Blocking effect of naloxone, dihydroergotamine and adrenalectomy in lithium-induced hyperglycaemia and glucose intolerance in the rat

The direct effect of lithium administration on plasma glucose levels and glucose-induced insulin release, and the role of opioid and amine systems in these effects were examined in rats. Naloxone, an opiate antagonist, and dihydroergotamine, an alpha-adrenergic blocking agent, reversed the hyperglycaemia as well as the inhibition of glucose-stimulated insulin release induced by lithium. In adrenalectomized rats, administration of lithium induced hypoglycaemia and not hyperglycaemia as in the intact rats. The results suggest that the interaction of secreted endorphins with the sympathetic nervous system is the likely cause of the hyperglycaemia and the inhibition of the glucose-stimulated insulin release induced by lithium.