Are cell redox or lactate dehydrogenase kinetics responsible for the absence of gluconeogenesis from lactate in sea raven, hepatocytes?

Changes in the apparent sensitivity and responsiveness of carbohydrate metabolism to glucagon and insulin were examined in hepatocytes isolated from fed and 6-week-fasted sea ravens (Hemitripterus americanus), with and without collagenase. The fasted group demonstrated higher rates of total glucose production (TGP) and gluconeogenesis from alanine than the fed group. Metabolic sensitivity to glucagon was increased with fasting, while the maximal responsiveness to both hormones was decreased with fasting; this latter effect may result from elevated control rates in the fasted group. Glucagon increased CO2 production from alanine in the fed group and decreased it in the fasted group. Insulin antagonized the effects of glucagon with respect to TGP and CO2 production, while the effects of the two hormones on gluconeogenesis were additive at high insulin concentrations in the fasted group. Hepatocytes isolated without collagenase perfusion had lower TGP, decreased sensitivity to glucagon, and decreased responsiveness to insulin than cells prepared with collagenase. Furthermore, the additive effects of insulin and glucagon on gluconeogenesis were not apparent when cells were isolated in the absence of collagenase. These results indicate that the response of hepatocyte carbohydrate metabolism to glucagon and insulin is affected by nutritional status, and that collagenase preparation significantly affects sea raven hepatocyte metabolism.

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Biometric Indices, Physio-Metabolic Responses and Carcass Quality in Rohu (Labeo rohita) during Feed Deprivation

Yengkokpam

Sahu

Pal

et al. 2022

Animals

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Understanding changes in biometric indices and metabolism in fish exposed to feed deprivation may be useful in aquaculture. The present study elucidates the effect of feed deprivation on physio-biochemical responses, such as changes in biometric indices, nutrient mobilization patterns, and enzyme activities in rohu (Labeo rohita). Experimental fish (av. wt. 3.41 ± 0.07 g) were deprived of feed and sampled at intervals of 0, 15, 30, 45, and 60 days to measure weight, length, body composition, and the activities of enzymes involved in digestion, metabolism, and antioxidation. A decrease in body weight, condition factor (CF), hepatosomatic index (HSI), and gastrosomatic index (GSI) was observed during the initial stage of feed deprivation (15 to 30 days) but remained unchanged thereafter. The total carbohydrate and lipid content also decreased rapidly up until 30 days, then stabilized. However, the reduction in tissue protein content (% wet weight) continued gradually with the duration of feed deprivation from 12.85 ± 0.36 at 0 days to 10.04 ± 0.67 at 15 days, 8.79 ± 0.59 at 30 days, 6.95 ± 0.69 at 45 days, and 6.16 ± 0.8 at 60 days, which was lower, compared to the other two body constituents. Amylase, protease. and lipase activities significantly reduced up until 30 days, but then stabilized. Although G6PDH enzyme activity decreased, gluconeogenic (LDH, AST, and ALT) and antioxidative (SOD and catalase) enzyme activities increased during initial feed deprivation (up to 30 days). A tissue-specific difference in amino acid metabolism with a major role of ALT in liver and AST in muscle was observed. This study revealed that rohu fingerlings adapted well to feed deprivation up until 30 days, beyond which there was an overall deterioration in the metabolic functions.

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Are cell redox or lactate dehydrogenase kinetics responsible for the absence of gluconeogenesis from lactate in sea raven, hepatocytes?

Cited by 3 publications

References 26 publications

Chapter 4 Tissue carbohydrate metabolism, gluconeogenesis and hormonal and environmental influences

Chapter 4 Tissue carbohydrate metabolism, gluconeogenesis and hormonal and environmental influences

Hormonal sensitivity and responsiveness in sea raven hepatocytes: changes with fasting and collagenase exposure

Biometric Indices, Physio-Metabolic Responses and Carcass Quality in Rohu (Labeo rohita) during Feed Deprivation

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