The locomotor effect of clonidine and its interaction with alpha-flupenthixol or haloperidol in the developing rat.

The interaction of clonidine with alpha-flupenthixol and haloperidol on the locomotion was investigation in the rat during postnatal development. A subcutaneous injection of clonidine 0.039--3.9 mu mol/kg produced a marked hypermotility in infant animals between day 1 and day 7 but hypomotility in animals older than 20 days. Pretreatment with alpha-flupenthixol and haloperidol significantly reduced clonidine-hypermotility in infants. In adult rats, clonidine-hypomotility were increased by a preceding administration of alpha-flupenthixol. It is suggested that intact function of both alpha-adrenoceptors and dopamine receptors is involved in the control of locomotor activity in developing rats and that there is the complex interaction of noradrenergic and dopaminergic system in the control of locomotor activity.