ABSTRACT
Dose-dependent, amphetamine-induced reductions in protein synthesis were determined in vivo by measuring [3H]lysine incorporation into trichloroacetic acid precipitated protein in homogenates prepared from different regions of the brain or liver. Low-to-moderate doses of amphetamine (1-5 mg/kg) decreased striatal protein synthesis whereas higher doses (10 mg/kg) reduced it in the cerebral cortices, cerebellum, and remaining portions of the cerebrum, as well as in the striatum and liver. Reductions in regional brain protein synthesis occur following amphetamine treatment in relatively low doses known to change various aspects of physiology and behavior.
Subject(s)
Brain/drug effects , Dextroamphetamine/pharmacology , Liver/drug effects , Nerve Tissue Proteins/biosynthesis , Protein Biosynthesis , Animals , Brain/metabolism , Depression, Chemical , Dose-Response Relationship, Drug , Liver/metabolism , Male , Rats , Rats, Inbred StrainsABSTRACT
Despite its fast autoxidation in vitro, ascorbate remains in its reduced form in vivo, indicating a special mechanism may be involved in its regeneration. The presence of an NADH-dependent reductase system, semidehydroascorbate reductase (SDR), for regeneration of ascorbate from its partially oxidized form, semidehydroascorbate (SDA), was demonstrated in bovine ocular tissues after extraction in Triton X-100. Highest SDR activity was detected in retinal extracts in the order of retina greater than pigment epithelium-choroid = ciliary body greater than iris. Minimal or no activity was observed in lens extracts or in aqueous fluid. Freezing and thawing, or boiling, destroyed the NADH-dependent SDR activity. NADH oxidation was significantly reduced (22% of total activity) when assays with retinal extracts were performed at 5 degrees C. Treatment with 4 mM, N-ethylmaleimide reduced the rate of NADH oxidation to 73 or 42% compared with control values with retinal or ciliary body extracts, respectively.
Subject(s)
Ascorbic Acid/metabolism , Eye/enzymology , NADH, NADPH Oxidoreductases/metabolism , Animals , Cattle , Dehydroascorbic Acid/metabolism , NAD/metabolism , Retina/enzymologySubject(s)
Brain/metabolism , Dextroamphetamine/pharmacology , Nerve Tissue Proteins/biosynthesis , Animals , Brain/drug effects , Brain Stem/drug effects , Cerebellum/drug effects , Cerebral Cortex/drug effects , Corpus Striatum/drug effects , Hypothalamus/drug effects , Lysine/metabolism , Male , Polyribosomes/drug effects , RatsABSTRACT
A lectin, whose specific activity in soluble extracts of embryonic chick pectoral muscle increases strikingly between 8 and 16 days of development, has been purified by affinity chromatography on derivatized Sepharose 4B coupled to p-aminophenyl-beta-D-lactoside. After affinity chromatography the lectin is pure except for minor contamination with another protein possibly representing a second muscle lectin. The latter can be completely removed by preparative isoelectric focusing. The purified lectin has an apparent molecular weight of 30,000 and an apparent subunit molecular weight of 15,000. Its isoelectric point is 4.0. The most potent saccharide inhibitors tested were thiodigalactoside and lactose. An antibody has been raised to the pure lectin. Studies with this antibody indicate that the lectin is present both on the surface of and within myoblasts.
