الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
 |  | from | 201 |  |  |
| | | from | 201 | | |
المستخلص
The present study shed the light on the toxicity of two organophosphorous insecticides which have a world wide uses in agriculture, veterinary and even indoors. This class of insecticides represents one of the most widely used classes of pesticides . The present work studied the toxicity of two organophosphorous insecticides which are still in use till now in Egypt and allover the world. The two selected insecticides were diazinon and fenitrothion. The effects were studied on the levels of neurotransmitters in the blood and different brain areas to investigate their neurotoxic effect on adult male albino rats (Rattus norvigicus) after acute and chronic administration. ALT, AST, total protein and glucose parameters also have been measured in serum. 105 adult male albino rats ranges between 120-150 gm. have been used during the study. They were classified to acute and chronic groups. Acute groups Treated animals were divided into three subgroups each of seven animals. The 1st were treated orally with ½ LD50 of diazinon, the 2nd were treated orally with ½ LD50 of fenitrothion and the third were treated with drinking water and used as a control group. Animals were sacrificed after 2hrs of treatment. Chronic groups Animals were subdivided into three groups. The 1st group were treated with 1/10 LD50 of diazinon, the 2nd were treated with 1/10 LD50 of fenitrothion and the 3rd group were treated with drinking water and used as a control group. Seven animals of each group were sacrificed after time intervals of one, two, three and four weeks of treatment. from the present study, the following results are obtained. Effects of treatments on the levels of neurotransmitters a- Effect of acute treatment with diazinon The present study showed that norepinephrine (NE) was significantly decreased in cortex and cerebellum. Serotonine (5-HT) was decreased in thalamus and cerebellum. The decreased serotonin level may be due to the acute decrease in the amino acid tryptophane which is the precursor of serotonin. b- Effect of chronic treatment with diazinon The results of the present work demonstrated that NE level was decreased allover the four weeks of treatment in cortex, cerebellum and thalamus. DA was significantly increased in cortex at the end of the 3rd week and in striatum at the end of the 4th week. 5-HT was significantly decreased during the four weeks in cortex. This change in the level of neurotransmitters may be due to accumulation of acetylcholine as a result of inhibition of acetylcholinesterase enzyme and in turn excitation of glutamate NMDA receptors which lead to huge influx of Ca++ ions in the post synaptic neurons and then alters neurotransmitters level. c- Effect of acute treatment with fenitrothion NE level was significantly decreased in all brain areas while 5-HT was significantly decreased in cortex, cerebellum and thalamus. This may be due to inhibition of acetylcholinesterase as a result of acute fenitrothion treatment. d- Effect of chronic treatment with fenitrothion The present study showed that NE was significantly decreased in cerebellum along the four weeks of treatment. DA was significantly increased in most of the brain areas while 5-HT was increased in the striatum. The increase in 5-HT and DA levels may be due to the inhibitory effect of fenitrothion on the enzyme monoamine oxidase which is responsible for DA and 5-HT catabolism. Effects of treatment on liver enzymes a- Effect of acute treatment with diazinon The present study have showed that AST level was decreased while ALT was not changed. This negative effect of diazinon on enzymes level may be due to that it has no acute effect on the permeability and integrity of hepatic cell membranes. Effect of chronic treatment with diazinon The levels of ALT and AST was not changed by the end of the 1st three weeks while they were increased at the end of the 4th week. This increase in the enzymes level may be accompanied with the accumulative effect and time related effect of diazinon on hepatocytes. Effect of acute treatment with fenitrothion The study showed no effect of acute fenitrothion treatment on ALT and AST levels. Effect of chronic treatment with fenitrothion The obtained results showed no change in the enzymes level after the first two weeks while they were significantly increased at the end of the last two weeks. This increase may be due to the accumulative effect of fenitrothion which is metabolized mainly in the liver. Effects of treatment on total protein a- Effect of diazinon The results of the present work showed that total protein level was significantly increased after acute, one week and two weeks of treatment, while significantly decreased at the end of the last two weeks. This decrease was in parallel with body weigh loss of treated animals and decreased food consumption. Also it may be due to generation of free radicals which alters protein synthesis as a result of diazinon toxicity. Effect of fenitrothion The results of the present study demonstrated that fenitrothion had the same effect of diazinon on total protein level which supports that they are of one group of insecticides. Effect of treatment on glucose level d- Effect of diazinon The results showed that glucose level was significantly decreased after acute diazinon treatment and at the end of the 1st week while it was significantly increased at the end of the last two weeks of treatment. This increase in glucose level may be due to glycogenolysis from tissue under the effect of increased glycogen phosphorylase. It also may be due to decrease in insulin level as a result of pancreatitis caused by diazinon. e- Effect of fenitrothion Glucose level was decreased after acute and one week of treatment with fenitrothion. Glucose level was gradually increased during the last three weeks. The increase in glucose level may be due to the increase in corticosterone level and the increased activity of phosphorylase which break down liver glycogen into glucose. This study makes it clear that the exposure to insecticides diazinon and fenitrothion leads to several toxic effects on the nervous system due to their effects on neurotransmitters. Another toxic effects were reported in liver after chronic exposure to insecticides. Hyperglycemia may also produced after chronic exposure to diazinon and fenitrothion. There was many similarities in the toxic effects reported in this study that supported that they are of one group of insecticides, organophosphorus, and they may be have the same mode of action.