The effect of a 24 hr starvation period on islet lysosomal enzyme activities and the
in vivo insulin response to glucose, glibenclamide and L-isopropyl-noradrenaline (L-IPNA)
was studied in mice. It was observed that fasting induced a significant decrease of
islet acid amyloglucosidase activity, whereas the activities of acid phosphatase,
(β-N-acetyl-glucosaminidase, and β-glucuronidase in islet tissue were unaffected by
the fasting period studied. Starvation markedly reduced the acute insulin response
to a maximal dose of glucose or glibenclamide. However, the insulin response to a
maximal dose of L-IPNA was of similar magnitude in both fed and fasted animals. Pretreatment
of fasted mice with purified fungal acid amyloglucosidase could restore the impaired
insulin response to glucose to the normal level seen in fed mice. It is suggested
that islet acid amyloglucosidase activity is of importance for glucose-stimulated
insulin secretion, and that reduced levels of islet amyloglucosidase may contribute
to the impairment of glucose-induced insulin release seen after fasting.
Insulin Secretion
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Islet Acid Amyloglucosidase
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Acid Phosphatase
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β-N-Acetylglucosaminidase
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β-Glucuronidase
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Glucose
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Fasting
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Mice
