Chronic nicotine pretreatment protects the blood-brain barrier against nicotine-induced seizures in the rat

This study was designed to investigate the possible protective actions of nicotine on cerebrovascular permeability in convulsions during nicotine-induced seizures. We have measured the permeability changes in the blood-brain barrier (BBB) macroscopically and spectrophotometrically by using Evans blue dye. Specific gravity measurements were also performed to assess brain edema which develops after blood-brain barrier opening. The experiments were carried out on Wistar rats. Rats were divided into two groups. They received acutely a convulsive dose of nicotine 3, 5, 8 and 9 mg kg(-1) i.p. or pretreated with a low dose of nicotine (0.8 mg kg(-1) i.p.) for 21 days followed by the procedure mentioned in the first group. Acute nicotine injection induced a significant increase in blood pressure and Evans-blue passage, despite a decline in specific gravity values. Low doses of chronic nicotine administration markedly reduced both the leakage of dye, and brain water content. Chronic treatment with low doses of nicotine (0.8 mg kg(-1) day(-1) s.c.) lessened the intensity of tonic-clonic seizures observed with a single dose of 3, 5, 8 or 9 mg kg-l nicotine. The data presented here demonstrate that nicotine pretreatment results in decreased sensitivity to nicotine-induced seizures in rats. (C) 1999 Academic Press

Leptin transport in the central nervous system

Synthesized and released by the adipose tissue, leptin is the widely studied 167-amino acid hormonal protein product of the obesity gene. Originally leptin was defined in association with satiety and energy balance and claimed to be an anti-obesity factor that functioned via a feedback effect from adipocytes to hypothalamus. There is a growing body of evidence that emphasizes the importance of leptin in the regulation of food intake and body weight in animals and humans, alike. Other research findings point out that it plays a role in the regulation of the metabolism, sexual development, reproduction, hematopoiesis, immunity, gastrointestinal functions, sympathetic activation, and angiogenesis. The aim of this review is to evaluate the relation between leptin and the central nervous system (CNS). Copyright (C) 2009 John Wiley & Soils, Ltd

THE CEREBROVASCULAR PERMEABILITY AND EPILEPSY - THE ROLE OF BLOOD-PRESSURE

This study was designed to evaluate the role of elevated blood pressure on cerebrovascular permeability and brain tissue specific gravity during epileptic seizures induced by Pentylenetetrazole (PTZ). The experiments were carried out on Wistar rats. Specific gravity was measured bilaterally in 10 regional brain areas and Evans-blue passage (across blood-brain barrier) was spectrophotometrically measured in 6 brain areas. Animals were divided into four groups: they received i.v. either saline, 80mg/kg PTZ (convulsive dose), 40mg/kg PTZ (subconvulsive dose) or 80mg/kg PTZ+phentolamine. 80 mg/kg PTZ induced significantly an increase in blood pressure, in specific gravity and in Evans-blue passage. 40mg/kg PTZ induced an increase in blood pressure and caused small changes in specific gravity but not in Evans-blue passage. The last group, in which the rise in blood pressure was prevented with Phentolamine, also showed a significant increase in brain specific gravity and in Evans-blue passage. The results clearly show that the increased blood pressure may contribute to but is not entirely responsible for the changes in the cerebrovascular permeability induced by epileptic seizures

Erythropoietin prevents the increase in blood-brain barrier permeability during pentylentetrazol induced seizures

Recombinant human erythropoietin (r-Hu EPO) has been shown to exert neuroprotection in ischemic, excitotoxicity, trauma, convulsions and neurodegenerative disorders. Blood-brain barrier (BBB) leakage plays a role in the pathogenesis of many pathological states of the brain including neurodegenerative disorders. This study aimed to investigate the effects of r-Hu EPO on BBB integrity in pentylentetrazol (PTZ) induced seizures in rats. Seizures were observed and evaluated regard to latency and intensity for an hour. Macroscopical and spectrophotometrical measurement of Evans Blue (EB) leakage were observed for BBB integrity. r-Hu EPO was given intraperitoneally 24 h prior to seizure induction. Total seizure duration of 720 +/- 50 s after single PTZ administration (80 mg/kg i.p.) was declined to 190 40 s in r-Hu EPO pretreatment. A typical BBB breakdown pattern (i.e. staining in cerebellum, cerebral cortex, midbrain, hippocampus, thalamus and corpus striatum) was observed in rat brains with PTZ induced seizures; whereas, EPO pretreatment confined BBB leakage to cerebellum and cortical areas, and lessened the intensity of tonic-clonic seizures observed in PTZ seizures. The protective effect of r-Hu EPO on BBB permeability in seizures is a new and original finding. The protective action of r-Hu EPO in seizures and some of CNS pathologies warrant further investigations. (c) 2005 Elsevier Inc. All rights reserved

Chronic (3-Weeks) Treatment of Estrogen (17 beta-Estradiol) Enhances Working and Reference Memory in Ovariectomized Rats: Role of Acetylcholine

Recently there has been a growing interest in the effects of estrogen on cognitive functions. In this study, we aimed to examine 17 beta-estradiol treatment on working and reference memory in ovariectomized rats. We also examined the changes in the acetylcholine (ACh) levels in the brain areas associated with learning and memory. The study was performed on Sprague-Dawley type 3-month-old female rats. The rats were divided into four groups as control, ovariectomy (OVX), and OVX and estrogen treatment (10 A mu g/day i.p. 17 beta-estradiol) groups for 3 (OVX + E3) and 21 days OVX + E21). The rats were trained on eight arm radial maze task with eight arms baited to assess spatial memory, in addition four arms baited to assess both working and reference memory performances. The electron microscope images of the ACh vesicles in the frontal cortex, temporal cortex and hippocampus areas of the brain which are important regions for learning and memory were screened. Results showed that long term 17 beta-estradiol treatment has positive effects on both reference memory and working memory and that ACh vesicles increased in the examined brain areas, especially in hippocampus. Our results suggest that 3 weeks 17 beta-estradiol treatment may have an ameliorative effect on the memory through the central cholinergic system