Does obesity affect the mucin secretion of the rat intestinal mucosa?

The gastrointestinal tract plays a key role in obesity through itscontributions to satiety, production of gut hormones, absorptionof nutrients, changes in microbiota and their metabolic products.There are many gastrointestinal diseases for which obesity is asignificant risk factor. Several data demonstrated that high-fatdiet (HFD) induced obesity causes gut hyper-permeability andsubclinical mucosal inflammation. In addition, nutritional factorsare suggested to induce neuroplastic changes in the enteric nerv-ous system (ENS). In our study we used diet-induced obesity (DIO) rats as a model to explore possible effects of HFD on thegastrointestinal system. The research interest was mainlyaddressed to point out modulations of the mucous secretion bythe secreting goblet cells (GC) of the intestinal mucosa. Theinvestigation was performed applying both lectins as marker forsialic acid recognition and antibodies useful to characterize theGC secretory products and secretion regulatory factors.Plasticity within myenteric and submucosal plexus were alsoinvestigated by an immunochemical approach. The analysis of theepithelium glucidic profile revealed a higher occurrence of sialo-glycoconjugates, characterized by Sia-D-Gal(ß1,3)-D-GalNActerminal sequences, in the duodenum and jejunum of DIO ratscompared with the controls, while a general weaker expression ofsialic acid 2,3-linked to D-Gal was found in the proximal colonof rats fed a HFD, than in controls. A distinctive features of sucha decrease is the quite complete loss of staining in the GCs. Amodulation of the parameters relative to the mucous secretionwas also observed: in DIO rats, a higher production of Muc2, themajor secretory gel-forming mucin, was observed in GCs of theproximal colon respect to the control rats. Likewise, only prelim-inary data have been obtained on modulation of the ENS in DIOrats. The hypothesis that leptin may contribute to membrane-associated and secreted mucin production via the activation ofleptin receptors may be suggested as a perspective for furtherinvestigation.