Pharmacokinetics of deramciclane and N-desmethylderamciclane after single and repeated oral doses in healthy volunteers.

OBJECTIVE: To study the pharmacokinetics and accumulation of deramciclane and its metabolite N-desmethylderamciclane after 60 mg twice daily doses for 4 weeks. METHODS: Sixteen healthy male subjects, age range of 20-29 years, participated in this randomized, double-blind, parallel-group, placebo-controlled study. Ten subjects first received a single 60 mg dose of deramciclane followed by 60 mg deramciclane b.i.d. between days 4 and 31. Six subjects received matching placebo in a similar manner. Pharmacokinetics of deramciclane and N-desmethylderamciclane were determined on days 1, 10, 17, 24 and 31. Plasma prolactin concentrations were measured before drug administration and 4 hours after on the same days. Safety was monitored using repeat laboratory determinations and ECG recordings. RESULTS: The mean (SD) AUC(0-infinity) of deramciclane was 1,251 (385) ng x h/ml after the first dose. The AUC(tau) calculated for the dosing interval was significantly higher at week 1 (p = 0.048) than the AUC(0-infinity) after the first dose but thereafter there was no further accumulation of deramciclane. The mean accumulation indices at weeks 1, 2, 3 and 4 varied between 2.3 and 2.7 with no tendency to increase over time. The mean apparent elimination half-life of deramciclane was 24.9 (3.5) hours after the first dose and 29.3 (9.3) hours after 4-week repeated dosing; this difference was not statistically significant. The accumulation index of N-desmethylderamciclane increased from week 1 to week 2 but remained stable thereafter. The treatment was well tolerated. Plasma prolactin levels were not influenced by deramciclane administration. CONCLUSIONS: Deramciclane administration, 60 mg twice daily for 4 weeks to healthy male volunteers, is well tolerated, and there is no evidence of continuous accumulation of the drug during maintenance treatment. Deramciclane at a dose of 60 mg b.i.d. does not antagonize dopamine receptors to a significant degree.

2-[(18)F]fluoro-2-deoxy-D-glucose combined with microdialysis can be used for the comparison of tissue glucose metabolism in obese and lean rats.

AIMS: Direct assessment of tissue metabolism in vivo is important to understand the pathogenesis of obesity. Labelled glucose analogues are potential candidates to be used for this purpose. The aim of this study was to compare the kinetics and metabolism of 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) in obese (fa/fa) and lean (Fa/?) Zucker rat tissues with microdialysis, and the measurement of uptake and phosphorylation with or without insulin bolus injection. METHODS: Obese (n = 10) and lean (n = 11) anaesthetized rats underwent a microdialysis study after FDG-injection either with or without insulin stimulation. Microdialysis probes were inserted in the jugular vein, quadriceps muscle and liver. After 110 min, tissue [(18)F]-uptake and intracellular phosphorylation of FDG were studied in blood, liver, skeletal muscle, subcutaneous adipose tissue, intra-abdominal adipose tissue and hypothalamus. RESULTS: When measured with microdialysis, insulin-enhanced FDG disappeared from the blood pool and interstitial space of skeletal muscle and liver more effectively in lean rather than in obese animals. Insulin-stimulated skeletal muscle and adipose tissue[(18)F]-uptake was impaired in obese Zucker rats compared with lean animals. Hypothalamic FDG uptake was six to sevenfold higher than in other measured tissues, but was attenuated in obese rats. In liver and in mesenteric fat, insulin-enhanced FDG phosphorylation in lean rats compared with obese animals. CONCLUSIONS: Positron-emitting glucose analogue FDG, combined with microdialysis and tissue analysis, is a feasible method in studying glucose metabolism at the cellular level in animal studies.

Intracerebroventricular glucocorticoid infusion in normal rats: induction of parasympathetic-mediated obesity and insulin resistance.

OBJECTIVE: The aims of the present study were to determine whether increased body weight resulting from intracerebroventricular (ICV) glucocorticoid (dexamethasone) infusion in normal rats is associated, as in obesity, with changes in glucose metabolism and to investigate whether the parasympathetic nervous system is involved in the glucocorticoid-induced effects. RESEARCH METHODS AND PROCEDURES: Male Sprague-Dawley rats were infused with ICV dexamethasone (2.5 microg/d) or its vehicle for 2 days during which food intake, body weight, and basal insulinemia were measured. Euglycemic-hyperinsulinemic clamps associated with the labeled 2-deoxyglucose technique were then performed to determine the total rate of glucose disappearance and the tissue glucose use indices. Similar experiments were carried out in vagotomized rats. RESULTS: Two days of ICV glucocorticoid infusion in normal rats resulted in increases in food intake, body weight, basal insulinemia, and produced decreases in the insulin-stimulated total rate of glucose disappearance, as well as in glucose use indices of all muscle types studied. None of these alterations was observed when glucocorticoid infusion was carried out in vagotomized rats. DISCUSSION: These data show that central glucocorticoid infusion favors anabolic processes, such as feeding behavior, body weight gain, and insulin output, while promoting muscle insulin resistance. These effects seem to be mediated by an activation of the parasympathetic nervous system, because they all disappear when tested in vagotomized rats.

Effects of estrous cycle and steroid replacement on the expression of leptin and uncoupling proteins in adipose tissue in the rat.

Among other actions, leptin has been suggested to increase energy expenditure and to modulate the menstrual cycle. In fact, the main effect of leptin seems to be modulating the sympathetic nervous system and gonadotropin-releasing hormone pulsatility. We investigated whether changes in the plasma steroid concentrations during the estrous cycle and after ovariectomy and steroid replacement can modulate plasma leptin levels, adipose tissue leptin mRNA expression, and some of the candidates for mediating energy expenditure (uncoupling proteins (UCP) 1, 2, and 3 mRNA) in white and brown adipose tissue. Rats in estrous cycle or ovariectomized rats with or without estradiol or progesterone replacement therapy for 18 days were studied. Plasma leptin, insulin, estradiol and progesterone were measured with radioimmunoassays. Leptin mRNA expression was measured in subcutaneous, periovarian and mesenteric white adipose tissue and in interscapular brown adipose tissue. Expression of UCP 1, 2, and 3 mRNA in periovarian white and brown adipose tissue was analyzed. Plasma leptin levels were significantly decreased in the estrous (1.1 +/- 0.4 ng/ml) compared with the pro-estrous (1.7 +/- 0.4 ng/ml, F = 3.0, p = 0.046) phase of cycle. UCP1 mRNA levels in brown adipose tissue were more elevated during pro-estrus than during metestrus (F = 3.17, p = 0.039). Gene expressions of leptin, UCP2 or UCP3 mRNA did not change significantly during the cycle. In ovariectomized rats, estradiol and/or progesterone treatment had no effect on plasma leptin levels. Gene expression analysis of leptin and UCP1, 2 and 3 in adipose tissue was not affected by steroid replacement. In conclusion, the estrous cycle appears to have a minor effect on modulation of leptin and uncoupling proteins. Only plasma leptin levels and expression of UCP1 mRNA are modestly elevated during the estrous cycle in the rat. Since estrogen and/or progesterone substitution in ovariectomized rats does not affect circulating leptin concentration or expression of leptin and UCPs in adipose tissue, it is unlikely that steroids play a major role in their regulation.

Involvement of thyroid hormones in the effect of intracerebroventricular leptin infusion on uncoupling protein-3 expression in rat muscle.

We have shown previously that continuous (6 days) intracerebroventricular (ICV) leptin infusion in normal rats resulted in decreases in food intake and body weight. A reduction of food intake imposed on control rats (pair-feeding), aimed at mimicking leptin-induced hyperphagia, produced a marked decrease in the expression of muscle uncoupling protein-3 (UCP-3), whereas ICV infusion of leptin prevented such a decrease in UCP-3. To investigate an involvement of thyroid hormones in this effect of leptin, plasma levels of these hormones were determined in ICV leptin-infused, ICV vehicle-infused ad libitum fed or pair-fed controls. ICV leptin infusion and pair-feeding resulted in decreased plasma thyroid-stimulating hormone (TSH) and T4 levels relative to ad libitum fed controls. ICV leptin infusion maintained plasma levels of T3, but the levels were decreased by pair-feeding. The activity of the enzyme (hepatic 5'-monodeiodinase) responsible for T4/T3 conversion was measured. In the leptin-infused group, the activity of 5'-monodeiodinase was maintained at the values measured in ad libitum fed rats; in pair-fed rats, activity was reduced. Thus, conversion of T4 to T3 is decreased by pair-feeding, whereas such is not the case during leptin infusion. To further substantiate an involvement of thyroid hormones in the effect of leptin on muscle UCP-3 expression, hypothyroid rats were ICV infused with leptin or vehicle. It was observed that in hypothyroid rats, ICV leptin was unable to maintain muscle UCP-3 expression at values measured in ad libitum fed controls. These results suggest that central leptin stimulates T3 production via an activation of T4 to T3 conversion, and that this stimulation could be responsible for the effect of leptin on muscle UCP-3 expression. Thyroid hormones could thus be important mediators of the effect of leptin on energy expenditure.

Effects of chronic celiprolol treatment on brown fat, feeding, and drinking in fa/fa Zucker rats.

Celiprolol is a novel beta-adrenoceptor blocking drug that displays clinically favorable effects on glucose and lipid metabolism. Because some other atypical beta-adrenoceptor blocking drugs have been described to act as agonists on beta(3)-adrenoceptors, we aimed to investigate the effects of celiprolol on brown fat and beta(3)-adrenoceptors. Chronic treatment of obese fa/fa Zucker rats with celiprolol (50 mg/kg/day orally for 20 days) increased GDP binding to brown fat mitochondria by 1.5-fold, whereas beta(3)-adrenoceptor agonist ZD7114 ((S)-4-[2-[(2-hydroxy-3-phenoxypropyl)amino]ethoxy]-N-(2-methoxyet hyl )phenoxyacetamide, 3 mg/kg/day) increased the binding by 3.3-fold. Weight gain was reduced by 19% due to decreased water and food intakes in celiprolol-treated rats. Celiprolol did not activate lipolysis in rat adipocytes in vitro or stimulate human beta(3)-adrenoceptors expressed in Chinese hamster ovary cells as measured with Cytosensor microphysiometer. Therefore, celiprolol does not seem to activate brown fat via beta(3)-adrenoceptors.

Celiprolol augments the effect of physical exercise on insulin sensitivity and serum lipid levels in chronic heart failure.

PURPOSE: Impaired insulin sensitivity has been linked with chronic heart failure (CHF). Exercise has a beneficial effect on insulin sensitivity in healthy subjects. It is used also as an adjunctive therapy in patients with CHF. We studied the effect of randomized treatment with celiprolol, a vasodilating beta(1)-adrenoceptor antagonist, 200 mg once daily (n=20) or placebo (n=11) on serum lipid levels and insulin sensitivity in patients with CHF. In addition, all subjects participated in a 6-month exercise training protocol. Thirteen subjects in the celiprolol and eight subjects in the control group were on additional beta(1)-adrenoceptor antagonist as part of their tailored CHF therapy. Insulin sensitivity was determined using the hyperinsulinemic euglycemic clamp test (diabetic subjects excluded, n=11 for the celiprolol group and n=8 for the placebo group). RESULTS: Insulin sensitivity index (ISI) increased by 33% (P<0.05) in the celiprolol group and by 17% (NS) in the control group. The mean increase in the whole group was 20% [from 68.2+/-11.5 to 81.7+/-10.7 ml/min/kg (mU/l), P<0.05]. No change was found in the total cholesterol level. HDL cholesterol levels increased by 12% (from 0.98+/-0.05 to 1.10+/-0.05 mmol/l, P<0. 005), and HDL/total cholesterol and HDL/LDL cholesterol ratios by 15% and 16%, respectively (P<0.005). The increase in serum fasting HDL cholesterol level was greater in the celiprolol-treated group (P<0.05). At baseline ISI correlated with maximal oxygen uptake (r=0. 65, P<0.0001) and body mass index (r=-0.55, P<0.001). The change in ISI correlated weakly with the improvement in muscle exercise capacity (r=0.53, P<0.05). CONCLUSIONS: Insulin sensitivity and serum lipid levels may be favorably affected by exercise training in subjects with mild-to-moderate CHF. Celiprolol, a vasodilating beta1- selective adrenoceptor antagonist, potentiates this effect.

Acute inhibition of oestrogen biosynthesis does not affect serum leptin levels in young men.

OBJECTIVE: Leptin plays an important role in the regulation of reproduction. To explore the contribution of oestradiol to serum leptin levels in men, we measured the concentrations of serum leptin and insulin after inhibition of oestrogen biosynthesis by selective blockade of the aromatase enzyme. DESIGN: The study had a double-blind parallel group design. METHODS: The aromatase inhibitor, MPV 2213ad, was given to eight healthy male volunteers as a single dose of 100mg. Eight men received placebo. Serum leptin and insulin were determined from blood samples collected at 0800h, 1600h and 2000h both on the actual test day (day 0) and on the previous day (day -1), and from single blood samples taken in the morning of days 1, 2, 4 and 7. Changes in serum leptin were correlated with those seen in serum oestradiol, testosterone, LH, FSH, cortisol and aldosterone, which were determined earlier. RESULTS: After the aromatase inhibitor administration, mean serum oestradiol concentration was reduced by 74% from the baseline compared with a 19% reduction in the placebo group (P for difference <0.001), and returned to pre-treatment levels within four days. Despite marked changes in serum oestradiol and sustained elevations in serum testosterone, LH and FSH concentrations, serum leptin concentrations were similar in the group receiving the aromatase inhibitor and in the placebo group. We found a weak correlation between serum oestradiol and leptin, which could not be reproduced when the percentage changes in these variables were analysed. CONCLUSION: Marked short-term reduction in serum oestradiol concentration has no effect on serum leptin levels in young men.

Pharmacokinetics and safety of deramciclane during multiple oral dosing.

UNLABELLED: Deramciclane is a new putative non-benzodiazepine-type anxiolytic compound. It is a selective serotonin 5-HT(2A) and 5-HT(2C) receptor antagonist and has also inverse agonist properties. The aim of this study was to reveal the pharmacokinetics and tolerability of deramciclane during repeated oral dosing in healthy male volunteers. SUBJECTS, MATERIAL AND METHODS: A randomized double-blind, placebo-controlled design was used. The study had three consecutive groups that received first a single oral dose of 10, 30 and 60 mg of deramciclane followed by twice a day administration for seven days. The total number of subjects was 28. The pharmacokinetic parameters were calculated for a single dose and after repeated administration. Tolerability was assessed by monitoring safety laboratory variables, electrocardiogram, heart rate, blood pressure and adverse events. RESULTS: The steady-state was reached during the seven-day administration. The pharmacokinetics of deramciclane was dose-proportional at steady-state at each dose level. Deramciclane accumulated about three-fold during repeated administration. The relative bioavailability of deramciclane increased about 1.4-fold compared to that of a single dose at each dose level. The mean elimination half-life of deramciclane for 10, 30 and 60 mg doses prolonged from 24.3, 20.9 and 22.9 h after a single dose to 30.5, 25.6 and 28.7 h at steady-state, respectively. Only few adverse events were reported, all mild and transient in nature. The most frequently reported adverse drug reactions were tiredness and headache. There were no deramciclane-induced changes in the clinical chemistry or hematology variables, blood pressure, heart rate or in electrocardiogram. CONCLUSIONS: In conclusion, the pharmacokinetics of deramciclane is linear over the dose range of 10 - 60 mg at steady-state. The slight non-linearity within the dose levels during repeated administration of seven days was regarded as clinically irrelevant. Deramciclane was safe and well tolerated up to doses of 60 mg b.i.d. for seven days.

Pharmacokinetics of oral entacapone after frequent multiple dosing and effects on levodopa disposition.

OBJECTIVE: Entacapone is a peripherally acting catechol O-methyltransferase (COMT) inhibitor used as an adjunct to each daily levodopa/dopa decarboxylase (DDC) inhibitor dose in the treatment of Parkinson's disease. Parkinsonian patients with advanced disease and motor fluctuations take several doses of levodopa daily, due to the short action of levodopa in this patient population. The present study was conducted in order to evaluate the pharmacokinetics of entacapone after multiple dosing and the pattern of COMT inhibition in erythrocytes during the first day of dosing as well as during steady state. Furthermore, the disposition of plasma levodopa and carbidopa was studied after a single dose of levodopa/carbidopa during the same conditions. METHODS: Twelve healthy male volunteers received 200 mg entacapone eight times daily during study day 1 and day 6 at 2-h intervals from 0800 hours to 2200 hours. During days 3, 4 and 5, 200 mg of entacapone was taken ten times daily, from 0800 hours to 0200 hours on the following day. One levodopa/carbidopa tablet (100/25 mg) was taken on study day 1 and day 6 at 1000 hours. Plasma entacapone concentrations and erythrocyte COMT activities were measured frequently on study days 1-2 and 6-7, and twice daily on study days 3-5. Pharmacokinetic parameters calculated from plasma drug concentrations on days 1-2 and 6-7 were compared with each other. RESULTS: There were no differences in maximal plasma concentration (Cmax), time to maximal drug concentration in plasma (tmax), elimination half-life (t1/2) and area under the plasma concentration-time curve (AUC) of entacapone between day 1 and day 6. The mean t1/2 values of entacapone were 1.3 h and 1.8 h during the first and sixth days, respectively; the difference was not significant. No signs of accumulation of entacapone were noted after the first day. Entacapone reduced erythrocyte COMT activity after the first dose, and this effect was quite stable during frequent dosing. There were no indications of accumulation of COMT inhibition during frequent dosing of entacapone. There were no between-day differences in Cmax, t1/2 (2.4 h on days 1-2 and 2.3 h on days 6-7) or AUC of levodopa, whereas tmax occurred at 0.8 h on day 1 and at 1.2 h on day 6 (P = 0.03). There were no between-day differences in the pharmacokinetic parameters (Cmax, tmax and AUC) of carbidopa. CONCLUSION: Even when dosed frequently, there are neither indications of accumulation of entacapone nor of its COMT inhibiting activity.

Effects of intravenously infused leptin on insulin sensitivity and on the expression of uncoupling proteins in brown adipose tissue.

Centrally administered leptin has been shown to increase insulin-stimulated glucose utilization and to favor the expression of uncoupling proteins (UCPs). To study if leptin also has direct peripherally mediated effects on these processes, this hormone (1 mg/day) or its vehicle was infused i.v. for 4 days to lean rats and insulin-stimulated glucose utilization in skeletal muscle and adipose tissue as well as the expression of UCP messenger RNAs (mRNAs) in brown adipose tissue were measured. I.v. leptin administration resulted in decreases in food intake (31%), body weight gain, and plasma insulin levels (45%), in increases in overall (23%) as well as brown adipose tissue and muscle glucose utilization, and in decreases in white adipose tissue glucose uptake. Most of these changes were mimicked, in control rats, by giving them the same amount of food as that consumed by the leptin-infused group (pair-feeding). I.v. leptin infusion also favored the expression of UCPs in brown adipose tissue, either by increasing their expression or preventing the fall occurring during the pair-feeding regimen. Relative UCP expression levels were 100, 104, and 33 for UCP1, 100, 191, and 125 for UCP2 and 100, 107, and 29 for UCP3 in ad libitum fed control rats, in leptin-treated rats and in pair-fed control rats, respectively. These results suggest that the overall effect of leptin on glucose utilization and on the expression of UCPs may be mediated through central mechanism.

Selective dependence of intracerebroventricular neuropeptide Y-elicited effects on central glucocorticoids.

It has been reported that hyperphagia and excessive body weight gain of genetically obese rodents were abolished by adrenalectomy. High hypothalamic levels of neuropeptide Y (NPY) were found in obese rodents. A chronic intracerebroventricular (icv) infusion of NPY in normal rats was shown to produce most hormono-metabolic abnormalities of genetically obese animals, and to be inefficient in doing so in adrenalectomized (ADX) rats. The combined presence of NPY and of glucocorticoids thus appeared to be necessary for inducing obesity. This study, therefore, was aimed at determining the consequences of a chronic i.c.v. NPY infusion in ADX rats receiving or not i.c.v. glucocorticoids. It was found that the combined i.c.v. infusion of NPY and dexamethasone in ADX rats increased food intake, body weight, plasma insulin, leptin, and triglyceride levels relative to vehicle-infused ADX controls. The infusion of NPY alone, or of dexamethasone alone in ADX rats failed to produce these effects. In contrast, the icv infusion of NPY alone greatly decreased the expression of brown adipose tissue uncoupling protein-1 and -3. This was not modified by the superimposed infusion of dexamethasone. It is concluded that, although many of centrally elicited NPY effects require the central presence of glucocorticoids, those bearing on the inhibition of uncoupling proteins expression (energy dissipation) do not require central glucocorticoids.

The single dose pharmacokinetics and safety of deramciclane in healthy male volunteers.

The pharmacokinetics and tolerability of a new putative non-benzodiazepine type anxiolytic compound deramciclane was studied in two consecutive studies. An open dose-escalation design was used to study doses from 0.2 to 50 mg in 18 healthy male volunteers. In the second study doses from 50 to 150 mg were investigated in 14 healthy males in a double-blind, placebo-controlled, dose escalation study. Deramciclane was rapidly absorbed from the GI-tract and T(max) was 2-4 h. The elimination half-life increased from about 20 h to about 32 h with the increasing dose. Nevertheless, the AUC(0-infinity) values increased linearly within the studies over the dose ranges of 3-50 and 50-150 mg. However, the increase was more than the ratio of the dose over the total dose range of 3-150 mg. Therefore, non-linear pharmacokinetics of deramciclane at high doses cannot be excluded. N-desmethyl deramciclane, which is the active metabolite of deramciclane, was determined in plasma. C(max) was reached at about 6 h. The AUC(0-48 h) for the N-desmethyl metabolite was about one third of the AUC(0-infinity) of the parent compound and the ratio remained constant at each dose level. Deramciclane was safe, and was well tolerated at each dose level.

Correlation between circulating leptin and luteinizing hormone during the menstrual cycle in normal-weight women.

OBJECTIVE: Leptin is the hormonal product of the ob gene. It is expressed in adipocytes and participates in the regulation of food intake and metabolism. Since leptin also seems to signal metabolic information to the reproductive system, we studied the association between reproductive hormones and plasma leptin in normal-weight young women. DESIGN: Eight young women with normal menstrual cycles (body mass index (BMI) 21.2 +/- 1.6 kg/m2) and eight young women using hormonal contraception (BMI 21.4 +/- 1.1 kg/m2) were studied. Furthermore, six women with normal menstrual cycles and no hormonal therapy (BMI 20.7 +/- 1.2 kg/m2) were studied around the time of the anticipated ovulation. METHODS: Serum leptin, estradiol, progesterone and luteinizing hormone (LH) concentrations were measured with radioimmunoassays. RESULTS: Serum leptin concentrations were similar at the beginning of the cycle, at the time of the anticipated ovulation and at the end of the menstrual cycle (10.2 +/- 7.1, 10.7 +/- 7.0 and 11.8 +/- 6.9 microg/l respectively). There was an association between leptin and LH concentrations (r= 0.37, P< 0.01) when values recorded during different time points during the cycle were plotted with each other. There was no change in serum leptin in samples taken at different times of the cyclic treatment with an oral contraceptive. There was no significant difference in mean serum leptin concentrations between women using oral contraceptives and women with no hormonal therapy. CONCLUSIONS: There is a link between serum leptin and LH concentrations during the menstrual cycle. Variations in circulating estrogen and/or progesterone concentrations have no major influence on circulating leptin in young female subjects.

Effects of ZD7114, a selective beta3-adrenoceptor agonist, on neuroendocrine mechanisms controlling energy balance.

Selective beta3-adrenoceptor agonists increase energy expenditure by increasing non-shivering thermogenesis in brown adipose tissue. The aim of this study was to investigate how changes in energy balance affect energy intake and interaction of peripheral metabolic feedback signals with central neuroendocrine mechanisms participating in the control of body energy balance. Expression of preproneuropeptide Y (preproNPY) mRNA in the arcuate nucleus and preprocorticotropin-releasing factor (CRF) mRNA in the paraventricular nucleus were measured by in situ hybridisation technique after 1 day, 1 and 5 weeks of treatment with ZD7114 ((S)-4-[2-[(2-hydroxy-3-phenoxypropyl)amino]ethoxy]-N-(2-methoxyet hyl)phenoxyacetamide, 3 mg kg(-1) day(-1) in drinking water) in obese fa/fa Zucker rats. In addition, expression of leptin mRNA in epididymal fat and serum levels of leptin were analysed. Food intake, body weights, binding of GDP to brown adipose tissue mitochondria, plasma insulin and glucose were also measured. Treatment with ZD7114 significantly reduced weight gain and activated brown adipose tissue thermogenesis, but had no effect on food intake. Expressions of preproNPY or preproCRF mRNAs were similarly not changed by treatment with ZD7114. Furthermore, ZD7114 had no effect on plasma insulin or leptin and the expression of leptin mRNA in epididymal fat. However, statistically significant correlations were found between preproNPY and preproCRF mRNA expressions and brown fat thermogenic activity and plasma insulin levels in the ZD7114 treated rats, but not in the control rats. It is concluded that treatment with ZD7114 markedly activated brown fat thermogenesis, but did not affect neuropeptide Y (NPY) and CRF gene expression per se. However, the correlation analyses suggest that ZD7114 may modulate feedback connections of brown adipose tissue thermogenesis and plasma insulin with the hypothalamic neuroendocrine mechanisms integrating body energy balance.

Differential regulation of uncoupling proteins by chronic treatments with beta 3-adrenergic agonist BRL 35135 and metformin in obese fa/fa Zucker rats.

The expressions of uncoupling proteins 2 and 3 (UCP2; UCP3) mRNA were studied in obese (fa/fa) Zucker rats treated with two weight gain reducing agents for three weeks. The specific beta 3-adrenoceptor agonist BRL 35135 (0.5 mg/kg/day orally) increased the expression of UCP3 mRNA by 3.8-fold (P < 0.0001; two-way ANOVA) and that of UCP1 mRNA by 2.6-fold (P = 0.014) in brown adipose tissue, but had no effect on expression of UCP3 mRNA in white fat or in the soleus muscle, or on UCP2 mRNA expression in brown or white fat. The antihyperglycemic metformin (300 mg/kg/day orally) had no effect on expressions of UCP1, UCP2 or UCP3 in any tissue studied. Concentrations of plasma insulin were significantly correlated with the levels of white fat UCP2 mRNA (in the control group: r = 0.89, P = 0.0015) and UCP3 mRNA (in the control group: r = 0.80, P = 0.009) suggesting that insulin may play a role in the control of UCP2 and UCP3 mRNA expressions in white adipose tissue.

Chronic treatment with BRL 35135 potentiates the action of insulin on lipid metabolism.

The effects of a beta 3-adrenoceptor agonist on insulin-induced changes in lipid metabolism were studied in obese male Zucker (fa/fa) rats during euglycaemic clamp. Rats were treated with BRL 35135 (R*, R*-(+/-)-methyl-4-[2-[2-hydroxy-2-(3-chlorophenyl)-ethyl-amino]-propyl] phenoxyacetate hydrobromide) (0.5 mg/kg per day in drinking water) for three weeks before an euglycaemic hyperinsulinaemic clamp was performed. Insulin infusion lowered serum non-esterified fatty acids and plasma glycerol more efficiently in BRL 35135-treated than in control rats although plasma insulin remained significantly lower in the BRL 35135-treated than in the control rats during the clamp. In conclusion, chronic treatment with BRL 35135 potentiates the effect of insulin on lipid metabolism.

Serum leptin concentrations in women with polycystic ovary syndrome.

The role of gonadotropins, androgens, and insulin in the regulation of circulating leptin levels is obscure. In order to clarify the relationships of these parameters we studied serum leptin levels in 19 healthy control subjects and in 35 hyperandrogenic and hyperinsulinemic patients with polycystic ovary syndrome (PCOS). Serum leptin concentrations did not differ significantly between PCOS patients and control subjects. When PCOS and control groups were analyzed together by univariate analysis, serum leptin was positively correlated with body mass index (BMI), body weight, serum insulin, serum triglyceride, and serum free testosterone concentrations. Serum leptin was inversely correlated with serum sex hormone binding globulin (SHBG) concentrations. There were no significant correlations between serum leptin and testosterone, androstenedione, or gonadotropin concentrations. Serum insulin, triglyceride, and free testosterone concentrations were positively correlated, and serum SHBG was negatively correlated with BMI. However, when BMI on one hand and serum insulin, triglyceride, free testosterone, or SHBG on other hand were used as independent variables in the partial correlation analysis with leptin, BMI turned out to be the variable primarily responsible for all of the correlations with leptin. In conclusion, the concept that circulating leptin levels would be different in PCOS patients than in regularly menstruating control subjects is not supported by our data.

Anti-obesity effect of MPV-1743 A III, a novel imidazoline derivative, in genetic obesity.

MPV-1743 A III ((+/-)-4-(5-fluoro-2,3-dihydro-1H-inden-2-yl)-1H-imidazole) is a novel imidazoline derivative. In this study, it was shown to bind with high affinity to alpha2-adrenoceptor subtypes alpha2A (IC50) = 0.66 +/- 0.06 nM), alpha2B (IC50) = 3.8 +/- 0.53 nM), alpha2C (IC50) = 3.1 +/- 0.61 nM) in the recombinant S115 cells and to alpha2D (IC50 = 0.94 +/- 0.10 nM) in the rat submandibular gland. MPV-1743 A III also showed remarkably high affinity to alpha1-adrenoceptors (IC50 = 150 +/- 12 nM) in the rat cerebral cortex and to imidazoline I2b-binding sites (IC50) = 150 +/- 5.0 nM) in the rat liver. The functional alpha2-adrenoceptor antagonistic effect of MPV-1743 A III was demonstrated by studying the ability of orally administered MPV-1743 A III to reverse and prevent the alpha2-adrenoceptor agonist detomidine-induced mydriasis in rat. The anti-obesity effect of MPV-1743 A III was investigated in genetically obese (fa/fa) Zucker rats in two different phases of obesity. Chronic treatment with MPV-1743 A III (0.3 3 mg/kg per day p.o. for 3 weeks) dose dependently decreased weight gain in early-phase obesity. In fully established obesity, GDP binding to mitochondria and expression of uncoupling protein mRNA were increased in brown adipose tissue by MPV-1743 A III indicating an activation of non-shivering thermogenesis. The present study shows that MPV- 1743 A III has a modest anti-obesity effect in the genetic rodent model of obesity. The relative importance of alpha2- and alpha1-adrenoceptors and imidazoline I2b-binding sites in mediating the effects of MPV-1743 A III needs further evaluation.