Adenylate cyclase activity in postmortem brain of suicide subjects: reduced response to beta-adrenergic stimulation
Valdizán, E.M.; Gutierrez, O.; Pazos, A.
Biological Psychiatry 54(12): 1457-1464
2003
ISSN/ISBN: 0006-3223 PMID: 14675811 Document Number: 556158
Background: Biochemical research on the etiopathogenesis of affective disorders has focused on transduction mechanisms beyond receptors, such as adenylate cyclase activity. Methods: Adenylate cyclase activity (AC) was measured in postmortem frontal cortex samples from 11 suicide victims with a firm antemortem diagnosis of major depressive disorder and 11 matched control cases. We analyzed the basal activity of the enyme and that following stimulation with forskolin, guanine nucleotides, and the beta1-adrenoceptor agonist xamoterol. Results: A significant negative correlation between the period of tissue storage and the response of AC to the different stimuli assayed was observed. No difference was found in the levels of basal, forskolin-, and GTPyS-stimulated activity between control and major depressive disorder cases, both in the drug-free and the drug-treated subgroups. In contrast, we found a significant lower response to beta1-adrenoceptors agonist-stimulated AC activity in the major depressive disorder group (p < .01). This pattern of reduced response was also found in the subgroup of patients with negative toxicology for antidepressants. Conclusions: These results, directly obtained from the brain of depressed patients, reinforce the involvement of noradrenergic neurotransmission in depressive illness. They also support the relevance of cyclic adenosine monophosphate signaling pathways in the etiopathogenesis of affective disorders.