Development of gluconeogenic enzymes in fetal sheep liver and kidney

In the sheep, the system of enzymes necessary for conversion of nonhexose substrates to glucose becomes active during late fetal life. Glucose-6-phosphatase and fructose-1,6-diphosphatase, two of the four key gluconeogenic enzymes, appear in significant amounts between 100 and 120 days gestation. Phosphoenolpyruvate carboxykinase activity is comparable to mature animals as early as 45 days gestation. Two aminotransferases, necessary to allow amino acid access to the gluconeogenic pathway, likewise have substantial activity as early as 45 days gestation. Hence, the surge of glucose-6-phosphatase and fructose-1,6-diphosphatase at 100-120 days gestation makes possible the endogenous production of new glucose by fetal sheep at a time when the amount of glucose transferred from the maternal circulation is less than the total aerobic substrate utilized by the fetus. Both renal cortex and liver have similar developmental patterns for the gluconeogenic enzymes, although renal cortex generally shows greater activity than liver. This observation holds true for tissue from both fetal and mature animals.     

Role of adrenals in the vitamin A-mediated increase in the activities of gluconeogenic enzymes of rat liver.

Oral administration of large doses of vitamin A to rats even for two days was found to cause marked increase in the activities of PEP-carboxykinase, fructose-1, 6-diphosphatase, glucose-6-phosphatase and alanine aminotransferase in liver. However, overdosage of this vitamin failed to enhance the activities of these enzymes in the livers of bilaterally adrenalectomized rats. The adrenalectomy was also found to abolish the vitamin A-mediated increase in the levels of glucose and lactic acid in the blood. Thus, it is concluded that stimulation of gluconeogenesis in hypervitaminosis is, perhaps, caused by the increase in the activities of the key gluconeogenic enzymes of the liver, and that adrenal hormones are directly or indirectly involved in this process.     

Biochemical compartmentation of fish tissues. Distribution of gluconeogenic enzymes in the brain

1. Specific glucose-6-phosphatase and fructose-1,6-diphosphatase activity were found to be biochemically compartmentalized in four parts of the brain in nine nutritionally important fishes. 2. Glucose-6-phosphatase and fructose-1,6-diphosphatase activity were highest in the cerebrum and lowest in the cerebellum. 3. Piscivorous fishes had the highest gluconeogenic enzyme content, followed by catfishes and major carps. 4. After the liver and muscles, the various parts of the brain play an important role in carbohydrate metabolism. 5. A direct relationship between the stage of evolution and elevation of gluconeogenic enzyme levels was observed. 6. It is evident from the results and the discussion that evolution modifies the biochemical organization of fishes in general and of their brain in particular.     

Dietary and hormonal regulation of some enzyme activities associated with gluconeogenesis in rabbit liver.

1. Starvation increases the activity of cytosolic P-enolpyruvate carboxkinase in rabbit liver some 4-5 fold but does not alter the activities of mitochondrial P-enolpyruvate carboxykinase, fructose-1,6-diphosphatase or glucose-6-phosphatase.2. Alloxan-induced diabetes increases the activities of cytosolic P-enolpyruvate carboxykinase, fructose-1,6-diphosphatase and glucose-6-phosphatase approx. 6-, 2- and 2-fold, respectively. Again the activity of mitochondrial P-enolpyruvate carboxykinase is not altered. 3. Administration of mannoheptulose rapidly increases blood glucose levels and also causes a significant increase in cytosolic P-enolpyruvate carboyxkinase activity within 4 h. The activities of mitochondrial P-enolpyruvate carboxykinase, fructose-1,6-diphosphatase and glucose-6-phosphatase are not affected. 4. Administration of hydrocortisone also increases blood glucose levels and the activities of cytosolic P-enolpyruvate carboxykinase and glucose-6-phosphatase are significantly increased within 12h. Again, mitochondrial P-enolpyruvate carboxykinase and fructose-1,6-diphosphatase activities remain unaffected. 5. The observations that (A) the activity of cytosolic P-enolpyruvate carboxykinase responds to more situations conducive to gluconeogenesis than do the activities of mitochondrial P-enolpyruvate carboxykinase, fructose-1,6-diphosphatase and glucose-6-phosphatase, and (B) cytosolic P-enolpyruvate carboxykinase activity is rapidly adaptive under appropriate circumstances, suggests that this particular enzyme's activity plays an important role in the regulation of gluconeogenesis in rabbits.     

Early effects of excessive retinol intake on gluconeogenesis. Involvement of adrenals in the increased activities on Gluconeogenic Enzymes of rat.

A stimulation of gluconeogenesis by excessive intake of retinol is suggested on the basis of enhanced incorporation of [2-¹⁴C]glycine into liver glycogen in rats fed excess retinol. Among the key gluconeogenic enzymes studied, activities of hepatic PEP-carboxykinase, fructose-1,6-bisphosphatase, glucose-6-phosphatase, and alanine aminotransferase were markedly increased, whereas that of pyruvate carboxylase remained unaltered. However, feeding of retinol to bilaterally adrenalectomized rats or rats treated with actinomycin D failed to cause significant increase in the activities of these enzymes. It is concluded that (i) gluconeogenesis is stimulated by excess retinol due to, perhaps, increased activities of key gluconeogenic enzymes, and (ii) adrenals are directly or indirectly involved in the retinol-mediated increase in the activities of the gluconeogenic enzymes. Also, data are presented that indicate a requirement for protein synthesis for the expression of retinol-mediated alterations in the activities of gluconeogenic enzymes.     

The appearance, properties, and functions of gluconeogenic enzymes in the liver and kidney of the guinea pig during fetal and early neonatal development.

The changes in the activity and properties of the four gluconeogenic enzymes have been followed during development of the guinea pig. Pyruvate carboxylase was almost exclusively mitochondrial and kinetically identical to the adult liver enzyme and did not appear in significant activity until after day 50 when it rose to values several times higher than those in the adult liver, then fell after birth. Little activity was detected in the fetal kidney. Phosphoenolpyruvate carboxylase appeared in the fetal liver from day 30 on, both in the mitochondrial and cytoplasmic fractions. The cytoplasmic enzyme was kinetically and chromatographically identical to the mitochondrial enzyme of the fetal and maternal liver. After birth the activity of the cytoplasmic enzyme increased and that of the particulate enzyme fell. Fetal kidney activity appeared several days before birth. Fructose 1,6-diphosphatase and glucose 6-phosphatase appeared in the fetal liver and kidney after day 40; the former showed no postnatal change while the latter rose 10-fold after birth. Fetal liver fructose 1,6-diphosphatase was more sensitive to AMP and fructose 1,6-diphosphate inhibition but was chromatographically indistinguishable from the maternal liver enzyme. Despite the presence of the gluconeogenic enzymes, gluconeogenesis and glyconeogenesis were not detected in the fetal liver until 7–9 days before birth. While the synthesis of glyceride-glycerol from 3-carbon compounds was detected from 35–40 days onwards and some of the gluconeogenic enzymes participate in that pathway, gluconeogenesis was not detected in the fetal kidney.     

Effects of insulin,glucagon and dexamethasone on pyruvate kinase in cultured hepatocytes

Long-term (24–48 h) and short-term (10–30 min) regulation by hormones of hepatic pyruvate kinase activity was investigated in adult rat hepatocytes cultured under serum-free conditions. In the absence of hormones, pyruvate kinase total activity decreased to 83%, 67% and 39% of the initial level at 24, 48 and 72 h of culture. Insulin (100 nM) maintained total activity significantly above control levels throughout this period. In contrast, glucagon (100 nM) and dexamethasone (100 nM) accelerated the gradual decrease within 24 h (glucagon) or 48 h (dexamethasone) of culture. In these long-term experiments, activity at non-saturating concentrations of phosphoenolpyruvate was decreased by glucagon and dexamethasone but not directly modulated by insulin. However, insulin increased the cellular content of the pyruvate kinase activator fructose-1,6-diphosphate. In short-term experiments on cells cultured under serum- and hormone-free conditions for 48 h, both glucagon and dexamethasone independently caused a rapid, dose-dependent increase of the K_0.5 for phosphoenolpyruvate within 10 min, while V_max was not affected. Insulin inhibited this action of glucagon and dexamethasone and, in their absence, significantly increased substrate affinity for phosphoenolpyruvate within 30 min. Cellular fructose-1,6-diphosphate contents remained unchanged under these conditions. The data identify glucocorticoids and insulin - in addition to glucagon - as short-term regulators of the catalytic properties of pyruvate kinase. All three hormones are effective in the long-term control of total enzyme activity.     

Activity of gluconeogenetic enzymes of rat kidney cortex during acute hypoxia]

The activities of gluconeogenic enzymes of the rat kidney cortex was studied after exposure to lowered atmospheric pressure (200 mm Hg) for 3 hours. The hypoxic stress was found to cause an increase in the activities of phosphoenolpyruvate carboxykinase and alanine aminotransferase, but failed to affect significantly the activities of fructose-1,6-diphosphatase, glucose-6-phosphatase, and aspartate aminotranspherase. The ratio of glucose-6-phosphatase/hexokinase activities was increased under these conditions.     

A comparison of the effects of diabetes induced with either alloxan or streptozotocin and of starvation on the activities in rat liver of the key enzymes of gluconeogenesis

1. Measurements of the activities in rat liver of the four key enzymes involved in gluconeogenesis, i.e. pyruvate carboxylase (EC 6.4.1.1), phosphoenolpyruvate carboxykinase (EC 4.1.1.32), fructose 1,6-diphosphatase (EC 3.1.3.11) and glucose 6-phosphatase (EC 3.1.3.9), have been carried out, all four enzymes being measured in the same liver sample. Changes in activities resulting from starvation and diabetes have been studied. Changes in concentration (activity/unit wet weight of tissue) were compared with changes in the hepatic cellular content (activity/unit of DNA). 2. Each enzyme was found to increase in concentration during starvation for up to 3 days, but only glucose 6-phosphatase and phosphoenolpyruvate carboxykinase showed a significant rise in content. Fructose 1,6-diphosphatase appeared to decrease in content somewhat during the early stages of starvation. 3. There was a marked increase in the concentration of all four enzymes in non-starved rats made diabetic with alloxan or streptozotocin, for the most part similar responses being found for the two diabetogenic agents. On starvation, however, the enzyme contents in the diabetic animals tended to fall, often with streptozotocin-treated animals to values no greater than for the normal overnight-starved rat. Deprivation of food during the period after induction of diabetes with streptozotocin lessened the rise in enzyme activity. 4. The results are compared with other published values and factors such as substrate and activator concentrations likely to influence activity in vivo are considered. 5. Lack of correlation of change in fructose 1,6-diphosphatase with the other enzymes questions whether it should be included in any postulation of control of gluconeogenic enzymes by a single gene unit.     

Adaptive alterations in Lactobacillus casei. Gluconeogenesis in cells grown on ribose.

Adaptive alterations of the enzymes involved in gluconeogenesis have been studied in homofermentative Lactobacillus casei after growth on ribose. Among the enzymes induced were phosphoenolpyruvate carboxykinase, fructose 1,6-diphosphatase and glucose 6-phosphatase. The activities of phosphoglucomutase and fructose 1,6-diphosphate aldolase, measured in the direction of condensation of triose phosphates, were also observed to be enhanced. Oxalacetate, the substrate of phosphoenolpyruvate carboxykinase, appears to be formed through aspartate aminotransferase activity developed in ribose-grown cells. The gluconeogenic enzymes were repressed when glucose was added to the pentose-containing medium during the growth of the organism. The relative participation of precursors, assessed from the extent of incorporation of radioactivity into cellular polysaccharides, suggested that the products of ribose fermentation did not contribute to new glucose synthesis.     

Gluconeogenesis in the amphibian retina. Lactate is preferred to glutamate as the gluconeogenic precursor.

The capacity for gluconeogenesis in the isolated amphibian retina was found to be approx. 70-fold greater with lactate than with glutamate as the gluconeogenic precursor, 1426 versus 21 pmol of glucose incorporated into glycogen/h per mg of protein. It was also found that 11-15% of the glucosyl units in glycogen are derived from C3 metabolites of the glycolytic pathway, suggesting that lactate is recycled within the retina. In concert with these metabolic observations, a full complement of the gluconeogenic enzymes was detected in retinal homogenates. These included: glucose-6-phosphatase, fructose-1,6-bisphosphatase, acetyl-CoA-dependent pyruvate carboxylase and phosphoenolpyruvate carboxykinase. Agents that regulate the rate of gluconeogenesis in hepatic tissue were tested on the retina. At concentrations of glutamate and lactate that are presumed to be relevant physiologically, it was found that vasoactive intestinal peptide, ionophore A23187 and elevated [K+] each enhanced the rate of gluconeogenesis in Ringer containing 50 microM-glutamate, whereas in Ringer containing 8.5 mM-lactate these agents inhibited the rate of gluconeogenesis. Further, it was found that the classic gluconeogenic hormone glucagon inhibited gluconeogenesis in both glutamate- and lactate-containing Ringer. Retinal energy metabolism was found to be altered in lactate-containing Ringer, in that lactate production was suppressed completely. In addition, glycogen metabolism appeared to be dependent on increased cytosolic Ca2+ and was insensitive to increased retinal cyclic AMP.     

Effect of plumbagin on some glucose metabolising enzymes studied in rats in experimental hepatoma

Plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone) isolated from Plumbago zeylanica Linn, when administered orally, at a dosage of 4 mg/kg body weight induces tumour regression in 3-methyl-4-dimethyl aminoazobenzene (3Me-DAB) induced hepatoma in Wistar male rats. The purpose of this investigation was to identify the changes in the rate of glycolysis and gluconeogenesis in tumour-bearing rats and the effects of treatment with Plumbagin. The levels of certain glycolytic enzymes, namely, hexokinase; phosphoglucoisomerase; and aldolase levels increased (p<0.001) in hepatoma bearing rats, whereas they decreased in Plumbagin administered rats to near normal levels. Certain gluconeogenic enzymes, namely, glucose-6-phosphatase and fructose-1,6-diphosphatase decreased (p<0.001) in tumour hosts, whereas Plumbagin administration increased the gluconeogenic enzyme levels in the treated animals. These investigations indicate the molecular basis of the different biological behaviour of 3MeDAB induced hepatoma and the anticarcinogenic property of Plumbagin against hepatoma studied in rats.     

Status of phosphatase activities in the liver and kidney of rats treated with isosaline leaf and stem-bark extracts of Harungana madagascariensis (L)

The activities of phosphatases and other biochemical parameters were examined in rats treated with isosaline leaf and stem-bark extracts of Harungana madagascariensis (L). Results show that both the leaf and stem-bark extracts significantly increased the activities of serum and liver alkaline phosphatase, liver acid phosphatase, liver and kidney glucose-6-phosphatase, fructose-1,6-diphosphatase and glycogen in the treated rats. While the stem-bark extract significantly elevated the activities of fructose-1,6-diphosphatase and glycogen in the kidney, these biochemical parameters were not affected by treatment with the leaf extract. The activity of serum acid phosphatase was unaffected by the two extracts. The results obtained clearly show that these extracts caused a marked increase in gluconeogenesis in the liver and kidney of the treated rats. While the stem-bark extract increased gluconeogenesis in both liver and kidney, the leaf extract caused an increase in gluconeogenesis only in the liver. The increased serum alkaline phosphatase activity caused by these extracts may, aside from having other tissues contributing to it, be due to damage caused by these extracts to the hepatocytes. The extent of pathological changes as well as the implications of these findings to folklore medicine requires further investigation.     

The permissive effects of glucocorticoid on hepatic gluconeogenesis. Glucagon stimulation of glucose-suppressed gluconeogenesis and inhibition of 6-phosphofructo-1-kinase in hepatocytes from fasted rats

Production of [14C]glucose from [14C]lactate in the perfused livers of 24-h fasted adrenalectomized rats was not stimulated by 1 nM glucagon but was significantly increased by 10 nM hormone. Crossover analysis of glycolytic intermediates in these livers revealed a significant reduction in glucagon action at site(s) between fructose 6-phosphate and fructose 1,6-bisphosphate as a result of adrenalectomy. Site(s) between pyruvate and P-enolpyruvate was not affected. In isolated hepatocytes, adrenalectomy reduced glucagon response in gluconeogenesis while not affecting glucagon inactivation of pyruvate kinase. A distinct lack of glucagon action on 6-phosphofructo-1-kinase activity was noted in these cells. When hepatocytes were incubated with 30 mM glucose, lactate gluconeogenesis was greatly stimulated by glucagon. A reduction in both sensitivity and responsiveness to the hormone in gluconeogenesis was seen in the adrenalectomized rat. These changes were well correlated with similar impairment in glucagon action on 6-phosphofructo-1-kinase activity and fructose 2,6-bisphosphate content in hepatocytes from adrenalectomized rats incubated with 30 mM glucose. These results suggest that adrenalectomy impaired the gluconeogenic action of glucagon in livers of fasted rats at the level of regulation of 6-phosphofructo-1-kinase and/or fructose 2,6-bisphosphate content.     

Purinergic regulation of glucose and glutamine synthesis in isolated rabbit kidney-cortex tubules

The effects of extracellular purinergic agonists and their breakdown products on glucose and glutamine synthesis in rabbit kidney-cortex tubules incubated with aspartate + glycerol or alanine + glycerol + octanoate were investigated. A rapid extracellular degradation of ATP was accompanied by an accumulation of AMP, inosine, and hypoxanthine. Extracellular ATP and its breakdown products accelerated glucose synthesis in renal tubules, while ammonium released from adenine-containing compounds enhanced glutamine synthesis and diminished the degree of gluconeogenesis stimulation. In contrast to AMP and inosine, ATP evoked calcium signals, while both ATP and inosine decreased intracellular cAMP content and accelerated the flux through fructose-1,6-bisphosphatase as concluded from changes in gluconeogenic intermediates. Since (i) the activity of partially purified renal fructose-1,6-bisphosphatase was increased upon protein phosphatase-1 treatment and decreased following treatment of previously dephosphorylated enzyme with protein kinase A catalytic subunit and (ii) both 8-bromoadenosine 3',5'-cyclic monophosphate and 8-(4-chlorophenyltio)-cAMP inhibited renal glucose synthesis, it seems likely that in rabbit renal tubules ATP and inosine stimulate gluconeogenesis via cAMP decrease, which favors the appearance of a more active, dephosphorylated form of fructose-1,6-bisphosphatase, a key gluconeogenic enzyme.     

Biochemical compartmentation of gluconeogenic enzymes in fish tissues

Compartmentation of liver, kidney muscle and gill tissues in relation to glucose-6-phosphatase and fructose 1,6-diphosphatase was examined in the fishes Labeo rohita, Clarias batrachus and Channa punctatus. The anterior region of the right and left lobes of the liver contained the maximum of fructose 1,6-diphosphatase and glucose-6-phosphatase, while the minimum was in the right and left lobes of gill tissue. Herbivore fish had the highest gluconeogenic enzyme content followed by carnivore and piscivore species. The observed enzymatic variations in the three fish species were discussed.     

Mechanism of action of 2,5-anhydro-D-mannitol in hepatocytes. Effects of phosphorylated metabolites on enzymes of carbohydrate metabolism

Isolated rat hepatocytes convert 2,5-anhydromannitol to 2,5-anhydromannitol-1-P and 2,5-anhydromannitol-1,6-P2. Cellular concentrations of the monophosphate and bisphosphate are proportional to the concentration of 2,5-anhydromannitol and are decreased by gluconeogenic substrates but not by glucose. Rat liver phosphofructokinase-1 phosphorylates 2,5-anhydromannitol-1-P; the rate is less than that for fructose-6-P but is stimulated by fructose-2,6-P2. At 1 mM fructose-6-P, bisphosphate compounds activate rat liver phosphofructokinase-1 in the following order of effectiveness: fructose-2,6-P2 much greater than 2,5-anhydromannitol-1,6-P2 greater than fructose-1,6-P2 greater than 2,5-anhydroglucitol-1,6-P2. High concentrations of fructose-1,6-P2 or 2,5-anhydromannitol-1,6-P2 inhibit phosphofructokinase-1. Rat liver fructose 1,6-bisphosphatase is inhibited competitively by 2,5-anhydromannitol-1,6-P2 and noncompetitively by 2,5-anhydroglucitol-1,6-P2. The AMP inhibition of fructose 1,6-bisphosphatase is potentiated by 2,5-anhydroglucitol-1,6-P2 but not by 2,5-anhydromannitol-1,6-P2. Rat liver pyruvate kinase is stimulated by micromolar concentrations of 2,5-anhydromannitol-1,6-P2; the maximal activation is the same as for fructose-1,6-P2. 2,5-Anhydroglucitol-1,6-P2 is a weak activator. 2,5-Anhydromannitol-1-P stimulates pyruvate kinase more effectively than fructose-1-P. Effects of glucagon on pyruvate kinase are not altered by prior treatment of hepatocytes with 2,5-anhydromannitol. Pyruvate kinase from glucagon-treated hepatocytes has the same activity as the control pyruvate kinase at saturating concentrations of 2,5-anhydromannitol-1,6-P2 but has a decreased affinity for 2,5-anhydromannitol-1,6-P2 and is not stimulated by 2,5-anhydromannitol-1-P. The inhibition of gluconeogenesis and enhancement of glycolysis from gluconeogenic precursors in hepatocytes treated with 2,5-anhydromannitol can be explained by an inhibition of fructose 1,6-bisphosphatase, an activation of pyruvate kinase, and an abolition of the influence of phosphorylation on pyruvate kinase.     

Hormonal and lipogenic and gluconeogenic enzymatic responses in LA/N-corpulent rats

Genetically obese normotensive rats, LA/N-corpulent (cp), were fed ad libitum diets containing either 54% sucrose or cooked corn starch for 12 weeks. Twenty-four rats were used for the study; half were corpulent (cp/cp) and half were lean (cp/+ or +/+). Fasting levels of plasma insulin, glucose, corticosterone, glucagon and growth hormone, and activities of liver and epididymal fat pad glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME), and liver and kidney glucose-6-phosphatase (G6Pase), fructose 1,6-diphosphatase (FDPase), and phosphoenolpyruvate carboxykinase (PEPCK) were measured. A significant phenotype effect was observed in insulin, corticosterone, growth hormone, and liver G6PD, ME, FDPase, and kidney PEPCK, G6Pase, FDPase, and epididymal fat pad G6PD and ME (corpulent greater than lean), and glucagon (lean greater than corpulent). Diet effect (sucrose greater than starch) was significant for plasma glucose, liver ME, and kidney G6Pase. Although not significant at the P less than 0.05 level, insulin, corticosterone, liver G6PD and FDPase and kidney FDPase tended to be higher in sucrose-fed rats. This study suggests that the corpulent rat is more lipogenic and gluconeogenic than the lean, and that the hormones responsible are effective in keeping both the lipogenic and gluconeogenic enzyme activity elevated.     

Carbohydrate metabolism in sheep when adding carboxyline to their diet

The content of glycogen and glucose, as well as aldolase, phosphofructokinase, phosphoglucomutase, glucose-6-phosphatase and fructose-1,6-diphosphatase activities in liver tissue and the same activities in skeletal muscle of sheep were determined under the influence of prolonged addition of carboxyline separately and in combination with methionine, diammonium phosphate and potassium iodine to their diet. It is established that under the influence of carboxyline the glycogen content as well as aldolase and fructose-1,6-diphosphatase activities rise significantly in the liver of the tested animals. In the skeletal muscle only aldolase activity increases.     

Mechanism of anti-diabetic action, efficacy and safety profile of GII purified from fenugreek (Trigonella foenum-graceum Linn.) seeds in diabetic animals

Mechanism of action of GII (100 mg/kg body weight, po for 15 days) purified from fenugreek (T. foenum-graecum) seeds was studied in the sub-diabetic and moderately diabetic rabbits. In the sub-diabetic rabbits it did not change much the content of total lipids, glycogen and proteins in the liver, muscle and heart (glycogen was not studied in the heart). However, in the moderately diabetic rabbits same treatment decreased total lipids more in the liver (21%) than those in the heart and muscle. Total protein content increased (14%) in the liver but negligible change (5-7%) was observed in heart and muscle. Glycogen increased (17%) in the liver but not in the muscle of the moderately diabetic rabbits (glycogen was not estimated in the heart). Among the enzymes of glycolysis, activity of glucokinase was not affected in the liver of both the sub-diabetic and moderately diabetic rabbits. Phosphofructokinase and pyruvate kinase activity in both sub-diabetic and moderately diabetic rabbits increased (13-50%) indicating stimulation of glycolysis. The activity of gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-diphosphatase of the sub-diabetic rabbits decreased in the liver (15-20%) but not in the kidneys. In the moderately diabetic rabbits after treatment with GII, glucokinase in the liver was not affected much (-9%) but increased well in the muscle (40%). Phosphofructokinase and pyruvate kinase were moderately increased both in the liver and the muscle (18-23%). The gluconeogenic enzyme glucose-6-phosphatase decreased reasonably well in the liver and kidneys (22, 32%). Fructose-1,6-diphosphatase decreased only slightly (10, 9%) in the moderately diabetic rabbits. Thus GII seems to decrease lipid content of liver and stimulate the enzymes of glycolysis (except glucokinase) and inhibit enzymes of gluconeogenesis in the liver of the diabetic especially moderately diabetic rabbits.