Innervated liver plays an inhibitory role in regulation of food intake

BACKGROUND: With the onset of eating, the associated rise of dopamine in the lateral hypothalamus (LHA-DA) is thought to regulate quantity of food consumed per meal. Early release of LHA-DA induced by eating is facilitated by oronasal stimulation; we propose that the subsequent LHA-DA response induced by nutrients in the portal vein is dampened by the innervated liver. This was tested by measuring LHA-DA in normal rats: during parenteral feeding to bypass oronasal stimulation, while eating during parenteral feeding, and while eating only. METHODS: Rats had either total liver denervation or sham operation, with placement of a jugular vein catheter and LHA-DA microdialysis cannula. After a 3-week recovery period total liver denervated rats were randomized to parenterally fed, food only, and parenteral plus food groups each with sham-operated controls in which LHA-DA was measured. RESULTS: No difference in LHA-DA release in food only groups occurred between total liver denervated or sham-operated rats. A significantly higher rise in LHA-DA was observed in total liver denervated versus sham-operated rats in parenterally fed (129% +/- 4% versus 116% +/- 2%; p < 0.05) and parenteral plus food (151% +/- 4% versus 134% +/- 4%; p < 0.05) groups. CONCLUSIONS: In total liver denervation versus sham operation, an increase in LHA-DA release occurs during parenteral feeding and eating during parenteral feeding, suggesting that innervated liver inhibits LHA-DA release.