الفهرس 
ِAcknowledgementOnly 14 pages are availabe for public view
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Abstract
The main proposal of the present study is the determination of the i. p. LD50 hostathione, endrin, lannate and sumicidine, and then revealing the toxic effects of these insecticides on the behavior of some free amino acids, which are prospectively acting as neurotransmitters in the CNS of frogs. The study is extended to investigate the effect of the previously mentioned insecticides on the activity of some enzymes – including GOT, GPT and AchE and also the total protein content in the CNS, liver and plasma of frogs.
The i. p. LD50 of the studied insecticides was determined according to Litchfield method and found to be 12.5, 6.81, 66.5 and 2.95 mg/kg for hostathione, endrin, lannate and sumicidine, respectively. It is obvious that sumicidine is the most toxic insecticide for the frog Rana ridibunda followed by endrin, hostathione and lannate.
The present data showed that the injection of the ¼ LD50 of the different insecticides caused a general increase in the brain concentration of the inhibitory amino acids GABA, glycine and alanine. However, there was a decrease in GABA concentration only after lannate treatment. On the other hand, a parallel decrease was observed in the main excitatory glutamic acid in brain throughout the experimental periods. Brain glutamine concentration showed a general increase after the injection of hostathione and endrin, and fluctuated increases and decreases in case of lannate and sumicidine. A marked increase in the excitatory aspartic acid was recorded in brain due to injection of all the insecticides, except hostathione, which induced an obvious decrease in the amino acid concentration.
The induced changes in the contents of the inhibitory amino acids, GABA, glycine and alanine, as well as in the excitatory glutamate in the spinal cord of frog Rana ridibunda are greatly similar to those described in brain, after the administration of different insecticides. However, an obvious increase in GABA concentration was noticed in spinal cord after lannate, instead of decrease in case of brain. With regard to aspartic acid and glutamine the induced changes in spinal cord are nearly reversible to those recorded in brain after endrin and lannate, but more or less similar after the other two insecticides.
The behavioural observations on the frogs, in the present study, revealed that in case of endrin there were severe convulsions. On the other hand, the neuronal state of frogs after the treatment with the other insecticides hostathione, lannate and sumicidine is a general inhibition. A correlation between the recorded behavioural notes and the changes in the individual amino acids and/or the calculated ratio glutamate + glutamine + asoartate/GABA supported the suggestion that the balance between the major inhibitory GABA and the metabolically related excitatory glutamate, aspartate and glutamine may be of considerable indication in maintaining the neuronal state in the brain of frogs.
The present data supposed that the enhancement of the synthesis of both aspartic acid and alanine from glutamate via transamination metabolic pathways in the CNS of frog is dependent on the administered insecticide, as well as on the nervous tissue. For example, the data showed that there was an enhancement of synthesizing aspartic acid from glutamate via transamination, using GOT, in both brain and spinal cord under the effect of endrin. A sminilar enhancement of synthesizing alanine from glutamate, using GPT, was detected in brain after endrin injection. On the other hand, the results suggest the promotion of another system (s) for enhancing the synthesis of aspartic acid in brain, after lannate and sumicidine, and another system (s) for synthesizing alanine in brain and spinal cord, after sumicidine. the latter system appear to be on the expense of glucose in the central nervous tissue cells.
The present study could support the hepatotoxic potency of the acute administration of the investigated insecticides through the significant changes in both GOT and GPT in the liver as well as in the plasma. The data showed a general decrease in the activity of GOT and GPT in both liver and plasma due the administration of hostathione, lannate and sumicidine, with the exception of an increase in GOT activity in liver (due to lannate administration) and plasma (due to hostathione administration). On the other hand, endrin administration induced a general increase in both GOT and GPT in liver and plasma.
The present study revelaed fluctuated decreases in AchE activity in brain, spinal cord and liver as a result of the i. p. administration of hostathione, endrin, lannate and sumicidine. The enzyme activity in plasma showed an obvious decrease due to hostathione and sumicidine and fluctuated increases due to lannate and endrin.
The insecticidal toxic effect on the total protein content – in the present study – varies with the various investigated tissues, as well as with the type of the administered insecticide. The total protein content in frog brain showed a more highly significant increase after administration of both hostathione and lannate at most of the tested periods. On the other hand, an obvious decrease in the total protein content was detected in the brain (due to endrin), in the spinal cord (due to hostathione), in the liver (due to the four insecticides but markedly with hostathione and lannate) and in plasma (due to hostathione and sumicidine).