Loss of Protein Kinase C‐αβ in Brain of Heroin Addicts and Morphine‐Dependent Rats

Abstract

The biochemical status of human brain protein kinase C (PKC)-a)3 during opiate dependence was studied by means of immunoblotting techniques in postmortem brain of heroin addicts who had died by opiate overdose . In the frontal cortex, a marked decrease (53%, p < 0.05) in the immunoreactivity of PKC-aß was found in heroin addicts compared with matched controls . The loss of PKC-(

Chronic Morphine Treatment Impaired Hippocampal Long-Term Potentiation and Spatial Memory via Accumulation of Extracellular Adenosine Acting on Adenosine A1Receptors

“…Furthermore, we found that PKC-␣/␤ isoforms modulate ENT2 function because downregulation of the expression of PKC-␣/␤ but not PKC-␥/ isoforms paralleled the reduction of PKC activity, adenosine uptake, and enhancement of extracellular adenosine concentration. In support of our findings, previous studies also reported that chronic exposure to opiates led to a significant reduction of PKC-␣/␤ isoform expression in the frontal cortex of the human and rat brains (Busquets et al, 1995;Ventayol et al, 1997). Although the present and previous studies clearly show the downregulation of PKC-␣/␤ isoform expression in brain after chronic morphine treatments, how the reduction of PKC-␣/␤ abundance in hippocampal synaptosome is achieved in the hippocampus by morphine remains unknown.…”

“…After slightly washing, the membrane was incubated with anti-ENT1 goat polyclonal antibody (1:50 Santa Cruz Biotechnology, sc-48488), anti-ENT2 goat polyclonal antibody (1:50, Santa Cruz Biotechnology sc-48491), anti-PKC-␣/␤ monoclonal antibody, anti-PKC-␥ rabbit polyclonal antibody (1:10,000, Santa Cruz Biotechnology sc-211), anti-PKC-mouse monoclonal antibody(1:50, Santa Cruz Biotechnology sc-56944) in TBS plus 5% BSA and 0.1% Tween 20, followed by incubation with horseradish peroxidaseconjugated IgG (Calbiochem) as the secondary antibody. Visualization was performed using an ECL (enhanced chemiluminescence) kit (GE Healthcare) for PKC-␣/␤ (Busquets et al, 1995) and PKC-␥, SuperSignal West Dura Extended Duration Substrate (Thermo Scientific) for ENT1/2 and PKC-. Band intensities were quantified by using Quantity One software from Bio-Rad.…”

Regulation of nonphosphorylated and phosphorylated forms of neurofilament proteins in the prefrontal cortex of human opioid addicts

“…In a preliminary study in humans, the abundance of NF-L proteins was also shown to be markedly decreased (47%) in prefrontal cortices from chronic opioid abusers (García-Sevilla et al, 1997a). This study also demonstrated that the opioid modulation of NF-L proteins also occurs in the prefrontal cortex, a brain region that is also a target for the chronic effects of opioid drugs in humans (Escribá et al, 1994;Busquets et al, 1995;Simonato, 1996). Recently, chronic treatment of rats with morphine also induced a marked decrease (49%) in NF-L immunoreactivity in the frontal cortex (Boronat et al, 1998).…”

The RACK1 Scaffold Protein: A Dynamic Cog in Cell Response Mechanisms

“…Somewhat confusingly, an earlier article by Shimohama et al (1998) reported that RACK1 levels were not significantly affected in brains of persons with AD, but this discrepancy may reflect a difference in the brain areas examined RACK1 protein levels are also modulated in parallel with levels of PKC␣ and ␤ in the brains of morphine-treated rats (Escriba and Garcia-Sevilla, 1999). Opiate drugs control the protein expression levels of conventional PKC isozymes in the brain, which may affect the activity of adenylyl cyclase, a principle mediator of opioid receptor signaling (Zhou et al, 1994;Busquets et al, 1995;Ammer and Schulz, 1997). This strong positive correlation between the levels of RACK1 and both PKC␣ and ␤ has not been found for other proteins involved in opioid signal transduction, such as G ␣ , G ␤ , GRK2, adenylyl cyclase, and PKA (Nestler and Tallman, 1988;Terwilliger et al, 1994;Escriba and Garcia-Sevilla, 1999).…”