Treatment with gut-specific nonsteroidal anti-inflammatory drug attenuates metabolic inflammation but not body mass in fattening ground squirrels.

The active season of hibernators corresponds to rapid adiposity in preparation for the next hibernation season. We have previously shown that this dramatic increase in adipose mass is associated with metabolic inflammation similar to what is seen in obesity and metabolic disease. We next sought to determine whether curbing this inflammation at its source (i.e., the gut) would attenuate weight gain in fattening 13-lined ground squirrels ( Ictidomys tridecemlineatus ). We fed active yearling ground squirrels a diet containing the gut-specific nonsteroidal anti-inflammatory drug mesalazine (5-aminosalicylic acid) for 10 wk. Mesalazine treatment had slight effects on microbial community diversity in the cecum and colon. Not surprisingly, mesalazine treatment decreased inflammatory cytokine levels in the ileum and colon. Mesalazine also decreased proinflammatory and increased anti-inflammatory cytokines in omental white adipose tissue (oWAT). Despite this, body mass was unaffected, and caloric intake increased in mesalazine-treated squirrels, mainly in males. Mass of the primary WAT depot, intra-abdominal WAT (iaWAT), or the highly metabolic oWAT were unaltered by treatment, as was adiposity index. Together, these results suggest that mesalazine treatment has some effects on adiposity in fattening ground squirrels, but this treatment needs to be modified to overcome the strong drive to fatten in this species. NEW & NOTEWORTHY Adiposity and obesity are caused, at least in part, by inflammation of metabolic tissues. Hibernators, like ground squirrels, undergo this same metabolic inflammation during their summer fattening period. We attempted to curb this inflammation, and thus fattening, using mesalazine. We found that mesalazine did curb the inflammation but did not affect fattening, likely due to the strong drive to fatten in hibernators.