Changes of Insulin Binding in
Rat Tissues After Exposure to Stress
L. MACHO, M. FICKOVÁ, Š. ZÓRAD,
R. KVETŇANSKÝ
Institute of Experimental Endocrinology, Slovak
Academy of Sciences, Bratislava, Slovak Republic
Received July 7, 1998
Accepted September 15, 1998
Summary
The effects of various stressors on insulin receptors in
adipose, liver and skeletal muscle tissues were studied in rats
exposed to acute or repeated stress. Adult male rats were
exposed to immobilization (IMO) for 2.5 hours daily for 1, 7 and
42 days, or to hypokinesia (HK) for 1, 7 and 21 days. We
determined the values of specific insulin binding (SIB) and
insulin receptor binding capacity (IR) of plasma cell membranes
from adipose, liver and muscle tissue (IMO groups), or insulin
binding to isolated adipocytes and hepatocytes (HK groups). A
significant decrease of SIB and IR was observed in rats exposed
to acute stress (1x IMO) in muscle, adipose and liver tissues.
However, in animals exposed to repeated stress (7x and 42x IMO),
SIB and IR were diminished in the muscle tissue, whereas no
significant changes were noted in the liver and adipose tissue.
When tissue samples were collected 3-24 hours after exposure to
IMO stress, no changes of SIB and IR were found in liver and
adipose tissue, but insulin binding was lowered in skeletal
muscles. In animals exposed to HK for one day, a decrease of SIB
and IR was found in isolated adipocytes, but no changes in
insulin binding were noted in the liver tissue. In rats exposed
to HK for 7 and 21 days, values of IR were similar as in control
group. Our results indicate a) the different changes of IR in
the liver, fat and muscle tissues after exposure to stress
situations, b) a long-term decrease of insulin binding in
muscles of rats exposed to repeated IMO stress, and c) the
return of reduced SIB and IR (induced by acute stress) to
control values in the liver and adipose tissue after a short
recovery period.
Key words
Stress – Insulin binding – Muscle – Liver – Adipocytes
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