ENGLISH VERSION

ZESZYT 327

Izabela Krakowska
The expression of the estrogenic receptors α and β in the neurons of hippocompal formation during the process of neurogenesis and at the sexually mature female rabbits

The aim of the present paper was to demonstrate the presence of estrogenic receptors α and β in the neurons of hippocampal formation. The obtained results indicate that estrogenic hormones can influence cognitive processes, learning and memory. The cognition of estrogen activity’s mechanisms and determining which brain structures they have an influence on, can be helpful in treating neurodegenerative diseases in human. 
The objective of the examination was to demonstrate the presence of Erα and Erβ in the neurons of hippocampal formation in rabbit females during the process of neurogenesis as well as in sexually mature females.
The presence of the above mentioned receptor genera was proved both in the neurons of sexually immature females as well as in mature ones.
As early as in the prenatal period, the reaction to antibody for Erα and Erβ was observed in single neuroblasts of hippocampal formation. By means of quantitative analysis, it was demonstrated that in a group of sexually immature females a number of neurons showing reaction increases together with the rabbit’s age. In earlier developmental periods reaction in the cytoplasm of neurons predominates. 
In mature female rabbits the examination was carried out in two groups. The first group consisted of females after ovariectomy, which were not administered 
17β estradiol, while in the second group females after ovariectomy were administered 17β estradiol. After the examinations had been carried out with a use of antibodies for Erα and Erβ, the results were compared. In mature female rabbits estrogenic receptors α occur in the neurons of hippocampal formation, in cytoplasm, in apical dendrites as well as in cell nucleus. In all examined areas of hippocampal formation cytoplasmic reaction predominates. The greatest predominance of reaction in cytoplasm was demonstrated in the neurons of CA1 and CA2 areas, in dental gyrus as well as in presubiculum and parasubiculum. Estrogenic receptors β in mature animals localize mainly in cytoplasm and neuron processes, to a lesser extent in cell nucleus. This refers to all examined areas except the neurons of dental gyrus’ granular layer, where the reaction was not found. 
The results of the examination carried out by means of electron microscope showed that in hippocampal formation there is a predominance of axodendritic synapses in comparison with very rarely occurring axoaxonic and dendritodendritic synapses.The administration of 17β estradiol caused positive reaction decrease in female rabbits to the applied primary antibodies for Erα and Erβ. The results reveal small sensitivity of hippocampal formation’s neurons to the down regulation phenomenon.