Neurological Disorder, Stroke: Relevance of Preclinical Studies

The neurological disorders and stroke represent the last century’s medical challenge. Despite increasing number of elderly people and the subsequent increase of neurological diseases, in socalled industrialized countries, we have no efficacious strategy to fight this plague. Probably, the more effective method to take on this challenge may be a rigorous prevention and principle risk factors (e.g. high-pressure, stress, obesity, smoke of tobacco and alcohol) elimination. On the other hand, further scientific research in this field could be very useful. This kind of research should be based on the use of animal models to improve current understanding of the pathophysiological features of these diseases and may yield important information on how to improve analysis of the “efficacy” of some possible molecules. Many authors, in a number of related medical fields, have evaluated the importance of preclinical research and they have written different review articles. However, in these models of disease, we often have some problem to acknowledge a precise human disorder. For instance, an animal model of stroke may use the focal cerebral ischemia. Actually, this model predicts the outcome of an ischemic insult but, it does not reproduce the general background pathophysiological that would cause an endogenous stroke. Therefore, we should accept the limitations inherent in these models and, follow early proof of efficacy studies in “young healthy animals” with more accurate studies in models incorporating age and co-morbidities. Presumably, translational problems may decrease with further improvement in preclinical study design and conduct. Recent preclinical studies underline the relevance of human cell-based approach to study stroke. Once again, these papers evidenced the crucial role of animal models. Moreover, these models were also appropriate to evaluate the effects of stem cell transplantation in Ischemic Stroke. It is the general opinion that the advantageous clinical translation of cell-based therapy requires the use, in preclinical research, of scientifically appropriate and of reproducible functional neurological result evaluations, which are adequately sensitive to investigate sensor motor asymmetry related to the site of ischemia

Obesity-related blood brain barrier changes in obese Zucker rats

The blood brain barrier (BBB) is the site of exchange between blood and the nervous tissue. Damage of it may impair physiological balance between blood stream and nervous tissue. Metabolic syndrome (MetS) is defined by several interconnected physiological, biochemical, and metabolic factors directly related to obesity. It increases the risk of atherosclerotic cardiovascular and cerebrovascular disease and of all cause mortality. Obese Zucker rats (OZRs), with a mutation in leptin receptor, represent a model of obesity exhibiting diabetes and moderate arterial hypertension. In OZRs hyperglycaemia, hyperinsulinaemia and hyperlipidaemia occur simultaneously. This work had characterized BBB and endothelial alterations of OZRs compared to their non-obese cohort lean Zucker rats (LZRs) for assessing the occurrence of an eventual cerebrovascular injury. Brains of male OZRs and LZRs of 12, 16 and 20 weeks were processed for the immunochemical and immunohistochemical detection of different BBB markers. The water channel protein Aquaporin-4 (AQP4) and the glucose transporter protein- 1 (GLUT1) involved in the glucose passage across the BBB endothelial cells were investigated. The expression of adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) was also assessed within cerebrovascular endothelium as a marker of inflammation. In intracerebral arteries of older OZRs, a decrease of lumen area with an increase of wall area was found. BBB of older OZRs revealed an augmented expression of AQP4 probably related to an edema formation. A downregulation of GLUT1 was observed in OZRs of 12 weeks of age. This may represent the adaptive reaction to prevent excessive glucose entering in neurons. On the contrary, in older OZRs an obvious increase in the expression of GLUT1 was found. These phenomena are probably related to vascular inflammation as confirmed by the increase of ICAM-1 and VCAM-1 expression in the endothelium of older OZRs. The above evidence shows that OZRs develope specific BBB changes. This could contribute to clarify the pathophysiology of nervous system damage reported in obese individuals. OZRs may represent an useful animal model for assessing the influence of obesity/MetS on the brain and the possible correlation of it with neurodegenerative disorders

Effect of treatment with the antioxidant alpha-lipoic (thioctic) acid on heart and kidney microvasculature in spontaneously hypertensive rats

Endothelial cells represent an important vascular site of signaling and development of damage during ischemia, inflammation and other pathological conditions. Excessive reactive oxygen species production causes pathological activation of endothelium including exposure of cell to adhesion molecules. Intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) are members of the immunoglobulin super-family which are present on the surface of endothelial cells. These molecules represent important markers of endothelial inflammation. The present study was designed to investigate, with immunochemical and immunohistochemical techniques, the effect of treatment with (+/-)-alpha lipoic (thioctic) acid and its enantiomers on heart and kidney endothelium in spontaneously hypertensive rats (SHR). Arterial hypertension is accompanied by an increased oxidative stress status in the heart characterized by thiobarbituric acid reactive substances (TBARS) and nucleic acid oxidation increase. The higher oxidative stress also modifies adhesion molecules expression. In the heart VCAM-1, which was higher than ICAM-1 and PECAM-1, was increased in SHR. ICAM-1, VCAM-1 and PECAM-1 expression was significantly greater in the renal endothelium of SHR. (+/-)-Alpha lipoic acid and (+)-alpha lipoic acid treatment significantly decreased TBARS levels, the nucleic acid oxidation and prevented adhesion molecules expression in cardiac and renal vascular endothelium. These data suggest that endothelial molecules may be used for studying the mechanisms of vascular injury on target organs of hypertension. The effects observed after treatment with (+)-alpha lipoic acid could open new perspectives for countering heart and kidney microvascular injury which represent a common feature in hypertensive end-organs damage

Choline and Choline alphoscerate Do Not Modulate Inflammatory Processes in the Rat Brain

Choline is involved in relevant neurochemical processes. In particular, it is the precursor and metabolite of acetylcholine (ACh). Choline is an essential component of different membrane phospholipids that are involved in intraneuronal signal transduction. On the other hand, cholinergic precursors are involved in ACh release and carry out a neuroprotective effect based on an anti-inflammatory action. Based on these findings, the present study was designed to evaluate the effects of choline and choline precursor (Choline alphoscerate, GPC) in the modulation of inflammatory processes in the rat brain. Male Wistar rats were intraperitoneally treated with 87 mg of choline chloride/kg/day (65 mg/kg/day of choline), and at choline-equivalent doses of GPC (150 mg/kg/day) and vehicle for two weeks. The brains were dissected and used for immunochemical and immunohistochemical analysis. Inflammatory cytokines (Interleukin-1β, IL-1β; Interleukin-6 , IL-6 and Tumor Necrosis Factor-α, TNF-α) and endothelial adhesion molecules (Intercellular Adhesion Molecule, ICAM-1 and Vascular cell Adhesion Molecule, VCAM-1) were studied in the frontal cortex, hippocampus, and cerebellum. The results clearly demonstrated that treatment with choline or GPC did not affect the expression of the inflammatory markers in the different cerebral areas evaluated. Therefore, choline and GPC did not stimulate the inflammatory processes that we assessed in this study

Heart morphology in Zucker-obese rat

Obesity represents the central and causal component of the metabolic syndrome (MetS), which is a growing medical challenge in western countries as a result of changes in lifestyle. Obesity is also associated with an increased incidence of arterial hypertension and of cardiovascular disease burden. In animal models of diet-induced obesity, endothelial inflammatory activation, demonstrated by changes in adhesion molecule expression, is one of the earliest manifestation of vascular and cardiac damage. The intercellular adhesion molecule-1 (ICAM-1) is a member of the immunoglobulin (Ig) superfamily present on the surface of several other cell types, including endothelial cells. Adhesion molecules [e.g., ICAM-1, vascular cell adhesion molecule 1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1)] if in contact with an activated endothelium could represent attractive targets for delivery of drugs and imaging probes to vascular pathological sites. The present study was designed to investigate, with morphological, immunochemical and immunohistochemical techniques, changes of heart and coronary arteries in Obese Zucker rats (OZR) compared to the lean Zucker rats (LZRs). The OZRs, with a mutation in leptin receptors, is a model of Type II diabetes mellitus, characterized by the presence of obesity, hyperglycemia, hyperinsulinemia, hyperlipidemia and moderate hypertension similar to MetS. The heart of OZRs of 12, 16 and 20 weeks was processed for microanatomical analysis and ICAM-1, VCAM-1 and PECAM-1 and pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) immunohistochemistry. OZRs at the different age, developed ventricular hypertrophy, characterized by increase size of cardiomyocytes but not fibrosis compared to LZRs. This phenomenon was more evident in 20-weeks-old OZRs. VCAM-1 was more expressed in the coronary arteries compared to other adhesion molecules, and increased in the OZRs of 20-weeks of age. In the same age, IL-6 expression was significantly increased. These results suggest that the obesity leads to heart tissue changes and coronary inflammation. Myocardial vascular inflammation, induced by metabolic comorbidities, could contribute to the development of heart failure. Protective strategies in obesity may be focussed versus body weight loss and countering of metabolic alterations induced by obesity