DISTRIBUTION OF NUCLEAR RECEPTORS FOR STEROID HORMONES IN THE HUMAN BRAIN: A PRELIMINARY STUDY

BACKGROUND
Expression of the nuclear steroid hormone receptors (SHR) within certain parts of the human brain has been described by many authors. However, a comprehensive analysis of SHR expression in the human brain still has not been performed.


AIM
To investigate the expression of SHR in different anatomical areas of the brain, especially within the neocortex.


METHOD
Immunohistochemical expression of estrogen receptors (ER), progesterone receptors (PR) and androgen receptors (AR) in different regions of the human brain was examined.


RESULTS
Nuclear expression of the AR was found in the mamillary body, praecentral gyrus and hippocampus of males. The same expression in analysed structures of female was not found. The expression of ER and PR was not observed.


CONCLUSIONS
The analysis revealed unexpected localization of SHR within the brain cortex, which could be the first step to the explanation of SHR action in brain as an interrelationship to function and behaviour. These results indicate on the possibility of SHR detection in post-mortal brain.


INTRODUCTION
Nuclear receptors for steroid hormones (SHR) are members of a superfamily of ligand-dependent transcription factors that mediate the steroid hormone action in target cells.SHRs are involved in reproduction and sexual biomorphysm as well as behaviour, but their proper role in aspects of brain function such as behaviour, perception, and memory is still not fully clear.Expression of AR and ER within the hypothalamus and hippocampus, as the archi-cortex structures of the human brain has been described 1,4,5,6 .However, their distribution relation to the brain structure, particulary in the structures of the neocortex, and during brain de velopment still have not been fully described.The possible role of SHRs have been suggested in pathogenesis of Alzheimer disease 4,6,8 ; their relationship to neuro degenerative diseases is also an emerging fi eld of interest.

MATERIALS AND METHODS
Samples of human brain tissue were taken from diff erent areas, icluding the precentral gyrus, postcentral and frontal gyruses, corpora mammillaria and hippocampus of three cadavers (the sex and age are documented in the Tab.1).The testes, ovary and prostate were included as positive control.Immunohistochemical staining of estrogen receptors (ER), androgen receptors (AR) and progesterone receptors (PR) was performed on 10% formalin-fi xed, paraffi n-embedded tissue sections of the brain cortex structures.Antibodies from Dako (Denmark) against estrogen receptors (ER; ER α -Monoclonal Mouse Anti-Human, Clone 1D5, Code M 7047); progesterone receptors (PR; PR -Polyclonal Rabbit Anti-Human, Code A 0098); and androgen receptors (AR; AR -Monoclonal Mouse Anti-Human, Clone AR441; CSA II, code K1497) were used.

RESULTS AND DISCUSSION
Typical nuclear SHR staining was observed within the steroid hormone receptor positive tissue used as positive controls (prostate, ovary, testes).Nuclear AR staining was observed within the mamillary body, precentral gyrus and the hippocampus of tissue taken from males but not female.Mamillary bodies as well as the hippocampus are considered to be a part of the archi-cortex.These areas have already been shown to express AR 4 .Lorenz et al. 7 (2005) observed AR positive cells in the cerebral cortex of postnatal rats where AR positivity was described in the majority of neurons.The precentral area where the AR was found in our investigation is the place of the true motor cortex (M1).Considerably higher cytoplasmic positivity, particular of ER in postcentral and frontal gyrus, was observed, suggesting possible localisation of non nuclear SHR within the cytoplasm.Further studies are required to determine whether this is real or an artefact related to post-mortem changes.
Our preliminary study of the expression of SHR within the brain cortex showed unexpected results which will be the base for the follow up research.

LIST OF ABBREVIATION:
SHR -steroid hormone receptor AR -androgen receptor ER -estrogen receptor PR -progesteron receptor F -female M -male

Table 1 .
Detailed of specifi cation of analysed samples.

Table 2 .
Results of immunohistochemistry.