Nucleic acid and protein synthesis inhibition in developing brain by ethanol in the absence of hypothermia

Abstract

Effects of acute or chronic ethanol administration have been studied on protein, RNA and DNA synthesis in the developing brain in the absence or presence of hypothermia. Acute ethanol was given intraperitoneally (4 g/kg) and for chronic ethanol treatment the pups were allowed to suckle on the ethanol-fed dams. Dams were pair-fed on nutritionally adequate liquid-sustacal diet. Ethanol administration, both acutely and chronically, inhibited the in vivo and in vitro protein synthesis in the absence or presence of hypothermia. This data suggests that ethanol per se is capable of producing the inhibition of protein synthesis in brain without its hypothermic effect. However, the inhibitory effect of ethanol is more pronounced in the presence of ethanol-mediated hypothermia. Hypothermia in itself also causes a decrease in the synthesis of proteins. Maternal ethanol consumption results in a significant decrease in the synthesis of both RNA and DNA in the developing brain of suckling newborn either in the absence or presence of hypothermia. RNA and DNA synthesis was measured by following the incorporation of (5-(3)H) uridine and (14C)thymidine respectively. Decrease in body temperature alone also resulted in decreased RNA and DNA synthesis in the developing brain. Ethanol reaching the suckling newborn from maternal milk resulted in decreased brain weights, total protein, ribosomal protein, total RNA, ribosomal RNA, and total DNA of the brain. Neonatal brain proteolytic and DNA-polymerase activities were inhibited in the ethanol-fed group. An inhibition of proteolytic activity reflects a compensatory mechanism of the developing brain to decrease the breakdown of proteins in response to the inhibitory effect of ethanol on protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)