Correlation of changes in alpha 2-adrenoceptor number and locomotor responses to clonidine following clorgyline discontinuation.

[3H]-clonidine binding in vitro and the locomotor response to clonidine in vivo were studied over an eight week period following four weeks of treatment with the monoamine oxidase-inhibiting antidepressant, clorgyline (1 mg kg-1 day-1). Long-term clorgyline administration caused decreases in responsiveness to clonidine and in the number of alpha 2-adrenoceptors; these changes reverted towards pretreatment values very gradually over an eight week period following discontinuation of the drug. This study provides some of the first detailed evidence regarding the slow return of adaptional changes following discontinuation of an antidepressant drug in animals and has implications for understanding some delayed drug interactions associated with MAO-inhibiting antidepressants in man.