Illicit drug use has been a growing concern over the past few decades. The rise in use of illegal drugs drove the government and law enforcement to aggressively tackle this problem and crackdown on the illicit use of drugs. However, this sparked a further interest in ‘legal highs.’ Before 2011, among the newly popular ‘legal highs’ was ‘Bath Salts.’ Cathinone is a monoamine alkaloid and the active ingredient found in the leaves of the khat plant. The psychoactive form of bath salts may contain a mixture of synthesized cathinones, including, 4-methyl-N-methcathinone (mephedrone), 3,4-methylenedioxy-N- methylcathinone (methylone) and methylenedioxypyrovalerone (MDPV). These three are commonly found in bath salts. One of the major psychoactive ingredients in bath salts is mephedrone. Mephedrone grew in popularity due to its low price, accessibility, and the shortage of MDMA, thus making mephedrone the prime drug to sell as a ‘legal high’ up until 2011 when it became banned in the United S / Pharmaceutical Sciences

Status epilepticus (SE) is a major clinical emergency resulting in continuous seizure activity that can cause brain injury and many molecular and pathophysiologic changes leading to neuronal plasticity. The neuronal plasticity following SE-induced brain injury can initiate epileptogenesis and lead to the ultimate expression of acquired epilepsy (AE), characterized clinically by spontaneous, recurrent seizures. Epileptogenesis is the process wherein healthy brain tissue is transformed into hyperexcitable neuronal networks that produce AE. Understanding these alterations induced by brain injury is an important clinical challenge and can lend insight into possible new therapeutic targets to halt the development of AE. Currently there are no means to prevent epileptogenesis following brain injury; thus, the elucidation of mechanisms of epileptogenesis will be useful in preventing the long-term clinical sequela. It has been demonstrated in vivo that calcium (Ca2+) dynamics are severely altered during SE and that elevations in intracellular Ca2+ ([Ca2+]i) in hippocampal neurons are maintained well past the duration of the injury itself (Ca2+ plateau). Here we report that similar changes in [Ca2+]i are observed in the hippocampal neuronal culture model of SE-induced AE. As an important second messenger, the maintenance of a Ca2+ plateau following injury can lead to several changes in gene expression, neurotransmitter release, and overall, neuronal plasticity. Thus, changes in post-SE [Ca2+]i and Ca2+ homeostasis may be important in understanding epileptogenesis and eventually preventing the progression to chronic epilepsy. This dissertation examines the development and maintenance of the Ca2+ plateau after SE and demonstrates the novel finding that pharmacological modulation of [Ca2+]i following SE may inhibit epileptogenesis in vitro.

Lorsque l’anesthésie par inhalation ne peut être utilisée chez le rat, la combinaison de kétamine et de xylazine est l’alternative la plus fréquemment utilisée. Les doses administrées peuvent varier selon le protocole expérimental. En présence de fièvre, d’infections ou de processus tumoral accompagné de fièvre, la pharmacocinétique de ces drogues peut être modifiée. Ce projet porte sur l’évaluation des changements physiologiques, hématologiques, biochimiques et pharmacocinétiques chez le rat Sprague Dawley lors d’anesthésie avec le mélange kétamine-xylazine suite à l’administration de trois doses différentes de lipopolysaccharide (LPS). Après l’administration de LPS, une anesthésie à la kétamine-xylazine fut induite chez des rats Sprague Dawley. Des prélèvements sanguins périodiques ainsi que des mesures des paramètres physiologiques furent effectués afin d’évaluer l’effet du LPS sur la pharmacocinétique des deux drogues ainsi que sur les paramètres biochimiques et hématologiques. Les différentes doses de LPS ont causé certaines modifications notamment en produisant une baisse marquée de la saturation en oxygène et de l’albumine sérique, une augmentation de la durée d’anesthésie ainsi que des lésions hépatiques mineures. Les paramètres pharmacocinétiques de la kétamine furent peu altérés par l’administration de LPS tandis qu’une diminution de la clairance et une augmentation de l’aire sous la courbe (AUC) furent observées pour la xylazine dans les groupes ayant reçu les doses moyenne et élevée de LPS. Ces résultats montrent que les doses de xylazine doivent être adaptées en présence de LPS pour permettre une anesthésie de courte durée et des changements physiologiques et biochimiques moindres lorsqu’elle est administrée avec de la kétamine. / When inhalation anesthesia cannot be used in laboratory rats, ketamine-xylazine combination is the most frequent alternate regimen. The administrated doses can vary according to the experimental protocol. During fever episodes, infections or tumoral process, the pharmacokinetics of these drugs can be modified. This project focuses on the evaluation of the physiological, hematological, biochemical and pharmacokinetics changes in Sprague Dawley rats during ketamine-xylazine anesthesia, after administration of three different doses of lipopolysaccharide (LPS). After administration of LPS to Sprague Dawley rats, ketamine-xylazine anesthesia was induced. Periodic blood samplings and monitoring of physiologic parameters were made in order to evaluate the effect of LPS on ketamine-xylazine pharmacokinetics and hematological and biochemical parameters. The different LPS doses caused specific parameter modifications including a marked decrease of oxygen blood saturation and serum albumin, a longer anesthesia duration and minor hepatic lesions. No significant modifications of pharmacokinetics parameters of ketamine were observed. An increase of area under curve (AUC) and a decrease of xylazine clearance were noted in groups who received medium and large doses of LPS. These results show that that xylazine doses need to be adapted in the presence of LPS, to allow a shorter duration anaesthesia and lesser physiological and biochemical changes when administered with ketamine.

Chez les animaux de laboratoire, même si les anesthésiques par inhalation sont généralement plus sécuritaires que les injectables, leur utilité est souvent restreinte lorsqu’un protocole expérimental exige une autre approche. Des combinaisons d’anesthésiques contenant de la kétamine sont considérées comme l’option de choix pour les anesthésies injectables chez les rats. Le vieillissement entraîne des changements dégénératifs au niveau de la structure et la fonction des organes, modifiant souvent à la pharmacocinétique des drogues. Ce projet porte sur l’évaluation des changements pharmacodynamiques (physiologiques, biochimiques et histologiques) et pharmacocinétiques, lors d’une combinaison anesthésique de kétamine-­‐xylazine chez le rat Sprague-­‐Dawley vieillissant. Une anesthésie à la kétamine-­‐xylazine fut induite chez des rats Sprague-­‐Dawley de différents âges. Afin d’évaluer l’effet du vieillissement sur le métabolisme des deux drogues, des prélèvements sanguins périodiques pour l’analyse de la pharmacocinétique ainsi que des mesures des paramètres physiologiques, biochimiques et une histopathologie furent effectués. Le vieillissement a causé certaines modifications notamment en produisant une diminution de la saturation d’oxygène, une baisse marquée de la fréquence cardiaque et respiratoire, une hypoalbuminémie ainsi qu’une augmentation de la durée d’anesthésie. Les paramètres pharmacocinétiques de la kétamine et de la xylazine furent grandement affectés par le vieillissement causant une augmentation progressive significative de l’aire sous la courbe (AUC) et du temps de demi-­‐vie, ainsi qu’une diminution de la clairance. À la lumière de ces résultats, les doses de kétamine et de xylazine doivent être adaptées chez les rats vieillissants pour permettre une anesthésie de durée raisonnable et un réveil sans complications. / In laboratory animals, even if inhalation anesthetics are generally safer than injecting, their usefulness is often restrained when an experimental design does not allow it. For this reason, ketamine combinations are considered the option of choice for injecting anesthesia in rats. Aging brings degenerative changes in the structure and function of the organs, often affecting the pharmacokinetics of drugs. This project focuses on the evaluation of physiological, pharmacokinetic, biochemical and histological changes during a ketamine-­‐xylazine anesthetic combination in aging Sprague-­‐Dawley rats. Anesthesia with ketamine-­‐xylazine was induced in Sprague-­‐Dawley rats of different ages. To assess the effect of aging on the metabolism of both drugs, periodic blood samples for pharmacokinetic analysis and measurements of physiological, biochemical and histological parameters were performed. Aging have made some changes for example a decrease in oxygen saturation, a sharp drop in heart and respiratory rate, hypoalbuminemia and an increase in the duration of anesthesia. The pharmacokinetic parameters of ketamine and xylazine were greatly affected in older animals, causing a significant increase in the area Under the curve (AUC) and the half-­‐life time, and a decrease in clearance. In the light of these results, dosage of ketamine and xylazine must be adapted in aging rats to allow a short anesthesia and an awakening without complications.

<p>Conclusion of this study: These data suggest that 6 weeks of high-fat feeding induces hypertension but does not produce obesity, dyslipidemia and insulin resistance. However, this model may be useful in studying vascular reactivity in hypertension in the absence of insulin resistance.</p>

Intratympanic injection of various otoprotectants through the round window membrane (RWM) might become available in the near future as an alternative to the currently available medical and surgical methods used to treat several inner ear diseases. The most common outcome of such diseases is sensorineural hearing loss (SNHL). Two examples of  these otoprotectants are Edaravone and Brain-Derived Neurotrophic Factor (BDNF), both of which have already proved effective against  noise-induced hair cell loss, barotrauma  and ototoxicity caused by cisplatin. In four different studies we used two electrophysiological methods, auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE), to study the effects of tobramycin and Pseudomonas aeruginosa exotoxin A (PaExoA) on the inner ears of 129 male Sprague-Dawley rats. In two investigations, not only the otoprotective effects of Edaravone on tobramycin-induced ABR threshold shifts and PaExoA-induced DPOAE  threshold changes, were studied but even different application times, in order to establish in which interval it was still possible to achieve effective otoprotection.We found that Edaravone gave otoprotection from tobramycin when injected simultaneously or within 7 days, but it had only a limited effect on the changes in DPOAE thresholds caused by PaExoA when injected 1, 2, or 4 hours after the exotoxin. The effect of BDNF on PaExoA-induced ABR threshold shifts was investigated in two studies, where different doses of intratympanically injected PaExoA were used and where BDNF was applied simultaneously, 12 or 72 hours efter exotoxin instillation. We found that BDNF had an otoprotective effect on SNHL induced by different doses PaExoA when injected simultaneously or with no more than 12 hours delay.

Lorsque l’anesthésie par inhalation ne peut être utilisée chez le rat, la combinaison de kétamine et de xylazine est l’alternative la plus fréquemment utilisée. Les doses administrées peuvent varier selon le protocole expérimental. En présence de fièvre, d’infections ou de processus tumoral accompagné de fièvre, la pharmacocinétique de ces drogues peut être modifiée. Ce projet porte sur l’évaluation des changements physiologiques, hématologiques, biochimiques et pharmacocinétiques chez le rat Sprague Dawley lors d’anesthésie avec le mélange kétamine-xylazine suite à l’administration de trois doses différentes de lipopolysaccharide (LPS). Après l’administration de LPS, une anesthésie à la kétamine-xylazine fut induite chez des rats Sprague Dawley. Des prélèvements sanguins périodiques ainsi que des mesures des paramètres physiologiques furent effectués afin d’évaluer l’effet du LPS sur la pharmacocinétique des deux drogues ainsi que sur les paramètres biochimiques et hématologiques. Les différentes doses de LPS ont causé certaines modifications notamment en produisant une baisse marquée de la saturation en oxygène et de l’albumine sérique, une augmentation de la durée d’anesthésie ainsi que des lésions hépatiques mineures. Les paramètres pharmacocinétiques de la kétamine furent peu altérés par l’administration de LPS tandis qu’une diminution de la clairance et une augmentation de l’aire sous la courbe (AUC) furent observées pour la xylazine dans les groupes ayant reçu les doses moyenne et élevée de LPS. Ces résultats montrent que les doses de xylazine doivent être adaptées en présence de LPS pour permettre une anesthésie de courte durée et des changements physiologiques et biochimiques moindres lorsqu’elle est administrée avec de la kétamine. / When inhalation anesthesia cannot be used in laboratory rats, ketamine-xylazine combination is the most frequent alternate regimen. The administrated doses can vary according to the experimental protocol. During fever episodes, infections or tumoral process, the pharmacokinetics of these drugs can be modified. This project focuses on the evaluation of the physiological, hematological, biochemical and pharmacokinetics changes in Sprague Dawley rats during ketamine-xylazine anesthesia, after administration of three different doses of lipopolysaccharide (LPS). After administration of LPS to Sprague Dawley rats, ketamine-xylazine anesthesia was induced. Periodic blood samplings and monitoring of physiologic parameters were made in order to evaluate the effect of LPS on ketamine-xylazine pharmacokinetics and hematological and biochemical parameters. The different LPS doses caused specific parameter modifications including a marked decrease of oxygen blood saturation and serum albumin, a longer anesthesia duration and minor hepatic lesions. No significant modifications of pharmacokinetics parameters of ketamine were observed. An increase of area under curve (AUC) and a decrease of xylazine clearance were noted in groups who received medium and large doses of LPS. These results show that that xylazine doses need to be adapted in the presence of LPS, to allow a shorter duration anaesthesia and lesser physiological and biochemical changes when administered with ketamine.

<p>Conclusion of this study: These data suggest that 6 weeks of high-fat feeding induces hypertension but does not produce obesity, dyslipidemia and insulin resistance. However, this model may be useful in studying vascular reactivity in hypertension in the absence of insulin resistance.</p>

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Conclusion of this study: These data suggest that 6 weeks of high-fat feeding induces hypertension but does not produce obesity, dyslipidemia and insulin resistance. However, this model may be useful in studying vascular reactivity in hypertension in the absence of insulin resistance. / South Africa

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Background: It is well known that some genetic factors and dietary factors, such as excessive salt intake and excessive caloric intake (resulting in obesity) are risk factors for hypertension. Fifty percent of all hypertensive patients are also insulin resistant. Both hypertension and insulin resistance are again risk factors for other cardiovascular diseases such as atherosclerosis and heart failure. The nature of the association between hypertension and insulin resistance has not been clearly elucidated. Spontaneously hypertensive rats are the ideal models to study the aspects of the relationships between hypertension and insulin resistance. Models of high-fat feeding induce obesity,hypertension and insulin resistance and are thus used extensively to study hypertension because these models closely mimic some of the renal and cardiovascular changes found in human hypertensive patients. The present study was initiated to evaluate if insulin resistance will develop within 6 weeks in a model of high-fat diet induced hypertension and if so, to determine whether captopril will affect the presence of insulin resistance.This model should in future be used to study vascular reactivity to phenylephrine (PHE),acetylcholine (ACH) and sodium nitroprusside (SNP) in hypertensive animals in theabsence or presence of insulin resistance and in normotensive insulin resistant animals. Methods: In a series of experiments, rats were divided into four groups that received different treatments: (i) laboratory pellets, (ii) high-fat diet, (iii) high-fat diet plus captopril and (iv) high-fat diet plus vehicle. Body weight was measured weekly for 6 weeks. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured every week during the 6-weeks feeding period by the tail cuff method using a two channel computerized non-invasive system from Kent Scientific Corporation, USA.m Intraperitonealy glucose tolerance tests (IPGTTs) were performed at week 3 and week 6.After 6 weeks, and after an overnight fast, the plasma lipid profile was determined using a portable CardiochekTM blood test system. Fasting plasma insulin was determined using an immunoenzymatic assay for the in vitro quantitative measurement of rat insulin (INS) in serum and plasma. Insulin sensitivity was estimated by the quantitative insulin sensitivity check index (QUICKI) using the fasting plasma insulin and fasting glucose levels. After week 6 on the high-fat diet, thoracic aortae from the control and high-fat fed(HFD) animals were excised and vascular response to PHE, ACH and SNP were assessed in intact and denuded endothelium.Result: High-fat feeding did not cause a significant increase in body weight. High-fat feeding significantly increased systolic blood pressure from 125±2.1 mmHg in control animals to 155±5.9 mmHg in the HFD group (P < 0.05) and 158±5.6 mmHg in the HFDV group (P < 0.05). Diastolic blood pressure was increased from 86±2.8 mmHg in the control group to 117±2.5 mmHg in the HFD group (P < 0.05) and 113±3.4 mmHg in the HFDV group (P < 0.05). Visceral fat was increased from 0.8±0.1g in the control group to 3.1±0.6 g in the HFD group and 3.8±0.6 g in the HFDV group. IPGTTs performed at weeks 3 and 6 respectively did not differ significantly from the control group as evidenced from the AUC’s at weeks 3 and 6 respectively. High-fat feeding had no significant effects on blood cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) values or and fasting plasma insulin levels. The KCl induced contraction in both aortic rings with intact and denuded endothelium did not differ significantly between the control and HFD groups (P= 0.4 and 0.8) respectively. The contraction mediated by KCl in aortic rings with intact and denuded endothelium from the control or HFD groups also did not differ significantly(control: intact vs denuded, P = 0.2; HFD: intact vs denuded, P = 1). Dose responsecurves(1-10 μM) to PHE indicated slightly stronger contractions in the high-fat fed animals at submaximal doses tested. The maximum contraction achieved was however the same (94±19% and 99±2.6% relative to KCl induced contraction, in the control and HFD group respectively, P<0.05). Relaxation responses to ACH and SNP represent preliminary data.Conclusion: These data suggest that 6 weeks of high-fat feeding induces hypertension but does not produce obesity, dyslipidemia and insulin resistance. However, this model may be useful in studying vascular reactivity in hypertension in the absence of insulin resistance.