Obesity and Changes of Alkaline Phosphatase
Activity in the Small Intestine of 40- and 80-day-old Rats Subjected to
Early Postnatal Overfeeding or Monosodium Glutamate
Š. MOZEŠ, Z. ŠEFČÍKOVÁ, Ľ. LENHARDT 1, Ľ. RAČEK
Institute of Animal Physiology, Slovak Academy of Sciences and 1Department
of Pathology, University of Veterinary Medicine, Košice, Slovak Republic
Received September 16, 2002
Accepted May 12, 2003
Summary
To investigate the relationship between development of obesity and the
small intestinal functions two experimental models of male Wistar rats
were used in the present work: 1) early postnatally overfed rats, nursed
from birth to weaning in small litters (SL, 4 pups/nest), and 2)
neonatally monosodium glutamate treated rats (MSG 2 mg/g b.w. administered
s.c. for 4 days after birth) submitted to the same early nutritional
manipulation. After weaning, all animals had free access to a standard
pellet diet and at 40 and 80 days of age their body weight, body fat
content and food consumption as well as changes of the brush-border-bound
duodenal and jejunal alkaline phosphatase (AP) activity were compared with
parameters of the offsprings raised under normal feeding conditions (NL, 8
pups/nest). At 40 and 80 days of age the postnatally overfed pups from SL
nests became heavier, displayed a significantly increased epididymal plus
retroperitoneal fat pad weight (P<0.01) and significantly higher AP
activity in both segments of the small intestine (P<0.01) in comparison
with rats nursed in NL nests, although their mean daily food intake did
not differ from that of non-obese rats during the postweaning periods
examined. In contrast, the same treatment of MSG rats had only a small
effect on late appearance of obesity, i.e. in early postnatally overfed
and normally fed MSG rats a similar pattern of body weight, food intake,
adiposity and AP activity was found after weaning. The effect of
MSG-treatment was also accompanied by the appearance of normophagia,
hypophagia and stunted growth on day 40 and day 80, respectively.
Moreover, the size of fat depots and the increase of brush-border-bound AP
activity in MSG rats belonging to the SL and NL groups was quantitatively
similar to the values size of these parameters observed in SL obese rats
subjected to early postnatal overnutrition. These results indicate that
postnatal nutritional experience (overnutrition) may represent a
predisposing factor in control rats from small litters for the development
of obesity in later life. Permanently increased small intestinal AP
activity observed after weaning in both models of obesity when hyperphagia
is not present suggest that these functional changes and associated
alterations in food digestion could be a component of regulatory
mechanisms contributing to the maintenance of their elevated body fat
weight.
Key words
Early postnatal overnutrition • Metabolic imprinting • Neonatal MSG
treatment • Alkaline phosphatase • Small intestine • Obesity
|