Tagesrhythmus des Ribosomensystems der Rattenleber unter der Wirkung von Cycloheximid / Daily Rhythm of the Ribosomal System in Rat Liver after Application of Cycloheximide

Abstract

Intraperitoneal injections of 2 mg or 5 mg cycloheximide per 100 g body weight into male Sprague-Dawley rats, 3 months old, induce a doubling of the amount of membrane-bound ribosomes after 1 hour. After 2-3 hours the control value is readied and a slow decrease in the number of bound ribosomes can be observed thereafter. The concentration of free ribosomes decreases very markedly during the first hour after injection and more slowly during the following time. Injections of cycloheximide (5 mg / 100 g; 20 min before sacrifice) at different times of day result in a bimodal curve of bound ribosomes with maxima at 9-12 h and 21 h, the maxima of free ribosomes appears at the same time as the maximum of the controls (9-12 h). Analysing the amount of bound ribosomes 3 hours after the injection of cycloheximide a bimodal rhythm can also be observed, the latter curve, however, is phaseshifted for 3-6 hours and appears at a lower level. No rhythm can be detected in the free ribosomal fraction after this treatment. Administration of cycloheximide causes a decrease in protein content of both free and bound ribosomes.