Nitric oxide synthesis in endothelial cytosol: Evidence for a calcium-dependent and a calcium-independent mechanism

Summary Release of nitric oxide (NO) from endothelial cells critically depends on a sustained increase in intracellular free calcium maintained by a transmembrane calcium influx into the cells. Therefore, we studied whether the free cytosolic calcium concentration directly affects the activity of the NO-forming enzyme(s) present in the cytosol from freshly harvested porcine aortic endothelial cells. NO was quantified by activation of a purified soluble guanylate cyclase coincubated with the cytosol. In the presence of 1 mM L-arginine, 0.1 mM NADPH and 0.1 mM EGTA, endothelial cytosol (0.2 mg of cytosolic protein per ml) stimulated the activity of guanylate cyclase 5.0 + 0.5-fold (from 31 + 9 to 153 + 15 nmol cyclic GMP formed per min per mg guanylate cyclase). Calcium chloride increased this stimulation further in a concentration-dependent fashion by up to 136 + 15% (with 2 M free calcium; EC₅₀ 0.3 M). The calcium-dependent and -independent activation of guanylate cyclase was enhanced by superoxide dismutase (0.3 M) and was inhibited by the stereospecifically acting inhibitor of L-arginine-dependent NO formation N^G-nitro-L-arginine (1 mM) and by LY 83583 (1 M), a generator of superoxide anions. Our findings suggest a calcium-dependent and -independent synthesis of NO from L-arginine by native porcine aortic endothelial cells. Send of fprint requests to A. Mülsch, at the above address     

Morphine-like discriminative stimulus effects of opioid peptides: possible modulatory role ofd-Ala2-d-Leu5-enkephalin (DADL) and dynorphin A(1-13)

The role of the different opioid receptors was studied in rats trained to discriminate SC injections of 3.0 mg/kg morphine from saline by tests for generalization to graded doses of morphine and receptor-selective peptides administered into the lateral cerebral ventricle. Dose-dependent morphine-like stimulus effects were produced over a wide range of doses (0.001–30 g), depending upon ligand and animal, by morphine, by themu-selective peptides DAGO[d-Ala²-NMePhe⁴-Gly(ol)-enkephalin] and FK33824[d-Ala²,NMePhe⁴-Met(O)⁵-(ol)-enkephalin], and by thedelta-selective peptide, DADL[d-Ala²,d-Leu⁵enkephalin]. The order of relative potency of these substances was: FK33824>DAGO>morphine>DADL. In contrast, DPLPE[d-Pen²,l-Pen⁵)enkephalin], which has much greaterdelta receptor selectivity than does DADL, and dynorphin A(1-13) (0.1–10 g), akappa-receptor agonist, engendered choice responding appropriate for saline. When 1.0 g DADL, a dose lacking morphine-like discriminative effects, was administered concurrently with SC morphine, the stimulus effects of morphine were potentiated. Concurrent administration of 10 g dynorphin A(1-13) and morphine attenuated the stimulus effects of morphine inconsistently. These results support previous findings thatmu-opioid receptors are of primary importance in mediating the morphine-like discriminative effects of opioid peptides. They also suggest that morphine-like discriminative effects can be modulated by other types of opioid receptors.     

Effect of tolbutamide on aminophylline-, 3,5-AMP-dibutyrate-or glucagon-induced insulin release from pancreatic islets after impairment of pyridine nucleotide metabolism caused by 6-aminonicotinamide (6-AN)

Summary The effect of tolbutamide on pyridine nucleotides and insulin secretion stimulated by aminophylline, 3,5-AMP-dibutyrate or glucagon was studied in pancreatic islets of rats previously treated with 6-aminonicotinamide (6-AN), an inhibitor of pyridine nucleotide synthesis.After being incubated for 60 min in a Krebs-Ringer-Bicarbonate-Buffer in the absence of glucose, pancreatic islets of rats i.p. injected with 35 mg/kg of 6-AN 6 hrs before pancreas removal contained about 30% less NADP and NADPH than did islets of control rats. No changes of NAD or NADH were observed in islets of 6-AN-treated animals. Addition of 16.5 mM glucose led to an increase of NADH, NADPH and a decrease of NADP in islets of both groups of animals; NAD levels remained unchanged. In vitro addition of tolbutamide to islets of control rats did not affect the levels of NADPH or NADP in the presence of 5.5 mM glucose. When 16.5 mM glucose were present, a decrease of NADPH and an increase of NADP was obvious. No effect of tolbutamide on insular NADPH or NADP was observed in islets of rats previously treated with 6-AN be it in the presence of 5.5 or 16.5 mM glucose.In islets of 6-AN-treated rats insulin release in response to aminophylline or 3,5-AMP-dibutyrate in the presence of 5.5 mM glucose was significantly depressed, when compared to islets of untreated controls. Addition of tolbutamide increased insulin release due to aminophylline, 3,5-AMP-dibutyrate or glucagon from islets of controls. Tolbutamide alone was without effect. In islets of 6-AN-treated rats aminophylline, 3,5-AMP-dibutyrate or glucagon stimulated insulin release only when tolbutamide was present.Our data suggest that there is no direct interference of tolbutamide with pyridine nucleotides of pancreatic islets, and that tolbutamide increases the secretory response of the -cell to aminophylline, 3,5-AMP-dibutyrate or glucagon when insulin release due to these agents is inhibited during decrease of insular NADP and NADPH, caused by 6-AN.Supported by the Deutsche Forschungsgemeinschaft.     

Intestinal decarboxylation of L-Dopa in relation to dose requirement in Parkinson's disease

Summary The magnitude of the decarboxylation of L-Dopa in the intestinal organs was determined by a method based on oral and intravenous administration of L-3,4-dihydroxyphenylalanine-1-¹⁴C (carboxyl labelled L-Dopa) and analysis of the radioactivity in urine.In 11 parkinsonian patients studied under standardized conditions 74% of L-Dopa given orally as a 0.5 g tablet was decarboxylated in the intestinal organs. Thus less than 26% of the ingested L-Dopa reached the general circulation.The possibility that individual variations in the magnitude of intestinal decarboxylation might be at least partly responsible for the individual variations in the dose requirement of parkinsonian patients was tested. There was neither any correlation between dose requirement of L-Dopa and the intestinal decarboxylation nor between that dose and the plasma disappearance rate of L-Dopa.It is concluded that other factors than those responsible for the peripheral metabolism of L-Dopa determine the individual dose requirement.     

Antifungal Activity of a New Triterpenoid Glycoside from Pithecellobium racemosum (M.)

Purpose. In a continuation of our search for novel antifungal compounds from higher plants, the standard extract of the bark of Pithecellobium racemosum was found to have good activity against important AIDS-related opportunistic yeasts. Methods. The extract was subjected to bioguided fractionation using silica gel column chromatography which led to purification of triterpene glycosides. The structures of these compounds were determined by a combination of spectroscopic (IR, NMR, HRMS) and chemical methods. Results. Compound 1 is a new glycoside, 3-O[-L-arabinopyranosyl (1 -2)][-L arabinopyranosyl (1 -6)]2-acetoamido-2-deoxy--D-gluco-pyranosyl oleanolic acid and Compound 2 was identified as the known compound 3-O-[-L-arabinopyranosyl (l-2)]-L-arabinopyranosyl (1-6)] 2-acetamido-2-deoxy--D-glucopyranosyl echinocystic acid. Conclusions. Compound 1 is a new glycoside, 3-O-[-L-arabinopyranosyl (1-2)]-L-arabinopyranosyl (l-6)]-2-acetoamido-2-deoxy--D-glucopyranosyl oleanolic acid and exhibits moderate antifungal activity against T. mentogrophytes, C. albicans and S. cerevisiae with MIC values of 6.25, 12.5 and 12.5 g/ml respectively.     

Studies on some metabolic effects of dopa and dopamine in the rat

Summary In male rats some metabolic effects of l-dopa and dopamine were compared with those of noradrenaline, adrenaline and tyramine by measuring the changes of plasma free fatty acids (FFA), plasma glycerol and plasma glucose as well as those of blood lactate and blood pyruvate. After intravenous injection of dopamine lactate and pyruvate concentrations were elevated maximally already within 5 min and returned to control levels after 10–20 min, i.e. at a time, when the levels of FFA, glycerol and glucose were maximally elevated in plasma. l-dopa had about 1/8 to 1/6 the potency of dopamine in producing these metabolic effects. The effects of dopamine were similar to those obtained with 1/20 the dose of noradrenaline, while adrenaline produced a more pronounced hyperglycaemic response than dopamine did when given in lipolytically equieffective doses.Pretreatment of the animals with phentolamine completely prevented the hyperglycaemic response to dopamine or noradrenaline without clearcut effects on the lipolytic effect of these catecholamines. Also, pretreatment with dihydroergotamine antagonized the hyperglycaemic effect of adrenaline and prevented that of dopamine and noradrenaline, while the effect of catecholamines on plasma glycerol concentration was not affected. However, the elevation in plasma FFA level induced by catecholamines was clearly antagonized by dihydroergotamine. The -adrenolytic drug Kö 592 had no effect on the hyperglycaemic effect of dopamine or noradrenaline, but antagonized the lipolytic effect of these amines. Pargyline enhanced the elevation of FFA and glycerol induced by dopamine or noradrenaline but reduced their hyperglycaemic effect. Chemical sympathectomy induced by pretreatment with 6-hydroxydopamine prevented the hyperglycaemic and lipolytic effects of tyramine, antagonized those of dopamine and potentiated the lipolytic response to noradrenaline. The effect of syrosingopine on the metabolic responses to the catecholamines was similar to that of 6-hydroxydopamine.Since the metabolic effects of dopamine were clearly antagonized by various - and -receptor-blocking agents and by chemical sympathectomy, we conclude that dopamine exerts its metabolic effects through a stimulation of - and -adrenoceptors and that part of this effect is mediated by a tyramine-like action of dopamine.     

Antidotes for zinc intoxication in mice

Sixteen chelating agents were examined to determine their relative efficacy as antidotes in acute zinc acetate intoxication in mice after i.p. administration. For a i. p. dose of 0.49 mmol/kg (LD₅₀) of zinc acetate, the i. p. administration of chelating agents at a 21 and 51 mole ratio resulted in a significant antidotal action for EDTA, DTPA, CDTA, d-penicillamine (d-PA), DMPS and DMSA. EGTA, l-cysteine, triethylentetraamine (TTHA), N-acetylcysteine (NAC), 4,5-dihydroxi-1,3-benzenedisulfonic acid (Tiron), sodium salicylate, glutathione, sodium diethyldithiocarbamate (DDC), 6-mercaptopurine and N-acetyl-d, l-penicillamine (NAPA) were not effective for acute zinc acetate poisoning. The therapeutic indices and therapeutic effectiveness of the most effective chelators were, respectively: EDTA (5.0, 7.0), DTPA (7.3, 13.7), CDTA (8.6, 6.3), d-PA (4.6, 1.9), DMPS (1.3, 1.0), DMSA (3.2, 5.4). DTPA, CDTA, and EDTA appear to be the most effective agents of those tested in offsetting acute zinc intoxication in mice.     

Reversal of the reserpine-induced ptosis by l-threo-3,4-dihydroxy-phenylserine (l-threo-DOPS), a (−)-norepinephrine precursor,and its potentiation by imipramine or nialamide

Summary The effect of l-threo-DOPS on the reserpine-induced ptosis in mice and its modification by imipramine, a norepinephrine (NE) uptake inhibitor, or nialamide, a monoamineoxidase inhibitor, were studied.Intraperitoneal (i.p.) injection of l-threo-DOPS (800 mg/kg) significantly reduced the severity of the ptosis. This reversal of the ptosis by l-threo-DOPS was markedly potentiated by i.p. injection of either imipramine (2.5 mg/kg) or nialamide (30 mg/kg). Response to l-threo-DOPS was also significantly potentiated by intracerebroventricular (i.c.v.) injection of imipramine (10 g). On the other hand, this treatment with imipramine (10 g, i.c.v.) also significantly potentiated the reversal of the ptosis by NE (20 g, i.c.v.), but the reversal by the subcutaneous (s.c.) injection of NE (1 and 3 mg/kg) was not affected.Reserpine (5 mg/kg, i.p.) markedly decreased the brain content of NE in mice, whereas l-threo-DOPS (400 mg/kg, i.p.) slightly restored it. Moreover, by the pretreatment with nialamide (30 mg/kg, i.p.), l-threo-DOPS produced a significant increase in the brain content of NE in reserpinetreated mice.These results suggested that l-threo-DOPS was capable of reversing the reserpine-induced ptosis due to the formation, at least in part of (–)-NE at the synaptic sites of central noradrenergic neurons.     

Lisuride,a potent drug in the treatment of muscular rigidity in rats

Summary Persistent and transient muscular rigidities were induced by 6-aminonicotinamide (6-AN) and reserpine, respectively, in rats and recorded electromyographically.Very low doses of lisuride (25 or 50 g/kg) reduced or abolished the increased electromyographic activity in the gastrocnemius muscle. Similar results were obtained with the combination of L-DOPA (100 mg/kg) plus benserazide (25 mg/kg). Methysergide was inactive. It is suggested that lisuride could be of value in the therapy of Parkinson's disease.N-(D-6-methyl-8-isoergolenyl)-N,N-diethylcarbamide hydrogen maleate     

Interaction of β-adrenoceptor agonists with the serotonergic system in rat brain

Summary The effect of -adrenoceptor agonists on the behavioral effect of l-5-HTP in rats and mice was studied. All -agonists potentiated the behavioral syndrome elicited by l-5-HTP. However no indication for a correlation between their potencies to stimulate peripheral beta-receptors and their potencies to enhance l-5-HTP effects was found. The potentiating effect of salbutamol in rats was intensified by the MAO A inhibitor clorgyline, completely inhibited by (±)-propranolol and partly inhibited by WB-4101, while practolol was without effect. Lesions of 5-HT pathways by i.c.v. injections of 5,7-DHT impaired the potentiating effect of salbutamol in rats. In contrast, 6-OHDA lesions or alphamethyl-p-tyrosine pretreatment were without effect. A central site of action of salbutamol is suggested by the fact that it intensified l-5-HTP effects also after i.c.v. administration. Therefore the results suggest that salbutamol facilitates 5-HT transmission in rat brain probably via stimulation of central beta receptors.A part of this study was presented at the meeting of the Deutsche Pharmakologische Gesellschaft in Mainz, March 18–21, 1980     

Selective potentiations in opioid analgesia following scopolamine pretreatment

The effects of the muscarinic receptor antagonist scopolamine upon analgesia induced by d-ala-d-leu-enkephalin (DADL), beta-endorphin (BEND) and morphine were examined. While scopolamine (10 mg/kg, IP) significantly potentiated the analgesic responses following DADL (40 g, ICV) and morphine (5 mg/kg, SC) on the jump test, it failed to alter significantly BEND (1 g, ICV) analgesia.     

N-acetyl-S-(2-hydroxyethyl)-L-cysteine as a potential tool in biological monitoring studies?

In mammalian species, including man, N-acetyl-S-(2-hydroxyethyl)-L-cysteine (2-HEMA) is a common urinary metabolite of a large number of structurally different xenobiotic chemicals. It is a common urinary end product of glutathione pathway metabolism of a variety of chemicals possessing electrophilic properties and, in most cases, also a genotoxic potential. Five different chemically reactive intermediates, with different electrophilic properties, may be involved in the formation of 2-HEMA. An inventory of chemicals known to lead to the formation of 2-HEMA, or based on their chemical structure expected to do so, is presented. Furthermore, an attempt is made to evaluate the possibilities and limitations in terms of the potential use of urinary 2-HEMA as a tool in biomonitoring studies. Two other related, sulfur-containing urinary metabolites, i. e. N-acetyl-(S-carboxymethyl)-L-cysteine and thio-diacetic acid, are proposed as possible alternatives to urinary 2-HEMA. It is suggested that 2-HEMA might be seen as a potentially useful and sensitive signal parameter for the assessment of exposure of animals and man to a variety of electrophilic and therefore potentially toxic xenobiotic chemicals.     

Neurotoxicity and pharmacology of Lathyrus sativus extracts of high- and low-toxicity strains

Neurolathyrism is characterized by spastic paraparesis of the legs. It is caused by overconsumption of grass pea (Lathyrus sativus L.; Leguminosae). We studied toxicity of extracts of L. sativus seeds from two different areas—Bangladesh and Canada—toward rat primary neuron/glia culture. Both extracts showed acute neurotoxicity within 24 h when the 75% ethanol extracts were added to the neuron/glia culture. Fractionation of the extracts showed that the water-soluble fraction accounted for ca. 75–84% of total toxicity in which 3-N-oxalyl-l-2,3-diaminopropanoic acid (l--ODAP) was present at the highest concentration. Toxicity of the water-soluble fraction obtained from Bangladeshi seeds was significantly higher than that obtained from Canada. Effects of these fractions were reversed almost completely by 1,2,3,4-tetrahydro-6-nitro-2,3-dioxobenzo[f]quinoxaline-7-sulfonamide (NBQX), an antagonist of AMPA-receptor. They were partially reversed by group I metabotropic glutamate receptor antagonists (RS)-1-aminoindan-1,5-dicarboxylic acid, or (S)--methyl-4-carboxyphenyl-glycine [(S)-MCPG]. Nitric oxide synthase inhibitor N^G-nitro-l-arginine methyl ester (l-NAME) strongly decreased the extracts toxicity. These data show that the neurotoxicity of grass pea seeds is attributable to l--ODAP, the toxicity of which is mediated by collective effects of l--ODAP on the AMPA-type receptor, metabotropic glutamate receptors, and NO production.     

Plasma glucose lowering effect of spartein sulphate infusion in non-insulin dependent (Type 2) diabetic subjects

Summary Sparteine sulphate, given i.v. as a bolus of 15 mg/ml plus 90 mg in 0.9% NaCl 100 ml over 60 min, increases plasma insulin and decreases plasma glucose and adrenaline in non-insulin dependent (Type II) diabetic subjects. The hypoglycaemic effect was also evident in the presence of a high plasma glucose level produced by Biostator changing glucose infusion from 20.2±2.8 to 26.4±4.2 mg · kg^–1 · min^–1 (p<0.01), and it was potentiated by simultaneous infusion of arginine.No additional effect of sparteine on the peripheral sensitivity to insulin were detected by the euglycaemic, hyperinsulinaemic glucose clamp technique, as the glucose infusion rate (3.1±0.8 vs 2.6±1.2 mg · kg^–1 · min^–1) was not statistically significant different in the last 60 min of the experiment.It is concluded that sparteine sulphate enhances -cell secretion, causing a fall in the plasma glucose concentration.     

Insulin release by tolbutamide and glibenclamide

Summary Glibenclamide, a second generation sulfonylurea, produced the same pattern of insulin release from the perfused rat pancreas as did tolbutamide. The stimulatory effect was closely dependent on the glucose concentration present. Both agents enhanced insulin secretion at 5–10 mM glucose, whereas no additional insulin was released when maximally stimulating levels of glucose (20 and 30 mM) were present. The concentrations of glibenclamide stimulating insulin release were 100–400 times lower than equieffective levels of tolbutamide. At glucose levels of 3 or 8 mM, however, glibenclamide did not liberate significantly more insulin from the pancreas than did tolbutamide. Thus the differences of tolbutamide and glibenclamide were quantitative rather than qualitative. Although the active concentrations differed the effects produced were comparable.     

Mutagenicity and cytotoxicity of two regioisomeric mercapturic acids and cysteine S-conjugates of trichloroethylene

The mutagenicity, cytotoxicity and metabolism of two regioisomicl-cysteine- and N-acetyl-l-cysteine-S-conjugates of trichloroethylene were studied. The 1,2-dichlorovinyl(1,2-DCV) isomers of both the cysteine conjugate and the mercapturate were much stronger mutagens in the Ames test withSalmonella typhimurium TA2638 when compared to the corresponding 2,2-dichlorovinyl (2,2-DCV) isomers. Similarly, the 1,2-DCV isomers were more cytotoxic towards isolated rat kidney proximal tubular cells, as assessed by inhibition of -methylglucose uptake, than the 2,2-DCV isomers. The 3–4-fold higher rate of -lyase-dependent activation of S-(1,2-dichlorovinyl)-l-cysteine (1,2-DCV-Cys) when compared to S-(1,2-dichlorovinyl)-l-cysteine (2,2-DCV-Cys) as well as the different nature of the reactive intermediates formed is probably responsible for these structure-dependent effects. The cytotoxicity of N-acetyl-S-(1,2-dichlorovinyl)-l-cysteine (1,2-DCV-NAc) toward isolated kidney cells showed a delayed time course as compared to that of 1,2-DCV-Cys, probably due to the relatively low rate of deacetylation of 1,2-DCV-NAc. The time course of cytotoxicity of N-acetyl-S-(2,2-dichlorovinyl)-l-cysteine (2,2-DCV-NAc), however, parallelled that of 2,2-DCV-Cys. Due to the relatively high rate of N-acetylation and low rate of -lyase activation, for 2,2-DCV-Nac the -lyase activation step may be rate limiting. Different rates of cellular uptake also may play a role in time course of toxicity of the cysteine conjugates and the mercapturic acids in the renal cells.     

Tryptophan antidepressant ‘physiological sedative’: Fact or fancy?

Some recent publications relating to the allegedly antidepressive and sedative effects of L-tryptophan the precursor of 5-HT have been reviewed.The evidence to date suggests that the amino acid is as effective as standard tricyclic drugs in alleviating the symptoms of depression, especially those cases presenting with mainly psychomotor retardation, and is synergistic with MAOIs. L-Tryptophan would also appear to be a physiological sedative. This action, however, appears to be related to the time of administration and at present has only been demonstrated at night, when endogenous levels of 5-HT are at their peak.In terms of practical therapeutics L-tryptophan would appear to have greater potential as an antidepressant than as a sedative.     

Comparison of penetration-enhancing ability of laurocapram, N-methyl-2-pyrrolidone and dodecyl-L-pyroglutamate

The study reports on penetration enhancers used to improve drug absorption through the skin. All experiments were carried out in permeation cellsin vitro. Insulin (2.5 mg/ml) and Brilliant Blue (50.0 mg/ml) served as model drugs. They were formulated into a 40% solution of propylene glycol with increasing concentrations ofN-methyl-2-pyrrolidone (NMP) (0.0 to 20.0%), dodecylazacycloheptan-2-one (laurocapram) and a new compound dodecyl-l-pyroglutamate (DLP; 0.0 to 0.5%). The maximum amount of insulin permeated within 24 h was almost 200 U/ml in the case of 0.1% laurocapram, while in the case of 0.1% DLP it was approximately half of that. The optimum concentration of NMP was 12.0%. Experiments performed with Brilliant Blue showed no significant difference among formulations containing either 6.0, 12.0 or 20.0% of NMP. When NMP was omitted, flux, permeability as well as the maximum concentration estimated after 26 h reached 50% of the values obtained with NMP. The lag time was twice as long in this case in comparison with the formulations containing NMP.     

Glucose both inhibits and stimulates insulin secretion from isolated pancreatic islets exposed to maximally effective concentrations of sulfonylureas

Summary Isolated pancreatic islets from mice were perifused with media containing maximally effective concentrations of glibenclamide (0.1–10 mol/l) or glipizide (1 mol/l). In these islets an increase of the glucose concentration from 10 mmol/l to 40 mmol/l or addition of d-glyc-eraldehyde (20 mmol/1) caused a temporary decrease in insulin release which was followed by a sustained enhancement of release. -Ketoisocaproate (3 or 20 mmol/1) did not inhibit insulin release; at high concentration it was an even stronger secretagogue than d-glucose or d-glyceraldehyde. It is concluded that high energy phosphates couple B-cell fuel metabolism and insulin release by acting both on the ATP-dependent K⁺ channel and on other targets not yet identified.Some of the results described here are part of the medical thesis of A. WallaschSend offprint requests to U. Panten at the above address     

Developmental Responses of a Terrestrial Insect Detritivore, <Emphasis Type="BoldItalic">Megaselia scalaris</Emphasis> (Loew) to Four Selenium Species

Megaselia scalaris (Loew) (Diptera: Phoridae) is an important and ubiquitous terrestrial detritivore that consumes both animal and plant material. Because both plants and animals convert selenium pollutants into various forms, the relative toxicities of ecologically relevant concentrations of sodium selenate, sodium selenite, seleno-L-methionine, and Se-(methyl) selenocysteine hydrochloride to larvae were assessed in diet bioassays. In addition, ovipositional preferences of adults and developmental effects on the eggs and larvae were measured. With chronic exposure selenocysteine was the most toxic of the selenium species to the larvae (LC₅₀: 83 g/g wet weight), followed by seleno-L-methionine (LC₅₀: 130 g/g), selenate (LC₅₀: 258 g/g), and selenite (LC₅₀: 392 g/g). Ovipositing females did not discriminate between the highest treatment concentrations of any of the pollutants as compared to the controls, indicating a lack of avoidance behavior. Larval development time was significantly increased with exposure to selenate at 100 g/g wet weight and above, selenite at 300 g/g and above, and at 50 g/g and 25 g/g and above for seleno-L-methionine and selenocysteine respectively. Pupal development was not affected by any of the selenium treatments. Significant differences between male and female adult eclosion times were observed, with females eclosing later than males as selenium concentrations increased. Significant decreases in larval survival relative to controls occurred at the lowest treatment tested (100 g/g) for both selenate and selenite and at 100 g/g for seleno-L-methionine, and 50 g/g for selenocysteine. The population level implications of lack of avoidance of contaminated food, and the effects of increased development times, reduced survivorship, and non-synchronized male and female emergence are discussed.