Effects of central and peripheral administration of an acute phase protein, alpha-1-acid-glycoprotein, on feed intake and rectal temperature in sheep

No mechanistic link has tied inflammation to suppression of feed intake. In rodents, an acute phase protein, α-1-acid glycoprotein (AGP), could provide this link by acting as a leptin receptor agonist. The objective of these studies was to determine the effects of AGP on food intake and rectal temperature in sheep. In the first experiment ewes (n=4) received 1 of 4 treatments [0 (control), 0.012 (low), 0.06 (medium), or 0.30 (high) mg / kg BW AGP] into the lateral ventricle. The study was repeated until all sheep received all treatments. In the second experiment ewes (n=10) received one of two treatments (0 and 3 mg / kg BW of AGP) intravenously. In the third experiment ewes (n = 19) received peripheral treatments (IV) of an antipyretic [0 (control) or 2.2 mg / kg BW flunixin meglumine] 30 minutes prior to receiving central treatments (ICV) [0 (control) or 0.3 mg / kg BW AGP]. In the first experiment there was no effect of treatment on feed intake rate (P = 0.37) or cumulative feed intake (P = 0.31). There was an effect of treatment on rectal temperature (P = 0.002) such that rectal temperatures were greater (P < 0.05) following the high dose of AGP. In the second experiment there was no effect of treatment on feed intake rate (P = 0.98), on cumulative feed intake (P = 0.41) or on rectal temperature (P = 0.71). In the third experiment there was an effect of central treatment (P < 0.0001) and an interaction of central treatment and time (P < 0.0001). There was no effect of peripheral treatments (P = 0.93) on rectal temperature, indicating that central AGP may increase rectal temperature in sheep by pathways that do not involve prostaglandins. Further research is needed to determine if AGP may be an important integrator of energy balance and inflammation.