Vol. 283, Issue 2, 692-697, 1997

Peptide YY Inhibits Intestinal Cl Secretion in Experimental Porcine Cryptosporidiosis Through a Prostaglandin-Activated Neural Pathway¹

Robert A. Argenzio, Martha Armstrong, Anthony Blikslager and J. Marc Rhoads

Department of Anatomy, Physiological Sciences and Radiology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina (R.A.A., M.A., A.B.), and Department of Pediatrics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina (J.M.R.)

Peptide YY (PYY) is a powerful inhibitor of intestinal secretion mediated by cAMP agonists such as vasoactive intestinal peptide and prostaglandin E₂. We hypothesized that PYY would attenuate the secretory diarrhea in piglet cryptosporidiosis, which is mediated by prostaglandins E₂ and I₂. Control and infected ileal tissues from piglets were studied in Ussing chambers. The addition of PYY to the serosal bathing solution abolished net Cl secretion in infected tissue. The inhibitory effect of PYY was eliminated with the prostaglandin synthesis inhibitor indomethacin and with the nerve conduction blocker tetrodotoxin. PYY completely blocked the antiabsorptive and secretory effects of the prostaglandin I₂ analog carbacyclin, which has previously been shown to operate through enteric nerve pathways in this tissue. In contrast, PYY had no inhibitory effect on the secretory responses induced by prostaglandin E₂ or vasoactive intestinal peptide. Results suggest that the antisecretory effects of PYY are mediated by inhibition of prostaglandin I₂ induction of enteric nerves. Thus, PYY may play an important role in moderating the secretory diarrhea in cryptosporidiosis.