Circadian and seasonal rhythm of beta-glucuronidase in rat liver
Bhattacharya, R.D.
Cellular and Molecular Biology 31(4): 305-307
1985
ISSN/ISBN: 0145-5680 PMID: 4028063 Document Number: 248906
The circadian rhythmicity of liver .beta.-glucuronidase activity was studied in rats kept throughout the year in an artificial, highly standardized environment. The activities of this lysosomal enzyme were determined in homogenates by the quantitative biochemical method of Fishman. Systematic investigations were performed in Jan., April, June and Sept. Despite the fact that influences of acknowledged seasonal synchronizers were excluded by the maintenance of the animals in a standardized environment, seasonal influences became evident. They are manifested by modifications of the following rhythm parameters of .beta.-glucuronidase activity in rat liver: The 24-h mean value: highest mean activities were observed in Jan. (41.73 mu/g liver wet wt), lowest in June (32.6 mu/g liver wet wt), statistically different (P = 0.001); Phasing: whereas the time points for the occurrence of maximal activities were found to be relatively constant between 22.00 and 01.00, the trough in Sept. is phase-shifted 6 h with respect to that in Jan./April; Amplitude: highest in Jan. and lowest in April.