Effects of imipramine treatment on delta-opioid
receptors of the rat brain cortex and striatum

by
Varona A, Gil J, Saracibar G, Maza JL, Echevarria E, Irazusta J.
Department of Physiology, Medical School,
University of the Basque Country, Bilbao, Spain.
Arzneimittelforschung 2003;53(1):21-5


ABSTRACT

Imipramine (CAS 113-52-0) is being utilized widely for the treatment of major depression. In recent years, there has been evidence of the involvement of the endogenous opioid system in major depression and its treatment. There is some evidence indicating that opioid receptors could be involved in the antidepressant mechanism of action. Regarding this topic, mood-related behavior of endogenous enkephalins seems to be mediated by delta-opioid receptors. In this work, the effects of subacute (5 day) and chronic (15 day) treatments of imipramine on the density and the affinity of the delta-receptors in the striatum and in the parietal and frontal cortices of the rat brain are described. Studied parameters (Bmax and Kd) were calculated by a saturation binding assay with the delta-opioid agonists [3H]-DPDPE (tyrosyl-2,6-3H(N)-(2-D-penicillamine-5-D-penicillamine)-enkephalin) as specific ligand and DSLET ([D-serine2]-D-leucine-enkephalin-threonine) as non-radioactive competing ligand. It was found that 15 days treatment significantly decreased the delta-opioid receptor density,without changing the affinity, in the frontal cortex of the rat brain. That decrease was confirmed by delta-opioid receptor immunostaining. These results suggest that delta-opioid receptors could play a role in the chronic action mechanism of imipramine.
D1
5-HT1a
Fluoxetine
Imipramine
Desipramine
TCAs v SSRIs
Antidepressants
Retarded depression
Selectivity or multiplicity?
Imipramine and enkephalin
Imipramine and depression
Noradrenaline and dopamine
Imipramine and dopamine d1
Antidepressants for pain-relief
Imipramine v DL-phenylalanine
Zinc, imipramine and depression
Imipramine plus amantadine (Symmetrel)
Venlafaxine (Effexor) analgesia and the opioid system
Tricyclic antidepressants as long-acting local anaesthetics


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