferation of cardiomyocytes during cardiac development are likely to contribute to the development of LVNC. SCN5A gene encoding the α-subunit of cardiac voltage gated sodium channel Nav1.5 has associated with LVNC- phenotype in a Finnish family. The direct correlation of SCN5A gene mutation and LVNC has not been studied before. There is strong evidence that Nav1.5 channel has an essential role in cardiac development and cardiomyocyte proliferation, therefore perturbed function of the channel might also contribute to the development of LVNC. We used patient-specific human induced pluripotent stem cell -derived cardiomyocytes (hiPSC-CMs), reprogrammed from fibroblasts obtained from LVNC patient carrying SCN5A to study the phenotype of the cells. We utilized immunofluorescent staining in combination with high content analysis (HCA) to investigate the proliferation and Nav1.5 cellular localization. Proliferation potential was assessed at multiple timepoints from three to six weeks. We also investigated the stress response of patient-specific hiPSC-CMs by exposing the cells to mechanical stretch, a hypertrophy inducer, followed by quantitative reverse transcription PCR to study changes in stress biomarker levels. According to our results, the patient-specific hiPSC-CMs have prolonged proliferation compared to control cells as the proliferation peaks towards the last timepoint, whereas in control cells it decreases. Differences were also observed in the hypertrophic gene expression after 24-hour mechanical stretching. An increase in NPPB expression levels caused by stretching was threefold in patient-specific cells to control cells. These results implicate that SCN5A gene has as an important role on cardiomyocyte proliferation. Mutations in SCN5A could correspond to increased proliferation in trabeculations during cardiac development, which might be preventing the compaction process and lead to the development of LVNC. Our results emphasizes that SCN5A has an important role in cardiomyocyte physiology unrelated solely to electrical activity.

Cardiomyocyte oxygen deprivation followed by apoptosis and cardiomyocytes being replaced with fibrotic tissue can lead to heart failure. Cardiovascular diseases are the most common cause of death world-wide, contributing to 17.8 million deaths in 2017. Treatments currently available aim to maintain cardiac function but are unable to repair the damage, resulting in a poor prognosis for heart failure. Cardiomyocytes are able to proliferate but the endogenous mechanisms of cardiac repair are insufficient to replace the damaged cardiomyocytes, as only an estimated 0.3-1 % of adult cardiomyocytes are regenerated annually. It is known that before birth and up to seven days after birth mice can maintain ability to regenerate cardiomyocytes even after large damage, but this capability is lost within seven days following birth. After this, cardiomyocytes exit cell cycle and will not re-enter it sufficiently to enable cardiac repair. In adults the growth of heart muscle results mainly from hypertrophic growth meaning that the cells grow in width and length. Cardiomyocyte regeneration is an important therapeutic target to which there are no effective pharmacological therapies available yet. The aim of this study was to investigate the effect of 14 novel compounds on cardiomyocyte viability, phenotype and cell cycle activation. Novel compounds were synthesized at the Faculty of Pharmacy, Division of Pharmaceutical Chemistry and Technology, University of Helsinki in Finland. Initial toxicity and cell viability screening was conducted with lactate dehydrogenase assay (LDH assay) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT assay) using COS-1 cells. Based on these assays tolerable concentrations of compounds were determined. Activity analysis was conducted using human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) and immunocytochemistry staining in conjunction with high-content analysis (HCA). Stress response was measured by imaging and analyzing expression of pro-B-type natriuretic peptide (proBNP) and cell cycle activation was imaged and analyzed by using 5- bromo-2’-deoxyuridine (BrdU) as a marker of active cell cycle. In addition, the DNA content of the cardiomyocytes was measured using 4’,6-diamidino-2-phenylindole (DAPI) staining as well as cardiomyocyte morphology investigated with cardiac troponin T (cTnT) staining. One of the compounds, K6, decreased proBNP expression, which can be considered as a sign of decreased stress response. However, K6 also decreased the number of BrdU positive cardiomyocytes that can be considered as a sign of decreased cell cycle activity. Together these markers indicate that the decreased activity may not be due to a stress response caused by the compound. Another compound, K12, increased proBNP expression in all tested concentrations and it also decreased the number of BrdU positive cardiomyocytes. Together these could be considered as an indication of cardiotoxicity. The rest of the compounds did not exhibit remarkable biological activity or there was too great variance between the results of the independent experiments (n=3) to draw definite conclusions. Compounds for this study were chosen for the sole reason of not been tested for biological effects before. Using a defined compound library or screening a larger number of compounds could deliver more predictable results. Early toxicity and viability screenings were a good approach allowing to define toxic compounds and concentrations before continuing with further studies. Pharmacological therapies to induce cardiac regeneration will continue to be an important area of interest in cardiovascular drug research. Phenotypic screening in conjunction with high-content analysis offers variable and statistically significant data on cardiomyocyte proliferation and stress response. The results of the screening could be improved with careful selections of test molecules based on their structure and biological activity. Early toxicity and viability screening further improve the predictability of results. As a result of this study a compound that would induce cardiomyocyte proliferation was not found, however, one compound that seemed to decrease cardiomyocyte stress response was detected and this compound could be of interest for further studies.