Genetic studies of daily variations of first-step enzymes of monoamines metabolism in the brain of inbred strains of mice and hybrids. I. Daily variations of tryptophan hydroxylase activity in the nuclei raphe dorsalis, raphe centralis and in the striatum.

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.