Protective Effect of Minocycline Against Bacterial Infection-Induced Sickness Behavior in Rats

Many studies suggest that bacterial infection generate adverse effects on the cognitive, behavioral and emotional status. Inflammation, oxidative stress and altered level of immune-cytokines are involved in the pathogenesis of sickness behavior in rats. Minocycline is a broad spectrum second generation semi synthetic derivative of the bacteriostatic antibiotic tetracycline. The present study aimed to determine effects of minocycline on neurobehavioral and some other related parameters in bacterially infected and noninfected rats. The levels of Interferon gamma (IFN ) and nitric oxide (NO) were assessed in brain tissue, serum C-reactive protein (CRP) as well as total and differential leukocytic counts (WBCs), also brain histopathological examination was evaluated. Male Sprague-Dawley rats received (90mg/kg) p.o. minocycline for three days. The infected animals were intraperitoneally injected 48 hours before sacrificing with 200 μl of E. coli 24 hours bacterial culture in nutrient broth containing approximately 1.8 x 10 cfu / ml. Animals were divided into four 8 groups: (1) Control group, (2) Escherichia coli infected group, (3) Minocycline treated group, (4) Minocycline and Escherichia coli treated group. The results revealed that minocycline blocked bacterial infection-associated sickness behavior in rats, reduced signs of cognitive impairment, decreased CRP, IFN , NO and total leucocytic count (WBCs).