RESUMO
A daily variation of tryptophan hydroxylase (TrH) activity was observed in the raphe dorsalis (RD), raphe centralis (RC) and striatum (St) of 3 inbred strains of mice (BALB/c, C57BL/6, C57BR) and of the reciprocal hybrids obtained from Balb/c and C57BL6. Significant differences of the characteristics of these rhythms have been found in the same strain between different structures and for the same structure between different strains. In RD and RC hybridization led to less defined daily variations which, in the striatum, remained well synchronized and could be controlled by a dominant genetic mechanism part. These results help to discuss evidence for selective control mechanisms of regulation responsible for daily variation of TrH in the 5-HT cell bodies and terminals and their relative independence.
Assuntos
Tronco Encefálico/enzimologia , Ritmo Circadiano , Corpo Estriado/enzimologia , Hibridização Genética , Núcleos da Rafe/enzimologia , Triptofano Hidroxilase/genética , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos , Triptofano Hidroxilase/metabolismoRESUMO
Daily variations of tyrosine hydroxylase (TH) activity in the locus coeruleus of 3 inbred strains of mice (BALB/c; C57BL6; C57Br) and the F1 hybrids obtained from BALB/c and C57BL/6 are discussed. Precise characteristics of the circadian rhythms were observed in each strain. They were found significantly different in two genetically pure parents (BALB/c and C57BL6). In their two F1 hybrids the daily variation of TH activity was similar to that observed in one of the parents (C57BL6). This strongly suggests selective and genetically controlled mechanisms of regulation responsible for the daily variation of TH activity in the locus coeruleus of mice.
Assuntos
Ritmo Circadiano , Hibridização Genética , Locus Cerúleo/enzimologia , Triptofano Hidroxilase/genética , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos , Proteínas do Tecido Nervoso/metabolismo , Triptofano Hidroxilase/metabolismoRESUMO
The uptake of radioactive l-phenylalanine and l-tyrosine into the tissue water of rat brain cerebral cortex slices was shown to have saturation kinetics. The apparent K(m) for the uptake of l-phenylalanine was 0.86mm and for l-tyrosine was 1.64mm; for phenylalanine the apparent V(max.) value was 0.64mumol/min per ml of tissue water, and for l-tyrosine it was 0.98mumol/min per ml of tissue water. The accumulation of the two amino acids by the tissue was depressed in the absence of O(2), at 0 degrees C, or in the presence of metabolic inhibitors. The influxes and effluxes of both l-isomers were more rapid than those of the d-isomers. Competition between these two amino acids and each with l-tryptophan in respect of uptake into tissue water was shown. Their rates of influx were faster, and rates of efflux were slower, in the presence than in the absence of Na(+). It was concluded that these amino acids were taken up by active transport via a carrier mechanism.