Summary
Recent reports have indicated that genetically obese hyperinsulinemic mice (ob/ob)
and Zucker rats (fa/fa) compared with their lean controls have elevated levels of
pituitary and plasma B-endorphins, opiates that can stimulate insulin secretion. In
this study we have measured opiate levels by a radio-receptor assay in gastro-intestinal
tissues and pancreas in ob/ob and fa/fa animals and their controls. Ob/ob mice showed
significantly higher levels than control mice (+/+) in most gastro-intestinal tissues
and pancreas. Levels in fa/fa rats did not differ from their controls. Radioimmunoassay
of pancreas for B-endorphins, revealed higher levels in ob/ob vs +/+ mice, while there
was no difference in the obese and lean rats. Fasting tended to decrease gastro-intestinal
opioids in mice, while B-endorphin levels rose.
It is concluded that opiates may play a significant role in the obesity of the ob/ob
mouse and that this genetic obesity differs from that in Zucker rats.
Key-Words:
Genetic Obesity
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Tissue Opiates
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fa/fa
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ob/ob
