Rat hippocampus and primary immune response.

During immune challenge hippocampal region shows time-dependent changes in neurotransmitter levels. Hence in the present study the effect of electrolytic lesion in the dorsolateral hippocampus (DLH) and ventral hippocampal formation (VHF) (to create a disturbance in neurotransmitter levels) on humoral immunity in albino rats has been studied along with appropriate controls. Haemagglutination titre, IgM and IgG levels were monitored on the 5th day after an immune challenge by sheep red blood cells (SRBC) suspension. Antigen challenged lesioned animals had low circulating antibody titre levels compared with the controls and their site-specific sham lesioned groups. The IgM levels were significantly lowered in both DLH and VHF lesioned and immunized animals compared to their immunized sham groups as well as immunized controls. However, only immunized VHF lesioned group showed a significant decrease in IgG level from their immunized sham group. It was concluded from the results that an intact hippocampal region is essential for the normal humoral immunity for the primary immune response in rats. Probably VHF region may be required for the secondary immune response as indicated by the alteration in IgG levels in these animals.