Repeated electroconvulsive shock treatment increases the expression of A kinase anchoring proteins in the rat hippocampus

Early antidepressant efficacy modulation by glutamatergic gene variants in the STAR*D

The glutamatergic system has been suggested as a modulator of rapid antidepressant response. Thus, 44 glutamatergic genes were selected according to the literature and investigated in 1541 major depressive patients from the STAR*D genome wide dataset. Outcomes of interest were early response (2nd week) and late response (from the 4th to the 14th week) compared to non-response and stability of response through the STAR*D level 1. A complete agglomerative clustering, based on pairwise identity-by-state (IBS) matrix, was applied in order to control for genetic admixture. A chi-square test was employed as exploratory analysis and a logistic regression was employed to corroborate SNPs associated to the outcomes at p<0.001. Covariates were selected accordingly to their impact on phenotypes. A Bonferroni correction was applied. PLINK served for the analysis. About 1995 SNPs were available after quality control. Our results suggested that the rs1083801 within the GRM7 (glutamate receptor, metabotropic 7) gene was associated to early response under a recessive model (GG genotype observed in 14.34% of early responders vs 5.25% of late responders, OR=0.33, 95% CI=0.21-0.54, p=6.41e-06. GG genotype observed in 5.34% of non-responders, OR=0.33, 95% CI=0.20-0.56, p=4.07e-05). The result was confirmed in the white non-Hispanic group (GG genotype observed in 17.46% of early responders vs 5.81% of the rest of the sample, OR=0.29, 95% CI=0.18-0.46, p=2.04e-07). No marker predicted the stability of response. Glutamatergic genes may be useful markers of early antidepressant efficacy. This result may be relevant in further understanding the pathophysiology of the drug induced antidepressant effect.

Repeated electroconvulsive seizure induces c-Myc down-regulation and Bad inactivation in the rat frontal cortex

Repeated electroconvulsive seizure (ECS), a model for electroconvulsive therapy (ECT), exerts neuroprotective and proliferative effects in the brain. This trophic action of ECS requires inhibition of apoptotic activity, in addition to activation of survival signals. c-Myc plays an important role in apoptosis of neurons, in cooperation with the Bcl-2 family proteins, and its activity and stability are regulated by phosphorylation and ubiquitination. We examined c-Myc and related proteins responsible for apoptosis after repeated ECS. In the rat frontal cortex, repeated ECS for 10 days reduced the total amount of c-Myc, while increasing phosphorylation of c-Myc at Thr58, which reportedly induces degradation of c-Myc. As expected, ubiquitination of both phosphorylated and total c-Myc increased after 10 days ECS, suggesting that ECS may reduce c-Myc protein level via ubiquitination-proteasomal degradation. Bcl-2 family proteins, caspase, and poly(ADP-ribose) polymerase (PARP) were investigated to determine the consequence of down-regulating c-Myc. Protein levels of Bcl-2, Bcl-X(L), Bax, and Bad showed no change, and cleavage of caspase-3 and PARP were not induced. However, phosphorylation of Bad at Ser-155 and binding of Bad to 14-3-3 increased without binding to Bcl-X(L) after repeated ECS, implying that repeated ECS sequesters apoptotic Bad and frees pro-survival Bcl-XL. Taken together, c-Myc down-regulation via ubiquitination-proteasomal degradation and Bad inactivation by binding to 14-3-3 may be anti-apoptotic mechanisms elicited by repeated ECS in the rat frontal cortex. This finding further supports the trophic effect of ECS blocking apoptosis as a possible therapeutic effect of ECT.