Evaluation of an article on the neurotoxic effects of gasoline inhalation in male rats

Section 1 Description of article
Title of article Impacts of gasoline inhalation on some neurobehavioural characteristics of male rats.
Source BMC Physiology, 24 November 2009, 9 (21), p.1-10.
Author Amal A. Kinawy, Psychology department, Faculty of Arts, Cairo University, Egypt.

Section 2 Type of article
Impacts of gasoline inhalation on some neurobehavioural characteristics of male rats  is a piece of Primary literature, meaning that it describes a research project and was published in a peer-reviewed scientific journal. As the content of the article presents new information based on original research, it can be also be qualified as an Original article. Furthermore, considering that the findings of this prospective study are on a health related factor, the article may also be qualified as an Investigation article.

Section 3 Summary of article
The above mentioned article is a prospective study on the effects of chronic exposure of rats to gasoline vapors. Recent abuse of gasoline (gasoline sniffing) has brought the potential toxic effects of these fumes to the attention of scientists. In 1992, it was noted that up to 110 million people are exposed to these toxic fumes while refueling their vehicles. Previous studies have suggested that unleaded gasoline may have less severe and more transient effects on the human central nervous system. The goal of the current study was to compare the toxic effects of the leaded and unleaded gasolines available on the Egyptian market on laboratory rats.

Materials  Methods
Forty-five male rats were randomly separated into three groups of fifteen. A dynamic respiration system (Haschek  Witschi, 1991, p. 78) was used to expose the rats to gasoline vapors at concentrations close to exposure levels in open air situations. The first group was exposed to 15 LC 50  of leaded gasoline vapors for 30 minutes at a time the second group was exposed to 15 LC 50 of unleaded gasoline vapors and the third group was exposed to gasoline-free air, serving as a control population. For the final 10 days of the six week experimental period, the rats were evaluated for aggressive behavior. At the end of the testing period, all rats were decapitated and their brains were excised and used to determine the concentrations of lipid peroxidation, GSH, SOD, protein, Na, K- ATPase, AchE and monoamines (norepinephrine, dopamine, serotonin). All results were statistically analyzed.

Significant variations in monoamines were noted in the cerebral cortex, hypothalamus, hippocampus andor cerebellum of rats submitted to leaded and unleaded gasoline inhalation when compared to the control group. Furthermore, a significant difference was noted between the two study groups and the control group in (AChE), Na, K-ATPase activity and total protein of the cerebral cortex. Significant differences were also noted  in the MAD, GSH and SOD cerebral cortex concentrations of rats subjected to gasoline fumes. In several situations,  the variation in physiological values between the unleaded gasoline inhalation group and the control group were significantly less important that the variations noted between the leaded gasoline group and the control group. Finally, both groups of gasoline inhaling rats displayed an increase in aggressive behavior when compared to the control group. No significant difference in aggression was noted between the leaded and unleaded groups.


In conclusion, inhalation of gasoline, be it leaded or unleaded, causes serious fluctuations in the levels of neurotransmitters in the brains of male rats. These variations are responsible for an increase in aggressive behavior.

Section 4 Relationship between article and physiology
To study the toxic effects of any substance, one must first understand the physiology of the system that is attacked by that substance. By first understanding the normal physiology, we can better determine how toxic substance interacts with the body to create pathological signs. The above described study could not have been achieved, and therefore is difficult to understand, without first understanding the actions of norepinephrine, dopamine and serotonin as neurotransmitters. For generations now, scientists have studied the importance of monoamines in behavioral and neurological medical conditions (Bernard, 1975, p. 1-84). It has been proven that these molecules play a fundamental role in neurophysiology by regulating many different functions such as, but not limited to behavior, mood, appetite, anxiety and sleep (cited in Kinawy, 2009, p.8). With this knowledge, the author was able to conduct a study on many neurophysiological components and the way they are affected by gasoline inhalation.

Section 5 Personal opinion of article
Impacts of gasoline inhalation on some neurobehavioural characteristics of male rats  by Kinawy is a report on a well carried out, interesting research project. The article not only taught me a lot about neurophysiology, but more importantly, introduced me to the risks of gasoline inhalation. The precise description of the laboratory techniques used combined with the extensive literary review present in the discussion made this article very convincing as to the harmful effects of gasoline. The data was impressive and well presented in eight comprehensible tables. However, table 6 was formatted differently from the other seven tables which made it more difficult to understand. Though the prospective study was well organized, it was unfortunate that the monitoring of aggressive behavior was not performed by a blinded observer. This would have increased the credibility of the results. Furthermore, the multiple variables studied did complicate the reading of the article. A table providing an overview of the toxic effects of the different components of gasoline would have been a valuable addition to this paper (Burbacher, 1993, p. 133-141) . For this reason, I would not suggest this paper to non-scientific people, even though the message of this study should interest everyone. As a final comment, I was disappointed that the author failed to discuss the medical significance of countries transferring from leaded to unleaded gasoline. A comment on the importance of this study in relation to the average human refueling at a gasoline station or at least a suggestion for further field studies would have greatly improved the interest level of the article s conclusion.


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