Acute exposure to stress leads to activation of the pituitary-adrenal axis (PA-axis) while repeated exposure to a homotypic stressor generally results in habituation of this response. Previous studies suggested that such habituation is largely due to changes in afferents of the PA-axis. To examine where within these afferents habituation occurs, we studied the effect of acute and repeated exposure to 2 hr restraint stress on expression of c-fos mRNA, as a marker of altered neuronal activity, in brain regions previously shown to influence the activity of the PA-axis. Acute restraint stress increased expression of c-fos mRNA in cortex, hippocampus, hypothalamus, septum, and brainstem. In contrast, the effect of restraint stress on c-fos expression in the aforementioned brain regions was much smaller in animals restrained once daily for 4 d, and nonexistent in animals restrained once daily for 9 d. A similar pattern of induction and habituation of jun-B, but not zif-268, c-jun, or jun-D mRNA expression, was observed in the cortex of animals exposed to acute versus repeated restraint stress. The habituation of c-fos responses was stressor specific: exposure of restraint-adapted animals to a novel (20 min swim) stress produced an increase in levels of c-fos mRNA in every examined brain region comparable to that seen in animals exposed to this stressor for the first time. Adrenalectomy did not alter the pattern of c-fos expression induced by acute and repeated restraint stress. Therefore, activation and habituation of these c-fos responses are independent of changes in circulating levels of corticosterone.

Six rhesus monkeys were trained to stable performance on neuropsychological tests of memory, reinforcer efficacy, reaction time and bimanual motor coordination. Three monkeys were then exposed to a high-dose, short course regimen of ( Ϯ )3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") (4 days, 10 mg/kg i.m., b.i.d.) Recreational use of the psychoactive drug ( Ϯ )3,4,-methylenedioxymethamphetamine (MDMA) has become increasingly popular over the past two decades (Peroutka 1987;Schuster et al. 1998). Although early studies focused on adverse physiological (e.g., hypertension, hyperthermia, hyponatraemia) or psychiatric (mood disorder, aggression) symptoms associated with acute and/or chronic MDMA exposure, recent evidence suggests that chronic MDMA use may also result in lasting disruption of cognitive function. A number of studies have shown that experienced, abstinent MDMA users are impaired on various tests of memory function (Bolla et al. 1998;Curran and Travill 1997;Krystal et al. 1992;Morgan 1999;, even when compared with users of other recreational drugs. The lasting functional effects of MDMA use may be relatively specific to mnemonic processing, since a number of studies have reported that MDMA users who are impaired on memory tasks exhibit normal performance on tests of reaction time, vigilance or selective attention (Krystal et al. 1992;Vollenweider et al. 1998). Additional evidence suggests that the degree of memory impairment in the MDMA user is positively correlated with the number of cumulative exposures to MDMA (Bolla et al. 1998;Parrott and Lasky 1998). Finally, recent studies have demonstrated that electroencephalographic and metabolic (PET) measures of brain function are altered in MDMA users (Dafters et al. 1999;

Application of a Myosplint device to a dilated impaired left ventricle resulted in reduced wall stress and improved left ventricular systolic function that was sustained at 1 month. Device-based shape change is a promising new opportunity to treat patients with dilated cardiomyopathy.

Recreational users of ( Ϯ )3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy")

No abstract