Studies on epidermal growth factor and the porcine upper gastrointestinal tract
Abstract
The factors controlling growth and maturation in the porcine gastrointestinal tract are not well-understood. Epidermal growth factor (EGF) is a polypeptide which has been implicated in the control of gastrointestinal growth, maturation, and protection in other species. The objective of these studies was to gain an understanding of the role that EGF might play in the upper gastrointestinal tract of young pigs by (1) quantifying EGF-like activity in porcine mammary secretions, (2) determining the effect of ingested EGF on jejunal disaccharidases in weanlings, and (3) identifying immunoreactive EGF (IR-EGF) and EGF receptors (EGF-R) in tissues of the upper digestive tract. Through the use of a radioreceptor assay, EGF-like activity was detected at high levels in colostrum and at significantly (P $\le$ 0.01) lower, unchanging concentrations in milk collected 9, 18, and 27 days postpartum. EGF administered orally to 21-day-old weanling pigs beginning the day of weaning, significantly (P $\le$ 0.05) increased jejunal lactase and sucrase activities on the third postweaning day when compared to weanling controls. In the third study, IR-EGF and EGF-R were immunohistochemically identified in formalin-fixed tissues of pigs which were 1-, 3-, 7-, 14-, 21-, and 28-days-old. The ductal epithelium consistently contained IR-EGF in the parotid salivary gland of all ages and in the mandibular salivary gland in pigs 7 days of age and older. Immunoreactive EGF was present in the mucosal epithelium of the esophagus and non-glandular stomach, and in the pancreas and liver in all pigs. Gastric gland IR-EGF was inconsistently present in pigs less than 14 days of age and routinely present thereafter. Enterocyte EGF immunoreactivity was usually weak and variably present in the duodenum of pigs 7 days old and less, in the jejunum of pigs 14 days and less, and was consistently observed in older pigs. Ileal reactivity was erratic. Immunoreactive EGF-R were present in the esophageal epithelium of all pigs, and in the non-glandular gastric and glandular gastric mucosae of all pigs except for two 7 day pigs and one 7 day pig, respectively. Immunoreactive EGF-R were detected in the duodenal, jejunal, and ileal enterocytes of all ages of pigs examined.
Degree
Ph.D.
Advisors
Lamar, Purdue University.
Subject Area
Anatomy & physiology|Veterinary services
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