A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of; Masters of Science in Medicine (Anatomical Sciences) School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg. 2017. / This research studied adult hippocampal neurogenesis in the dentate gyrus of the hippocampus of the Long-Evans rat. Eighteen male Long-Evans rats were exposed to complex enriched environment, the running wheel environment for exercise as single influencing factor and the standard laboratory environment for 28 days. Thereafter the rats were transcardially perfused with 0.9 normal saline followed by 4% paraformaldehyde. The brains were removed and frozen sagittal sections cut at 50 μm. Brain sections were stained with Cresyl violet for cytoarchitecture. Immunohistochemistry and immunofluorescence techniques were employed for the immature neurons with defined processes using the marker doublecortin (DCX), neuronal proliferation marker Ki-67, the synapse marker, synaptophysin and the dendritic spine marker, synaptobrevin. Giemsa staining was used to identify pyknotic neurons followed by counts for DCX, Ki-67, pyknotic positive cells, and volume density of the dentate gyrus. Results indicated a statistically significant increase in brain weight (p=0.5) for the complex enriched group when compared to the running group and control. The typical cytoarchitecture of the hippocampus in rodents was observed with more densely packed granule cell layer in the dorsal limb of the dentate gyrus compared to the ventral limb especially in the enriched group. The Ki-67 immunopositive cell number between groups showed a variable difference with a three-fold increase each between the standard control and exercise, and between the exercise and enriched but a six-fold increase between the standard control and the complex enriched groups. Comparing the DCX immunopositive results, we observed also that the neuronal numbers, structure, dendritic patterns as well as the neuronal arrangement on the dorsal and ventral limbs of the dentate gyrus varied significantly among groups. The apoptotic cell numberusing pyknotic cells, showed the standard control group to have the highest number of cells compared to the exercise versus the enriched group; noting a five-fold difference between the standard control and exercise, a twenty seven-fold difference between the standard control versus enriched and a twenty one-fold difference between 6 the exercise and complex enriched group. The volumetric analysis showed a 15-fold difference between the standard control and exercise groups, a five-fold difference between the exercise and complex enriched and a nineteen-fold difference between the standard control and complex enriched groups. However, no statistical significant difference was found in the volumetric analysis of the dentate gyrus between the groups. / MT2017

No description available.

<p>Transition metals such as manganese (Mn), iron (Fe) and zinc (Zn) are some of the essential metals for normal CNS development and function. Each must be present at specific levels to avoid deficiencies or toxic excess. The research in this thesis investigates the role of transition metals in diseases in which myelin is lost in the central nervous system (CNS). A loss of myelin is termed demyelination, and an example of a disease with prominent demyelination is multiple sclerosis. An incomplete formation of myelin sheaths is termed dysmyelination. This thesis focused on the measurements of manganese, iron and zinc concentrations in a rodent model of dysmyelination; the Long Evans Shaker (<em>les</em>) rat.<strong></strong></p> <p>The Long Evans Shaker (<em>les</em>) rat is a fragile, severely dysmyelinated rodent model with body tremors at a young age and severe ataxia in older rats. The mutation causing the severe dysmyelination in these rats is transmitted as an autosomal recessive trait. With a lifespan of 4 to 5 months, the <em>les</em> rat is markedly deficient in myelin in the CNS, where most axons are entirely naked and the remaining ones are surrounded by a loosely woven, thin myelin sheath.</p> <p>In this thesis we studied alterations in manganese, iron and zinc transition metal levels in 3 and 16-week-old <em>les</em> rats and their age-matched control counterparts. Using neutron activation analysis (NAA), manganese measurements were made in the brain, spinal cord and visceral organs using an existing protocol, while a new assay was developed for iron and zinc measurements that were made in the spinal cord tissues. The higher trend in manganese concentration observed within the 3 and 16 week old <em>les</em> rats in comparison to the controls, where there was a significant increase (ples cerebellum, supports evidence suggesting that manganese levels are associated with astrogliosis. Whereas for iron and zinc, which were measured in the spinal cord tissues, there was also an overall increase in the levels of these metals in the <em>les</em> mutant strain when compared to the controls; however, only significant increases in zinc concentration within the 16 week old <em>les </em>spinal cords were observed.</p> <p>The characterization of the <em>les</em> rodent model mutation and its biochemical abnormality will advance our understanding of not only the process of myelination, but also diseases related to aberrant myelination or the maintenance of myelin sheaths.</p> / Master of Science (MSc)

No description available.

When an organism is dehydrated, neurons in the Organum vasculosum lamina terminalis (OVL T) sense this variation in plasma osmolality (OSM) and excite magnocellular neurosecretory cells (MNCs) in the supraoptic nucleus (SON) via glutamatergic synapses. The resulting action potential firing of MNCs will result in the secretion of vasopressin (VP) into the blood, which will promote water reabsorption from the kidney. The relationship between plasma VP and OSM (know as the VP-OSM ratio) is known to change in sensitivity during the course of a day. / Lorsqu'un organisme est déshydraté, les neurones dans l'Organum vasculosum lamina terminalis (OVL T) détectent le changement dans l'osmolalité du plasma (OSM) et excitent les cellules magnocellulaires neurosécrétoires (MNCs) dans le noyau supraoptique (SON) avec des synapses glutamatergique. La décharge des potentiels d'action qui survient dans les MNCs génère la sécrétion de vasopressine (VP) dans le sang, qui permettra la réabsorption d'eau au niveau du rein. Le rapport entre la VP et OSM (connu comme étant le rapport VP/OSM) subit des changements de sensibilité durant une journée.

<p>Some individuals with alcohol use disorder (AUD) continue to drink because they have developed a habit in which they are not considering the consequences of their actions. Habitual actions persist despite changes in reward and are often studied using devaluation procedures. Stress hormones, such as corticotropin releasing factor (CRF), have been linked to AUD when examining binge-like drinking and withdrawal in rodents. Stress has been examined in the switch from goal-directed to habitual behavior, and CRF has often mimicked the effects of stress exposure. This study looked at the possible direct effects of CRF on habit expression in rats using an operant paradigm. Finding possible novel mechanisms of habit could create an avenue for future novel treatment options. Female and male Long Evans rats were trained on a variable interval schedule using sucrose as a reward. Rats then underwent devaluation procedures including both sensory-specific satiety and conditioned taste aversion (CTA) to test for habitual behaviors. Prior to an extinction session post-CTA, animals were treated with either 20 mg/kg R121919, a CRF1 receptor antagonist, or vehicle. A second extinction session was conducted where animals received the alternative treatment. Lever presses were recorded as a measure of goal-directed or habitual behavior. Sensory-specific satiety devaluation tests revealed that animals were not sensitive to devaluation. This was further supported by both post-CTA extinction sessions. R121919 had no effect on lever pressing in either devalued or valued groups. Further research is needed to explore how a CRF receptor antagonist may affect habit formation or the transition from goal-directed to habit behaviors. Future studies should also examine any possible interaction effects CRF may have with alcohol or stress on habitual behaviors.</p>

La maladie de Wilson est une maladie héréditaire due à un déficit du transporteur du cuivre, l’ATP7B. Cette maladie se présente sous forme d’insuffisance hépatique aiguë ou chronique, pour lesquels le traitement médical actuel consiste en l’administration d’agents chélateurs, ce qui ne résulte cependant pas en une guérison complète de la maladie. La transplantation orthotopique du foie est le seul traitement définitif actuellement, avec tous les désavantages qu’elle comporte. Un traitement alternatif à cette option est donc souhaitable. Cette étude porte sur la faisabilité de la transplantation d’hépatocytes chez le modèle animal de la maladie de Wilson, le rat Long Evans Cinnamon (LEC), avec pour buts d’en déterminer la sécurité et l’efficacité tant sur le plan clinique (amélioration de la survie, prévention de l’hépatite) que pathologique. Douze rats LEC ont reçu une injection intrasplénique de 2,6 x 105 – 3,6 x 107 hépatocytes prélevés chez des rats donneurs de souche LE. Ils ont été suivis durant 6 mois puis sacrifiés. Ils ont ensuite été comparés à un groupe contrôle de douze autres rats LEC. Aucune différence significative n’a été notée au niveau du poids, du bilan hépatique et des concentrations de cuivre biliaire et hépatique. Cependant, une amélioration de l’activité oxydase de la céruloplasmine post-transplantation a été démontrée chez le groupe de rats transplantés (49,6 ± 31,5 versus 8,9 ± 11,7). Les rats transplantés ont aussi eu une amélioration sur tous les critères histologiques étudiés. Enfin, l’ARNm de l’atp7b a été retrouvé chez 58% des rats transplantés avec un taux d’expression de 11,9% ± 13,6 par rapport à un rat LE normal. L’immunohistochimie a quant à elle démontré la présence de l’atp7b chez tous les rats transplantés. Les résultats obtenus sont considérés favorables à ce traitement alternatif, et indiquent que la transplantation d’hépatocytes est une technique sécuritaire qui peut contribuer à renverser le processus pathologique en cours dans la maladie de Wilson. / Wilson’s disease (WD) is a hereditary metabolic disease caused by a deficiency of copper-transporting ATP7B, resulting in copper accumulating to toxic levels in the liver. Its manifestations range from acute or chronic hepatic insufficiency to fulminant liver failure. The mainstay of therapy is the use of chelating agents. However selected patients may also require orthotopic liver transplantation (OTL), an invasive and complex procedure with life-long implications. Hepatocyte transplantation is an appealing alternative to OLT. Its safety and efficacy were evaluated in the animal model of WD, the Long Evans Cinnamon (LEC) rat. Twelve LEC rats received an intrasplenic injection of 2,6 x 105 – 3,6 x 107 hepatocytes obtained from LE donor rats. They were followed for 6 months before sacrifice. They were then compared to a control group of twelve rats. No difference was found when comparing their weights, biochemical parameters such as liver function tests and bilirubin, as well as their biliary and hepatic copper concentrations. However, the ceruloplasmin oxydase activity was improved in the transplanted rats (49,6 ± 31,5 versus 8,9 ± 11,7). After sacrifice, histologic evaluation and demonstration of atp7b mRNA in the recipient liver were performed. There was evidence of histological improvement and atp7b mRNA was found in 58% of transplanted rats with an expression of 11,9% ± 13,6 when compared to a normal LE rat. Evidence of successful engraftment of the transplanted cells was found in every transplanted rat using the technique of immunohistochemistry. These encouraging results are in accordance with previous studies on hepatocyte transplantation in the LEC rat. Its application to the human clinical setting is the next step, as it has already been tried in other metabolic liver diseases.

Pup directed maternal licking and grooming (LG) increases with corticosterone (CORT) supplimentation (Rees et al 2004). Increases in LG lead to an attenuation of the adult offspring's HPA response to stress (Liu et aI1997). Similarly, Neonatal increases in glucocorticoids lead, in adulthood, to the same attenuation of the HPA stress response (Catalani et aI1993). We hypothesize that dams exhibiting increased LG will have increased circulating CORT, and this increase will be reflected in their offspring. This thesis characterizes the HPA hormone profile adrenocorticotropic hormone (ACTH), CORT & Corticosterone Binding Globulin (CBG) in High LG (H) and Low LG (L) litters, 5 days postpartum (P4). Furthermore pup plasma CORT levels are determined at (P) 3,4,6,10 & 14. Finally P10 Hand L LG ACTH, CORT & CBG will be assessed after stress. RESULTS: H compared to L LG dams have significantly increased plasma CORT (p=0.03). At P4, H LG offspring have significantly increased plasma CORT (p=0.03) and significantly decreased plasma ACTH (p=0.04) as compared to L LG offspring. Plasma CBG levels are significantly lower in H compared to L LG offspring (p=0.01) at the same age. Across the Stress Hyporesponsive Period (SHRP) H LG offspring had significantly increased plasma CORT (p= 0.00) compared to L LG offspring at P3. Challenged with a stressor at P10, H LG offspring have an exaggerated plasma CORT response (p=0.00). This data suggests increases in plasma CORT in the dams leads to increased CORT in the high offspring, contributing perhaps to a more mature stress response at P10. / Key word abbreviation: (1) CORT - CORTicosterone, (2) ACTH - AdrenoCorticoTropin releasing Hormone, (3) CBG - Corticosteroid Binding Globulin, (4) SHRP - Stress Hypo-Responsive Period, (5) P - Post-natal day, (6) HPA - Hypothalamic-Pituitary-Adrenal, (7) LG - Licking/Grooming, (8) ADX/OVX - ADrenalectomized/OVarectomized.

La maladie de Wilson est une maladie héréditaire due à un déficit du transporteur du cuivre, l’ATP7B. Cette maladie se présente sous forme d’insuffisance hépatique aiguë ou chronique, pour lesquels le traitement médical actuel consiste en l’administration d’agents chélateurs, ce qui ne résulte cependant pas en une guérison complète de la maladie. La transplantation orthotopique du foie est le seul traitement définitif actuellement, avec tous les désavantages qu’elle comporte. Un traitement alternatif à cette option est donc souhaitable. Cette étude porte sur la faisabilité de la transplantation d’hépatocytes chez le modèle animal de la maladie de Wilson, le rat Long Evans Cinnamon (LEC), avec pour buts d’en déterminer la sécurité et l’efficacité tant sur le plan clinique (amélioration de la survie, prévention de l’hépatite) que pathologique. Douze rats LEC ont reçu une injection intrasplénique de 2,6 x 105 – 3,6 x 107 hépatocytes prélevés chez des rats donneurs de souche LE. Ils ont été suivis durant 6 mois puis sacrifiés. Ils ont ensuite été comparés à un groupe contrôle de douze autres rats LEC. Aucune différence significative n’a été notée au niveau du poids, du bilan hépatique et des concentrations de cuivre biliaire et hépatique. Cependant, une amélioration de l’activité oxydase de la céruloplasmine post-transplantation a été démontrée chez le groupe de rats transplantés (49,6 ± 31,5 versus 8,9 ± 11,7). Les rats transplantés ont aussi eu une amélioration sur tous les critères histologiques étudiés. Enfin, l’ARNm de l’atp7b a été retrouvé chez 58% des rats transplantés avec un taux d’expression de 11,9% ± 13,6 par rapport à un rat LE normal. L’immunohistochimie a quant à elle démontré la présence de l’atp7b chez tous les rats transplantés. Les résultats obtenus sont considérés favorables à ce traitement alternatif, et indiquent que la transplantation d’hépatocytes est une technique sécuritaire qui peut contribuer à renverser le processus pathologique en cours dans la maladie de Wilson. / Wilson’s disease (WD) is a hereditary metabolic disease caused by a deficiency of copper-transporting ATP7B, resulting in copper accumulating to toxic levels in the liver. Its manifestations range from acute or chronic hepatic insufficiency to fulminant liver failure. The mainstay of therapy is the use of chelating agents. However selected patients may also require orthotopic liver transplantation (OTL), an invasive and complex procedure with life-long implications. Hepatocyte transplantation is an appealing alternative to OLT. Its safety and efficacy were evaluated in the animal model of WD, the Long Evans Cinnamon (LEC) rat. Twelve LEC rats received an intrasplenic injection of 2,6 x 105 – 3,6 x 107 hepatocytes obtained from LE donor rats. They were followed for 6 months before sacrifice. They were then compared to a control group of twelve rats. No difference was found when comparing their weights, biochemical parameters such as liver function tests and bilirubin, as well as their biliary and hepatic copper concentrations. However, the ceruloplasmin oxydase activity was improved in the transplanted rats (49,6 ± 31,5 versus 8,9 ± 11,7). After sacrifice, histologic evaluation and demonstration of atp7b mRNA in the recipient liver were performed. There was evidence of histological improvement and atp7b mRNA was found in 58% of transplanted rats with an expression of 11,9% ± 13,6 when compared to a normal LE rat. Evidence of successful engraftment of the transplanted cells was found in every transplanted rat using the technique of immunohistochemistry. These encouraging results are in accordance with previous studies on hepatocyte transplantation in the LEC rat. Its application to the human clinical setting is the next step, as it has already been tried in other metabolic liver diseases.

No description available.