Effect of dietary phytosterols on cell proliferation and protein kinase C activity in rat colonic mucosa.
The present study investigated the role of phytosterols in colonic cell proliferation and examined the possible role of protein kinase C (PKC) in this process. A total of 18 male Sprague-Dawley rats weighing 240-270 g were fed, for a period of 22 days, one of three experimental diets: a control diet, a diet supplemented with 0.2% cholic acid, or a diet supplemented with 0.2% cholic acid + 2% dietary phytosterols. Two hours before decapitation, animals were injected with 5'-bromo-2'-deoxyuridine (BrdU, 50 mg/kg body wt ip). Cell proliferation in the proximal colon was measured using a monoclonal antibody to BrdU. PKC activity in the proximal colonic mucosa was assayed using a myelin basic protein as a substrate. Cell proliferation was significantly increased by 276% with 0.2% cholic acid feeding compared with controls. The presence of 2% phytosterols in the diet abolished the cholic acid-induced hyperplasia. Cholic acid induced a 31% expansion of the proliferative zone. Only the cytosolic PKC was significantly lower in the phytosterol-fed group. Neither the total PKC nor the particulate PKC demonstrated an effect of phytosterols on enzyme activity. In conclusion, we found that dietary supplementation with 2% phytosterol has a significant protective effect on enhanced cell proliferation and that this effect is not mediated through the PKC system.
Awad
A B
AB
Nutrition Program, State University of New York at Buffalo 14214, USA. awad@acsu.buffalo.edu
Hernandez
A Y
AY
Fink
C S
CS
Mendel
S L
SL
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001973:Bromodeoxyuridine / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects*; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology; D003106:Colon / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D004032:Diet; D004435:Eating / Q000187:drug effects; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008297:Male; D010840:Phytosterols / Q000008:administration & dosage / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002793:Cholic Acids; D010840:Phytosterols; D011493:Protein Kinase C; D019826:Cholic Acid; D001973:Bromodeoxyuridine