الفهرس 
Acknowledgement
Connections of the hippocampusOnly 14 pages are availabe for public view
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Abstract
The hippocampus is a neural structure in the medial temporal lobe of the brain that plays an important role in memory and spatial navigation. The hippocampus in albino rats continues to grow after birth.
Humans are exposed to cadmium which is a toxic agent that is present in industrial fumes, cigarette smoke. It is also present in foods especially those treated with phosphate fertilizers. L-carnitine is a nitrogenous compound which has been proved to be a strong antioxidant.
The present work aimed to study the effect of pre- and postnatal exposure to cadmium on the development of hippocampus in albino rat and the possible protective role of l-carnitine.
Albino rats had been used in this study. The animals were maintained under controlled conditions (12h:12 h dark/light cycle, normal room temperature and normal humidity) at the animal house.
They were divided into 3 groups: (pregnancy group, lactation group and adult group).
Each age group was divided into four subgroups:
I-Control group: Received no treatments.
II-Cadmium treated group: They received cadmium at dose of 4 mg b.w/ kg.
III-L-carnitine group: They received l-carnitine at dose of 200 mg b.w/ kg.
IV- Both cadmium and l-carnitine treated group: in this group, the l-carnitine was given at first followed by cadmium.
1-Pregnancy group: L-carnitine was given at 7th day of pregnancy while cadmium was given at 10th day of pregnancy and both were continued daily through the whole period of pregnancy until delivery.
2-Lactation group: drugs were given daily to the mothers from day 0 to day 21 of the off-springs.
3-Adult group: drugs were given to the rats from the age of 30 days and continued daily till the age of 60 days.
The granule cells of the dentate gyrus and the pyramidal neurons of the CA3 and CA1 regions of the hippocampus were studied by the light microscope and the electron microscope.
In addition, morphometric methods were used which include measurement of volume proportion, thickness and cell count of granule cells in dentate gyrus and pyramidal cells in CA1 & CA3 regions.
The present results demonstrate that the principle cells of the hippocampus in the cadmium treated animals of the three studied age groups had degenerative changes. Light microscopic study showed the presence of many cells with darkly stained nuclei and vacuolated cytoplasm. In addition there were some cells with pyknotic nuclei. The ultrastructure of the cells revealed condensation of chromatin of the nuclei and the cytoplasm showed apparent loss of free ribosomes, the presence of dilated rough endoplasmic reticulum and damaged mitochondria. Also many vacuoles could be observed in the cytoplasm.
In the l-carnitine treated group of the three studied age groups, cells were observed to be nearly similar to those of the control group.
In the cadmium and l-carnitine treated group of the three studied age groups, the light microscopic study revealed the presence of some cells with vacuolated cytoplasm and darkly stained nuclei. The ultrastructure of the cells of this group revealed the presence of few lysosomes, vacuoles and the presence of some dilated rough endoplasmic reticulum.
In conclusion, l-carnitine is an antioxidant that could protect the hippocampus from the toxic effect of cadmium. L-carnitine could protect the newborns as it crosses the placental barrier. It also could protect infants as it is excreted in milk. Finally, it could protect the hippocampus in adults as it could cross the blood brain barrier.