Nociceptive Thresholds of the Response to Lipopolysaccharide Injection into the Limbic Structures of the Brain in Rats

Microinjections of LPS into the limbic structures of rat brain (dorsal hippocampus and caudal compartment of the cingulate fascicle) caused opposite effects on the nociceptive thresholds: injection into the dorsal hippocampus enhanced perception and reduced the emotional affective perception of pain, while injection into the cingulate fascicle reduced the perceptual and enhanced the emotional components of the nociceptive reaction. These results indicated specific involvement of these limbic structures in nociception modulation during induction of the immune response in CNS.