Plasma insulin and glucagon responses to intravenous infusion of propionate and their autonomic control in sheep1

Abstract

Propionate (0, 1, 2, 4, 8, 16, 32, and 64 mumol.kg BW-1 x min-1 for 30 min) was infused i.v. to investigate the physiological effects of propionate on insulin and glucagon responses in sheep. An i.v. propionate infusion (32 mumol.kg BW-1 x min-1 for 30 min) with adrenergic and cholinergic blockades was also conducted to clarify the role of autonomic innervation in the control of propionate-induced insulin and glucagon responses. In the experiment in which we studied responses to propionate infusion, the concentrations of plasma insulin and glucagon during propionate infusion increased (P < .05) from the preinfusion concentrations at infusion rates of > 4 and 8 mumol.kg BW-1 x min-1, respectively. The incremental response areas of plasma insulin and glucagon during propionate infusion increased (P < .05) at infusion rates of > 16 and 32 mumol.kg BW-1 x min-1, respectively. In the experiment studying the effects of adrenergic and cholinergic blockades on responses to propionate, the insulin incremental response area during propionate infusion was suppressed (P < .05) by atropine infusion but it was not influenced by phentolamine, propranolol, or hexamethonium infusions. The glucagon response area was suppressed (P < .05) by phentolamine infusion, but it was not influenced by propranolol, atropine, or hexamethonium infusions. It is concluded that in sheep 1) propionate may have a physiological role in stimulating insulin and glucagon responses, 2) the propionate-induced insulin response is partly due to the parasympathetic nervous system through activation of a muscarinic receptor, and 3) the propionate-induced glucagon response is stimulated by adrenergic alpha-receptors.

Changes in Blood Values of Glucose, Insulin and Inorganic Phosphorus in Healthy and Ketotic Dairy Cows after Intravenous Infusion of Propionate Solution

“…After propionate infusion the significant increase of the concentration of glucose in blood occurs in both groups of cows, which clearly shows that propionate in the liver converts into glucose, which is in accordance with the results of other authors (Peters et al 1983;Peters and Elliot 1984;Sano et al 1993;Šamanc et al 1996).…”

“…The insulin concentration in blood is reduced in ketotic cows, compared to healthy animals before and after infusion of a glucose solution (Hove 1978;De Cupere et al 1991;Šamanc et al 1996). Similar results have been reported by other authors after intravenous infusion of propionate solution, because propionic acid directly stimulates pancreatic secretion of insulin in ruminants (Peters et al 1983;Peters and Elliot 1984;Sano et al 1993;Šamanc et al 1996;Lee and Hossner 2002).…”

“…Propionate loading test in ruminants is used for estimating the intensity of gluconeogenesis in the liver, such as the ability of endocrine pancreas for synthesis and secretion of insulin (Gröhn 1985;Sano et al 1993;Šamanc et al 1996;Constable 2000). The ability of endocrine pancreas for insulin release after intravenous infusion of glucose is well known.…”

Effect of supplemental calcium propionate on insulin action to blood glucose metabolism in adult sheep

“…However, the effects of supplementation and intraruminal infusion of propionate on blood glucose kinetics are not persistent in ruminants [6][7][8]. Intraruminal and intravascular infusions of propionate increase the release of insulin and glucagon [9,10]. Therefore, it is probable that propionate status in the rumen influences blood glucose metabolism and its endocrine control, and plays an important role in ruminant production.…”

Comparison of Enzyme Activities in Plasma and Leukocytes in Dairy and Beef Cattle

“…In the present study, plasma IRI concentrations in beef cattle at 24 mo of age were significantly higher than those in Holstein dairy cattle. Although infusion of glucose does not stimulate insulin secretion, infusion of the VFA propionate, but not acetate, stimulates insulin secretion in ruminants [16]. When a roughage diet was fed, the proportion of propionate as gluconeogenesis source in the rumen VFA was low compared with a concentrate-based diet fed to ruminants [21].…”