Histopathological studies of cardiac lesions after long term administration of methamphetamine in high dosage--Part II.

A small amount of Methamphetamine (MA) can produce behavioural changes such as euphoria, increased alertness, paranoia, decreased appetite and increased physical activity. In cardiovascular system, it can produce chest pain and hypertension which can result in cardiovascular collapse. In addition, MA causes accelerated heartbeat, elevated blood pressure. It can also cause irreversible damage to blood vessels in the brain. A number of sympathomimetic amines are capable of causing myocardial damage, but the cardio-toxic action of MA has been of particular interest since standardized dosage consistently produces myocardial lesions. As this drug is a choice of many teenagers and young adults, the damage to their health, as well as their future aspects could be greatly affected, therefore more evidence must be sought to convince them the negative root and show them the optimism of recovery and salvation. To clarify the effect of Methamphetamine (MA) on myocardium, 56 male Wister rats aged four weeks were divided equally into MA, Methamphetamine withdrawal (MW), Placebo (P) and Control (C) group were examined following daily intra-peritoneal administration of MA at a dose of 5 mg/kg body weight for 2, 4, 8 and 12 weeks. Normal saline was similarly injected in P group. Light microscopic changes was seen in the myocardium of MA treated group including eosinophilic degeneration, atrophy, hypertrophy, disarray, edema, cellular infiltration, myolysis, granulation tissue, fibrosis and vacuolization. On the other hand, the withdrawal group showed evidence of gradual recovery of those myocardial changes. Optimism is therefore generated about possibility of returning towards normal by withdrawing of this drug by the addicts.

Histopathological studies of cardiac lesions after an acute high dose administration of Methamphetamine

Eighteen male Wistar rats aged six weeks were divided equally into Methamphetamine (MA), Placebo and Control group. MA group were injected with 50mg/kg body weight of Methamphetamine hydrochloride (MAHCl) in normal saline, Placebo group were injected with normal saline only, while Control group not injected with anything. Five MA group rats died within four hours of injection and their hearts collected on the same day. Another MA group rat was sacrificed two days after injection. Placebo and control group were sacrificed at similar intervals. Collected hearts were studied for cardiac lesions under light microscopy using special staining and immunohistochemistry. Microscopic examination of the myocardium of the rats that died on the first day of injection showed loss of nuclei in some myocytes, indicating cell death. Some areas in the sub-endocardium region showed internalization and enlargement of myocyte nuclei, consistent with regeneration of cells. There were very few foci of necrosis observed in these samples. The heart samples from the single rat that survived injection for two days showed foci of infiltration of macrophage-like cells that were later revealed to be regenerating myocytes. There were also spindle-like fibroblasts, macrophages and a few leucocytes found within these foci. The overall appearance of the myocardium did not indicate any inflammatory response, and the expected signs of necrosis were not observed. These results suggest a need to re-evaluate the toxic and lethal dosages of MA for use in animals testing. Cause of death was suspected to be due to failure of other major organs from acute administration of MA. Death occurred within a time period where significant changes due to necrosis may not be evident in the myocardium. Further investigations of other organs are necessary to help detect death due to acute dosage of MA.