Regulation of Inflammatory Genes in Trigeminal Ganglion Neurons and Glia in Response to Cocoa Enriched Diets

Rats fed a diet enriched in cocoa have shown a decreased response to both chronic and acute inflammatory stimulus. The goal of my study was to identify the effects of a diet enriched in cocoa on neurons and glia of the trigeminal ganglion in response to inflammatory stimuli. Rats were fed a control diet, 1% cocoa, or 10% cocoa diet for 14 days prior to either an injection of capsaicin or CFA in either the V1 or V3 innervated regions of the face. Using immunohistochemistry, levels of several signaling proteins MKP1, MKP2, MKP3, active ERK, p38 and JNK as well as iNOS, and CGRP, were determined in the trigeminal ganglion. Expression of MKP1, and 3 were increased in response to both cocoa diets, while expression of p38, ERK, CGRP, and iNOS were decreased. Importantly, expression of MKP1, an anti-inflammatory protein, was increased basally in both neurons and glial cells. Results from my study provide evidence that cocoa may block peripheral sensitization through increases in MKP1, MKP2, and MKP3. Consistent with this, the expression of the inflammatory genes iNOS and CGRP were also decreased in rats on the high cocoa diet in response to acute and chronic inflammatory stimuli. Furthermore, my data suggests that cocoa may have important implications for the prevention of migraine and TMJ disorders. To my knowledge, this is first evidence to demonstrate that a dietary supplement can cause an up regulation of MKPs and thus is likely to have preventative affects on inflammatory and nociceptive responses during chronic and acute inflammation