AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 3 676-R682, Copyright © 1993 by American Physiological Society
Postnatal development of uncoupling protein, uncoupling protein mRNA, and GLUT4 in adipose tissues of goats
P. Trayhurn, M. E. Thomas and J. S. Keith
Division of Biochemical Sciences, Rowett Research Institute, Bucksburn, Aberdeen, United Kingdom.
Adipose tissues have been characterized in newborn goats on the basis of
the presence of the 32,000-M(r) mitochondrial uncoupling protein (UCP)
diagnostic of brown fat, and early postnatal developmental changes have
been determined. Both internal (perirenal, pericardial, and omental) and
subcutaneous (hindlimb and neck regions) adipose tissues in newborn goats
contained UCP and are therefore brown fat. The insulin-sensitive glucose
transporter, GLUT4, was also present in adipose tissues of newborn goats,
implying a potential for insulin-stimulated glucose uptake at birth. UCP
was still evident in the perirenal fat of goats at 3 wk of age, but the
mitochondrial concentration was only 4%, and the amount per cell a mere
0.2%, of that in the newborn. UCP was not detectable, however, in either
the omental or subcutaneous adipose tissue at 3 wk of age and had
disappeared from the subcutaneous fat before 2 wk. In contrast to UCP,
GLUT4 remained throughout the initial 3 wk of postnatal life. The mRNA for
UCP was detected in perirenal adipose tissue of newborn goats, indicating
that the gene coding for the protein is being expressed at around birth.
UCP mRNA was not, however, detectable in the other fat depots; nor was it
evident in the perirenal adipose tissue at > or = 2.5 days of age. It is
concluded that the adipose tissues of newborn goats (both internal and
subcutaneous) represent brown fat and that there is a rapid transition
toward white fat over the first weeks of life. This transition occurs at
different rates in different depots but is not markedly faster in goats
than in other ruminants.(ABSTRACT TRUNCATED AT 250 WORDS)
