Parenteral nutrition, brain glycogen, and food intake

M. M. Meguid, J. L. Beverly, Z. J. Yang, J. R. Gleason, R. A. Meguid and M. X. Yue Department of Surgery, University Hospital, State University of New York Health Science Center, Syracuse 13210. To determine whether brain glycogen concentrations change during parenteral nutrition, Fischer 344 rats with jugular vein catheters received 0.9 N saline or parenteral nutrition providing 100% of daily calories (PN-100). Rats were killed after 4 days of PN-100 and serially after PN-100 was stopped. Food intake decreased during PN-100 to approximately 15% of control, but total kilocalories eaten and infused over the 4-day PN-100 period was approximately 130% of control. Food intake of PN-100 rats remained low for 3-4 days post-PN-100. At the end of the 4-day PN-100 period, plasma glucose and insulin (P = 0.01) and whole brain glycogen (P < 0.005) were higher than but similar to control within 24 h of PN-100 being stopped. When PN-100 rats were not allowed to eat during the infusion period, plasma glucose was lower, plasma insulin higher, and brain glycogen content the same as in control rats after 4 days of PN-100. The increased brain glycogen was the likely consequence of the hyperglycemia and hyperinsulinemia during PN-100 and was not causally associated with the reduced food intake either during or immediately after PN-100.