Kindling induced changes in parvalbumin immunoreactivity in rat hippocampus and its relation to long-term decrease in GABA-immunoreactivity.
The immunoreactivity of parvalbumin (PV), a Ca2+-binding protein present in a subpopulation of interneurons, was studied in the hippocampal CA1 region during kindling epileptogenesis, induced by tetanic stimulation of the Schaffer collateral/commissural fibers. PV-immunoreactivity was increased in comparison to controls after 13 afterdischarges and after the induction of generalized seizures. A quantification of the number of PV-immunoreactive somata showed an increase of 20% in both stages of kindling. This level had returned to baseline level 31 days after the last seizure. These results imply that changes in PV-immunoreactivity are related to seizure activity rather than to the long-term increase in seizure sensitivity in kindled animals. Co-localization study in controls showed that 32% of PV-immunoreactive somata were also immunopositive for GABA. A colocalization study in stratum oriens and pyramidale on the stimulated side of kindled animals 31 days after the last generalized seizure showed neither a reduction in the number of PV-immunoreactive somata nor in the number of GABA-immunopositive cell bodies that co-localized with PV. In contrast, the number of GABA-immunoreactive somata that did not co-localize with PV was reduced by 50%. It has been shown that a large influx of Ca2+ plays a crucial role in epileptogenesis. Here we demonstrate that the presence of the calcium-binding protein parvalbumin seems to exert a protective effect against the process that leads to a decrease in GABA content.
Kamphuis
W
W
University of Amsterdam, Department of General Zoology, The Netherlands.
Huisman
E
E
Wadman
W J
WJ
Heizmann
C W
CW
Lopes da Silva
F H
FH
D000818:Animals; D006624:Hippocampus / Q000378:metabolism* / Q000503:physiopathology; D007150:Immunohistochemistry; D007696:Kindling, Neurologic; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism*; D010320:Parvalbumins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000378:metabolism* / Q000503:physiopathology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D009124:Muscle Proteins; D010320:Parvalbumins; D005680:gamma-Aminobutyric Acid