title: Acute and Chronic Effects of Dietary Lactose in Adult Rats Are not Explained by Residual Intestinal Lactase Activity.
abstract: Neonatal rats have a high intestinal lactase activity, which declines around weaning. Yet, the effects of lactose-containing products are often studied in adult animals. This report is on the residual, post-weaning lactase activity and on the short- and long-term effects of lactose exposure in adult rats. Acutely, the postprandial plasma response to increasing doses of lactose was studied, and chronically, the effects of a 30% lactose diet fed from postnatal (PN) Day 15 onwards were evaluated. Intestinal lactase activity, as assessed both in vivo and in vitro, was compared between both test methods and diet groups (lactose vs. control). A 50%-75% decreased digestive capability towards lactose was observed from weaning into adulthood. Instillation of lactose in adult rats showed disproportionally low increases in plasma glucose levels and did not elicit an insulin response. However, gavages comprising maltodextrin gave rise to significant plasma glucose and insulin responses, indicative of a bias of the adult GI tract to digest glucose polymers. Despite the residual intestinal lactase activity shown, a 30% lactose diet was poorly digested by adult rats: the lactose diet rendered the animals less heavy and virtually devoid of body fat, whereas their cecum tripled in size, suggesting an increased bacterial fermentation. The observed acute and chronic effects of lactose exposure in adult rats cannot be explained by the residual intestinal lactase activity assessed.
authors.affiliation: Danone Nutricia Research, PO Box 80141, 3508 TC Utrecht, The Netherlands. bert.vandeheijning@danone.com.
authors.forename: Bert J M
authors.initials: BJ
authors.lastname: van de Heijning
authors.affiliation: Danone Nutricia Research, PO Box 80141, 3508 TC Utrecht, The Netherlands. dianekegler@gmail.com.
authors.forename: Diane
authors.initials: D
authors.lastname: Kegler
authors.affiliation: Danone Nutricia Research, PO Box 80141, 3508 TC Utrecht, The Netherlands. lidewij.schipper@danone.com.
authors.forename: Lidewij
authors.initials: L
authors.lastname: Schipper
authors.affiliation: Danone Nutricia Research, PO Box 80141, 3508 TC Utrecht, The Netherlands. eline.voogd@danone.com.
authors.forename: Eline
authors.initials: E
authors.lastname: Voogd
authors.affiliation: Danone Nutricia Research, PO Box 80141, 3508 TC Utrecht, The Netherlands. annemarie.oosting@danone.com.
authors.forename: Annemarie
authors.initials: A
authors.lastname: Oosting
authors.affiliation: Danone Nutricia Research, PO Box 80141, 3508 TC Utrecht, The Netherlands. eline.vanderbeek@danone.com.
authors.forename: Eline M
authors.initials: EM
authors.lastname: van der Beek
mesh_terms: D000821:Animal Feed; D000818:Animals; D004032:Diet; D004334:Drug Administration Schedule; D005260:Female; D007422:Intestines / Q000201:enzymology*; D043322:Lactase / Q000378:metabolism*; D007785:Lactose / Q000009:adverse effects*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D043322:Lactase; D007785:Lactose
keywords: digestion; galactosyl xylose; infant milk formula; lactase; lactose; rats