Search results for "Locke"
showing 10 items of 332 documents
Generalization of seizures parallels the formation of "dark" neurons in the hippocampus and pontine reticular formation after focal-cortical applicat…
2008
Abstract Distribution and time course of the occurrence of “dark” neurons were compared with the EEG activity and behavior of rats during 4-aminopyridine (4-AP) induced epileptic seizures. A crystal of the K + channel blocker 4-AP (0.5 mg/kg) was placed onto the exposed parieto-occipital cortex of Halothane-anesthetized rats for 40 min. Thereafter, the anesthesia was discontinued and the behavioral signs of the epileptic seizure activity were observed. The presence of “dark” neurons was demonstrated by the sensitive silver method of Gallyas in rats sacrificed at 0, 3 and 6 h after the end of the 4-AP crystal application. The EEG activity was recorded in the rats with longer survival times. …
Memory-enhancing and brain protein expression-stimulating effects of novel calcium antagonist in Alzheimer’s disease transgenic female mice
2016
The prevalence of Alzheimer's disease (AD) is higher in females than in males, and causes more severe cognitive, memory and behavioral impairments. Previously, in male transgenic (Tg) APPSweDI mice, we reported that the novel lipophilic 1,4-dihydropyridine (DHP) derivative AP-12 crossed the blood-brain barrier, blocked neuronal and vascular calcium channels, changed brain protein expression and improved behavior. In this study, we used female Tg APPSweDI mice to assess the effects of AP-12 on behavior, and brain protein expression, with a particular focus on those of the GABAergic system. The results showed that in female Tg mice, similar to male Tg mice, AP-12 improved spatial learning/mem…
PD123319, angiotensin II type II receptor antagonist, inhibits oxidative stress and inflammation in 2, 4-dinitrobenzene sulfonic acid-induced colitis…
2019
Angiotensin II, the main effector of renin angiotensin system, plays an important role in the inflammatory process and most of its effects are mediated through the AT1 receptor activation. However, the knowledge about the AT2 receptor involvement in this process is still evolving. We previously found that in an experimental model of colitis, AT2 receptor activation can contribute to the impairment of the muscle contractility in vitro in the course of inflammation. Here, we investigated the potential alleviating effects of the in vivo treatment of PD123319 (1-[[4-(Dimethylamino)-3-methylphenyl]methyl]-5-(diphenylacetyl)-4,5,6,7- tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid ditriflu…
Endothelial and neural factors functionally involved in the modulation of noradrenergic vasoconstriction in healthy pig internal mammary artery
2011
The role of endothelial and neural factors as modulators of neurogenic- and noradrenaline-induced vasoconstriction was examined in healthy pig internal mammary artery (IMA). Tetrodotoxin-, guanethidine-sensitive electrical field stimulation (EFS)-, and noradrenaline-elicited contractions were significantly diminished by prazosin (n=8, P0.001) and less so by rauwolscine, indicating functional α₁- and α₂-adrenoceptor-mediated noradrenergic innervation of the IMA. Endothelium removal reduced neurogenic (n=8, P0.01) but augmented noradrenaline responses (n=8, P0.01), suggesting the release of two endothelium-dependent factors with opposite effects. In the presence of endothelium, neurogenic and…
Role of angiotensin II in arterial pressure and renal hemodynamics in rats with altered renal development: age- and sex-dependent differences
2012
Numerous studies have demonstrated that angiotensin II (ANG II) is involved in hypertension and renal changes occurring as a consequence of an adverse event during renal development. However, it was unknown whether this involvement is sex and age dependent. This study examines whether the increments in arterial pressure (AP) and in the renal sensitivity to ANG II are sex and age dependent in rats with altered renal development. It also evaluates whether the ANG II effects are accompanied by increments in AT1 receptors and oxidative stress. Experiments were performed in 3- to 4- and 10- to 11-mo-old rats treated with vehicle or an AT1 receptor antagonist (ARAnp) during the nephrogenic perio…
Effect of the CB1 cannabinoid agonist WIN 55212-2 on the acquisition and reinstatement of MDMA-induced conditioned place preference in mice
2010
AbstractBackgroundNumerous reports indicate that MDMA users consume other psychoactive drugs, among which cannabis is one of the most common. The aim of the present study was to evaluate, using the conditioned place preference, the effect of the cannabinoid agonist WIN 55,212-2 on the rewarding effects of MDMA in mice.MethodsIn the first experiment adolescent mice were initially conditioned with 1.25, 2.5 or 5 mg/kg of MDMA or 0.1 or 0.5 mg/kg of WIN and subsequently with both drugs. Reinstatement of the extinguished preference by priming doses was performed in the groups that showed CPP. In the second experiment, animals were conditioned with 2.5 or 5 mg/kg of MDMA and, after extinction, r…
Capacitative Ca2+ entry associated with α1-adrenoceptors in rat aorta
1997
In rat aorta, depletion of internal Ca2+ stores by addition of noradrenaline (1 microM) induces a biphasic response (an initial phasic response and a tonic one) mediated by two different intracellular Ca2+ pools. This response cannot be repeated, suggesting a depletion of internal Ca2+ stores sensitive to noradrenaline. In absence of the agonist, this depletion is the signal for the entry of extracellular Ca2+, not only to refill the stores but also, under our experimental conditions, to activate the contractile proteins thus inducing an increase in the resting tone (IRT) that constitutes functional evidence of this Ca2+ entry. The ionic channels involved in the mechanism of the IRT have be…
Arginine Vasopressin Enhances Sympathetic Constriction Through the V 1 Vasopressin Receptor in Human Saphenous Vein
1998
Background —Arginine vasopressin (AVP) not only acts directly on blood vessels through V 1 receptor stimulation but also may modulate adrenergic-mediated responses in animal experiments in vivo and in vitro. The aim of the present study was to investigate whether AVP can contribute to an abnormal adrenergic constrictor response of human saphenous veins. Methods and Results —Saphenous vein rings were obtained from 32 patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension. AVP (3×10 −9 mol/L) enhanced the contractions elicited by electrical field stimulation at 1, 2, and 4 Hz (by 80%, 70%, and 60%, respectiv…
Delayed inhibition of angiotensin II receptor type 1 reduces secondary brain damage and improves functional recovery after experimental brain trauma*
2011
OBJECTIVE:: To investigate the regulation of the cerebral renin-angiotensin system and the effect of angiotensin II receptor type 1 inhibition on secondary brain damage, cerebral inflammation, and neurologic outcome after head trauma. DESIGN:: The expression of renin-angiotensin system components was determined at 15 mins, 3 hrs, 6 hrs, 12 hrs, and 24 hrs after controlled cortical impact in mice. Angiotensin II receptor type 1 was inhibited using candesartan (0.1, 0.5, 1 mg/kg) after trauma to determine its effect on secondary brain damage, brain edema formation, and inflammation. The window of opportunity was tested by delaying angiotensin II receptor type 1 inhibition for 30 mins, 1 hr, 2…
Stimulation of the AT2 receptor reduced atherogenesis in ApoE−/−/AT1A−/− double knock out mice
2012
AT1 receptor blockers (ARB) and in part ACE inhibitors (ACI) potentially exert beneficial effects on atherogenesis independent of AT1 receptor inhibition. These pleiotropic effects might be related to angiotensin II mediated activation of the AT2 receptor. To analyze this hypothesis we investigated the development of atherosclerosis and the role of ACIs and ARBs in apolipoprotein E-deficient (ApoE(-/-)) mice and in ApoE/AT1A receptor double knockout mice (ApoE(-/-)/AT1A(-/-)). ApoE(-/-) mice and ApoE(-/-)/AT1A(-/-) mice were fed cholesterol-rich diet for 7 weeks. Vascular oxidative stress, endothelial dysfunction, and atherosclerotic lesion formation were evident in ApoE(-/-) mice, but were…