Organ culture of adult mouse intestine IV. Stimulation of glucose-6-phosphatase in vitro.

Explants of adult mouse jejunum have been maintained in organ culture with or without fructose added to the medium in order to stimulate the intestinal glucose-6-phosphatase (G-6-Pase). When the fructose is added, at the beginning of the culture, a three-fold increase of G-6-Pase in measured during the first 24 h. If the fructose is added after 24 h of culture, no significant increase of the G-6-Pase is registered in comparison with the controls. Proteins, DNA content and dissacharidase activities are not modified during the culture. Alkaline phosphatase activity presents a twofold increase in the controls and stimulated explants. The ultrastructural localization of the G-6-Pase is not altered during the culture.     

Organ culture of adult mouse intestine

Summary Explants of adult mouse jejunum have been maintained in organ culture with or without fructose added to the medium in order to stimulate the intestinal glucose-6-phosphatase (G-6-Pase). When the fructose is added, at the beginning of the culture, a three-fold increase of G-6-Pase is measured during the first 24h. If the fructose is added after 24 h of culture, no significant increase of the G-6-Pase is registered in comparison with the controls. Proteins, DNA content and dissacharidase activities are not modified during the culture. Alkaline phosphatase activity presents a twofold increase in the controls and stimulated explants. The ultrastructural localization of the G-6-Pase is not altered during the culture.This work was supported by research grants from the Medical Research Council of Canada (J.S.H.) (D.M.)Mr. Chabot is a recipient of a studentship from the Medical Research Council of CanadaD. Ménard, Ph.D. is chercheur-boursier from the CRSQ     

Ultrastructural localization of intestinal glucose-6-phosphatase activity during the postnatal development of the mouse

The development of the endoplasmic reticulum (ER) and the ultrastructural localization of glucose-6-phosphatase activity have been studied in the proximal jejunum and distal ileum during the postnatal period. One day after birth, the amount and the repartition of ER in the jejunal enterocytes are similar to that observed in postweaning period. In the following days an extensive proliferation of SER is noted in the supranuclear zone of the absorbing cells. From day 7 till postweaning period a gradual decrease of the amount of SER is observed and after weaning, the ultrastructure of the enterocytes is similar to that in the adult mouse enterocytes. At all time, a positive reaction for G-6-Pase activity is observed in the cisternae of the endoplasmic reticulum and in the nuclear envelope. In the distal ileum, the SER is poorly developed one day after birth. During the first two weeks, the ER increases but no extensive proliferation of SER can be noted as in the jejunum. The G-6-Pase activity can be visualized in the rough and smooth endoplasmic reticulum as well as in the nuclear envelope. It appears that the proliferation of SER could be interpreted as the morphologic expression of an increased G-6-Pase activity.     

无血清培养高密度乳猪肝细胞的形态和功能变化

本文研究了无血清培养高密度猪肝细胞的形态和功能变化。将分离的肝细胞以高密度(1×10~7/ml)培养在含激素、多种生长因子和营养成分的无血清培养基中,动态观察培养7天中肝细胞形态、活率、蛋白质合成功能、G-6-Pase活性、安定转化功能及LDH含量;同时以无血清培养低密度(5×10~5/ml)肝细胞作为对照组。研究结果表明:高密度培养的 肝细胞各项功能较低密度培养的肝细胞为低;高密度培养的肝细胞的形态、蛋白质合成功能在培养7天中保持稳定;活率随着培养时间的延长而下降,但均高于90％;安定转化功能在培养第2、3天最强;G-6-Pase活性在培养1天后明显下降,然后维持在较低水平;LDH含量在第1、2、3天较高。     

Influence of early visual deprivation on regional activity of brain ATPases in developing rats

The effects of light deprivation from birth to 40 days of age on the development of Na-K-ATPase and Mg-ATPase activity, enzymes significantly involved in cerebral energy exchange, ion transport, and synaptic function, were investigated in visual and non-visual brain areas of the rat. Although both enzymes generally showed a progressive depression with age in light-deprived rats, Na-K-ATPase was more depressed than Mg-ATPase, and significant effects were confined to the superior colliculi, visual cortex, frontal cortex and hypothalamus. A disparate developmental pattern was evidenced in Na-K-ATPase activity in the visual cortex, where it was higher than control values at day 10 but lower by day 40, and in the hypothalamus, where it was lower on days 10 and 25 but significantly higher on day 40. The depression of Mg-ATPase in the hypothalamus of light-deprived rats at all ages and the activation of Na-K-ATPase in this structure is interpreted to mean that discrete alterations may have occurred in neurosecretory functions of the hypothalamus, known to be responsive to light. Transferring dark-reared animals to normal light-cycle conditions at day 25 affected only Mg-ATPase in the visual cortex and Na-K-ATPase in the hypothalamus, both enzymes showing a significant increase by day 40 over values in continually light-deprived animals. These findings confirm that early light deprivation is associated with important biochemical and neuroendocrine changes that persist into adulthood.     

Interference of antioxidants E/O of some free radical "scavengers" with the activity of glucose-6-phosphatase after administration of carbon tetrachloride]

G-6-Pase activity was investigated in the microsomal fraction from rat liver in the presence of carbon tetrachloride and/or propyl gallate (PG), reduced glutathione (GSH) and superoxide dismutase. Results obtained "in vitro" demonstrated that CCl4 induced a 60% inhibition of the microsomal enzyme activity. Moreover, a marked inhibition of G-6-Pase activity was found also when propyl gallate and reduced glutathione were added, at different concentrations, to incubation mixture. In addition, these drugs were unable to interfere with the dangerous effect exerted on the enzymatic activity by the haloalkane. Additional experiments carried out "in vivo" with propyl gallate produced evidence that intraperitoneal administration of the antioxidant was followed by a significant inhibition of G-6-Pase activity, while the damaging action of CCl4 was unaffected. Some possible explanations of these results are reported.     

Nuclear membranes from mammalian liver. VI. Glucose-6-phosphatase in rat liver, a cytochemical and biochemical study

Activities of glucose-6-phosphatase (G-6-Pase) and other phosphatases were determined in nuclei, nuclear membrane and microsomal fractions and subfractions, and condensed chromatin isolated from the liver of adult, newly born and prenatal rats. The purity of the fractions was controlled by electron microscopic morphometry and by measurement of various marker enzymes. The specific G-6-Pase activity of the nuclear membranes was found to be about 60% that of the microsomes. However, when calculated on the basis of the phospholipid content, all fractions had similar activities. Determinations of G-6-Pase enrichments and recoveries were also made. The correspondence of the hydrolysing activities of glucose-6-phosphate, mannose-6-phosphate, and inorganic pyrophosphate, together with various phosphotransferases, showed the same association of the G-6-Pase with these enzymes in the nuclear envelope as in the microsomal membranes. G-6-Pase was also demonstrated in the fractions by cytochemistry, and the activity was localized alongside the cisternal surfaces of both, inner and outer, nuclear membrane. ‘Free’ inner nuclear membrane fragments contained also G-6-Pase. No activity was observed at the nuclear pore complexes. Both, nuclear and microsomal membranes revealed a parallel rapid perinatal increase of G-6-Pase activity climaxing at 23 to 28 h after birth. Triton-X-100 treatment of isolated nuclei, which was found not to selectively release outer nuclear membranes, resulted in a great decrease of G-6-Pase activity as well as in losses of membrane phospholipids. The results clarify the divergence of earlier reports concerning the presence of G-6-Pase in the perinuclear cisterna and add biochemical evidence to the morphologically derived view of the nuclear envelope as being a special form of the ER system.     

Selective tonic inhibition of G-6-Pase catalytic subunit, but not G-6-P transporter, gene expression by insulin in vivo

The regulation of glucose-6-phosphatase (G-6-Pase) catalytic subunit and glucose 6-phosphate (G-6-P) transporter gene expression by insulin in conscious dogs in vivo and in tissue culture cells in situ were compared. In pancreatic-clamped, euglycemic conscious dogs, a 5-h period of hypoinsulinemia led to a marked increase in hepatic G-6-Pase catalytic subunit mRNA; however, G-6-P transporter mRNA was unchanged. In contrast, a 5-h period of hyperinsulinemia resulted in a suppression of both G-6-Pase catalytic subunit and G-6-P transporter gene expression. Similarly, insulin suppressed G-6-Pase catalytic subunit and G-6-P transporter gene expression in H4IIE hepatoma cells. However, the magnitude of the insulin effect was much greater on G-6-Pase catalytic subunit gene expression and was manifested more rapidly. Furthermore, cAMP stimulated G-6-Pase catalytic subunit expression in H4IIE cells and in primary hepatocytes but had no effect on G-6-P transporter expression. These results suggest that the relative control strengths of the G-6-Pase catalytic subunit and G-6-P transporter in the G-6-Pase reaction are likely to vary depending on the in vivo environment.     

Ultrastructural localization of intestinal glucose-6-phosphatase activity during the postnatal development of the mouse

Summary The development of the endoplasmic reticulum (ER) and the ultrastructural localization of glucose-6-phosphatase activity have been studied in the proximal jejunum and distal ileum during the postnatal period. One day after birth, the amount and the repartition of ER in the jejunal enterocytes are similar to that observed in postweaning period. In the following days an extensive proliferation of SER is noted in the supranuclear zone of the absorbing cells. From day 7 till postweaning period a gradual decrease of the amount of SER is observed and after weaning, the ultrastructure of the enterocytes is similar to that in the adult mouse enterocytes. At all time, a positive reaction for G-6-Pase activity is observed in the cisternae of the endoplasmic reticulum and in the nuclear envelope. In the distal ileum, the SER is poorly developed one day after birth. During the first two weeks, the ER increases but no extensive proliferation of SER can be noted as in the jejunum. The G-6-Pase activity can be visualized in the rough and smooth endoplasmic reticulum as well as in the nuclear envelope. It appears that the proliferation of SER could be interpreted as the morphologic expression of an increased G-6-Pase activity.This work was supported by research grant from the Medical Research Council of CanadaD. Ménard, Ph. D. is «Chercheur-boursier du Conseil de la recherche en santé du Québec»     

Activation of liver G-6-Pase in response to insulin-induced hypoglycemia or epinephrine infusion in the rat

This study was conducted to test the hypothesis of the activation of glucose-6-phosphatase (G-6-Pase) in situations where the liver is supposed to sustain high glucose supply, such as during the counterregulatory response to hypoglycemia. Hypoglycemia was induced by insulin infusion in anesthetized rats. Despite hyperinsulinemia, endogenous glucose production (EGP), assessed by [3-(3)H]glucose tracer dilution, was paradoxically not suppressed in hypoglycemic rats. G-6-Pase activity, assayed in a freeze-clamped liver lobe, was increased by 30% in hypoglycemia (P < 0.01 vs. saline-infused controls). Infusion of epinephrine (1 microg x kg(-1) x min(-1)) in normal rats induced a dramatic 80% increase in EGP and a 60% increase in G-6-Pase activity. In contrast, infusion of dexamethasone had no effect on these parameters. Similar insulin-induced hypoglycemia experiments performed in adrenalectomized rats did not induce any stimulation of G-6-Pase. Infusion of epinephrine in adrenalectomized rats restored a stimulation of G-6-Pase similar to that triggered by hypoglycemia in normal rats. These results strongly suggest that specific activatory mechanisms of G-6-Pase take place and contribute to EGP in situations where the latter is supposed to be sustained.     

Enzymatic characterization of the pancreatic islet-specific glucose-6-phosphatase-related protein (IGRP)

Glucose is the main physiological stimulus for insulin biosynthesis and secretion by pancreatic beta-cells. Glucose-6-phosphatase (G-6-Pase) catalyzes the dephosphorylation of glucose-6-phosphate to glucose, an opposite process to glucose utilization. G-6-Pase activity in pancreatic islets could therefore be an important factor in the control of glucose metabolism and, consequently, of glucose-dependent insulin secretion. While G-6-Pase activity has been shown to be present in pancreatic islets, the gene responsible for this activity has not been conclusively identified. A homolog of liver glucose-6-phosphatase (LG-6-Pase) specifically expressed in islets was described earlier; however, the authors could not demonstrate enzymatic activity for this protein. Here we present evidence that the previously identified islet-specific glucose-6-phosphatase-related protein (IGRP) is indeed the major islet glucose-6-phosphatase. IGRP overexpressed in insect cells possesses enzymatic activity comparable to the previously described G-6-Pase activity in islets. The K(m) and V(max) values determined using glucose-6-phosphate as the substrate were 0.45 mm and 32 nmol/mg/min by malachite green assay, and 0.29 mm and 77 nmol/mg/min by glucose oxidase/peroxidase coupling assay, respectively. High-throughput screening of a small molecule library led to the identification of an active compound that specifically inhibits IGRP enzymatic activity. Interestingly, this inhibitor did not affect LG-6-Pase activity, while conversely LG-6-Pase inhibitors did not affect IGRP activity. These data demonstrate that IGRP is likely the authentic islet-specific glucose-6-phosphatase catalytic subunit, and selective inhibitors to this molecule can be obtained. IGRP inhibitors may be an attractive new approach for the treatment of insulin secretion defects in type 2 diabetes.     

Endoplasmic reticulum associated glucose-6-phosphatase activity is developmentally regulated and enriched in microsomes of endo/mesoderm in sea urchins

Summary Glucose-6-phosphatase (G-6-Pase) activity was analyzed during early embryogenesis of the sea urchinS. purpuratus. This activity is detected in very low levels in unfertilized eggs and early embryos but is present at high levels in preparations of endoplasmic reticulum (microsomes) from gastrula stage embryos. The approximately eight-fold increase in the relative activity of G-6-Pase associated with the ER occurs abruptly during a 12 h interval at gastrulation, and thereafter remains at a level comparable to that found in mammalian liver microsomes. The enzyme activity associated with the ER of gastrula stage embryos was completely eliminated from the microsomal pellet when cell lysates were first treated with non-ionic detergent. Analysis of germlayer tissues from late stage pluteus embryos revealed that G-6-Pase activity was more highly enriched in microsomes of endo/mesoderm tissues as compared to microsomes from ectoderm. The increase in ER associated G-6-Pase activity during embryonic development and its enriched activity in the ER of endo/mesoderm, as well as the observation that the signal recognition particle becomes associated with the ER at gastrulation (Le Blanc and Infante 1989), opens the question that this cellular organelle may be differentiating during embryogenesis in sea urchins.     

Kinetic analysis of glucose-6-phosphatase: an investigative approach to carbohydrate metabolism and kinetics

The enzyme glucose-6-phosphatase (G-6-Pase) catalyzes the hydrolysis of glucose-6-phosphate (G-6-P) to glucose. This is one of the key steps in gluconeogenesis and is critically important in maintaining stable blood glucose levels in most mammals. G-6-Pase is primarily found in the endoplasmic reticulum (ER) of hepatocytes and can easily be studied using isolated microsomes prepared from liver ER. A three-part undergraduate laboratory exercise uses rat liver microsomes to focus on the enzymatic analysis of G-6-Pase. The assessment of G-6-Pase activity is conducted using a stopped assay protocol combined with a colorimetric determination of inorganic phosphate (P_i) levels. The laboratory exercise was designed to carry out an independent inhibition investigation using orthovanadate, a competitive inhibitor of G-6-Pase with potential clinical importance. The format of the three-part investigation provides a useful mechanism for demonstrating enzyme kinetics and competitive inhibition using an enzyme that is important for carbohydrate metabolism and glycogen storage disease.     

Ultrastructural localization of phosphatase activity in the guinea pig pineal gland by the cerium technique

Thiamine pyrophosphatase (TPPase), nucleoside diphosphatase (NDPase), and glucose-6-phosphatase (G-6-Pase) were localized by the cerium technique in guinea pig pinealocytes and compared with the corresponding lead technique. NDPase and TPPase were also compared at different pH values using the cerium technique. Vibratome sections of perfusion-fixed tissue were incubated with cerium chloride or lead nitrate. Substrates used were thiamine pyrophosphate (for TPPase), sodium inosine diphosphate (NDPase), and disodium glucose-6-phosphate (G-6-Pase). The 1-2 trans saccules of the Golgi apparatus showed TPPase and NDPase activity but none for G-6-Pase. The endoplasmic reticulum (ER) cisternae and perinuclear space had NDPase and G-6-Pase activity but not TPPase. The abluminal plasmalemma of endothelial cells and the plasmalemma of Schwann cells demonstrated TPPase and NDPase activity but the luminal plasmalemma of the endothelial cells and the plasmalemma of pinealocyte processes showed only NDPase activity. TPPase was active at all pH values tested, but NDPase was most active at pH values of 6.5 and 7.0. Lead phosphate precipitate was frequently seen in nuclei, perinuclear space, ER cisternae, and "synaptic" vesicles when lead was used as the capturing agent. These sites were usually not labeled when cerium was used.     

Glucose-6-phosphatase proteins of the endoplasmic reticulum (Review)

Summary

Hepatic glucose-6-phosphatase (G-6-Pase) catalyses the terminal step of hepatic glucose production and it plays a key role in the maintenance of blood glucose homeostasis. Hepatic G-6-Pase is an integral resident endoplasmic reticulum (ER) protein and it is part of a multicomponent system. Its active site is situated inside the lumen of the ER and transport proteins are needed to allow its substrates, glucose-6-phosphate (G-6-P) (and pyrophosphate), and its products, phosphate and glucose, to cross the ER membrane. In addition, a calcium-binding protein is also associated with the G-6-Pase enzyme. Recent immunological studies have shown that G-6-Pase (which has conventionally been thought to be present only in the gluconeogenic organs) is present in minor cell types in a variety of human tissues and that its distribution changes dramatically during human development. In all the tissues, enzymatic analysis, direct transport assays and/or immunological detection of the ER glucose and phosphate transport proteins have been used to demonstrate the presence and activity of the whole G-6-Pase system. The G-6-Pase protein is very hydrophobic and has proved difficult to purify to homogeneity. Four proteins of the system have now been isolated and polyclonal antibodies have been raised against them; two have also been cloned. The available sequences, together with topologicai studies, have given some information about both the topology of the proteins in the ER and the probable mechanisms by which the proteins are retained in the ER.     

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

The amount and distribution of glycogen as well as the activity of glucose-6-phosphatase (G-6-Pase) in the livers of rats were analyzed by biochemical and/or histochemical techniques. During the first 5 hr of the light cycle, livers of rats were sampled prior to and 30 min following an injection of compound 48/80 or Ringer's solution. Glycogen decreased significantly in response to sampling; however, treatment with compound 48/80 provoked an additional significant decrease in hepatic glycogen. These differences occurred irrespective of the time during the 5 hr that this was studied. The livers of the majority of the rats treated with compound 48/80 displayed a periportal distribution of glycogen, while those treated with Ringer's showed a more uniform pattern. Hepatic G-6-Pase activity was unchanged in either the Ringer's or compound 48/80 treated rats. These results indicated that (1) the significant glycogenolytic response occurs independently of the amount of glycogen present, (2) G-6-Pase activity is not affected within 30 min following the stimulation of glycogenolysis, (3) variation in glycogen patterns during depletion depends on the nature of the stimulus and/or degree of response, and (4) the amount of glycogen available for release is limited.     

Cytochemical localization of glucose-6-phosphatase in rabbit mononuclear phagocytes during differentiation

Cytochemical and biochemical investigations have revealed glucose-6-phosphatase (G-6-Pase) activity in Kupffer cells of the liver. To determine whether other mononuclear phagocytes are also reactive for G-6-Pase, rabbit bone marrow, blood, and alveolar macrophages were tested for G-6-Pase by a modified Wachstein-Meisel method and prepared for electron microscopy. Some mononuclear phagocytes from all three tissues were intensely reactive; others were unreactive. In promonocytes, monocytes, and alveolar macrophages, reaction product for the enzyme was localized throughout all cisternae of the endoplasmic reticulum (ER) and the perinuclear cisternae, but it was absent from the Golgi complex, lysosomes, and occasional smooth tubular channels. These results indicate that mononuclear phagocytes at all stages of development contain cytochemically demonstrable G-6-Pase and that the distribution of the enzyme is not altered during their differentiation from immature cells in the bone marrow to mature macrophages in the lung.     

内质网及其标志酶在离体培养脊髓神经元中的发育变化

In an attempt to elucidate the relationship between synapse formation and cell development, the morphology and cytochemistry of the endoplasmic reticulum and its enzymic marker, glucose-6-phosphatase (G-6-Pase), in cultured mouse spinal neurons were investigated ultrastructurally. It was found that in the early period of the development, neurons were characterized by scarceness of organelles; only a few of granular or agranular endoplasmic reticulum and mitochondria were seen. The endoplasmic reticulum and nuclear envelope were packed specifically with G-6-Pase resection product but the product was weak. After a period of culture, most of the neurons had well-developed endoplasmic reticulum, Golgi apparatus, mitochondria and microtubules, etc. The Golgi apparatus was relatively large, having some cisternae associated with vesicles. Either concave of convex face of the saccules was labeled by thiamine pyrophosphatase (TPPase) specifically. GERL, labeled by cytidine monophosphatase (CMPase), was also seen close to the inner or outer face of some Golgi apparatus. The endoplasmic reticulum at this stage was distributed throughout the cytoplasm, including that in dendrites; its enzyme marker (G-6-Pase) localized consistently within the lumen of all endoplasmic reticulum, nuclear space and subsurface cisternae, and frequently in the concave saccules of the Golgi apparatus. After a long-term culture, some neurons became "aged". The endoplasmic reticulum cisternae enlarged and G-6-Pase reaction reduced. Along with the neuronal development, especially maturation of the endoplasmic reticulum and its enzymic marker, synapse formation was begun at the neuropile area. The axo-dendritic synapses always occurred between the axonal terminals and dendrites where the endoplasmic reticulum had showed positive G-6-Pase reactions. Considering the fact, it suggests that the appearance and change of these specific enzymes may be related to the maturation of the neurons in vitro, and also related to the synapse formation between neurons.     

Diets enriched in sucrose or fat increase gluconeogenesis and G-6-Pase but not basal glucose production in rats

High-fat (HFD) and high-sucrose diets (HSD) reduce insulin suppression of glucose production in vivo, increase the capacity for gluconeogenesis in vitro, and increase glucose-6-phosphatase (G-6-Pase) activity in whole cell homogenates. The present study examined the effects of HSD and HFD on in vivo gluconeogenesis, the catalytic and glucose-6-phosphate translocase subunits of G-6-Pase, glucokinase (GK) translocation, and glucose cycling. Rats were fed a high-starch control diet (STD; 68% cornstarch), HSD (68% sucrose), or HFD (45% fat) for 7-13 days. The ratio of 3H in C6:C2 of glucose after 3H2O injection into 6- to 8-h-fasted rats was significantly increased in HSD (0.68 +/- 0.07) and HFD (0.71 +/- 0.08) vs. STD (0.40 +/- 0.10). G-6-Pase activity was significantly higher in HSD and HFD vs. STD in both intact and disrupted liver microsomes. HSD and HFD significantly increased the amount of the p36 catalytic subunit protein, whereas the p46 glucose-6-phosphate translocase protein was increased in HSD only. Despite increased nonglycerol gluconeogenesis and increased G-6-Pase, basal glucose and insulin levels as well as glucose production were not significantly different among groups. Hepatocyte cell suspensions were used to ascertain whether diet-induced adaptations in glucose phosphorylation and GK might serve to compensate for upregulation of G-6-Pase. Tracer-estimated glucose phosphorylation and glucose cycling (glucose <--> glucose 6-phosphate) were significantly higher in cells isolated from HSD only. After incubation with either 5 or 20 mM glucose and no insulin, GK activity (nmol. mg protein(-1). min(-1)) in digitonin-treated eluates (translocated GK) was significantly higher in HSD (32 +/- 4 and 146 +/- 6) vs. HFD (4 +/- 1 and 83 +/- 10) and STD (9 +/- 2 and 87 +/- 9). Thus short-term, chronic exposure to HSD and HFD increase in vivo gluconeogenesis and the G-6-Pase catalytic subunit. Exposure to HSD diet also leads to adaptations in glucose phosphorylation and GK translocation.     

Role of thyroid hormone in intermediary metabolism of propranolol or alloxan-treated Calotes versicolor.

Administration of L-thyroxine (T4) to thyroidectomized Calotes versicolor significantly increased the activity of glucose-6-phosphatase (G-6-Pase) (liver and kidney), the concentrations of blood glucose and total protein (liver and kidney), and decreased hepatic cholesterol when compared to thyroidectomized lizards. Propranolol injections in thyroidectomized lizards increased the cholesterol concentration and did not change the other parameters. The activity of G-6-Pase and blood glucose content was stimulated, whereas the total protein and cholesterol contents were decreased after alloxan treatment. Administration of T4 to thyroidectomized animals pretreated with propranolol or alloxan significantly elevated the activity of G-6-Pase, the concentrations of blood glucose, and total protein, and reduced hepatic cholesterol level when compared to drug-treated lizards. From the results, it is evident that thyroid hormone has an independent stimulatory influence on intermediary metabolism in C. versicolor irrespective of the involvement of adrenaline or insulin.