Human Intravenous Immunoglobulins Suppress Seizure Activities and Inhibit the Activation of GFAP-Positive Astrocytes in the Hippocampus of Picrotoxin-Kindled Rats

Abstract

ABSTRACTWe previously showed that human intravenous immunoglobulin (IVIG) can lower seizure severity and prolong seizure latency in picrotoxin-kindled rats. The aim of this study was to further characterize the effects of IVIG on seizure activity and investigate its influence on astrocytes in the hippocampus of picrotoxin-kindled rats. A rat kindling model was established by peritoneal injections of picrotoxin for 21 days in Wistar rats. Seventy-five rats were equally divided into five groups: picrotoxin, IVIG pretreatment, IVIG post-treatment, normal saline control, and IVIG control. Seizure severity was evaluated according to a six-stage classification. The number and morphology of glial fibrillary acidic protein (GFAP)-positive astrocytes were studied by immunohistochemistry using the anti-GFAP antibody. The cross-sectional area and grayscale of GFAP-positive astrocytes were also determined. In picrotoxin-kindled rats, pretreatment with IVIG appeared to inhibit full kindling rates, and it significantly reduced the number of GFAP-positive cells in the hippocampus (p < .001). IVIG also significantly (p < .001) attenuated the increase in the cross-sectional area and grayscale of GFAP-positive astrocytes in the hippocampus. Our results suggest that by suppressing the expression of GFAP, IVIGs may reduce seizure activity and inhibit the activation of GFAP-positive astrocytes in picrotoxin-kindled rats.