La néphropathie aux plantes chinoises (CHN) est une maladie rénale grave qui a été décrite pour la première fois en 1993 chez des patientes ayant suivi un régime amaigrissant à base d’extraits de plantes chinoises (Aristolochia fangchi) contenant des acides aristolochiques (AA). Cette néphropathie se caractérise par une atrophie tubulaire et une fibrose interstitielle aboutissant à l’urémie terminale et se complique fréquemment de cancers des voies urinaires. Au moment d’initier ce travail, il subsistait toujours un large débat quant au rôle étiologique réel des acides aristolochiques dans la genèse de cette maladie. En effet, les gélules à visée amaigrissante contenaient d’autres substances potentiellement néphrotoxiques. Mais surtout, il n’existait aucune preuve expérimentale que les AA pouvaient induire une fibrose rénale interstitielle.<p>Dans la première partie de ce travail, nous démontrons que l’injection par voie sous-cutanée d’AA à la dose de 10 mg/Kg/jour à des rats Wistar mâles en déplétion sodée entraîne l’apparition au 35ème jour d’une atrophie tubulaire, d’une fibrose interstitielle et d’une insuffisance rénale, reproduisant ainsi les anomalies caractéristiques de la CHN. Nous avons ensuite montré que la dexfenfluramine, substance anorexigène à action de type sérotoninergique prise concomitamment par les patientes atteintes de CHN, ne potentialise pas la toxicité rénale des AA. Enfin, la stimulation du système rénine angiotensine (SRA) par la déplétion sodée ou l’inhibition de celui-ci par un traitement pharmacologique ne modifie pas la fibrose interstitielle ni l’insuffisance rénale induite par les AA.<p>En conclusion, nous avons réussi à développer un modèle in vivo de fibrose rénale interstitielle induite par les AA. Dès lors nous avons apporté la preuve expérimentale de l’implication des AA dans le développement de la CHN. Ce modèle a permis de démontrer que les autres éléments potentiellement néphrotoxiques contenues dans la cure d’amaigrissement (dexfenfluramine, diurétique, laxatif) n’influençaient pas l’évolution de la fibrose interstitielle, ce qui confirme que la prise isolée d’AA suffit à expliquer le développement de la CHN. Cette confirmation à d’importantes implications en santé publique dans la mesure où des plantes contenant des acides aristolochiques font toujours partie des phytothérapies traditionnelles. De plus, il est apparu que, dans ce modèle, les mécanismes de la fibrose rénale interstitielle pouvaient être largement indépendants du SRA. Enfin, de par sa durée limitée et sa grande reproductibilité, ce modèle constitue un outil expérimental d’avenir pour l’étude des mécanismes physiopathologiques de la fibrose rénale interstitielle en général.<p> / Doctorat en sciences médicales / info:eu-repo/semantics/nonPublished

Acute spinal cord injury is often caused by collisions with motor vehicles, falls or violence. This injury could potentially lead to paraplegia or tetraplegia, causing great economic and personal loss. The patophysiology is biphasic, with primary and secondary mechanisms. Regarding secondary spinal cord injury, glutamate and interleukin-1 beta (IL-1<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cbeta" data-classname="equation" data-title="" />) activates N-methyl-d-aspartate (NMDA)-receptors leading to prolonged excitotoxity, causing neuronal death and subsequently glial scarring. Cross-linked-hyaluronic acid gel and interleukin-1 receptor antagonist (IL-1RA) are believed to have a neuroprotective effect. The major aim of this study was to evaluate neuroprotection in the central neural system. Briefly, spinal cord slice cultures from mice (p9-12) were chemically injured with NMDA and treated with two hyaluronic acid-based gels with integrated, or added, IL1RA. RNA was extracted and transcripted to cDNA. The gene expression of Neuronal nuclear protein, <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cbeta" data-classname="equation" data-title="" />-aktin and IL-1<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cbeta" data-classname="equation" data-title="" /> were studies with RT-qPCR. Results showed that gel integrated with IL1RA had significant therapeutic effect, resembling undamaged cultures. Furthermore, axonal outgrowth was investigated in dorsal root ganglion (DRG) in which two preparations of the method were evaluated. Results demonstrated that changing medium every other day was more preferred, compared to adding 20 µl medium every day.  In conclusion, gels integrated with IL1RA have neuroprotective properties and in DRG preparations, medium should be changed every other day for optimal results.

In preclinical research on Alzheimer's disease pharmacotherapy, attention is paid to multipotent compounds, enabling intensification of the effect by targeting multiple pathophysiological mechanisms. The aim of the thesis was to assess the effect of multipotent compounds and combination therapy in models of cognitive deficit in the rat. The mechanism of action of the tested compounds was modulation of neurotransmitter systems. The aim of the first part of the study was to compare the effect of experimental monotherapy and combination therapy with an N-methyl-D-aspartate (NMDA) receptor antagonist and a γ-aminobutyric acid type A (GABAA) receptor positive modulator in the trimethyltin-induced model. Superiority of the combination therapy was proven by histological analysis of hippocampal neurodegeneration; however, it did not reach statistical significance in the cognitive test. The other part of the thesis focused on multipotent tacrine derivatives. We demonstrated a positive effect of 6- chlorotacrine-6-nitrobenzothiazole hybrid, as well as 6-chlorotacrine-L-tryptophan hybrid, acting as acetylcholinesterase inhibitors, in the scopolamine-induced model of cognitive deficit. Besides, we demonstrated a low risk of serious side effects of other tacrine derivatives acting as NMDA receptor antagonists....

認知功能的提升是當今神經科學領域中的研究重點之一，但其神經機制尚有待釐清。本研究利用一種用於改善阿茲海默症臨床的非競爭型N-甲基-D-天門冬胺酸受體拮抗劑memantine，檢測其對於大白鼠在不同時距相關操作式制約行為及空間工作記憶行為之影響效果。實驗一為針對時間屬性的操作式制約行為實驗，運用大白鼠的區辯性增強低頻反應作業（DRL 10秒行為）與固定時距作業（FI 30秒行為）之行為作業，並操弄連續訓練與間歇訓練的兩種不同模式，測試memantine對前述四組受試的操作式制約行為在表現、消除與自發恢復等三階段之劑量反應。實驗二利用配對性延遲T迷津作業區分出不等基準線(表現好與表現差)之受試，再加以藥理實驗，測試memantine對於前述兩組受試之劑量反應。實驗一結果顯示，受試在兩種不同訓練模式下經十五次習得訓練後，在兩種操作式壓桿行為的壓桿反應相關指標中都有明顯的差異，這證實不同的行為訓練模式會導致學習後的表現有差異之別。memantine藥理實驗結果顯示，此藥對於上述四組受試的操作式行為之三階段的影響效果，會因為不同訓練模式與不同作業而異。實驗二結果顯示，memantine提高空間工作記憶的正確率在表現不好的組別有很顯著的藥效，這證實memantine對於空間式工作記憶行為的影響，也會因學習基準線的不同水平而異。在行為實驗後所進行的蛋白質表現量檢測中，memantine（5 mg/kg）只對五個測試腦區中的背側紋狀體中ERK1磷酸化程度有明顯上升的影響，而其對ERK2及CREB的磷酸化在所有腦組織中皆沒有顯著的影響。綜合以上結果，memantine影響時間與空間屬性的相關行為之藥理效果，會依行為的不同習得歷程(或行為背景經驗)及基準線表現程度而異，而此項行為藥理效果，可能與紋狀體中ERK1的磷酸化有關。 / The neural basis of cognitive enhancement is one of the intriguing topics in neuroscience research; however, the underlying neural mechanisms remain to be elucidated. This study examined the effects of memantine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist which is used to treat Alzheimer’s disease in clinic, on operant behaviors and spatial working memory. In Experiment 1, using the differential reinforcement for low-rate-response 10 sec (DRL 10s) and the fixed-interval 30 sec (FI 30s) operant tasks, and with the manipulation of two different training regimens (continuous vs. intermittent) in the acquisition phase, the effects of memantine were evaluated in three stages of behavioral tests including the performance (right after the end of 15-day acquisition), the extinction, and the spontaneous recovery (after the extinction). In Experiment 2, memantine were tested in the subjects with different level of baseline performance (good vs. bad) on the distinctive patterns of operant responding in four different groups which received DRL 10s and FI 30s with different training regimens; indicating that behavioral task and training background are critical to the operant performance of temporal operant behaviors. Such behavioral outcomes led the dissociable effects of memantine appeared in between the four groups as tested in all three different stages. The results of Experiment 2 showed a profound improvement of the correct responses rate on spatial working memory in the low-baseline group as compared to the higher-baseline group. With a pretreatment of memantine (5 mg/kg), brain tissues in five selected areas were collected for western blot assays of ERK 1, ERK 2, and CREB. The results only revealed a significant increase of ERK 1 phosphorylation in the dorsal striatum. Together, the effects of memantine to improve cognition-associated processes in the temporal operant behaviors and the baseline of performance, and the present observation of cognition-enhancing effects of memantine may be resulted by the ERK 1 phosphorylation in the dorsal striatum.