VALIDITY OF SHAM PROCEDURE IN THE STUDY OF NEUROIMMUNOMODULATION

When a specific brain area is lesioned to study its role in neuroimmun omodulation, in addition to the area of interest, the brain structures in the electrode pathway are inevitably damaged. This study on some a spects of innate immunity was undertaken to reveal the site-specific s ham effects when sham lesions were performed in the ventromedial hypot halamus (VMH), amygdaloid complex (AMGC) and ventral hippocampal forma tion (VHF) in rats. The effects were compared with AMGC lesioned anima ls. Electrolytic lesions were performed bilaterally in the AMGC. Sham lesion were made in all the other areas. All sham groups and lesioned AMGC animals uniformly showed a decrease in their total, white blood c ell count and an increase in phagocytic index of neutrophils as compar ed to normal animals. The polymorph count declined and the lymphocyte count increased in lesioned AMGC and VHF sham animals. The lesioned AM GC and AMGC sham animals showed a significant increase in avidity inde x. The nitro blue tetrazolium (NBT) reduction (an index of the intrace llular killing ability of the neutrophils) was markedly greater in VMH and AMGC sham animals, but not in the VHF sham group, as compared to controls. The soluble immune complex levels in VMH sham, AMGC sham and AMGC lesioned animals showed a marked decrease as compared to control s. The NET reduction was significantly reduced in lesioned AMGC animal s as compared to AMGC sham animals. Thus, this study emphasises the ne ed for a site-specific sham in experimentally induced brain damage.