Biomedical subjects

Maria Mouratidis

Publications and source records attributed to Maria Mouratidis.

5 recordsLinked to original sources

PubMed2006

Effects of topiramate in combination with intravenous nicotine in overnight abstinent smokers.

RATIONALE: Topiramate, an anticonvulsant medication, may be effective as a treatment for alcohol and cocaine addiction. While a recent clinical study has demonstrated the potential utility of topiramate for smoking cessation in alcohol-dependent smokers, the effects of topiramate on tobacco addiction have not been systematically examined in humans. OBJECTIVES: To determine topiramate's effects on acute physiological and subjective responses to intravenous (IV) nicotine in overnight abstinent smokers. METHODS: Seven male and five female smokers participated in a double-blind, placebo-controlled, crossover study, which consisted of one adaptation and three experimental sessions. Before each session, participants were treated orally with either a single 25 or 50 mg topiramate dose or with placebo. Starting 2 h following the medication treatment, participants received an IV saline injection, followed by 0.5 and 1.0 mg/70 kg IV nicotine. RESULTS: Topiramate treatment at 50 mg, compared to 25 mg or placebo, attenuated heart rate increases induced by nicotine. Topiramate, compared to placebo, enhanced the ratings of subjective effects from nicotine including "drug strength," "good effects," "head rush," and "drug liking." Topiramate treatment did not affect performance on the Stroop test. CONCLUSIONS: These results suggest that topiramate may enhance the subjective effects of nicotine and attenuate the heart rate response to nicotine. While the exact mechanisms are unclear, enhancement of the dopaminergic system and attenuation of the noradrenergic system may mediate the topiramate's effects on the subjective and cardiovascular responses to nicotine, respectively. The utility of topiramate for smoking cessation needs to be examined further in controlled clinical trials.

Administration, Oral↗

PubMed2006

Adrenergic blocker carvedilol attenuates the cardiovascular and aversive effects of nicotine in abstinent smokers.

The cardiovascular response to nicotine is mediated mainly by noradrenergic activation. Whether noradrenergic activation mediates other effects of nicotine has not been well documented in humans. In this study, we examined the effects of an alpha and beta-adrenergic receptor blocker: carvedilol, on cardiovascular and subjective responses to nicotine lozenge and on the ability of nicotine lozenge to suppress tobacco withdrawal symptoms in overnight abstinent smokers. Fifteen smokers, nine men and six women, participated in a double-blind, placebo-controlled, crossover study. In each of the three experimental sessions, participants were treated orally with a single 25 or 50 mg dose of carvedilol or placebo. Two hours and 10 min following the medication treatment, participants received a single 4 mg nicotine lozenge. Carvedilol treatment attenuated the nicotine-induced heart rate, systolic and diastolic blood pressure increases. Carvedilol also attenuated the self-report rating of 'bad effects' in response to nicotine. Carvedilol, alone or in combination with nicotine lozenge, did not affect tobacco withdrawal symptoms. Carvedilol treatment did not affect performance on the Stroop Test. These results support the effectiveness of carvedilol for attenuating the cardiovascular effects of nicotine. Attenuation of the rating of 'bad effects' by carvedilol suggests that noradrenergic activation may also mediate the aversive effects of nicotine.

Adrenergic Antagonists↗

PubMed2005

Effects of tiagabine in combination with intravenous nicotine in overnight abstinent smokers.

RATIONALE: Preclinical studies suggest that medications enhancing the brain gamma amino butyric acid (GABA) system attenuate the rewarding effects of stimulants including nicotine. These preclinical studies have not been followed up in systematic human studies. OBJECTIVES: This study was conducted to examine the effects of a GABAergic medication, tiagabine, on acute physiological and subjective effects of intravenous (i.v.) nicotine and on tobacco withdrawal symptoms in overnight abstinent smokers. The proposed mechanism of action for tiagabine is selective inhibition of GABA transporter type I, which leads to increases in synaptic GABA levels. METHODS: Eight male and four female smokers participated in a double-blind, placebo-controlled, crossover study. In each of three experimental sessions, participants were treated orally with a single 4- or 8-mg dose of tiagabine or placebo. Two hours following the medication treatment, participants received i.v. saline, followed 30 min later by 1.5 mg/70 kg i.v. nicotine. RESULTS: Tiagabine treatment did not affect the heart rate or blood pressure changes induced by nicotine. There was a significant treatment effect for the subjective responses to nicotine, such that tiagabine, compared to placebo, attenuated the ratings of "good effects" and "drug liking." Tiagabine treatment at 8 mg attenuated the craving for cigarettes and enhanced the cognitive performance in the Classical Stoop Tests, compared to placebo or 4 mg tiagabine condition. CONCLUSIONS: These results suggest that GABA enhancing medication tiagabine may reduce the rewarding effects of nicotine and improve cognitive performance in abstinent smokers. The utility of GABA medications for smoking cessation needs to be examined further in controlled clinical trials.

Adult↗

PubMed2004

Prefrontal cortical dysfunction in abstinent cocaine abusers.

The anterior cingulate cortex (ACC) and lateral prefrontal (LPFC) cortex are brain regions important to executive cognitive functions (ECF). We determined ACC and LPFC function in 23-day abstinent cocaine abusers using positron emission tomography (PET H(2)(15)O) during performance of a modified version of the Stroop Task. Cocaine abusers showed less activation than non-drug-using comparison subjects in the left ACC and the right LPFC and greater activation in the right ACC. Average amount of cocaine used per week was negatively correlated with activity in the rostral ACC and right LPFC. Disruption of ECF in substance abusers could interfere with attempts to stop drug use and undermine treatment. Since impairment in ECF may be a common feature of various neuropsychiatric disorders, these findings have applicability beyond the neurobiology of addiction.

Adult↗

PubMed2002

Decision-making in a risk-taking task: a PET study.

As decision-making is central to motivated behavior, understanding its neural substrates can help elucidate the deficits that characterize various maladaptive behaviors. Twenty healthy adults performed a risk-taking task during positron emission tomography with (15)O-labeled water. The task, a computerized card game, tests the ability to weigh short-term rewards against long-term losses. A control task matched all components of the risk-taking task except for decision-making and the difference between responses to contingent and non-contingent reward and punishment. Decision-making (2 runs of the active task minus 2 runs of the control task) activated orbital and dorsolateral prefrontal cortex, anterior cingulate, insula, inferior parietal cortex and thalamus predominantly on the right side, and cerebellum predominantly on the left side. In an exploratory analysis, guessing (run 1 minus run 2 of the active task) accompanied activation of sensory-motor associative areas, and amygdala on the left side, whereas informed decision-making (run 2 minus run 1) activated areas that subserve memory (hippocampus, posterior cingulate) and motor control (striatum, cerebellum). The findings provide a framework for future investigations of decision-making in maladaptive behaviors.

Adult↗