B ALEWU, J ANUKA
carbofuran, food, rat, water
B ALEWU, J ANUKA. Toxicological Effects of Carbofuran on the Water and Food intake in Albino Wistar Rat. The Internet Journal of Toxicology. 2008 Volume 7 Number 1.
Carbofuran® is a white crystalline solid with a slightly phenolic odour. It is a broad-spectrum insecticide, a pesticide and a nematicide and is sprayed directly onto soil and plants just after emergence to control beetles, nematode and rootworms. The greatest use of carbofuran® is on the following plants: Alfalfa, rice, with turf and grapes making up most of the remainder. The chemical was first introduced onto the market in 1965 (United States Environmental Protection Agency (EPA), (2004). Pesticides differ from any other chemical substances because they are deliberately spread into the environment. As a consequence, the great part of the human population may be exposed either in the general environment or in the working settings. The occupational exposure involving the manufacturing, and the use of pesticides, takes place mainly through dermal or respiratory route (Kaliwal et al., 2002) while the environmental exposure, involving the general population, is mainly due to the ingestion of the contaminated foods and water. Both the environmental and occupational exposure may not produce effects attributable to the pesticides at low doses (Kaliwal et al., 2002). Carbofuran (2, 3-dihydro-2, 2-dimethyl-7-benzofuranylmethylcarbamate), is a systemic N-methyl carbamate pesticide with predominantly contact (dermal-absorption through the intact skin) and stomach action (vomiting, nausea, abdominal cramp, diarrhea) (Kaliwal et al., 2002). It is mainly used as a soil applied chemical to control soil dwelling and foliar feeding insects and nematodes on a variety of agricultural crops, including maize, corn, rice, potatoes, alfalfa and grapes (Gupta, 1994). Carbofuran® is a potent cholinesterase inhibitor and is highly toxic to humans and wildlife through the oral and inhalation routes of exposure (Baron, 1991). A report showed that carbofuran is also used as an insecticide (see” Farm chemical handbook” 1986). In a two (2) year study, Charles River mice were fed dietary carbofuran concentration equivalent to 0, 2, 8, 18, 70mg/kg of body weight per day. Mice receiving the highest dose showed a decrease in body weight gain and a statistically significant depression of brain acetylcholinesterase (FAO/WHO, 1987). Furadan is the registered trade name for insecticidal formulations of carbofuran 2, 3-dihydro-2, 2-dimethyl-7-benzofuranylmethylcarbamate (Edward, et al., 1980). The name Furadan is used predominantly in the field, whereas carbofuran® (the common name) accepted by the American Standard Association has become the accepted name for the formulation used in the laboratory (Edward et al., 1980). The names Furadan and carbofuran® have been used interchangeably (Niagara Chemical Division, FMC Corporation, unpublished). Furadan 3G granular (3% carbofuran® in a sand core granule) replaced aldrin in Texas in 1970 (Edward et al., 1980). In view of the above findings, the present study has been undertaken to attempt to characterize the effect of carbofuran® on the eating and drinking behavior of animals, specifically the laboratory rats.
Materials and Methods
Technical grade Furadan 3G (carbofuran) was kindly provided by Mercy Agro Allied Company Ltd., located along Zaria – Samaru road and dissolved in distilled water as a vehicle for oral administration. Laboratory bred male and female albino rats weighing between 150 – 180g of both sexes were randomly selected from the animal house of the Department of Pharmacology, Ahmadu Bello University, Samaru, Zaria. All the animals were housed in separate Perspex cages (55cm x 33.5cm x 20cm) bedded with sawdust in a well ventilated laboratory at a temperature of approximately 330c and 12-12 hour light and dark cycle. Stable water and food intake baselines (less than 5% daily variation) were determined for all the study rats. The animals were observed for one week prior to the study. Only healthy animals were used for this study. The animals were fed on a mixture of commercial Pfizer chick mash (livestock feed, Lagos, Nigeria).The animals were given water ad libitum except when fasting was needed in the course of the study. Doses were given that ranged below the acute LD50 level of intoxication (Fahmy, et al., 1970). Animals were divided into 4 groups having 5 animals in each cage. Carbofuran administered in doses of 0.05, 0.1, 0.15mg/kg orally for 5 days. The controls group received equal volume of distilled water. The quantity of food eaten and water consumption were determined throughout the experiment.
Determination of food and water intake
Determination of food intake was carried out according to Leonard et al (2001). Drinking behavior after water deprivation is one of the standard tests used to study thirst in humans and animals and in addition, diurnal cycle, food availability are known to influence water intake (Leonard et al., 2001). In this experiment, adult male wistar rats were placed in four (4) separate Perspex cages and allowed to acclimatize to the laboratory environment for a week. During this period, water and food were given ad libitum. Pfizer chick mash was given to the rats throughout the experimental period. The animals were given three levels of doses. The oral route was used in this experiment. There were four groups of animals. The first group served as the control and animals were given distilled water. Group IV, III and II received 0.15, 0.1, 0.05mg/kg body weight of carbofuran respectively. Each group contained five (5) animals. The animals were given carbofuran® on a daily basis in addition to food and water. The animals were deprived of water for twenty four (24) hours. This was followed by feeding with water for 6 hours i.e. from 1 pm to 7pm the same day. Approximately one hundred milliliters (100mL) of water in the rat’s feeding bottle was offered to the animal in each group. The animals were allowed free access to water for six (6) hours. After 6 hours, the final level of water was recorded. This was repeated for 5 times and the average taken. During this time the animals had free access to a measured amount of molded feed (chick mash) for thirteen (13) hours i.e. from 1pm to 2pm the following day. The cages were cleared of sawdust by the 13th hour and the animals were deprived of food for 10hours. The experiment was repeated for five (5) times for both day and night. That is two nights and three days. The feed intake in grams were calculated thus; the feed intake in grams (g) eating/13 hours/100g rat were calculated as shown below
Food eaten (E) = Weight of feed given – weight of leftover feed.
Time interval (T) = 13 hours
Weight of animals/cage = K
Therefore, weight (g) of rats ate (E) feed in 13 hours
Similarly, the hundred milliliters (100ml) of water were offered to the rats in each cage for six hours (6 hrs). The rats had access to the water
Water drank (B) = water given – water leftover.
Time interval (T) = 6 hours
Weight of animals/cage = J
Therefore, J (g) rats drank B (mls) of water in 6 hours.
Water consumed = Initial level of water in the cylinder – final level of water in the cylinder.
Data were expressed as mean ± S.E.M from the observations. Student two tailed t-test for unpaired data or one way analysis of variance (ANOVA) for comparison among groups were used to determine the statistical significance of the difference between groups (Singha, 1996). P < 0.05, P<0.02, P<0.01, P<0.001 were considered to be significant.
Administration of carbofuran® at doses of 0.05, 0.1, 0.15 mg/kg body weight to rats resulted in a significant (P<0.05, P<0.02, P<0.01) increase in water intake for 0.05, 0.1mg/kg and also a significant intake (P<0.05, P<0.02, P<0.01, P<0.001) for 0.15mg/kg compared to control (Table 1). The control rat exhibited normal drinking behavior as shown in figure 1.
Food consumption in rats administered 0.15mg/kg carbofuran® on a daily basis showed an increase in food consumption when compared to control, their difference was not significant (P<0.05) compared to control as seen in Fig 2; Table 2
At a reduced dose of 0.1mg/kg carbofuran® in group III showed a decrease in food consumption compared to control but the difference between the treated rats and control was not significant at P<0.05;Table 2
In group II, rats administered 0.05mg/kg carbofuran®, showed a decrease in weight of food consumed but was not significant compared to control (P<0.05); Table 2
Data were recorded as mean value of food consumed ±S.E.M.
In this study the toxicological effect of carbofuran on the water and food intake in laboratory rats were analyzed. A number of reports are available on the effect of carbofuran. We recently demonstrated in this study that albino Wistar rat administered 0.15, 0.1 and 0.05mg/kg carbofuran® does have a significant increase in food consumption compared to control. In order to examine the effect of carbofuran on the body weight of the albino Wistar rat it became necessary to also study how carbofuran influenced food and water intake. In this experiment, 0.05, 0.1 and 0.15mg/kg carbofuran® has a significant effect on food consumption compared with the control-there is an increase. However it has been reported that at higher dose of carbofuran® e.g. 100mg/kg, there were growth reduction and reduction in food consumption in mice treated with these doses of carbofuran® (Goldenthal, 1980; Brown, 1980). Similar report was given by Rapp (1980a). Prakash, et al., (2002) reported that there was a significant decrease in the body weight of rats in higher dose of carbofuran® treatment e.g. 100, 250mg/kg body weight as there may be suppression of food and water intake. In this present study, treatment of rat with 0.05, 0.1mg/kg carbofuran® showed a significant increase in water intake but at the 0.15mg/kg dose it showed a significance increase at in water consumption compared with the control. Several neuronal centres of the hypothalamus participate in the control of appetite. The lateral nuclei of the hypothalamus serve as the feeding centre, and stimulation of this area causes the animal to eat voraciously (hyperphagia), (Guyton and Hall, 2006). Conversely, destruction of the lateral hypothalamus causes lack of desire for food and progressive inanition, a condition characterized by weight loss, muscle weakness and decreased metabolism (Guyton and Hall, 2006). It was reported also that some environmental contaminants e.g. Carbofuran, endosulphan, influence motor and feeding behaviours in the ornate Wrasse (
I express my special gratitude to Professor J. A. Anuka, Professor (Mrs) H Kwanashie, Dr (Mrs) Maiha of the Department of Pharmacology, Amadu Bello University, Zaria-Nigeria for painstakingly reading and making some suggestion towards the success of this work. The author is also grateful to Dr. S. B. Danborno, Dr. S. Adebisi, Mr Dele in the Department of anatomy, Ahmadu Bello University, Zaria for their support and suggestions. I will like to thank Mr. K. John for providing me with materials for the experiment and rendering assistance too.