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Effects of acute and chronic morphine administration on glucose tolerance in mice
Abstract:
The effects of acute and chronic morphine treatment on glucose tolerance were investigated in mice. In acute experiments, a single dose of morphine (20 mg/kg i.p.) increased the serum and muscle glucose level. After glucose loading (1.5 g/kg), the rate of increase and the peak of serum glucose concentration were significantly lowered in morphine-treated mice, while the availability and the half-life of glucose were similar to those of controls. In morphine-dependent mice, the fasting serum and muscle glucose levels were similar to those of control but the liver glucose was significantly greater. After glucose loading the rate of increase in serum glucose level was faster and the availability of glucose was 10% greater than that in naive mice. Again, there was no difference in the half-life of serum glucose between naive and morphine-dependent mice.
Insights
Acute morphine increases glucose levels, impairing glucose tolerance. Chronic morphine dependence alters glucose metabolism, increasing liver glucose and enhancing glucose availability after loading in mice.
Area of Science:
- Endocrinology
- Pharmacology
- Metabolic Research
Background:
- Morphine, an opioid analgesic, is widely used for pain management.
- Its impact on glucose metabolism and tolerance is not fully elucidated.
- Understanding these effects is crucial for managing patients on opioid therapy.
Purpose of the Study:
- To investigate the acute and chronic effects of morphine on glucose tolerance in a mouse model.
- To differentiate the metabolic responses to single-dose versus long-term morphine exposure.
Main Methods:
- Acute morphine administration (20 mg/kg i.p.) and assessment of glucose levels.
- Glucose tolerance tests (1.5 g/kg glucose load) in acute and morphine-dependent mice.
- Measurement of serum, muscle, and liver glucose levels, glucose availability, and half-life.
Main Results:
- Acute morphine increased serum and muscle glucose; however, it lowered the peak and rate of increase in serum glucose post-glucose load.
- Morphine dependence showed similar fasting glucose but elevated liver glucose compared to controls.
- Morphine-dependent mice exhibited a faster serum glucose rise and 10% greater glucose availability after glucose loading.
Conclusions:
- Acute morphine administration impairs glucose tolerance by affecting glucose uptake and utilization.
- Chronic morphine dependence alters hepatic glucose production and enhances postprandial glucose availability.
- These findings highlight distinct effects of acute and chronic morphine on glucose homeostasis.