Changes in psychosocial health during a 7-week paediatric weight management program.

Youth with obesity are at increased risk of psychosocial symptoms; however, little is known regarding the impact of paediatric weight management (PWM) on psychosocial health. The aim of the study was to investigate changes in psychosocial health among children who completed a 7-week PWM program. Participants aged 5 to 16 years with a BMI ≥85th percentile completed a 7-week, family-centred PWM program focused on health behaviour education, exercise and mentored goal setting. The Paediatric Symptom Checklist (PSC) was assessed via parent report to evaluate psychosocial symptoms before and after the program, and subscales were calculated for internalizing (PSC-IS), externalizing (PSC-ES) and attention symptoms (PSC-AS). At baseline, positive screen rates for psychosocial symptoms among the 317 patients included 16.1% for PSC, 14.1% for PSC-ES, 18.6% for PSC-IS and 12.3% for PSC-AS. Among program completers, total PSC scores improved in those with normal (p = 0.010) and elevated p < .001 psychosocial symptoms at baseline. Youth with positive screens for elevated PSC subscales improved their subscale scores, on average, and the majority reduced scores to below elevated levels for PSC (54.2%), PSC-ES (64.7%), PSC-IS (78.3%) and PSC-AS (64.7%). Improvements in PSC remained significant after adjusting for BMI changes during treatment, but BMI differed across PSC-change groups, including BMI increases among participants with PSC deterioration (0.33 ± 0.64 kg m-2 ) (P = 0.035) and BMI decreases among patients with no reliable PSC change (-0.26 ± 1.04 kg m-2 ) (P = 0.038) or reliable PSC improvement (-0.22 ± 0.74 kg m-2 ) (P = 0.025). Youth with positive screens for psychosocial symptoms can improve emotional and behavioural functioning during short-term PWM. Future research is needed to elucidate mechanisms and long-term outcome durability.

Psychiatric diagnoses and medication treatment among patients presenting for paediatric weight management: associations with adiposity, aerobic fitness and cardiometabolic health.

We compared anthropometry, cardiometabolic risk and aerobic fitness among obese youth in weight management who were diagnosed with one or more psychiatric disorders (PD), with (PD+M) or without (PD-M) a prescribed psychotropic medication with those with no PD (NPD). Physical measures were evaluated at baseline, and psychiatric diagnoses and related medications were identified from medical records. Of 99 patients 64 (65%) had a diagnosed PD, and of those, 23 (36%) had a related medication (PD+M). Compared to NPD, PD-M had a higher body mass index (BMI) (P = 0.003), BMI z-score (P = 0.015), percent body fat (P = 0.005) and waist circumference (P < 0.001), after adjusting for age, but PD+M did not. Cardiometabolic risk did not differ between groups, but aerobic fitness was lower among PD-M (P = 0.001) and PD+M (P = 0.008) compared to NPD. Obese youth in weight management exhibit high rates of psychiatric diagnoses that are associated with lower fitness and higher adiposity and may impact treatment efficacy.

BIIE0246, a potent and highly selective non-peptide neuropeptide Y Y(2) receptor antagonist.

1. BIIE0246, a newly synthesized non-peptide neuropeptide Y (NPY) Y(2) receptor antagonist, was able to compete with high affinity (8 to 15 nM) for specific [(125)I]PYY(3 - 36) binding sites in HEK293 cells transfected with the rat Y(2) receptor cDNA, and in rat brain and human frontal cortex membrane homogenates. 2. Interestingly, in rat brain homogenates while NPY, C2-NPY and PYY(3 - 36) inhibited all specific [(125)I]PYY(3 - 36) labelling, BIIE0246 failed to compete for all specific binding suggesting that [(125)I]PYY(3 - 36) recognized, in addition to the Y(2) subtype, another population of specific NPY binding sites, most likely the Y(5) receptor. 3. Quantitative receptor autoradiographic data confirmed the presence of [(125)I]PYY(3 - 36)/BIIE0246-sensitive (Y(2)) and-insensitive (Y(5)) binding sites in the rat brain as well as in the marmoset monkey and human hippocampal formation. 4. In the rat vas deferens and dog saphenous vein (two prototypical Y(2) bioassays), BIIE0246 induced parallel shifts to the right of NPY concentration-response curves with pA(2) values of 8.1 and 8.6, respectively. In the rat colon (a Y(2)/Y(4) bioassay), BIIE0246 (1 microM) completely blocked the contraction induced by PYY(3 - 36), but not that of [Leu(31), Pro(34)]NPY (a Y(1), Y(4) and Y(5) agonist) and hPP (a Y(4) and Y(5) agonist). Additionally, BIIE0246 failed to alter the contractile effects of NPY in prototypical Y(1) in vitro bioassays. 5. Taken together, these results demonstrate that BIIE0246 is a highly potent, high affinity antagonist selective for the Y(2) receptor subtype. It should prove most useful to establish further the functional role of the Y(2) receptor in the organism.

Potent and selective tools to investigate neuropeptide Y receptors in the central and peripheral nervous systems: BIB03304 (Y1) and CGP71683A (Y5).

We have evaluated 3 newly developed neuropeptide Y receptor antagonists in various in vitro binding and bioassays: BIBO3304 (Y1), T4[NPY33-36]4 (Y2), and CGP71683A (Y5). In rat brain homogenates, BIBO3304 competes for the same population of [125I][Leu31,Pro34] peptide YY (PYY) binding sites (75%) as BIBP3226, but with a 10 fold greater affinity (IC50 of 0.2 +/- 0.04 nM for BIBO3304 vs. 2.4 +/- 0.07 nM for BIBP3226),while CGP71683A has high affinity for 25% of specific [125I][Leu31,Pro34]PYY binding sites. Both BIBO3304 and CGP71683A (at 1.0 microM) were unable to compete for a significant proportion of specific [125I]PYY3-36/Y2 sites. The purported Y2 antagonist T4[NPY33-36]4 competed against [125I]PYY3-36 binding sites with an affinity of 750 nM. These results were confirmed in HEK 293 cells transfected with either the rat Y1, Y2, Y4, or Y5 receptor cDNA. BIBO3304, but not CGP71683A, competed with high affinity for [125I][Leu31,Pro34]PYY binding sites in HEK 293 cells transfected with the rat Y1 receptor cDNA, whereas the reverse profile was observed upon transfection with the rat Y5 receptor cDNA. Additionally, both molecules were inactive at Y2 and Y4 receptor subtypes expressed in HEK 293 cells. Receptor autoradiographic studies revealed the presence of [125I][Leu31,Pro34]PYY/BIBO3304-insensitive sites in the rat brain as reported previously for BIBP3226. Finally, the selective antagonistic properties of BIBO3304 were demonstrated in a Y1 bioassay (rabbit saphenous vein; pA2 value of 9.04) while being inactive in Y2 (rat vas deferens) and Y4 (rat colon) bioassays. These results confirm the high affinity and selectivity of BIBO3304 and CGP71683A for the Y1 and Y5 receptor subtypes, respectively, while the purported Y2 antagonist, T4[NPY33-36]4 possesses rather low affinity for this receptor.

Neuropeptide Y-induced contraction is mediated by neuropeptide Y Y2 and Y4 receptors in the rat colon.

Ascending and descending segments of the rat colon were studied to analyze their contractile responses to neuropeptide Y and related peptides. These responses are (a) completely eliminated by tetrodotoxin (1 microM), (b) reduced to a variable extent (20 to 60%) by atropine (1 microM) and (c) not modified by indomethacin, diphenhydramine or methysergide. The order of potency of agonists for peptides related to neuropeptide Y was as follows: human pancreatic polypeptide = rat pancreatic polypeptide > peptide YY = peptide YY-(3-36) = [Leu31,Pro34]neuropeptide Y > neuropeptide Y-(2-36) > C2-neuropeptide Y = neuropeptide Y > neuropeptide Y-(13-36), with minor differences observed between the two parts of the colon. This selectivity pattern does not correspond to the profile of any known cloned neuropeptide Y receptors. BIBP3226, a selective antagonist for the neuropeptide Y Y1 receptor sub-type, was found to be inactive, while a neuropeptide Y Y2 receptor antagonist, T4-[NPY-(33-36)]4, reduced the effects of neuropeptide Y, peptide YY, peptide YY-(3-36) and C2-neuropeptide Y without affecting those of human pancreatic polypeptide, rat pancreatic polypeptide and [Leu31,Pro34]neuropeptide Y. JCF 104 (compound 28), a putative neuropeptide Y Y5 receptor antagonist, showed no effect or a weak inhibition of human pancreatic polypeptide or [Leu31,Pro34]neuropeptide Y-induced contraction. Taken together, these data suggest that: (1) at least two neuropeptide Y receptor types are present in the rat colon autonomic nerve terminals and modulate the release of acetylcholine and possibly other transmitters; (2) a proportion of the receptors mediating the contractile response of the rat colon (especially descending part) to neuropeptide Y and related peptides appears to be of the Y2 type and (3) the significant portion of the response is mediated by a receptor which is insensitive to neuropeptide Y Y1, Y2 and to neuropeptide Y Y5 receptor antagonists. This receptor behaves as a neuropeptide Y Y4 receptor sub-type and appears to be located on enteric nerves.

Nitric oxide limits the eicosanoid-dependent bronchoconstriction and hypotension induced by endothelin-1 in the guinea-pig.

1. This study attempts to investigate if endogenous nitric oxide (NO) can modulate the eicosanoid-releasing properties of intravenously administered endothelin-1 (ET-1) in the pulmonary and circulatory systems in the guinea-pig. 2. The nitric oxide synthase blocker N(omega)-nitro-L-arginine methyl ester (L-NAME; 300 microM; 30 min infusion) potentiated, in an L-arginine sensitive fashion, the release of thromboxane A2 (TxA2) stimulated by ET-1, the selective ET(B) receptor agonist IRL 1620 (Suc-[Glu9,Ala11,15]-ET-1(8-21)) or bradykinin (BK) (5, 50 and 50 nM, respectively, 3 min infusion) in guinea-pig isolated and perfused lungs. 3. In anaesthetized and ventilated guinea-pigs intravenous injection of ET-1 (0.1-1.0 nmol kg(-1)), IRL 1620 (0.2-1.6 nmol kg(-1)), BK (1.0-10.0 nmol kg(-1)) or U 46619 (0.2-5.7 nmol kg(-1)) each induced dose-dependent increases in pulmonary insufflation pressure (PIP). Pretreatment with L-NAME (5 mg kg(-1)) did not change basal PIP, but increased, in L-arginine sensitive manner, the magnitude of the PIP increases (in both amplitude and duration) triggered by each of the peptides (at 0.25, 0.4 and 1.0 nmol kg(-1), respectively), without modifying bronchoconstriction caused by U 46619 (0.57 nmol kg(-1)). 4. The increases in PIP induced by ET-1, IRL 1620 (0.25 and 0.4 nmol kg(-1), respectively) or U 46619 (0.57 nmol kg(-1)) were accompanied by rapid and transient increases of mean arterial blood pressure (MAP). Pretreatment with L-NAME (5 mg kg(-1); i.v. raised basal MAP persistently and, under this condition, subsequent administration of ET-1 or IRL 1620, but not of U-46619, induced hypotensive responses which were prevented by pretreatment with the cyclo-oxygenase inhibitor indomethacin. 5. Thus, endogenous NO appears to modulate ET-1-induced bronchoconstriction and pressor effects in the guinea-pig by limiting the peptide's ability to induce, possibly via ET(B) receptors, the release of TxA2 in the lungs and of vasodilatory prostanoids in the systemic circulation. Furthermore, it would seem that these eicosanoid-dependent actions of ET-1 in the pulmonary system and on systemic arterial resistance in this species are physiologically dissociated.

Acute and chronic role of 5-HT3 neuronal system on behavioral and neuroendocrine changes induced by intravenous cholecystokinin tetrapeptide administration in humans.

The influence of single and multiple oral doses of ondansetron, a selective 5-HT3 receptor antagonist, was evaluated against placebo on cholecystokinin tetrapeptide (CCK-4)-induced behavioral and neuroendocrine changes in humans. As compared to placebo, subjects receiving acute ondansetron treatment showed a significant decrease in the sum intensity of CCK-4-induced-panic symptoms (iPSS). Pre-CCK-4 neuropeptide Y (NPY) plasma levels were significantly higher and maximal changes in cortisol, growth hormone, and prolactin secretion from baseline (delta max) were significantly lower in the ondansetron group. After ondansetron and placebo chronic administration, there were no statistical differences in the iPSS between groups. Pre-CCK-4 NPY plasma levels were significantly higher; whereas, delta max for NPY significantly lower in the ondansetron group as compared to placebo. These results suggest a role for the 5-HT3 receptor in the neurobiology of panic disorder through a possible interaction with CCK and NPY systems. Ondansetron chronic effect on CCK-4-induced behavioral changes needs further exploration.

Bronchoprotector properties of calcitonin gene-related peptide in guinea pig and human airways. Effect of pulmonary inflammation.

Calcitonin gene-related peptide (CGRP), a neuropeptide released from sensory nerves during axonal reflexes, has strong bronchoprotector properties in rat isolated airways. In this study, we examined this ability of CGRP to prevent agonist-induced contraction in guinea pig and human airways and determined whether inflammatory reaction affects its function. CGRP administered intravenously (0.38 to 114 microgram/kg) in anesthesized guinea pig had no effect per se on airway resistance but caused a dose-related inhibition of substance P (SP; 13.5 microgram/kg)-induced bronchoconstriction (60% at 114 microgram/kg). Similarly, CGRP (10(-)9 to 10(-)6 M) prevented in a concentration-dependent manner the contraction elicited by SP (5 x 10(-)8 M) in guinea pig isolated main bronchi and parenchymal strips, the inhibition caused by CGRP being more pronounced in distal than in proximal airways (47 and 20%, respectively, at 10(-)6 M). The breaking effect of CGRP on SP-induced constriction was however significantly reduced (p < 0.05) in guinea pig actively sensitized to ovalbumin (OA) and the loss in its potency was of similar magnitude (> 40%) whether it was administered in vivo or in vitro. A same phenomenon was observed in human isolated peripheral bronchi. CGRP (10(-)6 M) reduced by more than 75% the extent of the contraction evoked by 10(-)6 M of carbamylcholine and its protector effect was totally abolished in bronchi showing clear morphological manifestation of inflammatory reaction. It is concluded that CGRP acts as a potent bronchoprotector agent on both guinea pig and human airways but its ability to limit the extent of airway responsiveness is strongly impaired in inflammatory conditions.

Epoxyeicosatrienoic acids relax airway smooth muscles and directly activate reconstituted KCa channels.

Epoxyeicosatrienoic acids (EETs) relax various smooth muscles by increasing outward K+ movement, but the molecular mode of action of EET regioisomers remains to be clarified. The effects of EETs were investigated on bovine airway smooth muscle tone and on reconstituted Ca2+-activated K+ (KCa) channels. 5,6-EET and 11, 12-EET induced dose-dependent relaxations of precontracted bronchial spirals. These effects were partly abolished by 10 nM iberiotoxin. Bilayer experiments have shown that 0.1-10 microM 11,12-EET produced up to fourfold increases in the open probability of KCa channels from the cis (extracellular) side by enhancing the mean open time constant and reducing the long closed time constant, without affecting the unitary conductance. EET-induced activations were blocked by 10 nM iberiotoxin. Addition of vehicles or other lipids as well as of GTP and guanosine 5'-O-(3-thiotriphosphate) in the absence of EET had no effect on channel activity. Thus EETs directly activate KCa channels from airway smooth muscle through an interaction with the extracellular face of the channel. We propose that EETs could represent candidate molecules as epithelium-derived hyperpolarizing factors.

Direct activation of K(Ca) channel in airway smooth muscle by nitric oxide: involvement of a nitrothiosylation mechanism?

Clinically, nitric oxide (NO*) is widely used as a pulmonary vaso- and bronchodilator agent. However, the precise molecular mechanisms by which NO. induces smooth muscle relaxation are not well established. It has been suggested that NO. relaxes airway smooth muscle (ASM) via a 3',5'-cyclic guanosine monophosphate (cGMP)-dependent pathway, and our previous work has shown that Ca2+-activated K+ (KCa) channels are susceptible to cGMP-dependent protein kinase (PKG)-dependent phosphorylation (A. Alioua, J. P. Huggins, and E. Rousseau. Am. J. Physiol. 1995;268:L1057-L1063). To assess whether KCa channels are also directly activated by NO. or one of its derivatives such as peroxynitrite, the activity of these channels was measured upon fusion of sarcolemmal vesicles derived from bovine tracheal smooth muscle cells into planar lipid bilayers (PLB). It was found that in the absence of adenosine triphosphate (ATP), cGMP, and cGMP-dependent protein kinase, NO* donors such as 1-propanamine-3-(2-hydroxy-2-nitroso-1-propylhydrazine) (PAPA NONOate) or 3-morpholinosydnonimine hydrochloride (SIN-1) in the presence of superoxide dismutase (SOD), added on either side of the bilayer, caused a concentration- dependent increase in the open probability (Po) of KCa channels without altering their unitary conductance. Release of NO*, which was measured by chemiluminescence analysis in parallel experiments, affected the gating behavior of KCa channels in the presence of SOD and ethyleneglycol-bis-(beta-aminoethyl ether)- N,N'-tetraacetic acid (EGTA) by reducing the mean closed times and increasing the number and duration of short open events. PAPA NONOate, a true NO. donor, had similar effects in the presence of ethylenediaminetetraacetic acid (EDTA), a heavy-metal chelator, and K-urate, a peroxynitrite scavenger. Addition of either 5 mM dithiothreitol (DTT) or 5 mM reduced glutathione (GSH), as well as 5 mM N-ethylmaleimide (NEM)-an alkylating agent-to the trans (intracellular) side of an experimental chamber slightly increased channel Po but prevented further channel activation by NO* donors. However, neither DTT nor GSH was able to reverse the effect of NO*. In contrast to SIN-1, DTT had no effect when added to the cis (extracellular) side of the chamber. This suggests that the effect of NO* is most likely due to a chemical modification (nitrothiosylation) of intracellular sulfhydryl group(s). Neither PAPA NONOate (NO*), nor SIN-1 had any effect on sarcolemmal Cl- channels reconstituted from the same membrane preparations. Pharmacomechanical measurements made on epithelium-denuded rat bronchus showed that 100 nM charybdotoxin decreased the sensitivity of bronchial smooth muscle to SIN-1-induced relaxations. Altogether, our data suggest that NO-induced bronchorelaxation occurs partly via a direct activation of KCa channels, possibly through a covalent interaction with the cytoplasmic side of their alpha subunit.

L-NAME potentiates endothelin-stimulated thromboxane release from guinea pig lung.

The bronchoconstrictor response after systemic administration of endothelins (ETs) in the guinea pig is indirectly mediated by thromboxane A2 (TxA2) release through ETB receptor activation. ETs also trigger the release of nitric oxide (NO) in endothelial cells by activation of ETB receptors. A growing body of evidence indicates that endogenous NO plays a key role in the regulation of pulmonary function. In this study we investigated the effect of an NO synthase inhibitor, L-NAME, on the release of TxA2 from the isolated, perfused guinea pig lung induced either by ET-1, the selective ETB receptor agonist IRL-1620, bradykinin (BK), or a TxA2-mimetic, U 46619. A 30 min intra-arterial (intra-arterial) infusion of L-NAME (300 microM) potentiated the TxA2 release with ET-1, IRL 1620, and BK (5, 50, and 50 nM, respectively) infused for 3 min (i.a.). U 46619 (10 nM) was ineffective as a stimulant of pulmonary eicosanoid release. Interestingly, L-NAME did not potentiate the release of prostacyclin (PGI2) triggered by ET-1, IRL 1620, or BK. Our results suggest a predominant role of ETB receptor activation in the release of TxA2. Furthermore, we suggest that NO in the guinea pig lung is a potent modulator of the TxA2 releasing activity of ET-1, IRL 1620, and BK, three agonists known to stimulate the release of NO.

Effect of aging on cholecystokinin-induced panic.

OBJECTIVE: Epidemiologic surveys have found that the incidence and prevalence of panic disorder decline in later life. The goal of this study was to determine whether aging has an effect on healthy subjects' responses to the panicogenic agent cholecystokinin tetrapeptide (CCK-4). METHOD: The study used a double-blind, placebo-controlled design: 40 subjects 20-35 years old and 40 subjects 65 years old or older were randomly assigned to receive an intravenous bolus of either 50 micrograms of CCK-4 or normal saline. RESULTS: When given CCK-4, older subjects had significantly fewer and less intense symptoms of panic, shorter duration of symptoms, and less of an increase in heart rate than did younger subjects. CONCLUSIONS: This study found an age-related change in responsiveness to CCK-4. Further research to delineate the mechanism of this change is warranted.

Mouse aorta: a preparation highly sensitive to the vasodilatory action of CGRP.

Calcitonin gene-related peptide (CGRP), carbamylcholine, and vasoactive intestinal peptide (VIP) caused a concentration-related relaxation in mouse aorta precontracted to noradrenaline. Maximal relaxations obtained were 110, 44, and 46% with median effective concentrations (EC50) values of 7.8, 813.7, and 24.5 nM for CGRP, carbamylcholine, and VIP, respectively. The carbamylcholine- and VIP-induced relaxations were exclusively mediated by endothelial cell-derived factors, whereas CGRP maintained a full vasodilatory action in denuded aorta. However, its concentration-response curve was slightly shifted to the right in the absence of endothelium. The relaxation caused by CGRP was also slightly inhibited at 2 x 10(-8) M by removal of endothelium and in the presence of methylene blue, NG-nitro-L-arginine methylester (L-NAME), or glibenclamide but was not affected by atropine, propranolol, indomethacin, or tetrodotoxin. Moreover, the absence of Ca2+ in the bathing solution had no inhibitory effect on CGRP-induced relaxation in noradrenaline-precontracted aorta. It is concluded that the relaxation evoked by CGRP in the mouse aorta does not mainly depend on an endothelium-derived factor or on the activation of ATP-sensitive K+ (KATP) channels but rather is caused by a mechanism primarily associated with the inhibition of the mobilization of intracellular Ca2+.

Effect of neuropeptide Y on bradykinin-induced release of prostacyclin and thromboxane from guinea pig perfused lung.

We have previously reported that neuropeptide Y (NPY) inhibits responses induced by various agonists (noradrenaline, vasoactive intestinal peptide, substance P,5-hydroxytryptamine) in isolated guinea pig trachea. Although the underlying mechanisms have not been fully characterized, it was found that the NPY-evoked inhibition was specifically expressed with agents for which locally released prostaglandins (PGs) are important determinants for their myotropic activity. In the present study, we have extended these findings by examining whether NPY was capable of regulating the release of prostacyclin and thromboxane A2 induced by bradykinin (BK) from naive and ovalbumin-sensitized guinea pig perfused lungs. Our results showed that infusion of NPY (0.24 microM) through the lung significantly inhibited the release of 6-keto-PGF1 alpha (> 30%) and thromboxane B2 (50%) induced by intraarterial administration of BK (3 micrograms) from untreated and ovalbumin-sensitized guinea pig perfused lung. However, the inhibitory effect of NPY was lost in the immunological production of prostaglandins. These results suggest that NPY may act as a regulatory agent of the release of cyclooxygenase-derived products by possibly acting on events preceding phospholipase A2 activation.

Relationship between self-concept and classroom behavior among learning and nonlearning disabled students in regular classes.

To investigate the relationships of the self-concept with classroom behaviors, the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children and the Self-perception Profile for Learning Disabled Students were administered to 140 learning disabled and 246 nonlearning disabled pupils while teachers completed the Questionnaire on Approach/Avoidance Classroom Behavior toward schoolwork. Correlations showed a meaningful association between scores on the self-concept Behavioral Conduct subscale and rated classroom behavior for subjects of Grades 1 to 4. Also, while the relationship was meaningful for the high achievers, analysis showed few significant relationships for learning-disabled pupils.

Elevated plasma levels of neuropeptide Y in patients with panic disorder.

OBJECTIVE: Neuropeptide Y is a pancreatic polypeptide closely associated with noradrenergic activity both in the central and peripheral nervous systems. The objective of this study was to assess plasma neuropeptide Y-like immunoreactivity in panic disorder. METHOD: Radioimmunoassays were performed in 12 patients with DSM-III-R panic disorder and two groups of normal comparison subjects (N = 22 and N = 16). RESULTS: Markedly higher plasma neuropeptide Y-like immunoreactivity was found in patients with panic disorder. CONCLUSIONS: Higher plasma neuropeptide Y-like immunoreactivity suggests that this peptide may be implicated in the etiology or expression of symptoms of panic disorder.

Specific cyclic nucleotide phosphodiesterase inhibitors differently modulate contractile kinetics in airway smooth muscle.

The involvement of various phosphodiesterases (PDEs) in controlling the time-dependent mechanical properties of guinea pig trachealis smooth muscles was determined by using different classes of PDE inhibitors as pharmacological tools. These drugs produced low amplitude and long-lasting dose-dependent relaxations on the resting tone with the following EC50 values: rolipram, 3 nM; indolidan, 0.11 microM; and zaprinast, 0.5 nM and 1 microM. These PDE inhibitors were 50% less active than 1 microM norepinephrine. The effects of the drugs were also tested on carbachol-induced contractions and norepinephrine-evoked relaxations. Zaprinast, but not rolipram nor indolidan, decreased the rate of rise of contraction, thus prolonging the time to reach the plateau by 75% without modifying the magnitude of the responses. Zaprinast and rolipram significantly increased the total length of the norepinephrine effect by 25 and 35%, respectively. Similar results were obtained in a dose-dependent manner on isoproterenol-induced relaxations. In contrast, a higher concentration of indolidan was required to affect the amplitude, duration, and time to peak of isoproterenol- or norepinephrine-induced relaxations. These results indicate that PDE IV (rolipram sensitive) and PDE I, and less likely PDE V (both zaprinast sensitive), are involved in the control of guinea pig airway contractile kinetics, whereas PDE III (indolidan sensitive) is essentially involved in the modulation of the resting tone. Four cytosolic isozymes were identified in bovine airway smooth muscles (ASMs); PDE I (calmodulin-dependent PDE), PDE II (cGMP-stimulated PDE), PDE IV (cAMP-specific and rolipram-sensitive PDE), and PDE V (cGMP-specific and zaprinast-sensitive PDE). Characterization of PDE isoforms present in the microsomal fraction by HPLC showed the presence of PDE IV, PDE V, and to a lesser extent PDE III. However, PDE III was not detected in ASM cytosol. Using newly synthesized radioligands, binding studies confirmed the low level of expression of PDE III and the presence of PDE IV. We conclude that PDE I controls the rate of contraction, whereas PDE V and PDE IV prolong the time of relaxation induced by NE. PDE V would control the ASM responsiveness by regulating the intracellular cGMP concentration, which in turn would both activate PKG and stimulate PDE II (cGS-PDE). Since the various isozymes of PDE are differently involved in the kinetic control of the mechanical events in ASM, they represent physiologically relevant and important pharmacological targets.

Rat adrenomedullin induces a selective arterial vasodilation via CGRP1 receptors in the double-perfused mesenteric bed of the rat.

The present work was undertaken to study the effect of rat adrenomedullin (rADM (1-50) and its C-terminal fragment (11-50)) in the endothelium-intact arterial and venous vasculatures of the rat perfused mesenteric bed. rADM (1-50) and the fragment rADM (11-50)(1-1000 pmol) induced a dose-dependent and endothelium-independent vasodilation on the arterial mesenteric vasculature. However, both peptides were inactive on the venous side of this vascular bed. The CGRP1 receptor antagonist, hCGRP8-37 (1 microM), markedly reduced the vasodilation caused by rADM (1-50) in the arterial mesenteric vasculature. Thus, our results show that rADM (1-50) in the arterial mesenteric vasculature. Thus, our results show that rADM (1-50) and its C-terminal fragment rADM(11-50) share properties similar to those of hCGRP. The blocking effect of hCGRP8-37 supports a role for CGRP1 receptor activation by adrenomedullin in this vascular preparation.

Apparent affinity and potency of BIBP3226, a non-peptide neuropeptide Y receptor antagonist, on purported neuropeptide Y Y1, Y2 and Y3 receptors.

The newly developed, purported non-peptide neuropeptide Y Y1 receptor antagonist BIBP3226 was evaluated for its potential effect on the recently characterized Y3 receptor subtype and for its apparent affinity in rat and human brain membrane binding assays using highly selective neuropeptide Y Y1 and Y2 radioligands. BIBP3226 potently blocked (pA2 = 7.36) the contractile effect of neuropeptide Y in the rabbit saphenous vein, a Y1 receptor bioassay and demonstrated nM affinity for Y1/[125I][Leu31,Pro34]peptide YY binding sites. In contrast, it failed to antagonize the biological effects of neuropeptide Y in the rat vas deferens (Y2) and rat colon (Y3) and did not significantly competed for Y2/[125I]peptide YY-(3-36) binding sites in rat and human brain homogenates. Taken together, the results demonstrate further the high potency and selectivity of BIBP3226 for the neuropeptide Y Y1 receptor by establishing its lack of antagonist activity on the Y3 subtype.

Peptide YY derivatives as selective neuropeptide Y/peptide YY Y1 and Y2 agonists devoided of activity for the Y3 receptor sub-type.

Peptide YY derivatives were evaluated for their respective ability to bind and activate the NPY/PYY receptor sub-types (Y1, Y2 and Y3) present in various preparations. The analogue [Leu31,Pro34]PYY demonstrated high (nM) affinity in rat frontoparietal cortical membrane preparations (Y1-enriched tissue) and the rabbit saphenous vein (Y1 in vitro bioassay) but only low affinity in a Y2-enriched preparation (rat hippocampus). In contrast, PYY C-terminal fragments such as PYY3-36 and PYY13-36 were more potent in Y2 than Y1 assays. Interestingly, and in contrast to [Leu31,Pro34]NPY and NPY13-36, the PYY derivatives [Leu31,Pro34]PYY and PYY3-36 were inactive in a purported Y3 bioassay (rat colon). These results suggest that [Leu31,Pro34]PYY and PYY3-36 respectively represent the first selective and potent Y1 and Y2 agonists, devoided of significant affinity/activity for the Y3 receptor class.