Abstract: 92

INTERACTIONS BETWEEN THE VAGUS NERVE, CHOLECYSTOKININ, AND NON-ESTERIFIED FATTY ACIDS IN EWE LAMBS.

BJ Holmberg¹ , DH Keisler¹
Department of Animal Science, University of Missouri, MO ¹

The vagus nerve is a neural link between the gastrointestinal system and the brain, consisting of both efferent and afferent fibers. Interruption of this pathway induced dissimilar patterns of LH secretion in the monogastric and ruminant. Transection of the vagus nerve in fasted rats resulted in an immediate increase in LH secretion, while ewe lambs exhibited a dramatic decrease in LH secretion independent of body condition. The goals of this study were to 1) determine if the loss of vagal transmission or hypomotility of the gut created an artificial anorexic state that was in turn responsible for the decrease in LH and 2) examine peripheral CCK release in response to vagotomy. The vagus nerve of sixteen ovariectomized ewe lambs was isolated during thoracic surgery by placing suture loops around the nerve. On treatment day 1 (period 1), blood samples were collected for 4h, the suture loops were pulled to transect the nerve, and ewes were sampled for an additional 4h (period 2). On d3 and d5 (periods 3 and 4, respectively), blood sampling was repeated for 4h, and serum samples were assayed for LH, CCK, and NEFA. NEFA are an estimate of fat mobilization from adipose tissue in response to decreased feed intake or nutrient absorption. Concentration of CCK among periods in all ewes changed over time after vagotomy (2.13 ± .33 pg/ml, 2.08 ± .57 pg/ml, 1.96 ± .58 pg/ml, 1.61 ± .42 pg/ml in periods 1,2,3, and 4 respectively). NEFA among all ewes over days did not increase with vagotomy and actually decreased during period 3 (P < 0.02). Across days, R lambs had greater mean NEFA levels compared to F lambs (P < 0.001). These data provide evidence to support the hypothesis that the decreased LH in vagotomized ewe lambs was due to nerve transection and not a pseudo-starvation state.

    This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.