Abstract
The purpose of this study is to examine the effect of repeated cocaine administration on the whole body of rats. Rats (male, 6 weeks old, Sprague Dawley) were injected intraperitoneally with cocaine (50 mg/kg) once a day for 1, 3 or 7 days, and major organs (heart, liver, lung, brain, kidney, spleen) were excised from the sacrificed animals. During autopsy, we found a reduction in spleen size, but not other organs, in cocaine-administered rats as compared to control rats. This reduction became to be noticed at 3 day and easily perceived at 7 day. No marked changes were observed in other organs examined. H&E and EMG staining showed a tendency for a decrease in the number of red blood cells (RBCs) as well as an increase in collagen fibers in the spleens of rats treated repeatedly with cocaine. Transcriptome analysis indicated that repeated cocaine administration depletes RBCs from the spleen. Immunoblot analysis showed that cocaine increases the phosphorylation of myosin light chain (MYL) as well as the levels of transgelin, both of which are involved in the contraction of myofibrils. Collectively, these results show that repeated cocaine administration results in sustained contraction of the spleen, which leads to the release of RBCs from the spleen into circulation.
Highlights
Due to its euphoric effects, cocaine is distributed in the world as an illegal recreational drug [1]
When we investigated multiple organ injury caused by repeated cocaine administration, we found a reduction in the volume of the spleen to be the most apparent finding in the gross pathological examination of major organs
We have shown that repeated cocaine administration leads to sustained contraction of spleen in rats
Summary
Due to its euphoric effects, cocaine is distributed in the world as an illegal recreational drug [1]. Cocaine induces feelings of intense pleasure and reward in humans through the excitement of the reward center in the central nerve system (CNS) [2]. This is a consequence of the inhibitory effects of cocaine on dopamine reuptake from the synaptic cleft and the resultant increase in dopamine levels [2]. Most cocaine abusers who visit emergency departments mention cardiovascular complaints as the reason for visiting [5]. In addition to above mentioned harmful effects of cocaine on CNS and cardiovascular system, for example, pulmonary complications such as edema could be produced by cocaine [8].
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