Responses of celiac and cervical vagal afferents to infusions of lipids inthe jejunum or ileum of the rat

Multiunit celiac and single-unit cervical recordings of vagal afferents mer e performed before and during infusions of fatty acids, triglycerides, or s aline into either the ileum or jejunum of the rat. In multiunit recordings, lipids increased activity of vagal afferents to a greater extent than sali ne. The greatest increases in vagal afferent activity resulted from infusio ns of linoleic acid, conjugated linoleic acid, or oleic acid. The triglycer ides, corn oil or Intralipid, were less effective than the fatty acids in a ffecting vagal afferent activity. Ileal pretreatment with the hydrophobic s urfactant Pluronic L-81 significantly attenuated the response of celiac vag al afferents to ileal infusion of linoleic acid. Single-unit recordings of cervical vagal afferents supported the multiunit, data in showing lipid-ind uced increased vagal afferent activity in similar to 50% of ileal units sam pled and 100% of a limited number of jejunal units sampled. These data demo nstrate that free fatty acids can activate ileal and jejunal vagal afferent s in the rat, and this effect can be attenuated by pretreatment with a chyl omicron inhibitor. These data are consistent with the view that lipid-induc ed activation of vagal afferents could be a potential substrate for the inh ibitory effects of intestinal Lipids on gastrointestinal function, food int ake, and body weight gain.