Imidazoline receptors: possible involvement in the pathophysiology and treatment of depression

Abstract

Imidazoline receptors (IR), a novel family of non-adrenergic receptors, are present in brain, especially the limbic system, and platelets among other organs. Their functions include central mediation of blood pressure control and possibly modulation of affective symptomatology. Studies of unipolar depressed patients have revealed consistent up-regulation of the I(1) subtype on the platelet. Treatment with cyclic antidepressants is accompanied by down-regulation in responders. Treatment with the non-cyclic bupropion produced similar findings. Studies of human post-mortem brain show changes in depressed subjects but the protein fragments assessed are of different molecular weights than in the platelet. Plasma agmatine is believed to be a putative endogenous ligand for I receptors. Thus, IR may be useful state markers of affective disorders. Copyright 2001 John Wiley & Sons, Ltd.

The Effects of Chronic Administration of Inhibitors of Flavin and Quinone Amine Oxidases on Imidazoline I1 Receptor Density in Rat Whole Brain

“…43 In addition, functional studies have suggested that trace amine agonists act as neuromodulators, rather than neurotransmitters, 44,45 and some of the synergistic interactions observed between central imidazolinergic and adrenergic systems in blood pressure control 26,46 are consistent with a neuromodulatory role for imidazoline agonists. Thus, some trace amine receptors share with some imidazoline receptors common ligands, common pathophysiologic implications 47 and responses to drug administration, and a common proposed neuromodulatory action. 26,48 It is an intriguing possibility that some of the imidazoline receptor subtypes described thus far might represent subtypes, perhaps as yet uncharacterized, of trace amine receptors.…”

Recent developments in the psychobiology and pharmacotherapy of depression: optimising existing treatments and novel approaches for the future

“…Plasma agmatine, the decarboxylated derivative of the amino acid arginine, is believed to be an endogenous ligand for IRs. There is some potential for IR as a state marker for MDD, but this approach has so far yielded no potential antidepressants [162].…”

Borne Identity: Leading Endogenous Suspects at Imidazoline Binding Sites

“…The current literature proposes that I 1 -BS and I 2 -BS play a role in major depression [61]. The expression of I 1 -BS and I 2 -BS were reported to be altered in platelets and brains of depressed patients [62][63][64][65].…”