京都大学 / 新制・課程博士 / 博士(医学) / 甲第23095号 / 医博第4722号 / 新制||医||1050(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 伊佐 正, 教授 井上 治久, 教授 渡邉 大 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Quinpirole is a dopamine D2 receptor agonist that if administered to rats from postnatal day (P)1-21 results in increased dopamine D2 receptor sensitivity throughout the animal’s lifetime. This increase in receptor sensitivity is consistent with schizophrenia. This model has additional consistencies with human schizophrenia, including sensorimotor gating deficits, enhanced behavioral and neurobiological responses to nicotine, and protein alterations consistent with the disorder. In this study, a second generation of the neonatal quinpirole (NQ) rodent model was created to investigate if long term changes caused by NQ treatment would be passed to offspring. NQ treated rats were mated and their offspring left untreated. To investigate if dopamine D2 receptor hypersensitivity was transmitted from the first to the second generation of the model, yawning behavior was assayed after acute quinpirole treatment. Prepulse inhibition (PPI) is a test of sensorimotor gating, and PPI testing was performed on adolescent second generation rats. Behavioral sensitization and conditioned place preference to nicotine (0.5 mg/kg and 0.6 mg/kg respectively) were examined in adolescence in both generations of the model. Several neurobiological assays were performed in both nicotine naïve and animals sensitized to nicotine (0.5 mg/kg) in order to investigate consistencies with the NQ model, which has shown enhanced responses to nicotine. These include enzyme linked immunosorbent assays (ELISAs) for brain-derived neurotrophic factor (BDNF) and cAMP response element-binding protein (CREB), as well as quantitative PCR (qPCR) to quantify messenger RNA (mRNA) of regulator of G-protein signaling 9 (rgs9). Results indicated that second generation rats of NQ-treated rats demonstrated increased yawning behavior in response to acute quinpirole treatment. PPI deficits and enhanced behavioral responses to nicotine were also observed. Increased BDNF expression was observed in the nucleus accumbens following nicotine sensitization, consistent with past work in first generation NQ-treated rats. CREB expression was also increased in both generations of the model, an effect linked to alterations in PPI and other schizophrenia-like symptomology. Rgs9 expression was generally unaltered in either generation of the model. This study provides basis for utilization of a second generation of the NQ model to study epigenetic influences in schizophrenia and drug abuse vulnerability.

Since the time of the introduction of the spontaneously hypertensive rat (SHR) into medical research, several neuropharmacological studies have been performed on these animals which have been unrelated to their cardiovascular systems. A few of these studies have indicated possible abnormalities in the dopaminergic systems of SHR. Therefore the present study was undertaken to examine more closely the sensitivity of SHR to stimulation of their dopamine (DA) receptors.

Parkinson’s disease (PD) is a common neurodegenerative disorder associated with dysfunction of the basal ganglia, which contributes to a range of motor, cognitive, and affective symptoms. Striatal dopaminergic deficits are one of the core pathological mechanisms thought to contribute to the extra-motor (i.e., cognitive and affective) symptoms in early PD. The present study investigated the relationship between striatal dopaminergic integrity and cognition in 21 patients with PD and 21 age and education matched controls. Each individual underwent dopamine transporter (DaT) imaging with single photon emission computed tomography (SPECT) (i.e., DaTscan) and standardized neuropsychological testing. Strong positive associations were found between DaT availability in the striatum and verbal memory (r = .52-.61) and problem solving/set-shifting (r = .55) in patients with PD. Additional moderate to strong positive associations (r = .49-.56) between DaT concentrations and visuospatial functions in patients with PD were found. However, similar significant associations between DaT and cognition were observed in age and education matched controls. Clinically, it is important for health care professionals to consider the role of both striatal and extra-striatal mechanisms as they relate to cognition in PD. Future studies examining the full range of pathological mechanisms that contribute to cognitive dysfunction in PD over time are warranted in order to inform more effective and targeted interventions.

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Tereza Kalinová Supervisor: Assoc. Prof. Přemysl Mladěnka, Pharm.D., Ph.D. Mentor: Assoc. Prof. Jana Hroudová, Pharm.D., Ph.D. Title of diploma thesis: Effect of cholinesterase inhibitors on monoaminergic system and energy metabolism Cholinesterase (ChE) inhibitors play an essential role in the treatment of Alzheimer's disease (AD). They effect positively cognitive, functional and behavior symptoms of AD. Up to date, donepezil, rivastigmine and galantamine represent the only ChE inhibitors approved for AD treatment. The first ChE inhibitor was tacrine, which was withdrawn from market due to its toxicity and adverse effects. Recently, novel tacrine and 7-methoxytacrine (7-MEOTA) derivatives were synthetized and extensively investigated to find less toxic compounds affecting pathological mechanisms associated with development of AD. There is less known about effects of these drugs on mitochondrial functions and cellular energy metabolism. The aim of this project is to examine in vitro effects of ChE inhibitors on energy metabolism and cellular respiration, specifically on mitochondrial electron transport chain complexes and an enzyme of the citric acid cycle - citrate synthase. Inhibitory effects...

Background: A single infusion of ketamine has rapid antidepressant properties, although the drawback is a lack of sustained effect. A previous study showed a rapid enhancement (within 2 hours) in ventral tegmental area (VTA) dopamine (DA) neuron population and locus coeruleus (LC) norepinephrine (NE) firing and bursting activity following a single ketamine administration. The current study investigated whether these changes are present 24 hours after a single administration and if they are maintained with repeated administration. Additionally, we examined dorsal raphe nucleus (DRN) serotonin (5-HT) neurons to assess the effects of single and repeated ketamine administration on these neurons. Methods: Ketamine (10 mg/kg, i.p.) was administered to male Sprague Dawley rats once or repeatedly (3 times/week) for 2 weeks. After single and repeated administration of ketamine, electrophysiological recordings were done in the VTA, LC and DRN in anesthetized rats, 24 hrs, 3 or 7 days post-administration. Spike frequency, bursting, and for VTA neurons, spontaneously active neurons/trajectory were assessed. Results: In the VTA, LC and DRN, 24 hrs after ketamine was injected acutely there was no significant difference between controls and treated animals in all parameters assessed. However, after repeated administration, there was an increase in bursting and number of spontaneously discharging neurons per tract of VTA DA neurons as well as an increase in frequency of discharge of LC NE neurons. While the increased number of spontaneously discharging neurons per tract had dissipated after 3 days, the enhanced bursting was still present but dissipated after 7 days. As for LC NE neurons, the increased frequency of discharge was no longer present after 3 days. No significant differences in the firing of DRN 5-HT neurons were observed between controls and treated animals even after ketamine was administered repeatedly. Conclusion: These results indicate that repeated but not acute administration of ketamine maintained the increase in population activity of DA neurons and firing activity of NE neurons.

Psychostimulants are known to alter visual function acutely and on withdrawal, and can cause attention deficit following prenatal exposure. However, psychostimulants can also improve visual attention in patients with attention deficit. The mechanisms involved in these contrasting effects remain largely unknown. To determine the role of specific brain regions and the dopamine system in the impact of cocaine exposure on visual processing, we employed two-photon microscopy and a transgenic larval zebrafish expressing the calcium indicator GCaMP-HS. We documented neuronal responses to contrasting visual stimuli, red light (LF) and dark (DF) flashes. We found that in the optic tectum neuropil (TOn), both stimuli elicited similar responses, though after repeated stimulus presentation, habituation developed to dark flash only. The dorsal telencephalon (dTe) responded and habituated to LF only. Acute cocaine (0.5 μM) reduced neuronal responses to LF in both brain regions and prevented habituation of dTe neurons to LF, but did not modify responses or habituation to dark flash. Prenatal cocaine exposure (PCE) did not modify baseline responses, but it prevented the acute effects of cocaine on LF responses in both regions and habituation in dTe, with no impact on dark flash responses. PCE also significantly reduced D1 dopamine receptor expression in TOn and cerebellum, but not dTe or the eye. Fish lacking the dopamine transporter (DATKO) retained normal D1 expression throughout the brain, baseline responses to LF in both TOn and dTe, and response reduction following cocaine in TOn. However, they demonstrated abnormal swimming behavior, and neither their swimming behavior nor dTe responses to LF were modified by cocaine. We discovered that in zebrafish, a diurnal vertebrate, responses to light not only require the primary visual processing center TO (superior colliculus in mammals), but also higher level processing by dTe. Responses to light but not darkness are modified by cocaine, unless the fish lack DAT or were exposed to PCE. Together, our results demonstrate specific effects of cocaine on visual processing mediated by the dopamine system, and provide a novel animal model for further investigation of these phenomena and development of new therapeutic approaches.

No description available.

Dopamine (DA) transmission is a key player in the rewarding aspects of ethanol as well as ethanol dependence. The current dogma is that DA transmission is increased during ethanol via the inhibition of ventral tegmental area (VTA) GABA neurons and that excitation of VTA GABA neurons during withdrawal results in decreased DA transmission. Microglia, the major neuroimmune effector in the brain, may be a key mediator in this process by releasing cytokines following activation. We evaluated the effect of ethanol on cytokine concentrations in the VTA and NAc using a cytometric bead array, and found that low dose ethanol (1.0 g/kg) decreased interleukin (IL)-10 levels, but high dose ethanol increased IL-10 levels (4.0 g/kg). We also used standard cell-attached mode electrophysiological techniques to evaluate the effects of select cytokines on VTA neuron firing rate in vitro. We found no change in firing rate in response to IL-6, but an increase in firing rate in VTA DA neurons response to IL-10. Consistent with the changes in firing rate, optically-evoked IPSCs were also found to be decreased in response to IL-10. Ex vivo voltammetry and in vivo microdialysis were done to determine whether IL-10 can directly result in an increase in DA release. Although ex vivo voltammetry showed no change in DA release, IL-10 increased DA release in vivo. These findings suggest that the rewarding and/or addictive effects of ethanol are mediated by cytokines, specifically the anti-inflammatory cytokine IL-10.

Intracellular membrane potential (Em) and force development were measured in rabbit basilar artery to help elucidate the mechanism of action of dopamine in this preparation. There was a strong correlation between membrane depolarization and contraction (r=0.95) between 3×10-7 M to 10-4 M dopamine. When the vascular muscle cells were depolarized by elevating [K]o there was a Em dependent decrease in force development in response to dopamine. Significant reduction of dopamine stimulated force development was observed when the vessel was depolarized by 5-6 mV by excess extracellular K+ and 90% inhibition was seen when the artery was depolarized to -20mv. When Ca++ influx was blocked, dopamine no longer induced force development. Such findings suggest that dopamine cotracts rabbit basilar artery by a mechanism involving membrane depolarization. This process may involve an influx of extracellular Ca++ through voltage sensitive channels.