No abstract

Multiple high-dose methamphetamine administrations cause long-lasting (>1 week) deficits in striatal dopaminergic neuronal function. This stimulant likewise causes rapid (within 1 h) and persistent (at least 48 h) decreases in activities of striatal: 1) dopamine transporters, as assessed in synaptosomes; and 2) vesicular monoamine transporter -2 (VMAT-2), as assessed in a non-membrane-associated (referred to herein as cytoplasmic) vesicular subcellular fraction. Importantly, not all brain areas are vulnerable to methamphetamine-induced long-lasting deficits. Similarly, the present study indicates that methamphetamine exerts differential acute effects on monoaminergic transporters according to brain region. In particular, results revealed that in the nucleus accumbens, methamphetamine rapidly, but reversibly (within 24 h), decreased plasmalemmal dopamine transporter function, without effect on plasmalemmal dopamine transporter immunoreactivity. Methamphetamine also rapidly and reversibly (within 48 h) decreased cytoplasmic VMAT-2 function in this region, with relatively little effect on cytoplasmic VMAT-2 immunoreactivity. In contrast, methamphetamine did not alter either dopamine transporter or VMAT-2 activity in the hypothalamus. Noteworthy, the nucleus accumbens and hypothalamus did not display the persistent long-lasting striatal dopamine depletions caused by the stimulant. Taken together, these data suggest that deficits in plasmalemmal and vesicular monoamine transporter activity lasting greater than 24-48 h may be linked to the long-lasting dopaminergic deficits caused by methamphetamine and appear to be region specific.

Background. Pepper spray is a common lacrimator used by law enforcement and the public to subdue individuals and for self-defense. The risk factors for severe injury due to pepper spray exposure are not well documented and there is a lack of guidelines to identify patients that require transport and medical evaluation in an emergency department. Objective. The aim of this study was to determine the prevalence of and circumstances associated with symptoms suggestive of tissue injury beyond transient irritation in persons exposed to pepper spray. Methods. We reviewed all human exposures to pepper spray reported to a poison control system between 2002 and 2011. Cases were differentiated into 2 outcome groups: minor or self-limiting symptoms versus those with more severe symptoms suggestive of tissue injury that warranted a medical evaluation. A comparison of the variables between the outcome groups was performed using odds ratios (ORs), 95% confidence intervals (CIs), and associated P values. Results. A total of 4,544 cases were identified and 3,671 met the inclusion criteria. Of these, 249 cases (6.8%) were found to have more severe symptoms that warranted a medical evaluation. There were no reported deaths. The cases with more severe symptoms most commonly involved the ocular (53.8%), respiratory (31.7%), and dermal (17.7%) organ systems. Factors with largest independent associations with more severe outcomes were use for law enforcement training (OR, 7.39; 95% CI,, direct intentional exposure for purposeful use to incapacitate (OR, 3.02; 95% CI, 1.80-5.06), and for law enforcement on individual target suspects or crowd control (OR, 2.45; 95% CI, 1.42-4.23). Conclusions. There was a low 1 in 15 potential risk for more severe adverse health effects in persons exposed to pepper spray that warranted a medical evaluation.

Repeated high-dose methamphetamine administrations can cause persistent dopaminergic deficits. As individuals abusing methamphetamine are often exposed to recurrent high-dose administration, the impact of its repeated exposure merits investigation. Accordingly, rats were pretreated with repeated high-dose injections of methamphetamine, and subsequently "challenged" with the same neurotoxic regimen 7 or 30 days later. Results revealed that the initial methamphetamine treatment caused persistent deficits in striatal dopamine levels, dopamine transporter function, and vesicular monoamine transporter-2 function. The subsequent methamphetamine challenge treatment was without further persistent effects on these parameters, as assessed 7 days after the challenge, regardless of the interval (7 or 30 days) between the initial and challenge drug exposures. Similarly, a methamphetamine challenge treatment administered 7 days after the initial drug treatment was without further acute effect on dopamine transporter or VMAT-2 function, as assessed 1 hour later. Thus, this study describes a model of resistance, possibly explained by: 1) the existence of dopaminergic neurons that are a priori refractory to deficits caused by methamphetamine; 2) the existence of dopaminergic neurons made persistently resistant consequent to a neurotoxic methamphetamine exposure; and/or 3) altered activation of post-synaptic basal ganglia systems necessary for the elaboration of methamphetamine-induced dopamine neurotoxicity.