Blood levels of gastrointestinal hormones and cachectin in piglets infected with Ascaris suum Goeze 1782

Shiguang Yang, Purdue University

Abstract

Anorexia in severe Ascaris suum infections of pigs results in heavy economical losses in the swine industry. The mechanism by which this anorexia is induced has not been determined. The present studies were designed to observe the effects of those infections on serum gastrointestinal (GI) hormone changes and on serum TNF/cachectin like cytotoxicity (TNFLC). A total of 96 piglets were used in eight separate but related experiments. Serum or plasma levels of GI hormones (gastrin, insulin, glucagon, and cholecystokinin) were determined in A. suum infected and non infected pigs by radioimmunoassays (RIA), and serum TNFLC was measured by a modified bioassay. Infected pigs were divided according to the inoculation dose into two groups: low dose infected (LDI) and high dose infected (HDI) groups and feed consumption was determined in each group. In Exp 1, Caesarian derived piglets were employed and no significant differences in the serum gastrin and insulin levels were seen between infected and control groups. These observations were confirmed in Exp 4, where normal farrowed pigs were used. In Experiments 2 and 3, intravenous and intraperitoneal infusion of test serum into normal healthy pigs (NHP) resulted in some decrease in feed intake in those NHP infused with serum from A. suum infected pigs but the differences were not statistically significant. In Experiments 5 to 8, however, serum levels of GI hormones, such as gastrin and cholecystokinin, showed some significant differences between infected pigs and controls. Gastrin levels in infected pigs were lower than in the controls 7-17 days after the first dose of infections (PFI). Serum insulin levels in the infected groups were sometimes lower than in the controls. Serum glucagon levels in infected pigs were often lower than in the controls during the last two weeks in experiments. Serum cholecystokinin (CCK) levels were significantly higher in the LDI group than in the controls 10 days PFI and the difference lasted to the end of the experiment. During that period the LDI pigs consumed less feed. The HDI group did not have significantly different CCK levels from the control except for one day. Although no statistical difference was observed in the levels of TNFLC between the sera of A. suum infected and non infected pigs, there was a difference in the groups' responses to endotoxin challenge. The TNFLC levels in the infected group returned to prechallenge levels much earlier than the non infected. Infected pigs had lower feed consumption, lower weight gain, and lower feed efficiency than controls. The LDI pigs consistently showed more severe ascariasis signs and worse performance than the HDI groups.

Degree

Ph.D.

Advisors

Gaafar, Purdue University.

Subject Area

Animal diseases

COinS