Effects of the interaction between methysergide and clonidine on growth hormone and prolactin secretion in normal man

The effects of methysergide (1 mg, p.o.), clonidine (50 micrograms, i.m.) and methysergide plus clonidine on growth hormone (GH) and prolactin (PRL) secretion in 8 normal male volunteers have been studied. Both methysergide and clonidine were found to enhance GH and to lower PRL plasma levels. The effects of methysergide are explained on the basis of a preferential action of methysergide metabolites on dopamine receptors, whereas the effects of clonidine are attributed to a stimulatory action on adrenaline receptors. The combined treatment methysergide plus clonidine resulted in a potentiation of the effects caused by the drugs when administered alone.