Lack of effect of morphine, reserpine, and halothane on oscillation of plasma insulin in M. mulatta.
Oscillating plasma insulin levels, with periods averaging 9 min, in fasting rhesus monkeys have been previously reported by us. To test whether an oscillator in the central nervous system might be driving these oscillations, we subjected five male rhesus monkeys to morphine, reserpine, and halothane, agents known to affect the central nervous system, in an attempt to either disrupt or change the frequency of the oscillations. We could demonstrate no significant effect of any of the three drugs on the oscillations. We conclude, therefore, that the oscillations in plasma insulin are not driven by an oscillator in the central nervous system. Coupled with the results of others, these data suggest that these oscillations are probably due to an intrinsic pancreatic pacemaker.
D000818:Animals; D002490:Central Nervous System / Q000187:drug effects; D006221:Halothane / Q000494:pharmacology*; D007328:Insulin / Q000097:blood*; D007515:Islets of Langerhans / Q000294:innervation; D008253:Macaca mulatta; D009020:Morphine / Q000494:pharmacology*; D010507:Periodicity; D012110:Reserpine / Q000494:pharmacology*
D007328:Insulin; D009020:Morphine; D012110:Reserpine; D006221:Halothane