Thus, the present study demonstrated that adjuvant treatment with lithium prevented short-term and long-term aversive memory impairments, as well as open-field habituation memory, while also reestablishing BDNF, NGF, and GDNF expression in the hippocampus of an experimental rodent model of pneumococcal meningitis. The gene discussed is GDNF; the disease is pneumococcal meningitis.