H Tischmeyer | PubMed Health

PubMed2000

A delta opioid receptor lacking the third cytoplasmic loop is generated by atypical mRNA processing in human malignomas.

delta Opioid receptors were identified in human melanomas by RT-PCR and radioligand binding. In all tumors an additional PCR amplificate was detected in which 144 bp within the third exon were deleted. This fragment corresponded to the third cytoplasmic domain of the receptor protein. The short variant resulted from atypical mRNA processing. There were no common splice recognition sequences around the deleted fragment; instead its excision resembled the removal of a transposon. The deletion was not detected in normal human melanocytes nor in human or rat brain. However, it was present in a human neuroblastoma cell line (SH-SY5Y). Thus, it appears that the occurrence of the short delta opioid receptor is correlated to malignancy.

Animals↗

PubMed1990

Effects of intraventricularly applied methylglucamine orotate on [3H] acetylglucosamine incorporation into rat brain tissue during a learning experiment.

The present work was undertaken to study the influence of intraventricularly applied methylglucamine orotate (MGO) at a memory-facilitating dose of 1 mumole vs. 1 mumole methylglucamine chloride (MGCl) as a control substance on the incorporation of intraventricularly injected [3H]acetylglucosamine into rat hippocampus and striatum plus thalamus. MGO or MGCl were applied 50 min prior to application of labelled aminosugar, the incorporation times being 1, 4 and 24 h. In non-trained animals, MGO produced an increased labelling of hippocampal proteins (20%) after 24 h, whereas labelling of the lipid fraction was virtually not altered. In trained animals (brightness discrimination model), the increase in labelling caused by MGO in hippocampal proteins was more marked (49%), and an even higher increase in labelling was noted for the hippocampal proteins was more marked (49%), and an even higher increase in labelling was noted for the hippocampal lipids (63%). The second brain region under investigation, striatum plus thalamus, showed no MGO-induced alterations in labelling. The findings are discussed in the light of the working hypothesis of the functional role of macromolecular changes occurring mainly in the hippocampus during memory formation.

Acetylglucosamine↗