Daily and annual variations of the hepatic Glucose 6‐phosphate dehydrogenase activity and seasonal changes in the body fats of the gilthead seabream Sparus aurata

Abstract

In mammalians, Glucose 6-phosphate dehydrogenase (G6PDH) is clearly related with the daily cycle lipogenesis/lipolysis and therefore with the photoperiod and activity. In fish the temporally changes on the activity of this enzyme have not been described. In this work, annual and diurnal activity of G6PDH was investigated in the liver of Sparus aurata in different seasonal conditions of temperature and photoperiod. During experiment the fish were kept in cages under natural temperature and photoperiod while consuming a commercial diet. The months studied were chosen to establish if there is any influence on the G6PDH activity, because of the change in temperature and photoperiod (equal photoperiod and different temperature, March and October; different photoperiod and equal temperature, May and November; and different photoperiod and temperature, June and January). To study the enzyme activity along the day, the livers of six fish were removed every 3 hr during 24 hr. Annual activity was determined as the average activity during 1 day. Also the annual changes on fat content in muscle and digestive system were studied. The Vmax (maximum velocity) showed seasonal changes in period and phase of the rhythms and for the Km (Michaelis-Menten constant) a period of 24 hr was found in all sampled months, except March, the phase time moves depending on the month. In addition, the annual variations in muscular fat and G6PDH-specific activity seem to be more related to the reproductive stage than any other variable considered.

The role of maslinic acid in the pentose phosphate pathway during growth of gilthead sea bream(Sparus Aurata)

“…). Results reported by others (Gomez‐Milan & Sanchez‐Muros Lozano ) showed a daily rhythm of G6PDH activity in S. aurata . In the present work, we demonstrate that the administration of a diet supplemented with MA significantly spurred G6PDH activity enzymatic and catalytic efficiency in the hepatic tissue and white muscle, according to the increases found in the expression levels of this enzyme.…”

Vitamin C and Chitosan Alleviate Toxic Effects of Paraquat on Some Biochemical Parameters in Hepatocytes of Common Carp

“…In G6PDH assay, this enzyme catalyzes the oxidation of glucose-6-phosphate (G6P) to 6-phospho-D-gluconate, along with the concomitant reduction of NADP + to NADPH. The rate of NADPH formation is proportional to G6PDH activity and is measured using spectrophotometry as increase in absorbance at 340 nm [16]. Protein levels in tissues were determined by standard procedures used in clinical biochemistry laboratories according to thebiochemical kits user manuals (Pars Azmoun Co, Iran) [17].…”