Normal effect of insulin to stimulate leg blood flow in NIDDM.

In patients with non-insulin-dependent diabetes mellitus (NIDDM), a decreased effect of insulin in stimulating leg blood flow (LBF) has been reported. We reinvestigated the effect of insulin on LBF and validated our data by use of other measures. Eight healthy men (control group) and seven men with NIDDM were studied (age 59 +/- 1 and 58 +/- 3 years, weight 83 +/- 3 and 86 +/- 6 kg, fat-free mass 66 +/- 1 and 64 +/- 3 kg, respectively [mean +/- SE, all P > 0.05]; body mass index 26 +/- 1 and 29 +/- 1 kg/m2, fasting plasma insulin 72 +/- 7 and 187 +/- 22 pmol/l, fasting plasma glucose 5.8 +/- 0.2 and 10.2 +/- 1.7 mmol/l [all P < 0.05]). A three-step hyperinsulinemic glucose clamp (ambient glucose level) was performed, combined with catheterization of an artery and both femoral veins. Expiratory air was collected, LBF was measured by thermodilution, and blood was sampled and analyzed for oxygen content. Insulin concentration was increased to 416 +/- 22 and 509 +/- 43 (step I), 1,170 +/- 79 and 1,299 +/- 122 (step II), and 15,936 +/- 1,126 and 16,524 +/- 1,916 (step III) pmol/l in control and NIDDM subjects, respectively (P > 0.05). LBF increased similarly (P > 0.05) in the two groups (from 287 +/- 23 and 302 +/- 12 [basal] to 308 +/- 31 and 362 +/- 9 [I], 371 +/- 29 and 409 +/- 17 [II], and 434 +/- 32 and 472 +/- 29 [III] ml.min-1.leg-1 in control and NIDDM subjects, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Physical training increases muscle GLUT4 protein and mRNA in patients with NIDDM.

Patients with non-insulin-dependent diabetes mellitus (NIDDM) exhibit insulin resistance and decreased glucose transport in skeletal muscle. Total content of muscle GLUT4 protein is not affected by NIDDM, whereas GLUT4 mRNA content is reported, variously, to be unaffected or increased. Physical training is recommended in the treatment of NIDDM, but the effect of training on muscle GLUT4 protein and mRNA content is unknown. To clarify the effect of training in NIDDM, seven men with NIDDM (58 +/- 2 years of age [mean +/- SE]) and eight healthy men (59 +/- 1 years of age) (control group) performed one-legged ergometer bicycle training for 9 weeks, 6 days/week, 30 min/day. Biopsies were obtained from the vastus lateralis leg muscle before and after training. GLUT4 protein analyses was performed along with analyses of muscle biopsies from five young (23 +/- 1 years of age) (young group), healthy subjects who participated in a previously published identical study. In response to training, maximal oxygen uptake increased (delta 3.3 +/- 1.8 in NIDDM subjects and 4.5 +/- 1.2 ml.min-1.kg-1 in control subjects [both P < 0.05]). Before training, GLUT4 protein content was similar in NIDDM, control, and young subjects (0.35 +/- 0.02, 0.34 +/- 0.03, and 0.41 +/- 0.03 arbitrary units, respectively), and it increased (P < 0.05) in all groups during training (to 0.43 +/- 0.03, 0.40 +/- 0.03, and 0.57 +/- 0.08 arbitrary units, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-stimulated muscle glucose clearance in patients with NIDDM. Effects of one-legged physical training.

Physical training increases insulin action in skeletal muscle in healthy men. In non-insulin-dependent diabetes mellitus (NIDDM), only minor improvements in whole-body insulin action are seen. We studied the effect of training on insulin-mediated glucose clearance rates (GCRs) in the whole body and in leg muscle in seven patients with NIDDM and in eight healthy control subjects. One-legged training was performed for 10 weeks. GCR in whole body and in both legs were measured before, the day after, and 6 days after training by hyperinsulinemic (28, 88, and 480 mU x min(-1) x m(-2)), isoglycemic clamps combined with the leg balance technique. On the 5th day of detraining, one bout of exercise was performed with the nontraining leg. Muscle biopsies were obtained before and after training. Whole-body GCRs were always lower (P < 0.05) in NIDDM patients compared with control subjects and increased (P < 0.05) in response to training. In untrained muscle, GCR was lower (P < 0.05) in NIDDM patients (13 +/- 4, 91 +/- 9, and 148 +/- 12 ml/min) compared with control subjects (56 +/- 12, 126 +/- 14, and 180 +/- 14 ml/min). It Increased (P < 0.05) in both groups in response to training (43 +/- 10, 144 +/- 17, and 205 +/- 24 [NIDDM patients] and 84 +/- 10, 212 +/- 20, and 249 +/- 16 ml/min [control subjects]). Acute exercise did not increase leg GCR. In NIDDM patients, the effect of training was lost after 6 days, while the effect lasted longer in control subjects. Training increased (P < 0.05) muscle lactate production and glucose storage as well as glycogen synthase (GS) mRNA in both groups. We conclude that training increases insulin action in skeletal muscle in control subjects and NIDDM patients, and in NIDDM patients normal values may be obtained. The increase in trained muscle cannot fully account for the increase in whole-body GCR. Improvements in GCR involve enhancement of insulin-mediated increase in muscle blood flow and the ability to extract glucose. They are accompanied by enhanced nonoxidative glucose disposal and increases in GS mRNA. The improvements in insulin action are short-lived.

Interaction of sulfonylureas and exercise on glucose homeostasis in type 2 diabetic patients.

OBJECTIVE: To determine whether the plasma glucose-lowering effects of sulfonylureas and acute submaximal exercise are additive and, accordingly, to determine whether they may increase the risk of hypoglycemia when combined in fasting patients. RESEARCH DESIGN AND METHODS: Eight postabsorptive type 2 diabetic patients were examined at three occasions: after oral sulfonylurea (7 mg glibenclamide), during 60 min of ergometer cycle exercise at 57 +/- 3% of VO2max, and during exercise after glibenclamide. RESULTS: Heart rate, VO2, and lactate responses to exercise were comparable (P > 0.05) on days with and without glibenclamide. Plasma insulin concentrations were always increased by glibenclamide, and they were lowered identically by exercise with and without glibenclamide. However, throughout exercise, absolute concentrations of insulin were lower on days without glibenclamide compared with days with glibenclamide (34.5 +/- 4.7 vs. 47.4 +/- 5.5 pmol/l; P < 0.05). At the start of exercise, glucose concentrations were similar between experiments (P > 0.05). The rate of decrease in glucose during exercise was higher (P < 0.05) on days with both glibenclamide and exercise, compared with days with glibenclamide alone and days with exercise alone (-0.035 +/- 0.009 vs. -0.016 +/- 0.002 and -0.022 +/- 0.005 mmol.l-1.min-1, respectively). Consequently, the glucose nadir was lower on days with glibenclamide and exercise than on days with glibenclamide or exercise alone (6.7 +/- 1.1 vs. 8.1 +/- 0.9 and 7.6 +/- 1.0 mmol/l, respectively; P < 0.05). During exercise, the rate of appearance of plasma glucose determined by 3-[3H]glucose infusion was lower on days with glibenclamide than on days without glibenclamide (2.3 +/- 0.1 vs. 2.9 +/- 0.1 mg.min-1.kg-1; P < 0.05). In contrast, glucose clearance was identical (P > 0.05). CONCLUSIONS: In postabsorptive type 2 diabetic patients, the hypoglycemic action of glibenclamide and exercise is enhanced when the treatments are combined. The interaction reflects an increased inhibition by glibenclamide-enhanced insulin levels of hepatic glucose production when hepatic glucose production is accelerated by exercise.

A novel class of conformationally restricted heterocyclic muscarinic agonists.

A series of conformationally restricted compounds containing the 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridin-3-ol (THPO) skeleton, including O-methyl-THPO (10a) and O,5-dimethyl-THPO (11a), were synthesized. The compounds were designed by bioisosteric replacement of the methyl ester groups of the muscarinic cholinergic agonists norarecoline and arecoline by the 3-methoxyisoxazole group, and their interactions with central and peripheral muscarinic receptors were tested in vitro. The compounds 10a, 11a, O-ethyl-THPO (10b), O-propargyl-THPO (10j), and O-ethyl-5-methyl-THPO (11b) were inhibitors of the binding of the muscarinic mustard [3H]PrBCM to rat brain membranes with an increasing order of potency. There was, however, a very low degree of correlation between these binding data and the effects of the compounds on peripheral (ileal) muscarinic receptors, where 11a, 10j, 11b, and 10a were agonists with a decreasing order of potency, whereas O-isopropyl-THPO (10e) showed antagonistic effects. The relatively low pKa values of the compounds (7.5-7.7 for compounds with secondary and 6.1-7.0 for compounds with tertiary amino groups) are likely to allow the compounds to penetrate the blood-brain barrier.

Discovery of a series of cyclohexylethylamine-containing protein farnesyltransferase inhibitors exhibiting potent cellular activity.

Synthesis of a library of secondary benzylic amines based on the Sebti-Hamilton type peptidomimetic farnesyltransferase (FTase) inhibitor FTI-276 (1) led to the identification of 6 as a potent enzyme inhibitor (IC(50) of 8 nM) which lacked the problematic thiol residue which had been a common theme in many of the more important FTase inhibitors reported to date. It has previously been disclosed that addition of o-tolyl substitution to FTase inhibitors of the general description 2 had a salutary effect on both FTase inhibition and inhibition of Ras prenylation in whole cells. Combination of these two observations led us to synthesize 7, a potent FTase inhibitor which displayed an IC(50) of 0.16 nM for in vitro inhibition of FTase and an EC(50) of 190 nM for inhibition of whole cell Ras prenylation. Modification of 7 by classical medicinal chemistry led to the discovery of a series of potent FTase inhibitors, culminating in the identification of 25 which exhibited an IC(50) of 0.20 nM and an EC(50) of 4.4 nM. In vivo tests in a nude mouse xenograft model of human pancreatic cancer (MiaPaCa cells) showed that oral dosing of 25 gave rise to impressive attenuation of the growth of this aggressive tumor cell line.

Educational outcome of neonatal intensive care graduates.

Studies of developmental outcome of neonatal intensive care unit graduates have generally been limited to the first 2 to 3 years of life, with outcome determined by psychometric tests. This study followed neonatal intensive care unit graduates born 1975 through 1983 (n = 457) into the public school system and compared their educational outcomes with those of newborn nursery graduates (n = 656). Outcomes were evaluated by placement in four academic categories: regular classroom, academic problems, speech/language impairment, and major impairment. Educational outcomes for children of both groups were essentially the same. Their placement in the four academic categories were equally affected by nonmedical variables, primarily income (below/above poverty level), race, and sex. Seventy percent of poverty-level children were in one of the three problem categories, compared with 40% of children above poverty level. Neither neonatal intensive care unit treatment nor low birth weight were major predictors of educational outcome. The only clear-cut neonatal intensive care unit effect occurred among children born with sensory or physical impairments. Therefore, in order to reduce poor educational outcomes, follow-up and intervention programs should be targeted primarily to children with diagnosable handicaps and from minority, low-income families.

alpha And beta-adrenoceptors in the detrusor muscle and bladder base of the pig and beta-adrenoceptors in the detrusor muscle of man.

1 The presence and type of adrenoceptors in the smooth muscle of the pig and human urinary bladder was assessed on the basis of the relative potency of alpha- and beta-adrenoceptor agonists and antagonists.2 In isolated, carbachol-contracted bladder strips from the pig detrusor muscle the relaxing potency of isoprenaline was four times that of salbutamol and ritodrine and thirty times that of noradrenaline.3 Propranolol caused a parallel shift to the right of the noradrenaline dose-response curve which was not changed by phentolamine.4 Propranolol and butoxamine showed, in contrast to practolol, a dose-dependent antagonism of the response to isoprenaline. A pA(2) value of 9.2 +/- 0.2 and 6.8 +/- 0.2 (mean +/- s.e. mean) for the first two antagonists was calculated.5 In the bladder base of the pig, propranolol caused a parallel shift to the right and phentolamine a shift to the left of the dose-response curve to noradrenaline.6 In the human detrusor muscle the potency and maximum effect of isoprenaline and salbutamol were less than those in the pig detrusor muscle. The potency of isoprenaline was sixty times that of salbutamol.7 Whereas a parallel shift to the right of the dose-response curve to isoprenaline was obtained with propranolol, no antagonism was obtained with butoxamine or practolol.8 The results are interpreted as indicating the presence of beta(2)-adrenoceptors in the detrusor muscle of the pig and beta-adrenoceptors with neither beta(1)- nor beta(2)-characteristics in the detrusor muscle of man. An indication of the presence of alpha-adrenoceptors in the bladder base but not in the detrusor muscle of the pig was obtained.

Dopamine receptor agonistic and antagonistic effects of 3-PPP enantiomers.

The pharmacological profile of the enantiomers of the proposed selective dopamine (DA) autoreceptor agonist 3-PPP [3-(3-hydroxyphenyl)-N-n-propylpiperidine] has been studied. In vitro both enantiomers showed weak DA agonistic activity, and (--)-3-PPP some DA antagonistic effect on DA-stimulated adenylate cyclase activity. Both enantiomers in low doses had a similar profile in vivo: Inhibition of locomotor activity of mice and rats, induction of contralateral circling behaviour in 6-hydroxy-DA-lesioned rats and an emetic effect in dogs. At higher doses, differential effects of the enantiomers were found: (+)-3-PPP induced hyperactivity, weak stereotyped behaviour and ipsilateral circling in hemitransected rats. (--)-3-PPP had depressant effects in high doses, inhibited d-amphetamine-induced hyperactivity and d-amphetamine-, methylphenidate- and apomorphine-induced stereotyped licking/biting in rats and antagonized apomorphine-induced emesis in dogs. However, (+)-3-PPP also showed a weak antagonistic activity against d-amphetamine-induced hyperactivity and d-amphetamine- and apomorphine-induced stereotypy in rats and inhibited apomorphine-induced emesis in dogs. It is suggested that both enantiomers have significant effects on postsynaptic DA receptors in high doses: (--)-3-PPP with weak antagonistic activity in some test models and (+)-3-PPP with agonistic and antagonistic effect. Since these effects of (+)-3-PPP were of low intensity at high doses, (+)-3-PPP may be a partial DA agonist at postsynaptic receptors in high doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Training-induced enhancement of insulin action in human skeletal muscle: the influence of aging.

Age-induced reduction of whole body insulin action has been attributed to decreased insulin action in skeletal muscle. Physical training improves insulin action, but the effect has never been investigated specifically in aged human skeletal muscle. Seven young men [age: 23 +/- 1 yr (mean +/- SE; range, 21-24 yr); weight: 70 +/- 1 kg; body fat: 8 +/- 1%] and eight aged men [59 +/- 1 yr (range, 58-64 yr); 83 +/- 2 kg; 20 +/- 2%] performed one-legged bicycle training on a modified ergometer cycle for 10 weeks, 6 days/week, at 70% of VO2 peak. Glucose clearance rates in whole body and leg were measured 16 hr after training by a hyperinsulinemic (28, 88, and 480 mU.min-1.min-2), isoglycemic clamp combined with leg balance technique. Peak oxygen uptake during the bicycle test was always lower (p < .05) in aged vs. young subjects. Furthermore, VO2 peak was higher after training in trained (T) vs. untrained (UT) (p < .05) legs. Whole body glucose clearance rate was lower in aged vs. young subjects (p < .05) when expressed per kg body weight, but similar when expressed relative to fat free mass. Leg blood flow was always lower in aged vs. young men (p < .05). At basal and during insulin infusion, leg blood flow in young men did not differ significantly in T vs. UT legs (maximum insulin: 81 +/- 7 vs. 71 +/- 5 ml.min-1.kg leg-1), while in aged subjects it increased (p < .05) with training (maximum insulin: 57 +/- 5 vs. 48 +/- 5 ml.min-1.kg leg-1). Leg glucose extraction was always higher in aged vs. young men during the two last clamp steps (p < .05). Furthermore, leg glucose extraction was increased by training in young (p < .05) but not significantly in aged subjects. Leg glucose clearance rates increased (p < .05) with training and was similar in aged men (T: 1 +/- 1, 8 +/- 1, 21 +/- 2, and 24 +/- 2; UT: 1 +/- 1, 6 +/- 1, 14 +/- 2, and 20 +/- 2 ml.min-1.kg leg-1) and young men (T: 1 +/- 1, 12 +/- 3, 23 +/- 3, and 26 +/- 3; UT: 1 +/- 1, 8 +/- 2, 17 +/- 2, and 21 +/- 2 ml.min-1.kg leg-1). Therefore, insulin action in muscle is not reduced by aging. At high insulin concentrations, the leg blood flow is lower, whereas glucose extraction is higher in aged compared with young men. Training increases overall insulin action on glucose clearance in skeletal muscle identically in aged and young subjects.

Glucose clearance in aged trained skeletal muscle during maximal insulin with superimposed exercise.

Insulin and muscle contractions are major stimuli for glucose uptake in skeletal muscle and have in young healthy people been shown to be additive. We studied the effect of superimposed exercise during a maximal insulin stimulus on glucose uptake and clearance in trained (T) (1-legged bicycle training, 30 min/day, 6 days/wk for 10 wk at approximately 70% of maximal O(2) uptake) and untrained (UT) legs of healthy men (H) [n = 6, age 60 +/- 2 (SE) yr] and patients with Type 2 diabetes mellitus (DM) (n = 4, age 56 +/- 3 yr) during a hyperinsulinemic ( approximately 16,000 pmol/l), isoglycemic clamp with a final 30 min of superimposed two-legged exercise at 70% of individual maximal heart rate. With superimposed exercise, leg glucose extraction decreased (P < 0.05), and leg blood flow and leg glucose clearance increased (P < 0.05), compared with hyperinsulinemia alone. During exercise, leg blood flow was similar in both groups of subjects and between T and UT legs, whereas glucose extraction was always higher (P < 0.05) in T compared with UT legs (15.8 +/- 1.2 vs. 14.6 +/- 1.8 and 11.9 +/- 0.8 vs. 8.8 +/- 1.8% for H and DM, respectively) and leg glucose clearance was higher in T (H: 73 +/- 8, DM: 70 +/- 10 ml. min(-1). kg leg(-1)) compared with UT (H: 63 +/- 8, DM: 45 +/- 7 ml. min(-1). kg leg(-1)) but not different between groups (P > 0.05). From these results it can be concluded that, in both diabetic and healthy aged muscle, exercise adds to a maximally insulin-stimulated glucose clearance and that glucose extraction and clearance are both enhanced by training.

Neurotransmitter-role of VIP in non-adrenergic relaxation of feline myometrium.

The feline myometrium is heavily innervated by VIP-containing nerve fibres. Transmural electrical stimulation (10 Hz, 2 msec, 150 mA) of muscle strips from feline myometrium in the presence of adrenoreceptor blocking agents caused a muscle relaxation. The smooth muscle relaxation was accompanied by a significant increase in immunoreactive VIP in the superfusate. Both the VIP release and the relaxation were completely annulled by tetrodotoxin, a selective blocker of axonal conduction. Furthermore, passive immunoneutralization with antiserum against VIP markedly reduced the smooth muscle relaxation induced by electrical stimulation. In the light of the previously demonstrated smooth muscle relaxant effect of VIP, the present findings indicate that the peptides may participate as neurotransmitter in non-adrenergic relaxation of the feline myometrium.

Influence of pregnancy and sex steroids on concentration, motor effect and receptor binding of VIP in the rabbit female genital tract.

The influence of sex steroid and pregnancy on the tissue concentration, uterine motor effect and receptor binding of VIP has been studied in the female genital tract of pregnant rabbits and oophorectomized rabbits during progesterone and/or oestrogen substitution. The concentration of immunoreactive VIP was high in the vagina and cervix, and lower in the uterine body of both pregnant and non-pregnant rabbits. A significant decrease in the VIP concentration (pmol/g wet weight) of the uterine body was observed toward term of pregnancy. The total uterine content of VIP, however, seems unchanged. Treatment of oophorectomized rabbits with ovarian steroids had no effect on the VIP concentration. The sensitivity for and potency of VIP on the relaxation of uterine muscle was significantly higher in oophorectomized rabbits treated with a combination of progesterone and oestrogen than in control rabbits. No difference was observed between non-pregnant and pregnant rabbits. The degradation and binding affinity for 125I-labelled VIP was highest in oophorectomized rabbits substituted with both oestrogen and progesterone. In the pregnant rabbits, the amount of receptors was decreased near term. In conclusion, sex steroids are able to influence the motor effect of VIP at the receptor level, but have no effect on the VIP concentration in the female genital tract.

SCH 23390--a selective dopamine D-1 receptor antagonist with putative 5-HT1 receptor agonistic activity.

The selective dopamine D-1 receptor antagonist SCH 23390 has been tested in vitro in the rat fundus model and in vivo in the electrically stimulated flexor reflex model. In the fundus model, SCH 23390 showed a potent agonistic activity compared to that of different 5-HT receptor agonists. Pindolol, 1-propranolol and pirenperone showed no or only weak inhibition of the SCH 23390-induced contractions in the fundus strip whereas methysergide was a potent inhibitor. The 5-HT3 receptor antagonist ICS 205-930 did not induce an inhibitory effect. In the electrically stimulated flexor reflex model in pithed rats, SCH 23390 induced a marked increase of the reflex. This increase was slightly inhibited by a mixed dopamine (DA) D-1/D-2 antagonist cis(Z)-flupentixol and by a specific DA D-2 antagonist YM 09151-2. Different reference antagonists: bicuculline (GABAergic), propranolol (beta-adrenergic), scopolamine (muscarinic), yohimbine (alpha 2-adrenergic), prazosin (alpha 1-adrenergic) were all without an antagonist effect on the SCH 23390-induced increase of the flexor reflex. Ketanserin, a selective 5-HT2 receptor antagonist, showed a weak and short-lasting inhibition of the SCH 23390 effect in high doses, whereas ritanserin showed only 35% inhibition of the SCH 23390-induced flexor reflex at a dose of 1.3 mumol/kg i.v. The mixed 5-HT1/5-HT2 antagonists methiothepin and metergoline showed a marked inhibitory effect at 2.6 mumol/kg i.v. and 3.1 mumol/kg i.v., respectively (1.3 mg/kg i.v.). These findings suggest that SCH 23390 might possess 5-HT1 receptor agonist activity.

Pharmacological profile of a novel class of muscarinic acetylcholine receptor agonists.

Some in vivo pharmacological effects of a number of muscarinic acetylcholine receptor agonists containing the bicyclic 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridin-3-ol (THPO) skeleton were studied in rats and mice. The key compounds O,N-dimethyl-THPO (2) and O-methyl-THPO (4) are bioisosteres of arecoline and norarecoline, respectively. The vasodepressor effects of arecoline and the title compounds in anaesthetized rats gave parallel log dose-response curves. The order of potency of the compounds in this test system was identical with that measured earlier using a guinea-pig ileum preparation, arecoline and 2 being the most active compounds. This order of potency was different from those for the antinociceptive and anticonvulsant effects of the compounds using grid shock and isoniazid antagonism tests, respectively, where O-propargyl-THPO (3) proved to be the most active. The pA2 values for the atropine or scopolamine antagonism of these effects of arecoline and 4 were calculated. The partition coefficients (log P values) of the compounds were measured and shown to conform with their ability to penetrate the blood-brain barrier.

Effects of S (+)-3-phenethyl-PP, a putative dopamine autoreceptors agonist with greater autoreceptor selectivity than 3-PPP enantiomers.

The experiments concerned the pharmacology of the enantiomers of the phenethyl-analogue (3-phenethyl-PP) of the putative dopamine (DA) autoreceptor agonist 3-PPP. In contrast to the almost equipotency of 3-PPP enantiomers, the phenethyl enantiomers showed marked stereoselectivity. S(+)-3-Phenethyl-PP had 25 times higher affinity to D-2 DA receptors in vitro than the R(-)-enantiomer. In vivo a similar potency difference was seen for the inhibition of motility, induction of circling behaviour in 6-OHDA-lesioned rats and emetic effect in dogs. None of the enantiomers induced stereotypy and hypermotility in normal rats or in rats pretreated with reserpine and alpha-methyl-p-tyrosine. In test models for antidopaminergic activity only slight activity of either enantiomer was observed. The S(+)-enantiomer had no antagonistic effect against apomorphine- and amphetamine-induced stereotypies, no cataleptogenic activity and only partially antagonized amphetamine-induced hypermotility. Apomorphine-induced emesis was weakly antagonized. The results indicate a greater and higher selectivity of S(+)-3-phenethyl-PP for DA receptors mediating sedation compared with 3-PPP enantiomers which previously have been shown to exert significant effects on postsynaptic DA receptors. Thus S(+)-3-phenethyl-PP may be a more selective model compound for the differential study of effects elicited by stimulation of pre- and postsynaptic DA receptors.

Quantification of antiandrogen effect determined by Lightcycler technology.

During the last decade, the possible effects of xenobiotics on male reproductive health have resulted in great concern. More recently, evidence of antiandrogen effect in vivo by certain chemicals has been reported. The classical Hershberger in vivo assay determining organ weight changes can be improved by measuring hormone levels as well as determining changes in gene expression of androgen-responsive genes. A real-time RT-PCR method using LightCycler technology (Roche) suitable for quantitative determination of gene expression is described. The technique combines rapid thermocycling with online fluorescence detection of PCR product formation. In this study, investigation of expression of prostate specific binding protein polypeptide C3 (PBP C3) and testosterone-repressed prostatic message 2 (TRPM-2) in the ventral prostate was performed in 60-days-old castrated Wistar rats treated daily with testosterone with or without addition of flutamide or vinclozolin for 7 days in total. We show that we can quantify the level of gene expression by use of LightCycler technology, supported by changes in reproductive organ weights as well as in hormone levels, and that analysis of gene expression levels is an even more sensitive endpoint.

Pharmacological effects of a specific dopamine D-1 antagonist SCH 23390 in comparison with neuroleptics.

Neuroleptics such as thioxanthenes (cis(Z)-flupentixol and cis(Z)-clopenthixol) and phenothiazines (fluphenazine and perphenazine), which block both dopamine (DA) D-1 and D-2 receptors and the butyrophenones (haloperidol and spiroperidol), which block D-2 receptors only, are equipotent both behaviorally and clinically. A new compound SCH 23390 which selectively blocks DA D-1 receptors, resembles many neuroleptics in its pharmacological profile: antistereotypic effects in mice, rats and dogs, cataleptogenic effect and inhibitory effect on amphetamine circling. In contrast SCH 23390 has no effect on apomorphine-induced vomiting in dogs and little effects on 6-OHDA-denervated supersensitive DA receptors, stimulated by the DA agonist 3-PPP. In a series of experiments where methylphenidate-induced stereotyped gnawing in mice was inhibited by neuroleptics, it was shown that concomitant treatment with scopolamine or diazepam attenuated the effect of butyrophenones (D-2 antagonists). The same treatment attenuated the effect of phenothiazines, to a lesser extent, and hardly attenuated the effect of thioxanthenes and SCH 23390 at all. It is concluded that DA D-1 receptors are as important as D-2 receptors for the expression of neuroleptic activity in most animal models believed to be predictive of antipsychotic and extrapyramidal side-effect potential. However, the D-1 antagonist is less sensitive than D-2 antagonists to antimuscarinic compounds and benzodiazepines.

The IPCS Collaborative Study on Neurobehavioral Screening Methods: III. Results of proficiency studies. Steering Group.

The goal of the IPCS Collaborative Study on Neurobehavioral Screening Methods was to determine the intra- and inter-laboratory reliability of a functional observational battery (FOB) and an automated assessment of motor activity in eight laboratories world-wide. The first phase of the Collaborative Study involved training the participants: evidence of training was then evaluated using positive-control compounds. The positive-control studies required the laboratories to identify, using the FOB, specific neurotoxic syndromes produced by acute exposure to p,p'-DDT, parathion, and by short-term repeated dosing with acrylamide. For the sake of expediency, only one dose of each chemical was used instead of collecting dose-response data. Motor activity test chambers were not of uniform design. The laboratories were therefore required to demonstrate adequate sensitivity by the ability to detect statistically-significant activity increases and decreases produced by triadimefon and chlorpromazine, respectively, following acute administration of a range of doses. The resulting FOB and motor activity data showed variability in the magnitude of effects obtained: some of these differences were attributed to miscommunications, difficulties with the techniques or protocol, or the limitations of having only one dose. All laboratories, however, successfully met the criteria set forth by the Study Steering Committee.

The IPCS Collaborative Study on Neurobehavioral Screening Methods: IV. Control data. Steering Group.

The goal of the International Programme on Chemical Safety (IPCS) Collaborative Study on Neurobehavioral Screening Methods was to determine the intra- and inter-laboratory reliability of a functional observational battery (FOB) and an automated assessment of motor activity in eight laboratories worldwide. The control data were crucial to the outcome of the studies in terms of sensitivity and reliability of the test measures, which in turn impact on the between-laboratory comparisons of chemical effects. In addition, analyses of control data can aid in determining endpoints that may require modification to improve their sensitivity and reliability. The control data from the eight laboratories were examined in terms of the following parameters: 1) control variability within studies for each laboratory; 2) within-laboratory replicability of control values across studies; 3) within-laboratory stability of control values over the course of testing for a given study; and 4) between-laboratory comparisons of parameters (1), (2), and (3). The analyses indicated considerable differences across endpoints, wherein some measures showed high variability and little replicability, while others were extremely reproducible. Generally, there were similar ranges of variability and replicability of control data across laboratories, although in some cases one or two laboratories were markedly different from the others. The physiological (weight, body temperature) and neuromuscular (grip strength, landing foot splay) endpoints exhibited the least variability, whereas the subjective assessments of reactivity varied the most. These data indicate a reasonable degree of comparability in the data generated in the participating laboratories.