Search results for "RATS"
showing 10 items of 3537 documents
Age-related changes in linoleic acid bioconversion by isolated hepatocytes from spontaneously hypertensive and normotensive rats
1994
This study points out the hepatocyte interconversion of the linoleic acid family during hypertension. Hepatocyte delta 6 desaturase activity was higher in 1 month-old spontaneously hypertensive rats than in normotensive controls. A similar tendency was observed in 6 month-old SHR. delta 5 desaturase activity was higher only in 1 month-old spontaneously hypertensive rats as compared to controls. Desaturase activities were particularly high at the age of 6 months. The hepatocyte fatty acid composition showed an impairment of n-6 polyunsaturated fatty acid metabolism in spontaneously hypertensive animals. Changes were greater in the young prehypertensive rats than in adults. A storage of n-3 l…
Physiological changes in glutathione metabolism in foetal and newborn rat liver
1991
Glutathione metabolism was studied in isolated hepatocytes from foetal, newborn and adult rats. The GSH/GSSG ratio decreased 15-20-fold through the foetal-neonatal-adult transition. This was mainly due to an increase in GSSG. All enzyme activities involved in the glutathione redox cycle tend to increase during that transition, but the relative increases in glutathione peroxidase and glutathione S-transferase were 3-5 times those of glutathione reductase or glucose-6-phosphate dehydrogenase. GSH synthesis from methionine as a sulphur source was 6 times lower in foetal than in adult hepatocytes. However, when N-acetylcysteine was used as a sulphur donor to by-pass the cystathionine pathway, t…
Glutamate Activates Phospholipase D in Hippocampal Slices of Newborn and Adult Rats
1993
Phospholipase D (PLD) is activated by many neurotransmitters in a novel signal transduction pathway. In the present work, PLD activity was studied comparatively in hippocampal slices of newborn and adult rats. Basal PLD activity in adult rats was almost three times higher than in newborn rats. In newborn rats, L-glutamate and 1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) time- and concentration-dependently enhanced the formation of [3H]phosphatidylpropanol ([3H]PP) and of [3H]phosphatidic acid in the presence of 2% propanol. N-Methyl-D-aspartate and kainate (both 1 mM) caused small, but significant increases (approximately 50%), whereas alpha-amino-3-hydroxy-5-methylisoxazole…
Impaired calcium homeostasis in aged hippocampal neurons
2009
Abstract Development of neurodegenerative diseases such as Alzheimer's and Parkinson's disease is strongly age-associated. The impairment of calcium homeostasis is considered to be a key pathological event leading to neuronal dysfunction and cell death. However, the exact impact of aging on calcium homeostasis in neurons remains largely unknown. In the present work we have investigated intracellular calcium levels in cultured primary hippocampal neurons from young (2 months) and aged (24 months) rat brains. Upon stimulation with glutamate or hydrogen peroxide aged neurons in comparison to young neurons demonstrated an increased vulnerability to these disease-related toxins. Measurement of c…
Phosphatidylserine counteracts physiological and pharmacological suppression of humoral immune response
1990
Phosphatidylserine (PS) is a necessary cofactor for protein kinase C (PKC) activation, and changes in the synthesis of PS have been shown to participate in the mechanism(s) involved in the transmembrane signaling of interleukin 1 (IL-1). In view of the age-associated defects in T-cell functions, in the present study we have addressed the question of whether an in vivo treatment with PS might interfere with such processes. Furthermore, the effect of an in vitro treatment with PS in human peripheral blood monocytes (PBMC) or splenocytes activated with a lectin mitogen, on the expression of IL-2 receptor, was assessed. While the process of ageing was accompanied by a marked decline of humoral …
Cardiac Micro–Computed Tomography Imaging of the Aging Coronary Vasculature
2012
Background— Alterations at the level of the coronary circulation with aging may play an important role in the evolution of age-associated changes in left ventricular (LV) fibrosis and function. However these age-associated changes in the coronary vasculature remain poorly defined primarily due to the lack of high resolution imaging technologies. The current study was designed to utilize cardiac micro–computed tomography (micro-CT) technology as a novel imaging strategy, to define the 3-dimensional coronary circulation in the young and aged heart and its relationship to LV fibrosis and function. Methods and Results— Young (2 months old; n=10) and aged (20 months old; n=10) Fischer rats unde…
Age-associated oxidative damage leads to absence of γ-cystathionase in over 50% of rat lenses: Relevance in cataractogenesis
2004
Oxidative damage to lens proteins and glutathione depletion play a major role in the development of senile cataract. We previously found that a deficiency in gamma-cystathionase activity may be responsible for glutathione depletion in old lenses. The aims of this study were: (1) to investigate the mechanism that causes the age-related deficiency in gamma-cystathionase activity in the eye lens, and (2) to determine the role of gamma-cystathionase deficiency in cataractogenesis. Two populations of old rats were found, one (56%) whose lenses lacked gamma-cystathionase activity and the rest that exhibited detectable enzyme activity. gamma-Cystathionase protein was absent in lenses from old rats…
Cannabinoid and nitric oxide signaling interplay in the modulation of hippocampal hyperexcitability: study on electrophysiological and behavioral mod…
2015
A growing bulk of evidence suggests that cannabinoid system plays a pivotal role in the control of hyperexcitability phenomena. Notwithstanding, the anticonvulsant action of cannabinoids has not been fully addressed, in particular the involvement of potential cellular neuromodulators, for instance nitric oxide. In the current study, we focused on two distinct rat models of temporal lobe epilepsy, the Maximal Dentate Activation and the pilocarpine-induced acute seizures, providing both electrophysiological and behavioral data on cannabinoid and nitrergic system interplay. We evaluated the antiepileptic effects of WIN 55,212-2, (R)-(+)-[2,3-dihydro-5-methyl-3-(4- morpholinylmethyl) pyrrolo[1,…
Evidences of cannabinoids-induced modulation of paroxysmal events in an experimental model of partial epilepsy in the rat.
2009
The anticonvulsant effect of cannabinoids (CB) has been shown to be mediated by the activation of the CB(1) receptor. This study evaluates the anticonvulsant activity of (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl) pyrrolo[1,2,3-de]-1,4-benzoxazin-6-Yl]-1-naphthalenylmethanone (WIN55,212-2, CB agonist) alone or preceded by the administration of N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251, selective CB(1) antagonist) in an experimental in vivo model of complex partial seizures (maximal dentate gyrus activation - MDA) in the rat. WIN55,212-2 (21mgkg(-1)) exerted an anticonvulsant effect, significantly reduced by the pre-treatme…
Induction of apoptosis in cardiac myocytes by an A3 adenosine receptor agonist.
1998
The effects of the selective adenosine (ADO) A3 receptor agonist IB-MECA (N6-(3-iodobenzyl)adenosine-5'-N-methylcarboxamide) on cultured newborn rat cardiomyocytes were examined in comparison with ADO, the ADO A1 receptor-selective agonist R-PIA (N6-R-phenylisopropyladenosine), or the ADO A3 selective antagonist MRS 1191 (3-ethyl-5-benzyl-2-methyl-6-phenyl-4-phenylethynyl-1, 4-(+/-)-dihydropyridine-3,5 dicarboxylate), using digital image analysis of Feulgen-stained nuclei. At high concentration, IB-MECA (/=10 microM ) and ADO (200 microM) induced apoptosis; however, R-PIA or MRS 1191 did not have any detectable effects on cardiac cells. In addition, DNA breaks in cardiomyocytes undergoing a…