Dopamine autoreceptors in the ventral tegmental area show subsensitivity following withdrawal from chronic antidepressant drug treatment

The suppression by apomorphine of food intake and eating time was used to assay the sensitivity of dopamine cell body autoreceptors during the course of treatment with DMI, amitriptyline and mianserin. Brief (2–4 days) DMI treatment enhanced the effects of apomorphine, administered systemically or centrally to DA cell body regions. During chronic DMI treatment (3–7 weeks) some evidence of autoreceptor subsensitivity was observed with systemic apomorphine, but not with central apomorphine. Responses to apomorphine applied systemically were reduced during withdrawal from chronic DMI, and responses to apomorphine applied to the ventral tegmental area were reduced during withdrawal from all three antidepressants. As evidence of DA autoreceptor subsensitivity was only observed reliably during withdrawal, this effect is unlikely to be of clinical importance.