Rodent nutritional model of non-alcoholic steatohepatitis: species, strain and sex difference studies.
OBJECTIVE
The methionine choline-deficient (MCD) diet leads to steatohepatitis in rodents. The aim of the present study was to investigate species, strain and sex differences in this nutritional model of non-alcoholic steatohepatitis (NASH).


METHODS
Male and female Wistar, Long-Evans and Sprague-Dawley rats, and C57/BL6 mice (n = 6 per group) were fed a MCD diet for 4 weeks. Control groups received an identical diet supplemented with choline bitartrate (0.2% w/w) and methionine (0.3% w/w). Liver pathology (steatosis and inflammation) and ultrastructure, liver lipid profile (total lipids, triglycerides, lipid peroxidation products), liver : body mass ratios and serum alanine aminotransferase (ALT) levels were compared between these groups.


RESULTS
The MCD diet-fed male rats developed greater steatosis (P < 0.001), had higher liver lipid content (P < 0.05) and had higher serum ALT levels (P < 0.005) than did female rats. Wistar rats (both sexes) had higher liver lipid levels (P < 0.05), serum ALT levels (P < 0.05), and liver mass : body mass ratios (P < 0.025) than did Long-Evans and Sprague-Dawley rats. In female groups, Wistar rats showed greater fatty change than did the other two strains (P < 0.05). All rats fed the MCD diet developed hepatic steatosis, but necrosis and inflammation were minor features and fibrosis was absent. Compared with Wistar rats, male C57/BL6 mice showed a marked increase in inflammatory foci (P < 0.001), end products of lipid peroxidation (free thiobarbituric acid reactive substances) (P < 0.005), and mitochondrial injury, while showing less steatosis (P < 0.005), lower hepatic triglyceride levels, (P < 0.005) and lower early lipid peroxidation products (conjugated dienes and lipid hydroperoxides; P < 0.005 and P < 0.01, respectively).


CONCLUSIONS
The Wistar strain and the male sex are associated with the greatest degree of steatosis in rats subjected to the MCD diet. Of the groups studied, male C57/BL6 mice develop the most inflammation and necrosis, lipid peroxidation, and ultrastructural injury, and best approximate the histological features of NASH.
Kirsch
Richard
R
Department of Anatomical Pathology, University of Cape Town, Cape Town, Western Cape, South Africa. rich@chempath.uct.ac.za
Clarkson
Vivian
V
Shephard
Enid G
EG
Marais
David A
DA
Jaffer
Mohamed A
MA
Woodburne
Vivienne E
VE
Kirsch
Ralph E
RE
Hall
Pauline de la M
Pde L
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D002796:Choline Deficiency / Q000150:complications; D004195:Disease Models, Animal; D005234:Fatty Liver / Q000209:etiology* / Q000235:genetics / Q000473:pathology; D005260:Female; D015227:Lipid Peroxidation; D008099:Liver / Q000378:metabolism; D008297:Male; D044342:Malnutrition / Q000150:complications*; D008715:Methionine / Q000172:deficiency; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D012737:Sex Factors; D013045:Species Specificity
D008715:Methionine; D000410:Alanine Transaminase