According to a study from Canberra, Australia, "Cyclic adenosine monophosphpate (cAMP) signaling is thought to be involved in the pathophysiology of major depressive disorder and antidepressant action; however, relatively little is known about the possible role of cyclic guanosine monophosphate (cGMP) signaling. Accumulating evidence suggests that crosstalk occurs between cAMP and cGMP pathways."

"There is a need to clarify the trajectory of cAMP and cGMP concentrations, their synthesis by cyclases. and degradation by phosphodiesterases (PDEs) to understand the role of cyclic mononucleotide signaling in the effect of chronic antidepressant therapy : We used quantitative real-time PCR and enzyme immunoassay to systematically investigate the expression of intracellular signaling cascade elements in the hippocampus of rats chronically treated with the antidepressants fluoxetine and amitriptyline. We found increased cGMP levels, which were consistent with our findings of decreased PDE gene expression. Immunoassay results showed unchanged cAMP levels," wrote G.W. Reierson and colleagues, Australian National University (see also Depression).

The researchers concluded: "Increased cGMP signaling might underlie the efficacy of chronic antidepressant treatment."

Reierson and colleagues published their study in Neuroscience Letters (Repeated antidepressant therapy increases cyclic GMP signaling in rat hippocampus. Neuroscience Letters, 2009;466(3):149-153).

For more information, contact M.L. Wong, Australian National University, John Curtin School of Medicine Research, Bldg 31, Garran Rd., Canberra, ACT 0200, Australia.

Publisher contact information for the journal Neuroscience Letters is: Elsevier Ireland Ltd., Elsevier House, Brookvale Plaza, East Park Shannon, Co. Clare, Ireland.