9 1988 by The Humana Press Inc. All rights of any nature, whatsoever, reserved. 0163-4984/88/1800-0115502.00 Zinc Deficiency Is Associated with Suppression of Colonocyte Proliferation in the Distal Large Bowel of Rats MICHAEL J. LAWSON, *'~ ROSS N. BUTLER, 1 GARY J . GOLAND, ~ IVAN G. JARRETT, ~ IAN C. ROBERTS-THOMSON, ~ ERIC J. PARTICK,2 AND IVOR E. DREOSTI 2 'Department of Gastroenterology, The Queen Elizabeth Hospital, Woodville SA, Australia 5011; and 2CSIRO (Australia), Division of Human Nutrition, Kintore Avenue, Adelaide SA, Australia _5001 Received April 2, 1988; Accepted May 8, 1988 ABSTRACT As zinc status may influence susceptibility to colon cancer, we examined the effect of dietary zinc deficiency on the proliferation of epithelial cells (colonocytes) in the large bowel of rats. When com- pared to feed-restricted rats, those with zinc deficiency showed a sig- nificant reduction in proliferation in the distal colon as assessed by accumulated metaphase arrest and crypt cell production rates in vivo. Zinc deficiency had no apparent effect on thymidine kinase activity in colonocytes but was accompanied by minor changes in fecal mass and fecal pH. In rats, zinc deficiency is associated with a reduction in the rate of proliferation of colonocytes in the distal colon. Index Entries: Colonocyte proliferation; zinc deficiency; volatile fatty acids; thymidine kinase activity. *Author to whom all correspondence and reprint requests should be addressed. Supported by a grant from the National Health and Medical Research Council of Aus- tralia. Biological Trace Element Research 1 1 5 Vol. 18, 1988