Effects of Opiate Drugs on Fas-Associated Protein with Death Domain (FADD) and Effector Caspases in the Rat Brain: Regulation by the ERK1/2 MAP Kinase Pathway

Abstract

This study was designed to assess the effects of opiate treatment on the expression of Fas-associated protein with death domain (FADD) in the rat brain. FADD is involved in the transmission of Fas-death signals that have been suggested to contribute to the development of opiate tolerance and addiction. Acute treatments with high doses of sufentanil and morphine (m-agonists), , and U50488H (k-agonist) induced significant decreases (30-60%) in FADD immunodensity in the cerebral cortex, through specific opioid receptor mechanisms (effects antagonized by naloxone, naltrindole, or nor-binaltorphimine). The cannabinoid CB 1 receptor agonist WIN 55,212-2 did not alter FADD content in the brain. Chronic (5 days) morphine (10-100 mg/kg), SNC-80 (10 mg/kg), or U50488H (10 mg/kg) was associated with the induction of tachyphylaxis to the acute effects. In morphine-and SNC-80-tolerant rats, antagonistprecipitated (2 h) or spontaneous withdrawal (24-48 h) induced a new and sustained inhibition of FADD (13-50%). None of these treatments altered the densities of caspases 8/3 (including the active cleaved forms) in the brain. Pretreatment of rats with SL 327 (a selective MEK1/2 inhibitor that blocks ERK activation) fully prevented the reduction of FADD content induced by SNC-80 in the cerebral cortex (43%) and corpus striatum (29%), demonstrating the direct involvement of ERK1/2 signaling in the regulation of FADD by the opiate agonist. The results indicate that m-and d-opioid receptors have a prominent role in the modulation of FADD (opposite to that of Fas) shortly after initiating treatment. Opiate drugs (and specifically the d-agonists) could promote survival signals in the brain through inhibition of FADD, which in turn is dependent on the activation of the antiapoptotic ERK1/2 signaling pathway.

Effect of Cocaine on Fas-Associated Protein with Death Domain in the Rat Brain: Individual Differences in a Model of Differential Vulnerability to Drug Abuse

“…This sequential extraction method relies on the different solubility of proteins in certain subcellular compartments to yield four subproteomes enriched in cytosolic (F1), membrane and membrane organelle-localized (F2), soluble and DNAassociated nuclear (F3), and cytoskeletal (F4) proteins. The efficiency and selectivity of this subcellular extraction procedure have been reported (Abdolzade-Bavil et al, 2004), and in the current study, the assay's selectivity was assessed by the immunodetection of neurofilament (NF-L) protein, a specific cytoskeletal marker of mature neurons, which was only identified in F4 (Garcia-Fuster et al, 2007).…”

“…The subcellular localization (cerebral cortex) and the effect of cocaine (7.5 mg/kg, i.p., 1 h) on the content of FADD in the different compartments was monitored by use of the Subcellular Proteome Extraction Kit (ProteoExtract; Calbiochem, Darmstadt, Germany) as per the manufacturer's instructions (Garcia-Fuster et al, 2007). This sequential extraction method relies on the different solubility of proteins in certain subcellular compartments to yield four subproteomes enriched in cytosolic (F1), membrane and membrane organelle-localized (F2), soluble and DNAassociated nuclear (F3), and cytoskeletal (F4) proteins.…”

“…Brain tissue samples (right-half cerebral cortex) were prepared in the presence of various protease inhibitors as previously reported (Garcia-Fuster et al, 2007). Aliquots of total homogenate were mixed with equal volumes of electrophoresis loading buffer, denatured, and stored at À201C until use.…”

“…Therefore, FADD is instrumental in controlling a variety of intracellular processes that regulate cell growth/survival/ apoptosis in a complex dance of changing partners and overlapping steps. Indeed, other drugs of abuse (ie opiates) have recently been shown to promote either survival or proliferating neural signals (Tegeder and Geisslinger, 2004;Barry and Zuo, 2005) perhaps through inhibition of FADD by a mechanism dependent on the activation of the antiapoptotic ERK1/2 signaling pathway (Garcia-Fuster et al, 2007).…”

“…The present study assessed whether (1) FADD modulation is drug specific (opiate drugs; Garcia-Fuster et al, 2007) or is associated with common neuroplastic mechanisms induced by multiple drugs of abuse (cocaine in this study); (2) cocaine's impact on FADD shifts cell fate toward apoptotic mechanisms (drug-induced neurotoxicity measured by poly-(ADP-ribose) polymerase (PARP) enzyme cleavage, a molecular cell death marker involved in DNA damage following caspase-3 activation (Cagnol et al, 2006)) or nonapoptotic mechanisms; and (3) the activation and/or imbalance of these pathways could underlie a new potential mechanism relevant to the early neural changes instigated by different drugs of abuse.…”