الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 224 |  |  |
| | | from | 224 | | |
Abstract
The present study tried to evaluate the effect of Sodium Fluoride on the grey matter of spinal cord of adult male albino rats and the possible protective role of green tea.
Material &Methods:
Twenty four adult male albino rats were used in this study. They were divided into four groups as follows:
group I (Negative control group): consisted of six rats that received distilled water at a dose of 2.4 ml/ rat/ day, daily for four weeks by gastric intubation.
group II (Positive control group): consisted of six rats that received green tea extract at a dose of 10mg/ kg/ day, daily for four weeks by gastric intubation.
group III (treated group): consisted of six rats that received NaF at a dose of 12 mg/ kg/ day, daily for four weeks by gastric intubation.
group IV (protected group): consisted of six rats that received green tea extract at a dose of 10mg/ kg/ day followed after 30 minutes by NaF at a dose of 12 mg/ kg/ day, daily for four weeks by gastric intubation.
All rats were weighed before & after the experiment. At the end of the experiment, rats were anaesthetized and the spinal cord was dissected. The cervical and thoracic parts of the spinal cord were collected and exposed to light microscopic studies (using H. & E., silver, toluidine blue, caspase-3 and GFAP stains) as well as electron microscopic study.
Summary
- 166 -
Morphometric measurements were done for detection of number of astrocytes, color intensity of Nissl’s granules and percent area of astrocytes. A molecular study was performed using agarose gel electrophoresis for detection of the DNA fragmentation.
Results:
The body weight of the animals:
The animals of the negative control group showed a significant increase in the body weight at the end of the experiment, while the animals of the positive control, treated and protected groups showed a significant decrease in their body weights. However, the percentage of decrease in the body weight of protected group was higher than the percentage of decrease in both positive control and treated groups.
Histological results:
- Light microscopic results:
Both the negative and the positive control groups showed similar normal spinal cord structure, dense Nissl’s granules content inside the neurons, negative immune reaction to caspase-3 and few, small astrocytes with short processes by the GFAP immune staining .
The NaF treated group showed various degrees of neurodegeneration. Many cells were shrunken with dark cytoplasm & loss of nuclear details. Other cells showed central chromatolysis while few appeared as ghost-like cells. The neuropil showed many areas of vacuolation and haemorrhage with many abnormal blood vessels and significant increase in the number and size of astrocytes.
Summary
- 167 -
Moreover, the neurons of the NaF treated group showed significant decrease of their Nissl’s granules content and positive immune reaction to caspase-3.
- Electron microscopic results:
Both the negative and the positive control groups showed similar normal intracellular structure of the spinal cord. The nerve cells had regular euchromatic nuclei with prominent nucleoli. The cytoplasm contained rough endoplasmic reticulum, Golgi apparatus, mitochondria and many scattered free ribosomes in the form of black granules.
The NaF treated group showed abnormal intracellular structure of the spinal cord. Some nerve cells had irregular or shrunken nuclei. Other cells showed condensation of chromatin inside the nucleus or ill-defined nuclear envelope. The cytoplasm contained many swollen vacuolated mitochondria with destructed cristae, dilated Golgi apparatus and dilated rough endoplasmic reticulum. Also, some areas of vacuolation could be detected inside the cytoplasm.
Results of agarose gel electrophoresis:
Both the negative and the positive control groups showed no apoptotic bands. However, the NaF treated group showed apoptotic bands in the form of a ladder-like DNA fragmentation pattern (a characteristic of apoptosis).
Lastly, addition of green tea extract to the NaF resulted in histological, immunohistochemical, morphometric, ultrastructural and molecular improvements.
Summary
- 168 -
Conclusion:
from the present study, it is concluded that:
1- Both NaF and green tea extract have weight reducing effects.
2- chronic exposure to NaF produces marked neurodegenerative changes in the spinal cord.
3- NaF has genotoxic effect that leads to destruction of DNA.
4- Green tea extract proved to be an effective agent for protection against NaF induced neurotoxicity, thus delaying its sequelae, mainly through its antioxidant properties.
Recommendations:
from the present study, it is recommended that:
1- Fluoride containing products (such as fluoridated water and toothpastes) should be avoided as much as possible.
2- Green tea ”being orally safe & inexpensive” is recommended to be used to counteract the toxic effects of NaF.
3- More research for new natural agents that reduce the NaF toxicity should be encouraged.
4- Further studies should be done to explore more about the effects of NaF exposure on other body organs.