Morphine treatment affects the regulation of high mobility group I-type chromosomal phosphoproteins in C6 glioma cells.

High mobility group (HMG) I-type chromosomal phosphoproteins HMG I/Y and HMG I-C were investigated following morphine treatment of C6BU-1 glioma. Cells were labelled with [32P]-orthophosphoric acid. Electrophoretic profiles and autoradiograms of the control cells revealed the presence of HMG I and HMG I-C proteins. HMG Y was not detected. Northern blot analysis showed a single HMG I/Y transcript. Treatment with morphine lowered the [32P]-incorporation in HMG I and HMGI-C proteins and the level of the HMG I/Y transcript. However, it did not change the protein ratios on the Coomassie stained gels. These results suggest that morphine may trigger independent reaction pathways affecting either transcription regulation and/or postsynthetic phosphorylation of the preexisting HMG I-type proteins. In addition, opposing changes in the postsynthetic phosphorylation of HMG 14 and histones H1AB were also noticed.

Opioid regulation of AP-1 DNA-binding activity in NG108-15 cells under conditions of opioid-receptor adaptation.

Opioid-receptor adaptation may lead to changes in transcriptional regulation by sequence-specific DNA-binding proteins. Gel-shift assays of nuclear extracts from NG108-15 cells revealed that an increase of AP-1 DNA-binding activity ensues under conditions previously established to induce down- or up-regulation of delta-opioid receptors.

Morphine-induced alterations on DNA-binding proteins in developing rat brain.

Endogenous opioids and opiate drugs inhibit nervous system maturation through both direct and indirect mechanisms. Recently much attention has been directed toward changes in the postreceptor events and it has been speculated that the regulation of gene expression may be involved in the development of drug tolerance and dependence. We investigated the changes in the levels of in vitro RNA synthesis in developing rat brain after continuous block of opioid receptors. Repeated naloxone treatment induced increased levels (27-48%) of RNA synthesis during the early postnatal period. Using mobility gel shift assay the presence of octamer binding proteins (Oct-1) and the replication differentiation transcription factor CTF/NF1 in the developing rat brain were studied both after single or repeated morphine and naloxone treatment. Decreased Oct-1 binding activity in brain protein extracts 1 h after morphine application was registered, while opioid antagonist naloxone exerted an opposite effect on this octamer protein following single drug treatment. Repeated administration of morphine or naloxone decreased markedly the DNA-binding affinity of Oct-1. The binding activity of CTF/NF1 changes differently showed higher levels assessed 30-120 min after morphine administration. The opposite trend of the changes in opiate drug and opioid antagonist animals suggests opioid receptor-mediated regulation of Oct-1 and CTF/NF1 transcription factors.

[The 32P-incorporation into nucleic acids and adenosine phosphates of the rat brain after acute and chronic influence of meclofenoxate (author's transl)]. / 32P-Einbau in Nukleinsäuren und Adenosinphosphate des Rattengehirns nach akuter und chronischer Einwirkung von Meclofenoxat

Beta-Dimethylaminoethyl-p-chlorophenoxyacetate hydrochloride (meclofenoxate, Helfergin) was adminstered orally in dosages of 300 mg/kg 3 times during an 18-h period. The incorporation rate of the total and cytoplasmic RNA as well as of ATP, ADP and AMP decreased. Contradictory results were obtained after a 16-day treatment with orally 300 mg/kg per day: while the 32P-incorporation rate of the cytoplasmic RNA and the 3 adenosine phosphates increased, the nuclear RNA showed a correspondent diminishing. No changes of the ATP content could be observed in any group. The differences between the acute and chronic experiments could be explained by a different excitation of the animals and by the very different dosages. The increased 32P-incorporation into the cytoplasmic and into the adenosine phosphates in the chronic experiments are explained by a stimulation of the pentose phosphate shunt which yields mainly the phosphate group for the synthesis of AMP.