EFFECTS OF ACUTE EXPOSURE TO GENERATOR EXHAUST FUMES ON LEARNING, MEMORY AND MOTOR COORDINATION IN ALBINO MICE

EFFECTS OF ACUTE EXPOSURE TO GENERATOR EXHAUST FUMES ON LEARNING, MEMORY AND MOTOR COORDINATION IN ALBINO MICE

Abstract:

The study involved assessment of the effects produced by exposure of mice to generator exhaust fumes on the learning, memory and motor coordination. Carbon monoxide (CO) which is produced from combustion of any carbonaceous substance is among the toxic contents and was studied in detail. Twenty four animals were grouped into two major groups; the first group was tested for motor coordination using beam walk; and the other group for learning and memory, using elevated plus maze (EPM). Mean transfer latencies (TL) were measured in seconds. Gasoline powered generator (TIGER, TG950, 220v/24 0v) manufactured by Suzhou Tiger Power Machine Co., Ltd., China served as the source of CO. Carbon monoxide monitor (Amprobe, CM100) was used to record the dose of CO in parts per million (ppm). The dose of 100–150 ppm of CO exposure was maintained throughout the study. Values of P< 0.05 were considered to be statistically significant. Each of the two major groups was subdivided into control group, which was exposed to room air, and experimental group that was placed into a partially enclosed gas chamber and exposed directly to the exhaust fumes of the generator for 30 minutes, 1 hour and 2 hour periods before the neurobehavioural tests. During the learning task (Day 1), experimental animals showed significant decrease in the mean TL of 13.4 ± 1.5 seconds and an increase of 73 ± 8.4 seconds at 30 minutes and one hour, respectively, when compared to their controls (28.6 ± 5.2 seconds) and (21.8 ± 4.4 seconds). However, there was no significant change in the mean TL during the 2-hour exposure. The memory task (Day 2), recorded significant increase in the mean TLs during the 30 minutes (48.4 ± 12.8 seconds) and two hour exposures (66.8 ± 15.3 seconds), when compared to the corresponding controls (13.6 ± 1.9 seconds) and (22.6 ± 6.6 seconds), respectively. This result suggests decreased ability of the exposed mice to learn (Day 1) and also to recall (Day 2) the learned behaviour. Results of the motor coordination did not show any significant difference in the mean TLs and foot slips in all the three periods of exposure, when compared to the controls. Therefore, CO at this range and periods of exposure could have minimal or no effect on motor coordination in the exposed animals. The blood carboxyhaemoglobin (COHb) measured at the end of the study showed significant increase in the mean percentage COHb levels of the experimental groups (2.06 ± 0.012 %) as compared to those of the control groups (0.76 ± 0.089 %). The results also suggest that impairment in the motor coordination may occur at higher exposure periods to CO. The results corroborate other acute CO exposure studies where neuronal cell death and functional impairment of learning and memory were recorded. In conclusion, exposure to generator exhaust fumes that produced 100 – 150 ppm of CO resulted in enhanced learning behaviour during the 30 minutes exposure, impaired learning at 1 hour; memory at 30 minutes and 2 hours, respectively. Motor coordination deficits may be affected at higher CO concentration and blood COHb suggested exogenous intake in the experimental mice

EFFECTS OF ACUTE EXPOSURE TO GENERATOR EXHAUST FUMES ON LEARNING, MEMORY AND MOTOR COORDINATION IN ALBINO MICE

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