Effects of maternal immunoglobulin G in infant rats with NMDA-induced spasms and the expressions of FOS protein in neurocytes

Objective Infantile is an age-dependent expression of a damaged brain. The term spasms has been used to describe the seizure type, the epilepsy syndrome. The traditional medical treatment of West syndrome has not changed for many years. A lot of new drugs were applied to this syndrome, but the effect was uncertain. High dose Immunoglobulin G and ACTH infusion were the main medical treatment methods. In our study, we investigated the protective effect of maternal immunoglobulin G on spasm activity and FOS protein expression in infant rats with NMDA-induced spasm. The purpose of this investigation was to determine the role of maternal immunoglobulin G in infantile spasm rat model.Methods Three female Wistar rats and 30 their neonatal rats were used. After giving birth, 8-10 mL blood was drawn from the three female Wistar rats. γ Globulin was abstracted from their blood, then was purified to get rat maternal Immunoglobulin G. Thirty neonatal rats were randomly divided into three groups: Control Group (n=6): from postnatal days 11, normal saline injection was given subcutaneously at 8AM for five consecutive days and normal saline injection was given intraperitoneally one hour after the last subcutaneous injection. NMDA(N-methyl-D-aspartate) Group(n=12):postnatal days 11, normal saline was also injected subcutaneously at 8AM for five consecutive days and NMDA (15 mg·kg-1) was injected intraperitoneally at about one hour after the last saline injection; maternal immunoglobulin G Group(n=12):From postnatal days 11, corresponding maternal immunoglobulin G (10 mg·kg-1) was injected subcutaneously at 8AM for five consecutive days and NMDA (15 mg·kg-1) injection was given intrapritoneally at 9AM after the last subcutaneous injection. All perfused brain tissues of rats were sectioned, and the c-fos expression was detected by immunohistochemistry staining on the 15th day in rat pups of the infantile spasm model. In neocortex, thalamencephalon, piriform cortex,dentate gyrus and hippocampal areas CA2 and CA3, the same particular region had been selected to count FOS protein postive nuclei cells in a HP field in three groups,respectively. Results ①The number of the emprosthotonus onset in NMDA group(339) was much bigger than those in maternal immunoglobulin G group(109)(P0.05). The average seizure grade of maternal immunoglobulin G group (3.35) was significantly lower than that of NMDA group (5.67). The ratio of emprosthotonus onset latent period which was longer than 40 minutes in maternal Immunoglobulin G group was significantly higher than that in NMDA group. ②Few positive FOS protein cells were detected in neocortex, thalamencephalon, piriform cortex, dentate gyrus and the hippocampal areas CA2 and CA3in control group. On the contrast, robust FOS protein positive cells were observed in the neocortex layer Ⅰ-Ⅴ , thala-mencephalon, piriform cortex, dentate gyrus and the hippocampal areas CA2 and CA3 in NMDA group. However, the FOS protein positive cells in maternal Immunoglobulin G group dramatically decreased at the same region of brain tissues compared to those in NMDA group (P0.01). In maternal immunoglobulin G Group, some FOS protein positive cells were detected in layerⅡand Ⅳin neocortex ,but few were observed in the ether layers. Conclusions Maternal immunoglobulin G could suppress behavioral spasm in infant rats with NMDA-induced spasm and reduce the expression of FOS protein. The area of FOS protein expression was consistent with the distribution of NMDA-receptor in brain. Neocortex, hippocamal, thalamencephalon, piriform cortex might play an important role in infantile spasms.