الفهرس 
INTRODUCTIONANDAIM OF WORKOnly 14 pages are availabe for public view
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Abstract
The present study was designed to determine the effect of long term exposure of rats, one hour a day, 6 days a week for 6 weeks to the alternating magnetic field (alternating current AC, The exposure was at density flux of 3.5 mille tesla (mT) = 35 Gauss (G), would alert the structural integrity of the inferior colliculus as example of nervous tissue by light microscopic, histochemical and quantitative examination. One hundred and twenty rat pups were divided into three main groups 2– week – old , 4– week – old , and 6 – week – old , were included in this study.from each of the exposed and control groups 5 animals were sacrificed by decapitation as follows:1. After one day of the end of exposure (E2w-1d, C2w-1d); (E4w-1d, C4w1d); (E6w-1d, C6w-1d).2.After 7 days of the end of exposure (E2w-7d, C2w-7d); (E4w-7d, C4w-7d); (E6w-7d, C6w-7d).
3. After 14 days of the end of exposure (E2w-14d, C2w-14d); (E4w-14d, C4w-14d); (E6w-14d, C6w-14d).
4. After 28 days of the end of exposure (E2w-28d, C2w-28d); (E4w-28d, C4w-28d); (E6w-28d, C6w-28d).
Fresh specimens were taken from the inferior colliculus of all studied rats and processed till be stained as following :
I. Histological Stains:
• Harris’s haematoxylin and eosin .
II. Histochemical Stains :
• Cresyl fast violet for detection of Nissl granules and cytoplasmic RNA.
III . Quantitative Analysis :
The quantitative histological study was performed on histological section images using Image pro plus programme software at x 400 magnefication.
1. Haematoxylin and eosin stained sections of inferior colliculus were used in each group to assess the effect of EMF exposure on:
1.1. (Cell Proliferation): by measuring Cell density, clustering and distribution in the central nucleus of inferior colliculus.
1.2. (Cell Death): by measuring Percent of cells with pale nuclei.
1.3. Vaculation : ( ٪ per area of vacuoles)
1.4. By measuring Mean chromatin density.
2. Cresyl fast violet stained sections were used in each group to assess the following :
2.2. by measuring Mean Optical density of cresyle fast violet stained RNA
IV. Body weight.
V. Behavioral observations.
VI. Statistical Analysis.
In the present study, the changes in the animal behaviors due to the exposure to ELF EMF over the rest of experimental period during the exposure time in glass cage of Helmholtiz coil apparatus, and after returned animals to ordinary cage showed that the activity (motion) of animals in glass cage were decreased, and increased after the end of exposure and returned to normal value gradually. The respond to sound and vision of animals in glass cage decreased, and increased after the end of exposure and reached to medium values.
While, the eating behavior not found in glass cage , and fluctuated after the end of exposure between decreased and increased manner , these results approved with the results of the body weight which had increased as in the 2 – week – old group, while , in 4, and 6 – week – old groups decreased .
Also, in the present study, the animal behaviors resulted showed that during exposure to ELF EMF the note about the extended of hair while found in glass cage were decreased, and increased after the end of exposure and returned to normal value gradually. The redness of limbs while animals found in glass cage were increased, which arrived at maximum values by the end of exposure period (1 hour), but after the end of exposure returned to normal value gradually.
In the 2, 4, and 6 – week – old animals exposed to the alternating current electromagnetic field (AC EMF), it was difficult to distinguish neuron types in some exposed subgroups. Observed changes included different stages of degeneration as atrophied neurons, pyknotic nuclei , cell death of neurons ( karyolysis, apoptosis), small and large vacuolization in matrix, collections of inflammatory cells as neuronophagia, glial cells (gliosis), and dilatation in some of blood vessels . Some tissues appeared with matrix edema. All these changes fluctuated from subgroup to another one as illustrated in results chapter.
In the 2, 4, and 6 – week – old animals exposed to the alternating current electromagnetic field (AC EMF), the total cell number (cell density or cell population),where founded that in 2 , and 4 week – old – age groups decreased .on the other hand the 6 – week – old group had slight increased change as compared with the control group .
The cell proliferation measured as the number of clusters in each subgroups, where founded that in 4, and 6 weeks old age groups decrease .While on the other hand, in 2 weeks old age group increased .
The cell distribution (number of cells in clusters, and number of single cells). Firstly, the number of cells in clusters founded in 2 , 4, and 6 – week – old groups decrease . Secondly, the number of single cells found in 2, and 4 – week – old group slightly increased .While in 6 – week – old group decreased as compared with the control subgroup.
The cell death (number of cells with pale nuclei). In 2 – week – old group, the rate of recovery was increased than in 4, and 6 weeks old age groups. So , the lowest rate of recovery was found in 6 – week – old group, and the fastest rate of recovery was found in 2 – week – old group.
In the present study, the results of vacuolation ( ٪ per area of vacuoles) approximately synchronized with the results of cell death ,and had controversy relation with the recovery as in 4, and 6 – week – old groups , but in the 2 – week – old group as ( E2W28d) the ٪ per area of vacuoles considered as the largest percent of vacuoles in this group .
In the present study, the biological activity of inferior colliculus measured and expressed as (euchromatin activity, and polysomes activity as indication of protein synthesizing activity in Nissl granules of nerve cells). The values of euchromatin, and polysomes had moderate increased.
In the 2, 4, and 6 – week – old animals exposed to the alternating current electromagnetic field (AC EMF), had a sign of chromatolysis phenomenon .
Finally, may be explained all last observations according to two important mechanism of cell damage, firstly, is the injury induced by free radicals. Secondly, by Ca+2 disturbances mechanism.
SUMMARY
The present study was designed to determine the effect of long term exposure of rats, one hour a day, 6 days a week for 6 weeks to the alternating magnetic field (alternating current AC, The exposure was at density flux of 3.5 mille tesla (mT) = 35 Gauss (G), would alert the structural integrity of the inferior colliculus as example of nervous tissue by light microscopic, histochemical and quantitative examination. One hundred and twenty rat pups were divided into three main groups 2– week – old , 4– week – old , and 6 – week – old , were included in this study.
from each of the exposed and control groups 5 animals were sacrificed by decapitation as follows:
1. After one day of the end of exposure (E2w-1d, C2w-1d); (E4w-1d, C4w1d); (E6w-1d, C6w-1d).
2. After 7 days of the end of exposure (E2w-7d, C2w-7d); (E4w-7d, C4w-7d); (E6w-7d, C6w-7d).
3. After 14 days of the end of exposure (E2w-14d, C2w-14d); (E4w-14d, C4w-14d); (E6w-14d, C6w-14d).
4. After 28 days of the end of exposure (E2w-28d, C2w-28d); (E4w-28d, C4w-28d); (E6w-28d, C6w-28d).
Fresh specimens were taken from the inferior colliculus of all studied rats and processed till be stained as following :
I. Histological Stains:
• Harris’s haematoxylin and eosin .
II. Histochemical Stains :
• Cresyl fast violet for detection of Nissl granules and cytoplasmic RNA.
III . Quantitative Analysis :
The quantitative histological study was performed on histological section images using Image pro plus programme software at x 400 magnefication.
1. Haematoxylin and eosin stained sections of inferior colliculus were used in each group to assess the effect of EMF exposure on:
1.1. (Cell Proliferation): by measuring Cell density, clustering and distribution in the central nucleus of inferior colliculus.
1.2. (Cell Death): by measuring Percent of cells with pale nuclei.
1.3. Vaculation : ( ٪ per area of vacuoles)
1.4. By measuring Mean chromatin density.
2. Cresyl fast violet stained sections were used in each group to assess the following :
2.2. by measuring Mean Optical density of cresyle fast violet stained RNA
IV. Body weight.
V. Behavioral observations.
VI. Statistical Analysis.
In the present study, the changes in the animal behaviors due to the exposure to ELF EMF over the rest of experimental period during the exposure time in glass cage of Helmholtiz coil apparatus, and after returned animals to ordinary cage showed that the activity (motion) of animals in glass cage were decreased, and increased after the end of exposure and returned to normal value gradually. The respond to sound and vision of animals in glass cage decreased, and increased after the end of exposure and reached to medium values.
While, the eating behavior not found in glass cage , and fluctuated after the end of exposure between decreased and increased manner , these results approved with the results of the body weight which had increased as in the 2 – week – old group, while , in 4, and 6 – week – old groups decreased .
Also, in the present study, the animal behaviors resulted showed that during exposure to ELF EMF the note about the extended of hair while found in glass cage were decreased, and increased after the end of exposure and returned to normal value gradually. The redness of limbs while animals found in glass cage were increased, which arrived at maximum values by the end of exposure period (1 hour), but after the end of exposure returned to normal value gradually.
In the 2, 4, and 6 – week – old animals exposed to the alternating current electromagnetic field (AC EMF), it was difficult to distinguish neuron types in some exposed subgroups. Observed changes included different stages of degeneration as atrophied neurons, pyknotic nuclei , cell death of neurons ( karyolysis, apoptosis), small and large vacuolization in matrix, collections of inflammatory cells as neuronophagia, glial cells (gliosis), and dilatation in some of blood vessels . Some tissues appeared with matrix edema. All these changes fluctuated from subgroup to another one as illustrated in results chapter.
In the 2, 4, and 6 – week – old animals exposed to the alternating current electromagnetic field (AC EMF), the total cell number (cell density or cell population),where founded that in 2 , and 4 week – old – age groups decreased .on the other hand the 6 – week – old group had slight increased change as compared with the control group .
The cell proliferation measured as the number of clusters in each subgroups, where founded that in 4, and 6 weeks old age groups decrease .While on the other hand, in 2 weeks old age group increased .
The cell distribution (number of cells in clusters, and number of single cells). Firstly, the number of cells in clusters founded in 2 , 4, and 6 – week – old groups decrease . Secondly, the number of single cells found in 2, and 4 – week – old group slightly increased .While in 6 – week – old group decreased as compared with the control subgroup.
The cell death (number of cells with pale nuclei). In 2 – week – old group, the rate of recovery was increased than in 4, and 6 weeks old age groups. So , the lowest rate of recovery was found in 6 – week – old group, and the fastest rate of recovery was found in 2 – week – old group.
In the present study, the results of vacuolation ( ٪ per area of vacuoles) approximately synchronized with the results of cell death ,and had controversy relation with the recovery as in 4, and 6 – week – old groups , but in the 2 – week – old group as ( E2W28d) the ٪ per area of vacuoles considered as the largest percent of vacuoles in this group .
In the present study, the biological activity of inferior colliculus measured and expressed as (euchromatin activity, and polysomes activity as indication of protein synthesizing activity in Nissl granules of nerve cells). The values of euchromatin, and polysomes had moderate increased.
In the 2, 4, and 6 – week – old animals exposed to the alternating current electromagnetic field (AC EMF), had a sign of chromatolysis phenomenon .
Finally, may be explained all last observations according to two important mechanism of cell damage, firstly, is the injury induced by free radicals. Secondly, by Ca+2 disturbances mechanism.