Dopamine D2 receptor availability in opiate-dependent subjects before and after naloxone-precipitated withdrawal

Dopamine may play a role in opiate withdrawal and dependence. We measured dopamine D2 receptor availability in 11 opiate-dependent subjects using PFT and [11C]raclopride at baseline and during naloxone-precipitated withdrawal. Because [11C]raclopride is sensitive to endogenous dopamine, this strategy enabled us to test whether we could document in humans the DA reductions reported in animal models of opiate withdrawal. Results were compared with values from 11 controls, two of which also received naloxone. The ratio of the distribution volume in striatum to that in cerebellum (Bmax/Kd + 1) was used as model parameter for D2 receptor availability. Baseline measures for Bmax/Kd were lower in opiate-dependent subjects (2.44 +/- 0.4) than in controls (2.97 +/- 0.45 P < or = .009). Naloxone precipitated an intense withdrawal in the abusers but did not change the Bmax/Kd ratio. This study documents decreases in D2 receptors in opiate-dependent subjects but does not document significant changes in striatal DA concentration during acute withdrawal.

Extra-adrenal pheochromocytoma

Extra-adrenal pheochromocytomas, or gangliomas, develop in the paraganglion chromaffin cells of the sympathetic nervous system. They account for 10% of all pheochromocytomas in adults and 30-40% in children. These tumors are usually larger than their adrenal counterpart. The most common site of extra-adrenal phenochromocytomas is the para-adrenal area, but they also occur at the aortic bifurcation, chest, inferior mesenteric and iliac arteries, bladder, heart and brain. In this report, we describe a 13-year-old girl with a pheochromocytoma along the course of the left ureter, a finding which to our knowledge was previously described only once. Clinical presentation, diagnosis, and treatment are similar to adrenal tumors. Patients should be closely monitored with serum and urine catecholamine determination and MIBG scan to detect any recurrence or distant metastasis. Prognosis is usually good if the tumor is detected early to avoid major complications related to catecholamine excess.

Early organ-specific hemorrhage-induced increases in tissue cytokine content: associated neurohormonal and opioid alterations

Hemorrhage is associated with an impairment in the immune response and with increased concentrations of circulating inflammatory cytokines. The present study determined the time course and localization of alterations in circulating and tissue pro-inflammatory cytokines (TNF-alpha, IL-1-alpha and -beta) in response to fixed-pressure (40 mm Hg) hemorrhage as well as the associated hanges in circulating neurohormonal and opioid mediators. Conscious unrestrained non-heparinized male Sprague-Dawley rats (n = 24) underwent hemorrhage followed by standard resuscitation with lactated Ringer's solution. Animals were sacrificed at three time points; immediately after the hemorrhage period, at completion of resuscitation and 1.5 h after the resuscitation period. Hemorrhage resulted in marked elevations in circulating levels of TNF-alpha, which averaged 860 +/- 201 pg/ml. The levels were similarly elevated following fluid resuscitation (877 +/- 196 pg/ml) and had decreased towards baseline 1.5 h after completion of resuscitation (281 +/- 134 pg/ml). TNF-alpha was not detectable in plasma of time-matched controls. Hemorrhage elevated TNF-alpha content in spleen (25%), lung (55%) and heart (20%), and tissue content remained elevated despite resuscitation. No significant changes in tissue content of TNF-alpha were detected in the liver, kidney or brain. Circulating levels of IL1-alpha and -beta were not detectable in either the time-matched controls or hemorrhaged animals. However, statistically significant elevations in tissue content of IL-1 alpha were observed in heart, spleen, lung, gut and whole brain (15-30%). Tissue content of IL-1 beta did not change in response to hemorrhage and/or fluid resuscitation. Activation of sympathetic outflow, as evidenced by a 3- to 4-fold elevation in circulating epinephrine and norepinephrine levels, was observed immediately after hemorrhage, and was associated with a 5-fold rise in circulating beta-endorphin. These results demonstrate an early increase in tissue cytokine content following hemorrhagic shock, which is associated with elevations in circulating catecholamines and endogenous opioids, consistent with their potential modulatory role in this response.

Central effects of morphine and morphine-6-glucuronide on tissue protein synthesis

The central and peripheral effects of morphine sulfate (Mor) and morphine-6-glucuronide (M6G) on the fractional rates of tissue protein synthesis (kappa s) were determined. We determined ks in conscious rats 2 h after intracerebroventricular injection of Mor (80 micrograms/rat), M6G (1 microgram/rat), or H2O (5 microliters). Intracerebroventricular Mor and M6G administration decreased ks in the liver by 19 and 18% spleen by 19 and 17%, and gastrocnemius by 18 and 17%, respectively. Intravenous injection of Mor (8 mg/kg) or M6G (0.4 mg/kg) did not affect ks in any of the tissues studied. Intracerebroventricular Mor and M6G resulted in an equivalent 10- to 15-fold increase in plasma epinephrine, 2- to 3-fold increase in norepinephrine, and 80-90% increase in corticosterone, with no change in insulin levels. Intracerebroventricular Mor produced a significant 30% decrease in arterial partial O2 pressure (PaO2) and no significant changes in arterial pH and arterial partial CO2 pressure (PacO2). Intracerebroventricular M6G decreased PaO2 (40%) and pH (from 7.44 +/- 0.01 to 7.34 +/- 0.02) and increased Paco2 (36%). The potential contribution of hypoxia to the opiate-induced decrease in ks was assessed in an additional set of rats exposed to 5% O2-95% N2. One or 2 h of hypoxia decreased protein synthesis in the brain by 47 and 56%, liver by 69 and 69%, and skeletal muscle by 51 and 52%, respectively. Our results indicate that Mor and M6G suppress tissue protein synthesis through central mechanisms, most likely mediated by opiate-induced respiratory depression in association with neural and hormonal alterations.

Double minutes in the papillary thyroid cancer cell line PTC-1113A

The cell line PTC-1113A was established from a metastasizing recurrent papillary thyroid cancer. The cell line was growing as monolayer and showed a complex karyotype with chromosome numbers ranging from 30 to 140/metaphase. A proportion of metaphases contained double minutes and/or pulverized chromosomes. Extrachromosomal DNA seemed to originate from a B-group chromosome. A chromosome 4 painting probe hybridized to extrachromosomal material, representing double minutes (dmin) and possibly minutes. In addition, fluorescence in situ hybridization (FISH) with the chromosome 4 library detected a translocation chromosome and a pulverized chromosome originating from chromosome 4. PTC-1113A is, to our knowledge, the single papillary thyroid cancer cell line demonstrating evidence of gene amplification.

Resuscitation with lactated Ringer's solution after hemorrhage: lack of cardiac toxicity

The toxicity of D-lactate has been recognized for almost 30 years. This compound is found in the racemic mixture of lactated Ringer's solutions routinely used for peritoneal dialysis and the resuscitation of trauma victims. The current study was designed to investigate whether toxicity occurred at the D-lactate concentrations achieved during hemorrhage resuscitation with racemic lactated Ringer's solution. Conscious unrestrained male Sprague-Dawley rats (n = 24) were monitored for electrocardiographic abnormalities while undergoing hemorrhage and subsequent resuscitation with either L-lactated, D-lactated, or racemic lactated Ringer's solution. The rats infused with D-lactate showed significant toxicity as evidenced by bradycardia, premature ventricular contractions, and ventricular fibrillation. No such alterations were observed in the animals resuscitated with L-lactate or racemic solutions. Resuscitation with the racemic lactate mixture increased the D-lactate concentrations in the blood, but was not associated with overt changes in cardiac rhythm. The infusion of the different resuscitation fluids produced few significant differences in acid-base status of hemorrhaged rats. These findings indicate that although toxicity may be achieved with a Ringer's solution containing only D-lactate, resuscitation using the racemic mixture does not achieve D-lactate concentrations high enough to be detrimental to the animal.

Contribution of excitatory amino acids to morphine-induced metabolic alterations

Previous studies have indicated that excitatory amino acids are involved in the analgesic and addictive properties of morphine. However, their role in the morphine-induced alterations in glucose metabolism is not known. This study assessed the contribution of NMDA receptor activation to the morphine-induced hormonal and metabolic alterations in conscious unrestrained chronically catheterized rats. Whole body glucose flux was assessed with a primed constant intravenous infusion of [3-3H]glucose in rats pretreated with the NMDA-receptor antagonist MK-801 (0.25 mg/kg, intraarterial) or an equal volume (1.5 ml) of sterile saline (0.9%) administered 15 min prior to i.c.v. injection of H2O (Con; 5 microliters) or morphine sulfate (80 micrograms). No significant alterations were noted in metabolic and hormonal parameters of H2O injected rats. i.c.v. morphine increased the plasma glucose concentration (60%), hepatic glucose production (Ra; 60%) and whole body glucose utilization (Rd; 53%), but did not alter the glucose metabolic clearance rate (MCR). MK-801 alone resulted in transient hyperglycemia (25%), stimulation of glucose Ra (60%) and glucose Rd (53%), and a significant (30%) increase in MCR. MK-801 pretreatment blunted the morphine-induced hyperglycemia and the increased glucose Ra and Rd. Morphine increased the plasma concentration of epinephrine (4-fold), norepinephrine (2-fold) and corticosterone (67%); however, no alterations in plasma insulin and glucagon were detected. MK-801 pretreatment, blunted the morphine-induced increase in corticosterone and norepinephrine, and elicited a significant rise in insulin concentrations. These results indicate that activation of the NMDA receptors contributes to the morphine-induced hyperglycemia and hormonal alterations. Furthermore, this response appears partially mediated by activation of sympathetic outflow and suppression of insulin release, which is blunted by inhibition of NMDA receptors.

Central opiate modulation of growth hormone and insulin-like growth factor-I

The effects of central administration of morphine-sulfate (MOR:80 micrograms) and morphine-6-glucuronide (M6G:1 microgram) on the growth hormone (GH)/insulin-like growth factor (IGF) system were assessed. MOR and M6G were injected intracerebroventricularly (ICV) in chronically catheterized 24 h fasted rats; time-matched control animals received H2O (5 microliters). MOR increased plasma GH concentrations 3-fold 2 h after i.c.v. injection, and transiently increased the plasma concentration and liver content of IGF-I (60% and 90%, respectively) 30 min after i.c.v injection. M6G did not produce any significant alterations in plasma GH and IGF-I levels at the time-points measured. Both MOR and M6G increased the concentration of IGF binding protein-1 (IGFBP-1) in plasma and liver 2 h after injection. However, MOR showed 2- to 2.5-fold greater effect than M6G in stimulating plasma and liver IGFBP-1. MOR and M6G produced similar increases in plasma epinephrine (5-fold), norepinephrine (3-fold) and corticosterone (1.5-fold). Neither opiate significantly altered circulating insulin levels. These findings suggest that opiate modulation of GH and IGF may be hormone-independent and centrally modulated. We speculate that differential affinities of MOR and M6G to the different opiate receptor subtypes might be responsible for their distinct effects on GH/IGF-I system.

Calcium beta-hydroxy-beta-methylbutyrate. 1. Potential role as a phosphate binder in uremia: in vitro study

The binding capacity of calcium beta-hydroxy-beta-methylbutyrate (calcium HMB), compared to other binders, was investigated in an in vitro study. Fifty milliequivalents of either calcium HMB, calcium acetate, calcium carbonate, aluminum hydroxide gel or non-gel aluminum hydroxide was added to a phosphate solution, titrated (HCl or NaOH), shaken and centrifuged to four different pH levels at 37 degrees C (simulating the gastrointestinal milieu). The difference in phosphate concentration between that of the initial and that of the supernatant represented from the bound phosphate in the precipitate. After 4 h at a pH of 6 (representing the intestinal condition after a meal), the binding percentage was: calcium acetate = 95.6%, calcium HMB = 92.6%, calcium carbonate = 46.4%, aluminum hydroxide gel = 33.4% and non-gel aluminum hydroxide = 17.8%. There was no significant difference (p > 0.05) between calcium HMB and calcium acetate. These results suggest that calcium HMB is an efficient phosphate binder in vitro, which may predict its effective role in vivo.

Endogenous opiates do not modulate LPS-induced alterations in carbohydrate metabolism

This study aimed to determine the contribution of endogenous opiates to the hormonal and glucose metabolic response to lipopolysaccharide (LPS). Rats were infused with naloxone (NAL) (32 micrograms/h) for 2 h prior to the injection of LPS (100 micrograms/100 g body weight) and hemodynamic, hormonal, and metabolic parameters were determined. NAL produced no detectable alterations in any of the parameters assessed. LPS transiently decreases (26%) mean arterial blood pressure (MABP) and increased plasma glucose concentration (100-130%), glucose rate of appearance (50-100%), and glucose rate of disappearance (50-100%). NAL did not alter the LPS-induced drop in mean arterial blood pressure or the glucose response to LPS. LPS reduced plasma insulin (54%), and increased glucagon (270%), corticosterone (180%), and tumor necrosis factor concentrations in plasma (peak 3200-4600 pg/mL at 90 min), with no modification by NAL pretreatment. These results suggest a lack of involvement of endogenous opiate pathways in the glucose metabolic and hormonal responses to LPS.

Morphine-3-glucuronide: hyperglycemic and neuroendocrine potentiating effects

The greater potency of morphine-6-glucuronide (M6G) as well as the inactivity of morphine-3-glucuronide (M3G) with respect to the antinociceptive effects of the parent molecule, morphine (MOR), have been well established. It has been suggested that M3G is an antagonist of MOR's antinociceptive and respiratory depressive effects. The present study addressed the central nervous system (CNS) interaction of these opiate metabolites on their metabolic and hormonal effects. Whole body glucose kinetics were assessed on conscious, chronically catheterized, unrestrained rats. M3G (5 microg) or H2O (5 microl) was injected intracerebroventricularly (i.c.v.) 15 min prior to the bolus administration of H2O (5 microl), M6G (1 microg), or MOR (80 microg). i.c.v. M3G (5 microg) resulted in behavioral excitation, hyperglycemia (+50%), stimulation of glucose rate of appearance (Ra; +100%), glucose rate of disappearance (Rd; +70%), and metabolic clearance rate (MCR; +33%) within 30 min after injection with no alterations in hormone concentrations. i.c.v. M6G and MOR produced progressive hyperglycemia with significantly high catecholamine and corticosterone levels. M3G pretreatment resulted in enhanced elevations in plasma glucose levels (+52% and + 18%), plasma lactate (+138% and +108%), norepinephrine (+96% and +30%), and epinephrine (+62% and +67%) in response to both i.c.v. MOR and M6G administration. These findings suggest a non-opiate and non-hormonal mechanism for M3G-induced hyperglycemia. In contrast, the metabolic and hormonal responses to i.c.v. M6G and MOR are associated with elevations in catecholamine and corticosterone levels. which are remarkably enhanced by M3G pretreatment, most likely through accelerated catecholamine release. Our findings suggest a modulatory role for MOR glucuronidation, not only by rendering it inactive, as in the case of M3G, but by an interplay of the metabolic effects of the parent molecule and its metabolite.

Theories and assumptions on energy expenditure. Determinations in the clinical setting

Energy metabolism is defined as the sum of complex and integrated chemical reactions by which the body derives energy from the environment and maintains the proper functioning of all biologic processes. The final common pathway for all these processes is the complete oxidation of carbohydrates and fats and partial oxidation of proteins to carbon dioxide and water. These processes occur primarily in the mitochondria and are coupled to the biochemical reactions of the tricarboxylic acid cycle (better known as the Krebs cycle).

Effects of an acute increase in epinephrine and cortisol on carbohydrate metabolism during insulin deficiency

This study was undertaken to investigate the effects of an acute increase in the plasma epinephrine level, with or without an accompanying increase in the plasma cortisol level, during selective insulin deficiency on glycogenolysis and gluconeogenesis in conscious overnight-fasted dogs. Experiments consisted of an 80-min tracer and dye equilibration period, a 40-min basal period, and a 180-min experimental period. In all protocols, selective insulin deficiency was created during the experimental period by infusing somatostatin peripherally (0.8 micrograms.kg-1.min-1) with basal replacement of glucagon intraportally (0.65 ng.kg-1.min-1). In EPI+SAL (n = 6), an additional infusion of epinephrine (0.04 micrograms.kg-1.min-1) was infused during the experimental period along with saline. In EPI+CORT (n = 6), hydrocortisone (3.0 microgram.kg-1.min-1) was infused in addition to epinephrine during the experimental period. In SAL+CORT (n = 5), hydrocortisone was infused during the experimental period. In SALINE (n = 5), neither epinephrine nor cortisol was infused. [3-3H]glucose, [U-14C]alanine, and indocyanine green dye were used to assess glucose production (rate of appearance [Ra]) and gluconeogenesis using tracer and arteriovenous difference techniques. During selective insulin deficiency in SALINE, the arterial plasma glucose level increased from 6.0 +/- 0.1 to 15.8 +/- 1.1 mmol/l; Ra increased from 14.7 +/- 0.7 to 24.9 +/- 1.7 mumol.kg-1.min-1. Gluconeogenic efficiency and the conversion of alanine and lactate to glucose increased to 300 +/- 55 and 355 +/- 67% of basal. In EPI+SAL and EPI+CORT, plasma glucose increased from 6.2 +/- 0.1 to 19.8 +/- 0.9 mmol/l and from 6.3 +/- 0.1 to 19.5 +/- 0.9 mmol/l. In EPI+SAL and EPI+CORT, Ra increased from 16.5 +/- 1.1 to 29.3 +/- 3.2 mumol.kg-1.min-1 and from 15.4 +/- 1.3 to 28.3 +/- 2.5 mumol.kg-1.min-1. The rise in gluconeogenic efficiency was similar to the rise that occurred in SALINE, but gluconeogenic conversion increased 17-fold in each of the two epinephrine groups. During the epinephrine infusion, gluconeogenesis accounted for a maximum of 55% of total glucose production as opposed to 31% during insulin deficiency alone. An increase in cortisol alone during insulin deficiency (SAL+CORT) had no effect on glucose level, glucose production, or gluconeogenesis. These results suggest that small increases in the plasma epinephrine level during insulin deficiency can significantly worsen the resulting hyperglycemia through stimulation of both glycogenolysis and gluconeogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)

Modulation of endogenous opiate production: effect of fasting

The endogenous opiate alkaloid content in tissues from fed, 24 h and 48 h fasted rats was determined. Plasma morphine and codeine concentrations did not change in response to fasting. Morphine levels in the spleen increased 3-fold after 24 h of fasting and were lower than fed rats by 48 h of fasting; no change was detected in spleen codeine levels. Brain morphine levels were elevated 5-fold after 24 h of fasting and were two-fold higher than those of fed rats after 48 h of fasting. Brain codeine levels did not change with fasting. These results indicate that opiate alkaloids are endogenously produced in rodent tissues, particularly in the spleen, liver, and adrenals. The synthesis of morphine, in the spleen and brain, is maximally stimulated after 24 h of fasting, without alterations in tissue codeine synthesis. These suggest differential regulation of the endogenous synthetic pathways of morphine and codeine in response to the stress of fasting.

Modulation of metabolic effects of morphine-6-glucuronide by morphine-3-glucuronide

Modification of pharmacological effects of morphine by its glucuronides has been recently reported. Morphine-6-glucuronide (M6G) is a more potent opioid agonist than morphine, whereas morphine-3-glucuronide (M3G) has no opioid effects and has been suggested to be an antagonist of morphine's antinociceptive and respiratory depressive effects. This study addressed the metabolic effects of direct central nervous system administration of M3G and its interaction with the hyperglycemic effects of M6G. Hormonal and whole body glucose metabolic effects of M3G, M6G, and M3G + M6G ICV administration were studied in conscious unrestrained chronically catheterized rats. Whole body glucose kinetics were assessed with a primed constant intravenous infusion of 3[3H]glucose in rats injected intracerebroventricularly (ICV) with H2O (5 microliters), M3G (1 microgram), M6G (1 microgram), or M3G (1 microgram) + M6G (1 microgram). A significant rise in plasma glucose level was observed after ICV injection of M6G (28%), and M3G + M6G (41%), but not after M3G as compared to time-matched H2O control. Early increases in the rate of glucose appearance (Ra) and whole body glucose utilization (Rd) were observed (58% and 48%, respectively) 30 min after M3G + M6G administration, whereas the increases after M6G injection were progressive and reached values 47% higher than basal 180 min after injection. M3G administration enhanced the M6G induced increase in plasma glucose level (+21%), Ra (+29%), Rd (+26%), and plasma lactate level (+21%). Though no significant hormonal change was observed in H2O, M3G, and M6G injected animals, the combination of M3G + M6G resulted in a significant increase in circulating catecholamine levels with no alterations in plasma corticosterone, insulin, and glucagon.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of glucagon in the control of protein and amino acid metabolism in vivo

The relative contribution of hyperglucagonemia to the mechanisms of nitrogen loss during catabolic states has not been clearly established. The present study examines the independent effect of physiologic elevations of plasma glucagon on whole-body protein kinetics, as well as on net amino acid balance across the liver and gastrointestinal tract tissues, in conscious 18-hour-fasted dogs (n = 7). Each study consisted of a 120-minute equilibration period, a 30-minute basal period, and a 150-minute experimental period. Leucine kinetics were measured using L-[1-14C]leucine. Pancreatic hormones were maintained by infusing intravenous somatostatin (0.8 micrograms/kg.min), intraportal insulin (275 microU/kg.min), and intraportal glucagon (0.65 ng/kg.min basally and 2.5 experimentally). Dextrose was infused to maintain plasma glucose constant (14.1 +/- 0.3 mumol/L), thereby providing a consistent metabolic steady state for the study of protein and amino acid metabolism. In the experimental period, plasma glucagon was fourfold basal levels (112 +/- 10 v 32 +/- 6 pg/mL), whereas plasma insulin remained stable (mean, 10 +/- 1 microU/mL). Hepatic glucose production was increased 30%, but leucine rates of appearance ([Ra] proteolysis), oxidative disappearance (Rd), and nonoxidative Rd (protein synthesis) were not altered during the experimental period. Furthermore, the net release of amino acids by the gastrointestinal tract was not increased by glucagon. However, uptake and extraction of amino acids by the liver were increased, resulting in a 17% decrease in total plasma amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential hemodynamic, metabolic and hormonal effects of morphine and morphine-6-glucuronide

Although the hyperglycemic effect of morphine has been previously described, it is not clear whether this is the result of increased glucose production and/or decreased glucose utilization and if this metabolic effect is lost with glucuronidation. This study assessed the hemodynamic (heart rate; HR and mean arterial blood pressure; MABP), hormonal and whole body glucose metabolic effects of morphine (MOR) and its metabolite morphine 6-glucuronide (MOR-6G) in conscious unrestrained chronically catheterized rats. Whole body glucose kinetics were assessed with a primed constant intravenous infusion of [3-3H]glucose in rats infused i.c.v. with H2O (Con; 5 microliters/h), MOR (80 micrograms/h) or MOR-6G (1 microgram/h) for a total of 4 h. MOR administration resulted in a significant 20% elevation in HR and no change in MABP. MOR-6G produced a 14% increase in HR and no change in MABP. A significant rise in plasma glucose (+23%), hepatic glucose production (Ra; +27-61%) and whole body glucose utilization (Rd; +31-61%) was also observed within 60 min of MOR administration. I.c.v. MOR-6G resulted in hyperglycemia (+60%), stimulation of glucose Ra (+60%) and glucose Rd (+50%). No significant alterations were noted in hemodynamic, metabolic and hormonal parameters of H2O infused rats. I.c.v. MOR resulted in a significant increases in epinephrine (2-fold), norepinephrine (50%), corticosterone (97%) with no alterations in plasma insulin and glucagon. I.c.v. MOR-6G resulted in more marked elevations in norepinephrine (5-fold), epinephrine (7-fold) and similar elevation in corticosterone (99%) and modest elevation of glucagon (40%).(ABSTRACT TRUNCATED AT 250 WORDS)

Gut-derived proteolysis during insulin-induced hypoglycemia: the pain that breaks down the gut

The metabolic events associated with early response to injury have received little attention because of the confounding effects of the hemodynamic alterations that normally occur during this early phase. We have used a well established and reproducible model of insulin-induced hypoglycemia in the conscious dog to define the glucose and amino acid kinetic alterations as well as the hormonal and interorgan amino acid and gluconeogenic precursor flux characteristics of the "ebb" phase of postinjury metabolism. The results from our whole-body response have demonstrated on enhanced rate of whole body proteolysis and amino acid oxidation. The site of the majority of the proteolytic response has been demonstrated to be the extra-hepatic splanchnic tissues or gut. These findings have been supported by studies focusing on the specific organ changes, which have demonstrated alterations compatible with impaired proliferation at the level of the gut mucosa. Furthermore, the regulation of this gut-derived proteolysis has been demonstrated to be mediated by the glucopenia at the level of the central nervous system. The specific site of this response is still elusive; however, the mediators seem to involve not only the traditional hormonal and neurotransmitter pathways but also the release of endogenous opioids and opiates. Although a cause-effect relationship has not yet been demonstrated for the control of gut-derived proteolysis by opioids and opiates, we present evidence that leads us to hypothesize that relationship as a possible regulatory mechanism.

Effect of acute ethanol intoxication on glucoregulation during prolonged insulin-induced hypoglycemia

This study examined the interaction of acute ethanol administration on glucose homeostasis during insulin-induced hypoglycemia (IIH). Glucose kinetics and net hepatic balances of alanine, glycerol, and lactate were estimated in three groups of dogs: group I underwent 3 h of IIH; group II received a continuous ethanol infusion in addition to IIH; group III received ethanol for 3 h. In group I, IIH resulted in a sustained twofold increase in glucose rate of appearance (Ra) and net hepatic uptake (NHU) of glycerol and lactate but no change in NHU of alanine. In group II, glucose Ra rose transiently, NHU of alanine and glycerol increased two- and fivefold, respectively, whereas NHU of lactate dropped 60%. In group III, no alterations in plasma glucose levels, glucose Ra, and NHU of alanine and glycerol were observed, but NHU of lactate switched to a net output. These results demonstrate that ethanol alone or with IIH exclusively inhibited NHU of lactate, and this was responsible, in a stoichiometric fashion, for the failure of the delayed increase in glucose Ra during IIH.

Glucose-6-phosphatase gene expression and activity are modulated in hemorrhagic shock: evidence for a new heat-sensitive activator

Decreased hepatic fructose 2,6-bisphosphate levels were observed in the early phase of hemorrhagic shock. The lower sugar bisphosphatae level was a result of increased phosphoenolpyruvate levels and decreased glucose-6-phosphate and fructose-6-phosphate levels. The decreased glucose-6-phosphate levels correlated with increased activity of liver glucose-6-phosphatase and a concomitant 2.5-fold increase in glucose-6-phosphatase mRNA abundance. In addition, protein-free filtrate from hemorrhagic shock rats, but not from control rats, increased glucose-6-phosphatase activity. However, when control and hemorrhagic shock protein-free filtrates were heated, they both increased the glucose-6-phosphatase activity of the respective microsomes to the same extent. It is concluded that the early hyperglycemic phase of hemorrhagic shock is due to enhanced glucose-6-phosphatase gene expression and activity and the generation of a heat sensitive activator of the enzyme.

Impact of suprapharmacological androgenic steroid administration on basal and insulin-stimulated glucose and amino acid metabolism

Effects of androgenic steroids at doses used by athletes were studied in a canine model system in which dosage, diet, and activity were controlled. Dogs were treated with 19-nortestosterone (200 mg/wk intramuscularly) or vehicle and were studied at 18 (n = 4 in steroid and vehicle) or 32 (n = 6 in steroid and n = 4 in vehicle) days. A laparotomy was performed under general anesthesia 17 days before experimentation, and catheters were placed in an artery, portal vein, and hepatic vein. Studies consisted of an equilibration (120 minutes) and a control (40 minutes) period and a three-step immunoreactive insulin euglycemic clamp (1, 2, and 15 mU/kg.min). Step 1 was 150 minutes, and steps 2 and 3 were 90 minutes. Data were collected during the last 30 minutes of each step. Glucose and leucine kinetics were assessed with 3H-glucose and 14C-leucine. Plasma glucose in steroid and vehicle groups was 104 +/- 5 (mean +/- SE) versus 108 +/- 3 mg/dL and 100 +/- 5 versus 107 +/- 4 mg/dL at 18 and 32 days. Glucose turnover was similar at 18 days in steroid and vehicle groups (3.9 +/- 0.3 v 3.6 +/- 0.3 mg/kg.min, respectively), but was elevated in the steroid group at 32 days (5.4 +/- 0.5 v 3.2 +/- 0.4 mg/kg.min). Glucose infusion rates were lower in the steroid group with 15 mU/kg.min immunoreactive insulin at 32 days (15.0 +/- 1.1 v 21.2 +/- 1.4 mU/kg.min). Immunoreactive insulin-independent glucose utilization (Rd) was unaffected at 18 days of steroid treatment, but was increased by almost fourfold at 32 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of central and peripheral adrenergic stimulation to IL-1 alpha-mediated glucoregulation

The present study determined the contribution of central adrenoceptors and the peripheral sympathetic nervous system in regulating the hormonal and glucose metabolic response to intracerebroventricular injection of interleukin (IL)-1 alpha. After an overnight fast, hepatic glucose production (HGP) and peripheral glucose uptake (GU) were assessed in catheterized conscious unrestrained rats using [3-3H]glucose. Intracerebroventricular injection of IL-1 alpha (100 ng) produced a hyperglycemia that resulted from an early increase in HGP (108%) that exceeded a smaller elevation (82%) in GU. Intracerebroventricular injection of the alpha- and beta-adrenergic antagonists phentolamine and propranolol before IL-1 alpha blunted the glucose metabolic response 30-50%. This attenuated response was associated with normalization of the IL-1 alpha-induced hyperglucagonemia and hyperinsulinemia and a 50-60% reduction in the incremental increase in plasma catecholamines. In contrast to central administration, systemic infusion of adrenergic blockers completely prevented the IL-1 alpha-induced increases in plasma glucose, as well as HGP and GU. In these rats, the elevated plasma levels of insulin, glucagon, and corticosterone produced by intracerebroventricular injection of IL-1 alpha were still present. The results indicate that 1) the enhanced whole body glucose metabolism seen after central administration of IL-1 alpha is mediated by increased sympathoadrenal activity and 2) the IL-1 alpha-induced increase in pancreatic insulin and glucagon secretion as well as part of the peripheral catecholamine release is mediated by central adrenoreceptors.

Thiamin deficiency impairs endotoxin-induced increases in hepatic glucose output

We addressed the role of thiamin, a cofactor for several enzymes involved in glucose metabolism, in the glucose metabolic response to endotoxin. Characterized by hyperglycemia, increased hepatic glucose production exceeding elevated rates of whole-body glucose utilization, this response is mediated by hormones and cytokines and is dependent on the immune and nutritional status of the host. We hypothesized that a thiamin-deficient state would impair the metabolic response to endotoxin. Rats were fed a thiamin-deficient or control diet for 6 wk before in vivo assessment of glucose kinetics. In control rats, Escherichia coli endotoxin increased the rate of glucose appearance (+76%), disappearance (+70%), and metabolic clearance (+50%). Thiamin deficiency resulted in increased plasma glucose (18%) and lactate (3- to 4-fold) as well as in a 30% decrease in insulin and an increase in glucagon (2.6-fold) and corticosterone (3.6-fold). Thiamin deficiency inhibited the endotoxin-induced hyperglycemia and the rise in hepatic glucose production, glucose utilization, and metabolic clearance rate.