Comparison of astrocytes and gap junction proteins in the white matter of genetic absence epileptic and control rats: an experimental study

ABSTRACT

Objectives

The role of white matter astrocytes in absence epilepsy is unknown. The present study aims to quantify astrocytic markers glial fibrillary acidic protein (GFAP), gap junction’s proteins connexin 30 (Cx30) and connexin 43 (Cx43) in the corpus callosum (CC) of genetic absence epileptic rats from Strasbourg (GAERS), Wistar albino glaxo rats from Rijswijk (WAG/Rij)and compare the results with control animals.

Methods

-The density of GFAP, Cx30 and Cx43 positive astrocytes in per unite area were quantified in the CC of GAERS, WAG/Rij and control animals using immunohistochemistry and real-time quantitative polymerase chain reaction (RT-qPCR). The quantifications were made from three regions of CC; below the primary somatosensory (S1BF), below the motor (M1) and below the retrosplenial (RSG) cortices.

Results

oThe number GFAP, Cx30 and Cx43 immunopositive astrocytes showed heterogeneous distribution within the CC. The GFAP immunopositive astrocytes was significantly high in the S1BF region of the three strains. The immunopositive GFAP and Cx43 showed significant decrease in the S1BF and M1 regions in GAERS and WAG/Rij compared to control animals, however, an increase in the immunopositive Cx30 was observed in the same regions in both GAERS and WAG/Rij compared to control Wistar animals but the increase was significant for GAERS but not for WAG/Rij. The RT-qPCR analysis was corroborated by GFAP immunohistochemistry results.

Conclusion

The different expression pattern of the two Cx’s in the CC of the epileptic strains compared to control animals may indicate a compensatory response or maybe the cause of generalization of absence seizures.

KEYWORDS:

• Corpus callosum
• connexin
• glial fibrillary acidic protein
• absence epilepsy
• immunohistochemistry
• rt-qPCR

Acknowledgments

The authors would like to thank Koç University Research Center for Translational Medicine (KUTTAM) for using the facilities.

Ethical statement

The institutional Animal Care and Use Committee of Koç University approved all procedures. The guide line of NIH Publications No. 8023, revised 1978 have been followed.

Disclosure statement

All authors declare that they have no actual or potential conflict of interest.

Additional information

Funding

The authors reported there is no funding associated with the work featured in this article.