115. Dissociation between learning and memory impairment and other sickness behaviours during simulated central Mycoplasma infection in rats

Abstract

Despite the fact that multiple strains of Mycoplasma activate the immune system and cause disease, surprisingly little is known about the pathophysiology of sickness behaviours in Mycoplasma -induced infections. There is evidence linking two particular strains of Mycoplasma , namely Mycoplasma pneumoniae ( M. pneumoniae ) and Mycoplasma salivarium ( M. salivarium ) with inflammation of the central nervous system (CNS). Using a rodent model to simulate infection, the aim of our study was to determine the pathophysiological effects of simulated M.pneumoniae and M. salivarium infection within the CNS, by measuring body temperature, physical activity, growth, as well as memory in rats. Male Sprague–Dawley rats (∼300 g) were randomly assigned to receive FAM-20 (10 μ g5 μ l), a moiety derived from M. pneumoniae , or FSL-1 (10 μ g/ μ l), a moiety derived from M. salivarium , or vehicle, via the cisterna magna. Body mass and food intake were measured daily. Administration of either FAM-20 or FSL-1 induced a fever (∼1 °C), lethargy (∼80%) and anorexia (∼60%) for three to four days, and body mass stunting (∼7%) for at least seven days. Memory consolidation of the hippocampal-dependent contextual fear-conditioning task was not significantly impaired in the rats seven days after administration of either FAM-20 or FSL-1. Our results support emerging evidence showing dissociation between learning and memory impairment and other sickness behaviours during infection, which may be linked to interleukin-1 beta synthesis in the brain during infection.