Jm. Oldham et al., POSTNATAL AGE AND FOOD-INTAKE ALTER INSULIN-LIKE GROWTH FACTOR-II MANNOSE-6-PHOSPHATE RECEPTORS IN OVINE SKELETAL-MUSCLES/, Growth regulation, 6(2), 1996, pp. 88-95
In female lambs aged from 2 days to 2 years, specific binding of I-125
-IGF-II in muscle fibre and connective tissue of M. biceps femoris and
M. gastrocnemius was demonstrated using histological autoradiography.
The binding site was characterized as the IGF-II/M6P receptor in memb
rane preparations using competitive displacement assay and SDS-PAGE. I
n both muscles, I-125-IGF-II binding was more abundant in connective t
issue than muscle fibre (P less than or equal to 0.001). Levels change
d significantly with age in all cell types studied (P less than or equ
al to 0.001), while changes as a result of fasting were limited to a d
ecrease in binding to the connective tissue of M. biceps femoris (P le
ss than or equal to 0.01). The overall decline of I-125-IGF-II binding
with increasing age is correlated with a slowing of postnatal growth,
while the reduction in I-125-IGF-II binding with fasting may be assoc
iated with modulating growth and composition of connective tissue, or
increasing the bioavailability of IGF-II to specific muscles.