Efficacy and safety of basal insulin degludec 100 IU/mL versus glargine 300 IU/mL for type 1 diabetes: The single-center INEOX randomized controlled trial

AIMS

To compare efficacy and safety of degludec 100 IU/mL (Deg-100) and glargine 300 IU/mL (Gla-300) in adults with type 1 diabetes.

METHODS

Open-label, single-center, randomized, parallel-group, 24-week trial in adults with type 1 diabetes, on basal-bolus insulin therapy, HbA1c ≤ 10%, using self-monitoring blood glucose. Participants were randomized 1:1 to a basal-bolus insulin regimen with Deg-100 (N = 129) or Gla-300 (N = 131). Primary efficacy endpoint: mean change in HbA1c from baseline to week-24. Main safety outcome: incidence rate of hypoglycemia during the study. Quality of life (DQOL) and satisfaction with diabetes treatment (DTSQ) were assessed.

RESULTS

At week 24, after adjusting for baseline HbA1c, the decrease in HbA1c did not differ between groups: Deg-100 (-0.07 ± 0.7%) and Gla-300 (-0.16 ± 0.77%) (P = 0.320). There were no significant differences between groups in HbA1c, nocturnal hypoglycemia, severe hypoglycemia, DQOL, or DTSQ scores. The incidence rates of hypoglycemia < 3.9 mmol/L (Deg-100: 115.24 events/person-year vs Gla-300: 99.01 events/person-year, p < 0.001); and < 3.0 mmol/L (Deg-100: 41.17 events/person-year vs Gla-300: 34.29 events/person-year, p < 0.001) were different between groups.

CONCLUSIONS

Deg-100 and Gla-300 have similar metabolic efficacy, incidence ratio of nocturnal and severe hypoglycemia, DQOL and DTSQ scores. Differences in the incidence rate of hypoglycemia < 3.9 mmol/L and < 3.0 mmol/L should be confirmed.

Inadequate control of thyroid hormones sensitizes to hepatocarcinogenesis and unhealthy aging

An inverse correlation between thyroid hormone levels and longevity has been reported in several species and reduced thyroid hormone levels have been proposed as a biomarker for healthy aging and metabolic fitness. However, hypothyroidism is a medical condition associated with compromised health and reduced life expectancy. Herein, we show, using wild-type and the Pax8 ablated model of hypothyroidism in mice, that hyperthyroidism and severe hypothyroidism are associated with an overall unhealthy status and shorter lifespan. Mild hypothyroid Pax8 +/- mice were heavier and displayed insulin resistance, hepatic steatosis and increased prevalence of liver cancer yet had normal lifespan. These pathophysiological conditions were precipitated by hepatic mitochondrial dysfunction and oxidative damage accumulation. These findings indicate that individuals carrying mutations on PAX8 may be susceptible to develop liver cancer and/or diabetes and raise concerns regarding the development of interventions aiming to modulate thyroid hormones to promote healthy aging or lifespan in mammals.

LH-21 and abnormal cannabidiol improve β-cell function in isolated human and mouse islets through GPR55-dependent and -independent signalling

AIMS

To examine the effects of Abn-CBD (GPR55 agonist) and LH-21 (CB1 antagonist) on human and mouse islet function, and to determine signalling via GPR55 using islets from GPR55^-/- mice.

MATERIALS AND METHODS

Islets isolated from human organ donors and mice were incubated in the absence or presence of Abn-CBD or LH-21, and insulin secretion, [Ca²⁺ ]_i, cAMP_, apoptosis, β-cell proliferation and CREB and AKT phosphorylation were examined using standard techniques.

RESULTS

Abn-CBD potentiated glucose-stimulated insulin secretion and elevated [Ca²⁺ ]_i in human islets and islets from both GPR55^+/+ and GPR55^-/- mice. LH-21 also increased insulin secretion and [Ca²⁺ ]_i in human islets and GPR55^+/+ mouse islets, but concentrations of LH-21 up to 0.1 μM were ineffective in islets from GPR55^-/- mice. Neither ligand affected basal insulin secretion or islet cAMP levels. Abn-CBD and LH-21 reduced cytokine-induced apoptosis in human islets and GPR55^+/+ mouse islets, and these effects were suppressed after GPR55 deletion. They also increased β-cell proliferation: the effects of Abn-CBD were preserved in islets from GPR55^-/- mice, while those of LH-21 were abolished. Abn-CBD and LH-21 increased AKT phosphorylation in mouse and human islets.

CONCLUSIONS

This study showed that Abn-CBD and LH-21 improve human and mouse islet β-cell function and viability. Use of islets from GPR55^-/- mice suggests that designation of Abn-CBD and LH-21 as a GPR55 agonist and a CB1 antagonist, should be revised.

Leucine supplementation modulates fuel substrates utilization and glucose metabolism in previously obese mice

OBJECTIVE

High-protein diets favor weight loss and its maintenance. Whether these effects might be recapitulated by certain amino acids is unknown. Therefore, the impact of leucine supplementation on energy balance and associated metabolic changes in diet-induced obese (DIO) mice during and after weight loss was investigated.

METHODS

DIO C57BL/6J mice were fed a normocaloric diet to induce weight loss while receiving or not the amino acid leucine in drinking water. Body weight, food intake, body composition, energy expenditure, glucose tolerance, insulin, and leptin sensitivity were evaluated. Q-PCR analysis was performed on muscle, brown and white adipose tissues.

RESULTS

DIO mice decreased body weight and fat mass in response to chow, but supplementation with leucine did not affect these parameters. During weight maintenance, mice supplemented with leucine had improved glucose tolerance, increased leptin sensitivity, and lower respiratory quotient. The latter was associated with changes in the expression of several genes modulating fatty acid metabolism and mitochondrial activity in the epididymal white and the brown adipose tissues, but not muscle.

CONCLUSIONS

Leucine supplementation might represent an adjuvant beneficial nutritional therapy during weight loss and maintenance, because it improves lipid and glucose metabolism and restores leptin sensitivity in previously obese animals.

Anti-obesity efficacy of LH-21, a cannabinoid CB(1) receptor antagonist with poor brain penetration, in diet-induced obese rats

BACKGROUND AND PURPOSE

Peripheral blockade of cannabinoid CB(1) receptors has been proposed as a safe and effective therapy against obesity, putatively devoid of the adverse psychiatric side effects of centrally acting CB(1) receptor antagonists. In this study we analysed the effects of LH-21, a peripherally acting neutral cannabinoid receptor antagonist with poor brain penetration, in an animal model of diet-induced obesity.

EXPERIMENTAL APPROACH

To induce obesity, male Wistar rats were fed a high-fat diet (HFD; 60 kcal% fat) whereas controls received a standard diet (SD; 10 kcal% fat). Following 10 weeks of feeding, animals received a daily i.p. injection of vehicle or 3 mg·kg(-1) LH-21 for 10 days. Plasma and liver samples were used for biochemical analyses whereas visceral fat-pad samples were analysed for lipid metabolism gene expression using real-time RT-PCR. In addition, the potential of LH-21 to interact with hepatic cytochrome P450 isoforms and cardiac human Ether-à-go-go Related Gene (hERG) channels was evaluated.

KEY RESULTS

LH-21 reduced feeding and body weight gain in HFD-fed animals compared with the control group fed SD. In adipose tissue, this effect was associated with decreased gene expression of: (i) leptin; (ii) lipogenic enzymes, including SCD-1; (iii) CB(1) receptors; and (iv) both PPARα and PPARγ. Although there were no significant differences in plasma parameters between HFD- and SD-fed rats, LH-21 did not seem to induce hepatic, cardiac or renal toxicity.

CONCLUSIONS AND IMPLICATIONS

These results support the hypothesis that treatment with the peripherally neutral acting CB(1) receptor antagonist, LH-21, may promote weight loss through modulation of visceral adipose tissue.

Reduction of body weight, liver steatosis and expression of stearoyl-CoA desaturase 1 by the isoflavone daidzein in diet-induced obesity

BACKGROUND AND PURPOSE

The lack of safe and effective treatments for obesity has increased interest in natural products that may serve as alternative therapies. From this perspective, we have analysed the effects of daidzein, one of the main soy isoflavones, on diet-induced obesity in rats.

EXPERIMENTAL APPROACH

Rats made obese after exposure to a very (60%) high fat-content diet were treated with daidzein (50 mg·kg(-1)) for 14 days. The dose was selected on the basis of the acute effects of this isoflavone on a feeding test. After 14 days, animals were killed and plasma, white and brown adipose tissue, muscle and liver studied for the levels and expression of metabolites, proteins and genes relevant to lipid metabolism.

KEY RESULTS

A single treatment (acute) with daidzein dose-dependently reduced food intake. Chronic treatment (daily for 14 days) reduced weight gain and fat content in liver, accompanied by high leptin and low adiponectin levels in plasma. While skeletal muscle was weakly affected by treatment, both adipose tissue and liver displayed marked changes after treatment with daidzein, affecting transcription factors and lipogenic enzymes, particularly stearoyl coenzyme A desaturase 1, a pivotal enzyme in obesity. Expression of uncoupling protein 1, an important enzyme for thermogenesis, was increased in brown adipose tissue after daidzein treatment.

CONCLUSIONS AND IMPLICATIONS

These results support the use of isoflavones in diet-induced obesity, especially when hepatic steatosis is present and open a new field of use for these natural products.

Distribution of diacylglycerol lipase alpha, an endocannabinoid synthesizing enzyme, in the rat forebrain

1,2-diacylglycerol lipase alpha (DAGLα) is responsible for the biosynthesis and release of 2-arachidonoyl-glycerol (2-AG), the most abundant endocannabinoid in the brain. Although its expression has been detected in discrete regions, we showed here an integrated description of the distribution of DAGLα mRNA and protein in the rat forebrain using in situ hybridization histochemistry and immunohistochemistry. As novelty, we described the distribution of DAGLα protein expression in the olfactory system, the rostral migratory stream, neocortex, septum, thalamus, and hypothalamus. Similar DAGLα immunostaining pattern was also found in the brain of wild-type, but not of DAGLα knockout mice. Immunohistochemical data were correlated by the identification of DAGLα mRNA expression, for instance, in the somata of specific cells in olfactory structures, rostral migratory stream and neocortex, cells in some septal-basal-amygdaloid areas and the medial habenula, and magnocellular cells of the paraventricular hypothalamic nucleus. This widespread neuronal distribution of DAGLα is consistent with multiple roles for endocannabinoids in synaptic plasticity, including presynaptic inhibition of neurotransmitter release. We discuss our comparative analysis of the forebrain expression patterns of DAGLα and other components of the endocannabinoid signaling system, including the CB(1) receptor, monoacylglyceride lipase (MAGL), and fatty acid amide hydrolase (FAAH), providing some insight into the potential physiological and behavioral roles of this system.

Synthesis of fatty acid amides of catechol metabolites that exhibit antiobesity properties

A series of fatty acid amides of 3,4-methylenedioxymethamphetamine (MDMA) catechol metabolites were synthesized in order to evaluate their biological activities. Upon administration, all synthesized compounds resulted in negative modulation of food intake in rats. The most active compounds have affinity for the CB(1) receptor and/or PPAR-α; part of their biological activity may be caused by these double interactions.

A sensitive method to analyse the effect of putative regulatory ligands on the release of glycoprotein from primary cultures of dispersed bovine subcommissural organ cells

The subcommissural organ (SCO) releases into the cerebrospinal fluid (CSF) large glycoproteins that polymerize forming the Reissner's fibre (RF), which is involved in CSF circulation and homeostasis. We obtained high purity primary cultures of bovine secretory SCO cells and measured glycoprotein release by a reliable and sensitive ELISA method. We also analysed the effect of regulatory ligands known to control the secretory activity of the SCO. Cells cultured for short time (4h) released a high amount of glycoproteins that decreased with time. In young cultures, ATP increased and serotonin inhibited secretion rate. By contrast the acetylcholine agonist carbachol and high potassium did not evoke any detectable change in SCO glycoprotein release. These results support not only the suitability of the methodological approach but an important role of both ATP and serotonin in regulating SCO secretory activity as well.

Central versus peripheral antagonism of cannabinoid CB1 receptor in obesity: effects of LH-21, a peripherally acting neutral cannabinoid receptor antagonist, in Zucker rats

The endogenous cannabinoid system plays an important modulatory role in feeding behaviour and metabolism, acting at both central and peripheral levels. Chronic administration of cannabinoid CB(1) receptor antagonists has been found to be effective in experimental obesity. However, clinically available cannabinoid receptor antagonists are inverse agonists that can target CB(1) receptors located in both central circuits regulating appetite and motivation and in peripheral organs regulating metabolism and energy expenditure. This profile complicates understanding of cannabinoid CB(1) receptor blockade as a therapeutic strategy in obesity and metabolic disorders. This review aims to explore the relevance of both inverse agonism and peripheral cannabinoid receptor blockade on the beneficial actions of chronic cannabinoid receptor blockade, by comparing the actions of the reference antagonist/inverse agonist rimonabant and the newly designed drug LH-21. LH-21 is a triazol derivative and a neutral cannabinoid receptor antagonist; it has a poor penetration rate into the central nervous system. When given acutely it decreases food intake and enhances the anorectic actions of oleoylethanolamide, a feeding suppressant lipid that acts on peripheral sensory terminals in a similar way as rimonabant. Unlike rimonabant, chronic administration of LH-21 (3 mg/kg) reduces feeding but does not improve hypertriglyceridaemia or hypercholesterolaemia; nor does it reduce liver fat deposits in Zucker rats. These results suggest that the inverse agonism and/or the antagonism of central cannabinoid CB(1) receptors are necessary for the metabolic benefits of cannabinoid CB(1) receptor blockade, but not for the appetite reduction.

Presence of functional cannabinoid receptors in human endocrine pancreas

AIMS/HYPOTHESIS

We examined the presence of functional cannabinoid receptors 1 and 2 (CB1, CB2) in isolated human islets, phenotyped the cells producing cannabinoid receptors and analysed the actions of selective cannabinoid receptor agonists on insulin, glucagon and somatostatin secretion in vitro. We also described the localisation on islet cells of: (1) the endocannabinoid-producing enzymes N-acyl-phosphatidyl ethanolamine-hydrolysing phospholipase D and diacylglycerol lipase; and (2) the endocannabinoid-degrading enzymes fatty acid amidohydrolase and monoacyl glycerol lipase.

METHODS

Real-time PCR, western blotting and immunocytochemistry were used to analyse the presence of endocannabinoid-related proteins and genes. Static secretion experiments were used to examine the effects of activating CB1 or CB2 on insulin, glucagon and somatostatin secretion and to measure changes in 2-arachidonoylglycerol (2-AG) levels within islets. Analyses were performed in isolated human islets and in paraffin-embedded sections of human pancreas.

RESULTS

Human islets of Langerhans expressed CB1 and CB2 (also known as CNR1 and CNR2) mRNA and CB1 and CB2 proteins, and also the machinery involved in synthesis and degradation of 2-AG (the most abundant endocannabinoid, levels of which were modulated by glucose). Immunofluorescence revealed that CB1 was densely located in glucagon-secreting alpha cells and less so in insulin-secreting beta cells. CB2 was densely present in somatostatin-secreting delta cells, but absent in alpha and beta cells. In vitro experiments revealed that CB1 stimulation enhanced insulin and glucagon secretion, while CB2 agonism lowered glucose-dependent insulin secretion, showing these cannabinoid receptors to be functional.

CONCLUSIONS/INTERPRETATION

Together, these results suggest a role for endogenous endocannabinoid signalling in regulation of endocrine secretion in the human pancreas.

Liver expression of proteins controlling interferon-mediated signalling as predictive factors in the response to therapy in patients with hepatitis C virus infection

Combination therapy with interferon-alpha (IFNalpha) and ribavirin is the current treatment of choice for hepatitis C virus (HCV) infection. However, an important number of patients fail to respond to this therapeutic strategy. Factors determining IFN responsiveness are not well understood, and assessment of biomarkers that predict the response to IFN therapy in HCV patients is necessary. Several studies show that particular HCV proteins are able to block IFN function through interaction with important IFN-signal mediators, such as signal transducers and activators of transcription (STATs). We performed immunostaining analysis of STATs in liver tissue from IFN-responder vs. non-responder HCV patients in order to compare the expression profile of these proteins between both groups. Tissue arrays of liver biopsies were used to study the expression of STAT1, STAT2, STAT5 and PIAS1 (protein inhibitor of activated STAT1). Robust and higher expression levels of STAT1, STAT2 and STAT5 in liver tissue from HCV patients were found when compared with samples from healthy donors. However, no significant differences were observed between IFN-responder and -non-responder groups, but rather increasing levels of STAT1, STAT2 and STAT5 paralleled the degree of liver injury. Importantly, PIAS1 expression in the nucleus of most hepatocytes in HCV tissue biopsy sections, particularly of non-responder HCV patients, strongly indicated a regulatory effect on STAT1-DNA binding, likely affecting the IFN late signalling. In conclusion, our evidence indicates that intense PIAS1 nuclear staining, widely distributed in hepatocytes of infected livers, could be a good predictive factor of a defective response to IFN treatment, and a biomarker that is easily detectable by immunostaining during standard histopathological liver biopsy analysis.

[Experimental models used in research into genetic disorders that involve intellectual disability]

INTRODUCTION

A basic principle of molecular and clinical medicine states that the function of the organs and the cells they are made up of is determined by the overall set of specific proteins. Therefore, the function of each organ depends on the molecules present in each cell, and hence it comes as no surprise to find that when tissue function is altered, different changes have taken place in the proteins. In the nervous system there are numerous examples of changes in proteins that correlate with functional alterations, either during normal or pathological development.

DEVELOPMENT

In order to understand these relations, and to establish models in which to study the aetiopathogenesis of the disease, it is necessary to direct steady synthesis or to suppress synthesis in the brain of the protein that is potentially involved in the development of the disease. In consequence, it is possible to determine whether the presence or the absence of the protein is the direct or indirect cause of the effects; this is one of the main goals that must be achieved in order to enable researchers to define potential therapeutic targets in hereditary diseases. In order to manipulate the specific protein causing a pathology, we use experimental animal models as essential research tools, since they enable us to determine which mechanisms are altered and how the function of a particular protein affects the mechanisms being studied.

CONCLUSIONS

Suppressing a gene or its over-expression in models using genetically modified mice will provide us with a means of modifying the genome and, eventually, the protein in the different tissues as well as in the nervous system in an attempt to imitate the genetic pathology that involves mental retardation. By controlling or suppressing the expression of a protein in the brain it becomes possible to remodel the functional profile of the tissue and study the consequences of molecular genetic manipulation, together with the biochemical, cytological and physiological processes, under normal basal conditions and under specific stimuli or conditions such as stress.

Oleylethanolamide impairs glucose tolerance and inhibits insulin-stimulated glucose uptake in rat adipocytes through p38 and JNK MAPK pathways

Oleylethanolamide (OEA) is a lipid mediator that inhibits food intake and body weight gain and also exhibits hypolipemiant actions. OEA exerts its anorectic effects peripherally through the stimulation of C-fibers. OEA is synthesized in the intestine in response to feeding, increasing its levels in portal blood after the meal. Moreover, OEA is produced by adipose tissue, and a lipolytic effect has been found. In this work, we have examined the effect of OEA on glucose metabolism in rats in vivo and in isolated adipocytes. In vivo studies showed that acute administration (30 min and 6 h) of OEA produced glucose intolerance without decreasing insulin levels. Ex vivo, we found that 10 min of preincubation with OEA inhibited 30% insulin-stimulated glucose uptake in isolated adipocytes. Maximal effect was achieved at 1 microM OEA. The related compounds palmitylethanolamide and oleic acid had no effect, suggesting a specific mechanism. Insulin-stimulated GLUT4 translocation was not affected, but OEA promoted Ser/Thr phosphorylation of GLUT4, which may impair transport activity. This phosphorylation may be partly mediated by p38 and JNK kinases, since specific inhibitors (SB-203580 and SP-600125) partly reverted the inhibitory effect of OEA on insulin-stimulated glucose uptake. These results suggest that the lipid mediator OEA inhibits insulin action in the adipocyte, impairing glucose uptake via p38 and JNK kinases, and these effects may at least in part explain the glucose intolerance produced in rats in vivo. These effects of OEA may contribute to the anorectic effects induced by this mediator, and they might be also relevant for insulin resistance in adipose tissue.

Acute delta9-tetrahydrocannabinol exposure facilitates quinpirole-induced hyperlocomotion

The endogenous cannabinoid system works as a feedback signal controlling dopamine-induced facilitation of motor behaviors. The present study explored whether a single acute stimulation of CB1 cannabinoid receptors with (-)-Delta9-tetrahydrocannabinol (THC, 5 mg kg(-1) i.p.) results in modifications in the sensitivity to the acute behavioral effects of the dopamine D2/D3 receptor agonist quinpirole (0.025, 0.25 and 1 mg kg(-1), s.c.) 24 h after THC administration. Cannabinoid pretreatment increased the sensitivity to quinpirole-induced hyperlocomotion 24 h after its administration. The data indicated that THC induced a desensitization of cannabinoid receptors, as revealed by a reduction in CB1 receptor-agonist induced GTP-gamma-S incorporation in striatal membranes. These results might be relevant for understanding the effect of cannabinoid exposure in dopamine-related neuropsychiatric disorders.

Cannabinoid CB1 receptor antagonism reduces conditioned reinstatement of ethanol-seeking behavior in rats

The endocannabinoid system is involved in a variety of effects of drugs of misuse, and blockade of the cannabinoid CB1 receptor by selective antagonists elicits marked reductions in opioid and alcohol self-administration. The present study was designed to extend our knowledge of the role of the cannabinoid CB1 receptor in the modulation of alcohol misuse vulnerability in rats. Accordingly, using nonselected Wistar rats and genetically selected Marchigian Sardinian alcohol-preferring (msP) rats, we investigated the effect of the CB1 antagonist SR141716A on operant alcohol self-administration and on reinstatement of alcohol-seeking behavior by environmental conditioning factors. In addition, in situ hybridization studies in both strains were performed to measure cannabinoid CB1 receptor mRNA in different brain areas of these animals. Results showed that intraperitoneal administration of SR141716A (0.03, 1.0 and 3.0 mg/kg) markedly inhibits ethanol self-administration and conditioned reinstatement of ethanol-seeking behavior in both strains of rats. ED50 analysis showed significantly higher sensitivity (P < 0.05) to the effect of SR141716A in msP rats than in heterogeneous Wistar rats. In situ hybridization studies revealed that, compared with Wistar rats, msP animals have consistently greater cannabinoid CB1 receptor mRNA expression in a number of brain areas, including the frontoparietal cortex, caudate-putamen and hippocampus (CA1 and dentate gyrus areas). In conclusion, we provide clear evidence that blockade of CB1 receptors reduces both ethanol self-administration and conditioned reinstatement of alcohol-seeking behavior in rats. In addition, current pharmacological and neuroanatomical data suggest that an altered function of the CB1 receptor system exists between genetically selected alcohol-preferring msP rats and a heterogeneous animal population.

Neurogenesis in explants from the walls of the lateral ventricle of adult bovine brain: role of endogenous IGF-1 as a survival factor

Previous studies have shown the existence of proliferating cells in explants from bovine (Bos Taurus) lateral ventricle walls that were maintained for several days in vitro in the absence of serum and growth factors. In this study we have characterized the nature of new cells and have assessed whether the insulin-like growth factor-1 (IGF-1) receptor regulates their survival and/or proliferation. The explants were composed of the ependymal layer and attached subependymal cells. Ependymal cells in culture were labelled with glial markers (S-100, vimentin, GFAP, BLBP, 3A7 and 3CB2) and did not incorporate bromodeoxiuridine when this molecule was added to the culture media. Most subependymal cells were immunoreactive for beta III-tubulin, a neuronal marker, and did incorporate bromodeoxiuridine. Subependymal neurons displayed immunoreactivity for IGF-1 and its receptor and expressed IGF-1 mRNA, indicating that IGF-1 is produced in the explants and may act on new neurons. Addition to the culture media of an IGF-1 receptor antagonist, the peptide JB1, did not affect the incorporation of bromodeoxiuridine to proliferating subependymal cells. However, JB1 significantly increased the number of TUNEL positive cells in the subependymal zone, suggesting that IGF-1 receptor is involved in the survival of subependymal neurons. In conclusion, these findings indicate that neurogenesis is maintained in explants from the lateral cerebral ventricle of adult bovine brains and that IGF-1 is locally produced in the explants and may regulate the survival of the proliferating neurons.

Quantification of the secretory glycoproteins of the subcommissural organ by a sensitive sandwich ELISA with a polyclonal antibody and a set of monoclonal antibodies against the bovine Reissner's fiber

The subcommissural organ (SCO) is an ependymal brain gland that releases glycoproteins into the ventricular cerebrospinal fluid where they condense to form the Reissner's fiber (RF). We have developed a highly sensitive and specific two-antibody sandwich enzyme-linked immunosorbent assay (ELISA) for the quantification of the bovine SCO secretory material. The assay was based on the use of the IgG fraction of a polyclonal antiserum against the bovine RF as capture antibody and a pool of three peroxidase-labeled monoclonal antibodies that recognize non-overlapping epitopes of the RF glycoproteins as detection antibody. The detection limit was 1 ng/ml and the working range extended from 1 to 4000 ng/ml. The calibration curve, generated with RF glycoproteins, showed two linear segments: one of low sensitivity, ranging from 1 to 125 ng/ml, and the other of high sensitivity between 125 and 4000 ng/ml. This assay was highly reproducible (mean intra- and interassay coefficient of variation 2.2% and 5.3%, respectively) and its detectability and sensitivity were higher than those of ELISAs using exclusively either polyclonal or monoclonal antibodies against RF glycoproteins. The assay succeeded in detecting and measuring secretory material in crude extracts of bovine SCO, culture medium supernatant of SCO explants and incubation medium of bovine RF; however, soluble secretory material was not detected in bovine cerebrospinal fluid.