The Contribution of the Pancreas and the Intestine to the Regulation of Lipolysis in Birds - I. Existence of Highly Potent Lipolytic Factors in Ileum Extracts

Abstract

Duck intestinal extracts were separated into three main peaks of proteins by chromatography on P6 BioGel columns. The first, which crossreacted with glucagon antibodies, gut "GLI", did not stimulate lipolysis in isolated chicken adipocytes. Both second and third peaks, corresponding to smaller molecular-size peptides were even more lipolytic than pancreatic glucagon.

Avian Adjustments to Cold

“…Inhibition is not, however, provided by insulin, which has high antilipolytic activity in mammals (McCumbee and Hazelwood 1978). A third pancreatic hormone, avian pancreatic polypeptide is antilipolytic in birds (McCumbee and Hazelwood 1978), as is a glucagonlike material found in the intestine (Krug and Mialhe 1975;Krug 1978). The physiological role of these substances in cold stress or exercise has not been investigated.…”

“…Harvey et al (1985) found increases in glucagon levels in exercising mallard ducks, suggesting a physiological role of glucagon under conditions of accelerated energy demand. Other hormones, or putative hormones that have lipolytic activity in birds and could potentially contribute to physiological regulation of lipolysis, include growth hormone (LeClerq 1984) and two intestinal peptides (Krug and Mialhe 1975;Krug 1978). Lipid mobilization can also potentially be modulated by altering levels of inhibitory hormones.…”

Roles of insulin and glucose in the regulation of plasma FFA in the duck

“…In addition, glucagon is a very strong lipolytic factor [3,21,22]. Fifteen minutes after a single IV injection of 2 ~tg glucagon/kg, plasma FFA are doubled, while adipose tissue of fed or fasted ducks responds in vitro to very low concentrations of the hormone [8], as low as 50 pg/ml. We have therefore tried to explain why total pancreatectomy is followed by such a delayed drop in plasma FFA [3].…”

“…1. Compensation for pancreatic glucagon by other lipolytic agents, the anterior pituitary and the intestine being possible sources [3,6,7,8] (APP being secreted in the fed animal [9], and somatostatin having been shown to have an indirect effect in mammals [10]).…”