Hepatic glycogen patterns in fasted and fed rats

Abstract

Hepatic glycogen patterns are described for rats adapted to a precisely controlled feeding schedule and ad libitum fed rats. Liver samples were processed for biochemical and histochemical glycogen analysis at precise intervals following a 22 hour fast and a 2 hour meal. Histochemical determination of glycogen (PAS) after freeze substitution showed lobular patterns of hepatic glycogen which correlate with chemically determined glycogen levels and nutritional states of the rats. After 22 hour fasting, hepatocytes from rats with low glycogen levels (< 0.09% ) exhibited no significant staining. In control fed rats, feeding caused glycogen deposition throughout the lobule but in greatest concentration centrilobularly throughout the early phases of glycogen accumulation. As glycogen deposition continued, periportal lobular patterns were observed in rats with high glycogen levels (> 5% ). Glycogen depletion reduced glycogen staining in cells throughout the lobule, but centrilobular patterns prevailed until late in depletion when periportal patterns appeared. Ad libitum-fed rats showed similar glycogen patterns except maximum deposition was characterized by centrilobular or even lobular distribution of glycogen, and periportal patterns of glycogen were seen only rarely in extreme fasted rats. Differences in lobular patterns between ad libitum and control fed rats is apparently related to lower maximum hepatic glycogen levels reached by ad libitum-fed animals.The mammalian liver is important in regulating blood glucose by storing and breaking down hepatic glycogen after appropriate stimulation. Many biochemical details of glycogenolysis and glycogenesis have been reported and much work has been directed toward elucidating the control mechanisms of these processes. (Scrutton and Utter, '68; Robison et al., '68; Villar-Palasi and Larner, '70; Ryman and Whelan, '71). A problem of considerable importance for studies of glycogen metabolism at the cellular level is an accurate description of glycogen patterns in the liver during deposition and depletion of the carbohydrate.In general, investigators have agreed that hepatic intralobular differences in glycogen distribution exist during a cycle of feeding and fasting, but the precise pattern was unclear. Bock and Hoffman (1872) reported that liver glycogen in rabbits was deposited initially around the central vein and only later in more peripheral regions. This finding was confirmed in studies of livers from a variety of species AM. J. ANAT., 140: 299-338.by several workers (Noel, '23; Kater, '33; Forsgren, '35; Eger and Ottensmeir, '52; Themann, '63; Corrin and Aterman, '68). In contrast to this, others claimed that glycogen deposition proceeded from the periphery of the lobule to more centrally situated hepatocytes (Smith, '31; Kater, '33; Edlund and Holmgren, '40; Deane, '44; Ekman and Holmgren, '49).Literature on glycogen patterns during depletion also presents conflicting results. Noel ('23) reported that hepatic glycogen patterns during glycogenolysis were the reve...

Fetal Programming of Perivenous Glucose Uptake Reveals a Regulatory Mechanism Governing Hepatic Glucose Output During Refeeding

“…After 2 h of refeeding, 80% of liver glycogen is therefore contained within the perivenous zone, confirming the perivenous preponderance of glycogen obtained by PAS staining (Fig. 3) (20).…”

“…Because PVGU in perfused MLP liver was markedly diminished, we anticipated that glycogen synthesis would also be decreased, and indeed the glycogen content was 28% less in MLP liver after 2 h of refeeding. The quantitative mapping of glycogen distribution using direct chemical analysis confirms the predominantly perivenous distribution of PAS staining at 2 h. Corroboration was necessary because of the differing morphology of glycogen deposits perivenously (diffuse) and periportally (granular) (20). The glycogen mapping and PAS staining show that the perivenous zone, which lacks gluconeogenic capability (10), accumulates glycogen approximately four times faster than that of the remainder of the lobule in the first 2 h of refeeding.…”

A Molecular Order in the Synthesis and Degradation of Glycogen in the Liver

“…It has indeed been proposed that glycogen synthesis would occur first near the centrolobular vein and that degradation would start in the periportal zone [22]. The fact that the order of degradation is maintained in isolated hepatocytes and also in the concanavalinbound glycogen opposes this interpretation and suggests further that the structure of the glycogen molecule itself is responsible for the order.…”

Effects of compound 48/80 on hepatic glycogen and glucose‐6‐phosphatase early in the diurnal cycle of the rat

“…The early part of the light phase was chosen since glycogen is at a maximum a t this time (e.g., Sasse, 19751, and this period corresponds to the time of previous experiments (e.g., . Controversy exists concerning the intralobular distribution of glycogen during depletion (Babcock and Cardell, 1974;Sasse, 1975;Richards and Potter, 1980). The variation in results is due in part to the fact that the intralobular distribution of glycogen varies with time as well as the metabolic state of the rat (Babcock and Cardell, 1974;Sasse, 1975;Richards and Potter, 1980).…”