Acquisition of flavour preferences in pigs through interactions with conspecifics that had previously consumed flavoured protein solutions.

It is known that pigs can acquire flavour preferences by brief social interactions with conspecifics that previously consumed a flavoured solid feed. However, there is no information about whether a flavoured solution could support flavour preferences through social transmission. Ninety-six pigs (49 days old) were housed in 12 pens (8 pigs/pen). Four animals per pen were randomly selected to act as observers and four as demonstrators. Demonstrator animals were temporarily moved to an empty pen where a protein solution was offered (porcine digestive peptides (PDPs), 4% weight/volume) with the addition of 0.075% aniseed (six pens) or garlic (six pens) powdered artificial flavours for 30 min. Afterwards, demonstrators were returned to interact with observer animals for 30 min. A choice test (30 min) between aniseed and garlic PDP was performed for each observer group after the interaction. Observers showed a higher intake of solutions previously consumed by their demonstrator conspecifics (648 v. 468 ml; SEM 61.36, P < 0.05). As with flavoured solid feeds, protein solutions containing artificial flavours can create preferences in pigs for those flavours through social transmission from conspecifics.

Changes in floral biology and inbreeding depression in native and invaded regions of Datura stramonium.

Plant populations invading new environments might compromise their fitness contribution to the next generation, because of the lack of native specialist pollinators and/or potential mates. Thus, changes in plant mating system and traits linked to it are expected in populations colonising new environments where selection would favour selfing and floral traits that maximise reproductive output. To test this, we studied native (Mexico) and non-native (Spain) populations of the obligate sexual reproducing annual weed Datura stramonium. Flower size, herkogamy, total number of seeds per plant, number of visits by and type of pollinators, and inbreeding depression were assessed in native and non-native populations. Finally, we measured phenotypic selection on corolla size and herkogamy in each population. Flower size and herkogamy showed wide and similar variation in both ranges. However, the largest average flower size was found in one non-native population whereas the highest average positive herkogamy was detected in one native population. On average, flowers in the native range received more visits by pollinators. Hawkmoths were the main visitors in the native populations while only bees were observed visiting flowers in Spain's populations. Only in the native range was inbreeding depression detected. Selection to reduce herkogamy was found only in one native population. Absence of both inbreeding depression and selection on floral traits suggest a change in mating system of D. stramonium in a new range where generalist pollinators may be promoting high reproductive success. Selection against deleterious alleles might explain the reduction of inbreeding depression, promoting the evolution of selfing.

The use of porcine digestible peptides and their continuity effect in nursery pigs.

A total of 552 entire male and female nursery pigs were selected to be used in 2 different experiments that aimed to study if milk ingredients can be replaced by highly preferred protein sources (Exp. 1) and if pre- and postnatal exposure of those protein ingredients through the maternal diet may increase pig performance (Exp. 2). In Exp. 1, 240 pigs were separated after weaning (28 d) into 2 groups depending on the presence of lactose in their diets. Pigs ( =120) fed diets with the precence of lactose (lactose +) were given prestarter (0-14 d) and starter (15-33 d) diets with 142 and 50 g/kg of sweet milk whey, respectively; the lactose-free group ( = 120) was offered an isoenergetic diet with 20 g/kg of porcine-digestible peptides (PDP; Palbio 62SP; Bioibérica S.A., Palafolls, Spain) and wheat replacing sweet milk whey. Choice and 1-feeder tests were performed in another group of animals ( = 72) to evaluate the preference and acceptance for both diets. Pigs preferred ( = 0.039) the lactose+ over the lactose-free diet after a 30-min choice test and consumed more ( = 0.001) lactose+ than lactose-free diet in a 1-feeder test. However, no difference ( > 0.467) in performance was observed between groups for the entire nursery period. In Exp. 2, 120 animals were obtained from sows that, during late gestation (14 d) and lactation (28 d), were fed diets containing 20 g/kg of PDP and another 120 animals were obtained from sows fed an isoenergetic diet without PDP inclusion. Placenta samples were collected at farrowing to assess the volatile compounds present in the placental fluid of sows. After weaning, all pigs received a feed containing 20 g/kg of PDP in the prestarter and starter diets. A principal components analysis of the total volatile compounds showed the exclusive presence of sulfur-containing compounds and a higher presence of terpene compounds in the placental fluid of PDP-supplemented sows. In addition, pigs coming from sows fed diets supplemented with PDP tended to show a higher ADFI ( = 0.07) and ADG ( = 0.06) than did pigs coming from control sows during the 15 to 33 d after-weaning period. These results suggest that dietary incorporation of sweet milk whey may be replaced by a specific protein source without affecting performance of pigs after weaning. However, more experiments are needed to elucidate the mechanism for the sow's diets' influence over pig's performance.

Dietary energy density affects the preference for protein or carbohydrate solutions and piglet performance after weaning.

Physiological state or dietary nutrient content can be determinants of the sensory perception with consequences for feed preferences. The aim of the present study was to assess whether the preference for protein or carbohydrate of piglets is affected by dietary energy density. In total, 240 weanling piglets (28 d old; initial BW 7.2 ± 1.1 kg) were allocated to 24 pens (10 pigs/pen) according to BW. Piglets were split up into 2 groups and had ad libitum access to a high energy (HE; 3.90 Mcal DE/kg; crude fat 129 g/kg) or a low energy (LE; 3.35 Mcal DE/kg; crude fat 60 g/kg) diet with similar CP content (190 g/kg). Piglet performance and preference for protein [porcine digestible peptides (PDP; Palbio 62SP, Bioibérica, Palafolls, Spain) 20 g/L] or carbohydrate (sucrose 20 g/L) solutions were measured on days 14 and 21 after weaning using a double-choice test (DCHT). The LE diet promoted a higher (P < 0.05) ADFI and ADG than the HE diet. Final BW on day 21 was higher (P < 0.001) for piglets fed the LE diet than piglets fed the HE diet (12.8 vs. 11.5 kg). Preference (P > 0.05) was not observed for protein or carbohydrate solutions on day 14 or 21 in piglets fed the LE diet. On the other hand, piglets fed the HE diet had higher (75% on day 14 and 65% on day 21; P < 0.01) preference for the sucrose solution. Dietary energy level and consequent nutrient imbalances, such as dietary protein-to-energy ratio, may affect feed preference for protein or carbohydrate solutions in piglets.

Flavor preferences conditioned by postingestive effect of sucrose and porcine digestive peptides in postweaning pigs.

Pigs can learn to prefer a flavor if it has been previously associated to positive consequences. The aim of this experiment was to study flavor preferences conditioned by the postingestive effect of nutrients in pigs. In total, 240 weanling piglets were allocated in 24 pens (10 piglets/pen) and distributed to 2 groups of animals (12 pens per group). Pigs in Group 1 (G1) were trained during 8 d with one flavor [positive conditioned stimulus (CS+)] into a protein solution [4% porcine digestible peptides (PDP)] on odd days and another flavor [negative conditioned stimulus (CS-)] into 100 mM of monosodium glutamate (MSG) solution on even days (5-L bottle for 24 h). In the second group of pigs [Group 2 (G2)], CS+ was mixed into a 4% sucrose solution in odd days and CS- into 1% sucrose + 0.08% saccharine on even days. Therefore, treatments were defined as CS+, the flavor associated with PDP or sucrose, on odd days, which were assumed to have a higher postingestive effect than MSG or saccharine + sucrose, the ingredients associated to CS-. Concentration of ingredients in the solutions were chosen to ensure that hedonic attraction for PDP and MSG solutions and for sucrose and saccharine + sucrose were similar (checked in previous double-choice studies). The amount of solution offered during training period was prepared to be totally consumed each day to equalize flavors intake. Flavors (0.0375% anise or garlic) were counterbalanced across replicates to act as CS+ or CS-. Double-choice test between flavors dissolved in water (CS+ and CS-) were performed by selecting 2 pigs/pen on days 1, 6, and 8 after the training period. Solution intake was measured after 30 min. Piglets showed higher intakes for CS+ than CS- in G2 [212 vs. 76 mL and 168 vs. 86 mL (P < 0.05) and 195 vs. 78 mL (P = 0.15)] on days 1, 6, and 8, respectively. Differences between CS+ and CS- consumption were observed in G1 on day 8 (231 vs. 130 mL; P < 0.05). In conclusion, weanling pigs can acquire flavor preferences through associative learning between a flavor and postingestive effects of some nutrients.

Increase nitric oxide synthase activity in parotid glands from rats with experimental periodontitis.

OBJECTIVE: In this study we investigated the activity of the nitric oxide synthase (NOS) in parotid glands from rats with experimental periodontitis and controls. METHODS: Periodontitis was produced by a ligature placed around the cervix of the two lower first molar. Experiments were carried out 22 days after the ligature. RESULTS: Ligation caused an increase in parotid NOS activity. The selective blocker of the inducible isoform of the enzyme partially inhibited its activity in parotid glands from rat with ligature. In controls, the activity was partially inhibited by the antagonists of the selective neural and endothelial isoforms. NOS activity in rats with ligature was cyclic adenosine monophosphate (cAMP)-dependent while in controls it was calcium-dependent. Prostaglandin E2 concentration was increased in parotid gland from rats with ligature. The inhibitor of prostaglandin production, FR 122047, diminished both, prostaglandin production and NOS activity. In rats with ligature unstimulated amylase released is increased. Both, prostaglandin and NOS were involved in the increment of amylase release. CONCLUSION: It can be concluded that in parotid glands from ligated rats, prostaglandin E2 production is increased and, through cAMP accumulation, activates the inducible NOS isoform. The increment of nitric oxide production participates in the increase in basal amylase release.

Differential cholinoceptor modulation of nitric oxide isoforms in experimentally-induced inflammation of dental pulp tissue.

AIM: The aim of the study was to investigate the role of muscarinic acetylcholine receptor (mAChR) activity in the regulation of endothelial (e), neuronal (n) and inducible (i) nitric oxide synthase (NOS) activity and expression in experimentally induced inflammation of rat dental pulp tissue. METHODOLOGY: Inflammation was induced by application of bacterial lipopolysaccharide (LPS) to the pulp. Extirpated pulp-tissue samples were incubated in saline solution until the various experiments were performed. Saline-treated pulp and healthy pulp tissues were used as controls. NOS activity was measured by the production of [U-(14)C]-citrulline from [U-(14)C]-arginine. Nitrite/nitrate assay was evaluated by the conversion of nitrate to nitrite in the presence of nicotinamide adenine dinucleotide phosphate. i-nos, e-nos and n-nos mRNA levels were measured using reverse-transcriptase polymerase chain reaction by co-amplification of target cDNA with a single set of primers. RESULTS: Application of LPS to the pulp increased NOS activity and nitrate production (P < 0.001), generated by iNOS over-activity and expression. Pilocarpine acting on mAChRs triggered a biphasic action on NOS activity and NO accumulation. At low concentrations, pilocarpine induced a negative effect associated with a decrease in i-nos mRNA level, whilst at high concentration, it produced a positive effect associated with increased e-nos and n-nos mRNA levels. In control pulp tissue, only the positive effect of pilocarpine was observed. CONCLUSIONS: Irreversible pulpitis changes mAChR conformation increasing its efficiency of coupling to transducing molecules that in turn induce activate iNOS. The capacity of pilocarpine to prevent NO accumulation and iNOS activity, by acting on mAChR mutation induced by pulpitis, might be useful therapeutically as a local treatment.

Autoantibodies to beta1-adrenoceptors in human chronic periodontitis induce overexpression of fibroblast CD40 and trigger prostaglandin E2 generation.

BACKGROUND AND OBJECTIVE: Autoimmune mechanisms may contribute to the pathogenesis of periodontal disease. Autoantibodies with the potential to bind and activate beta(1)-adrenoceptors (beta(1)-AR) of human gingival fibroblasts were studied to provide evidence of altered humoral immune response in chronic periodontal disease. MATERIAL AND METHODS: Flow cytometry and enzyme-linked immunosorbent assay using cell culture-adherent gingival fibroblasts and/or their purified membranes and/or a synthetic peptide corresponding to the second extracellular loop of human beta(1)-AR were used to detect serum antibodies. The effects of antibodies from chronic periodontal disease patients on PGE(2) generation and CD40 expression were also tested. RESULTS: Circulating immunoglobulin G (IgG) from chronic periodontal disease patients (but not from normal individuals) interacted with the fibroblast surface, activating beta(1)-AR. Atenolol or CGP 20712 (beta 1-AR antagonists) and beta(1) synthetic peptide inhibited the interaction of IgG with beta(1)-AR. Immunoglobulin G from chronic periodontal disease patients also displayed agonist-like activity associated with specific beta(1)-AR activation, increasing PGE(2) generation and CD40 overexpression. The corresponding affinity-purified anti-beta(1)-AR peptide IgG mimicked these effects. Both effects were prevented by inhibition of cyclo-oxygenase. CONCLUSION: This article supports the participation of humoral immune alterations in chronic periodontal disease resulting in postsynaptic functional deregulation. Overproduction of proinflammatory mediators (PGE(2) and CD40 expression) is induced as a consequence of antibody-beta(1)-AR interaction. The PGE(2)-CD40-IgG axis may play a part in the pathophysiological mechanisms underlying the inflammatory process in chronic periodontal disease.

Cholinoreceptor autoantibodies in Sjögren syndrome.

Previous studies have demonstrated that antibodies against cholinoreceptors of exocrine glands correlate with dry mouth in persons with primary Sjögren syndrome (pSS). The aim of the present investigation was to establish if serum IgG antibodies (pSS IgG) were able to interact with cholinoreceptors in rat submandibular gland-dependent stimulation of cyclooxygenase 2 (COX-2) mRNA expression and PGE(2) production. Our findings indicated that pSS IgG-stimulating M(3), M(4), and M(1) cholinoreceptors exerted an increase in COX-2 mRNA without affecting COX-1 mRNA expression and increased PGE(2) production. Inhibitors of phospholipase A(2), COX- s, L-type calcium channel currents, and Ca(2+)-ATPase from sarcoplasmic reticulum prevented the pSS IgG effect on PGE(2) production. An ionophore of calcium mimicked pSS IgG action, suggesting a crucial role of calcium homeostasis in the cholinoreceptor-stimulated increase in PGE(2) production. Moreover, the amounts of PGE(2) in saliva and in sera from persons with pSS were significantly higher than in pre- or post-menopausal women. These findings illustrate the importance of autoantibodies to cholinoreceptors in the generation of chronic inflammation of target tissues in SS.

Differential signalling pathways involved in cholinoceptor-dependent stimulation of nitric oxide isoforms in dental pulp.

AIM: To investigate the role of muscarinic acetylcholine receptor (mAChR) subtype activity in the regulation of endothelial- (e) and neuronal- (n) nitric oxide synthase (NOS) expression and activity. METHODOLOGY: Rat dental pulp tissue was used throughout the study. The e-nos and n-nos mRNA levels were specifically measured using reverse transcriptase polymerase chain reaction procedures that involve simultaneous co-amplification of both target cDNA and a reference template with a single set of primers. NOS activity was measured by the production of [U-(14)C]-citrulline from [U-(14)C]-arginine. RESULTS: Stimulation of M(1)/M(2) and M(3)/M(4) mAChRs with pilocarpine caused an increase in e-nos and n-nos mRNA levels and NOS activity in the dental pulp. The specific mAChR subtype antagonists, L-NMMA, l-NIO and N(2)-propyl-L-arginine but not aminoguanidine attenuated all these effects. Inhibitors of phospholipase C (PLC), protein kinase C (PKC) and calcium/calmodulin (CaM) prevented the pilocarpine-dependent increase in n-nos and e-nos mRNA levels and NOS activity. CONCLUSIONS: Activation of mAChR subtypes stimulated NOS activity by increasing the production of NO through e-nos and n-nos gene expression and NOS activity. The mechanism appears to occur secondarily to stimulation of CaM and PKC enzymatic activity.

Mechanisms involved in the regulation of mRNA for M2 muscarinic acetylcholine receptors and endothelial and neuronal NO synthases in rat atria.

BACKGROUND AND PURPOSE: Agonists of the M(2) muscarinic acetylcholine receptor (mAChR) increase mRNA for this receptor and mRNA for endothelial and neuronal isoforms of NO synthase (eNOS or nNOS). Here we examine the different signalling pathways involved in such events in rat cardiac atria. EXPERIMENTAL APPROACH: In isolated atria, the effects of carbachol on mRNA for M(2) receptors, eNOS and nNOS were measured along with changes in phosphoinositide (PI) turnover, translocation of protein kinase C (PKC), NOS activity and atrial contractility. KEY RESULTS: Carbachol increased mRNA for M(2) receptors, activation of PI turnover, translocation of PKC and NOS activity and decreased atrial contractility. Inhibitors of phospholipase C (PLC), calcium/calmodulin (CaM), NOS and PKC prevented the carbachol-dependent increase in mRNA for M(2) receptors. These inhibitors also attenuated the carbachol induced increase in nNOS- and eNOS-mRNA levels. Inhibition of nNOS shifted the dose response curve of carbachol on contractility to the right, whereas inhibition of eNOS shifted it to the left. CONCLUSIONS AND IMPLICATIONS: From our results, activation of M(2) receptors induced nNOS and eNOS expression and activation of NOS up-regulated M(2) receptor gene expression. The signalling pathways involved included stimulation of PI turnover via PLC activation, CaM and PKC. nNOS and eNOS mediated opposing effects on the negative inotropic effect in atria, induced by stimulation of M(2) receptors. These results may contribute to a better understanding of the effects and side effects of cholinomimetic treatment in patients with cardiac neuromyopathy.

Muscarinic cholinoceptor activation modulates DNA synthesis and CD40 expression in fibroblast cells.

1 The aim of the present work was to examine the role of muscarinic acetylcholine receptors (mAChR) on DNA synthesis and CD40 expression in human fibroblast cells. Neonatal human skin fibroblast cultures were stimulated with carbachol in presence or absence of specific antagonists and the following parameters were measured: identification of mAChR subtypes, DNA synthesis, inositol phosphates (InsP) production and CD40 expression. 2 Human fibroblasts express mAChR with Kd 0.47 +/- 0.11 nm and Bmax 236 +/- 22 fmol mg protein(-1). Carbachol stimulates DNA synthesis, InsP and the expression of CD40. All these effects were inhibited by atropine, mustard hydrochloride (4-DAMP) and pirenzepine but not by AF-DX 116 and tropicamide, indicating that M3 and M1 mAChR are implicated in carbachol action. The relative Ki of the antagonists obtained by competition binding assay was in parallel to the relative potency for blocking both carbachol-stimulated InsP accumulation and DNA synthesis. 3 The intracellular pathway leading to carbachol-induced biological effects involved phospholipase C and calcium/calmodulin, as U-73122 and trifluoroperazine blocked carbachol effects, respectively. Calphostin C, a protein kinase C inhibitor, had no effect, indicating that this enzyme does not participate in the system. 4 These results may contribute to a better understanding of the modulatory role of the parasympathetic muscarinic system on normal human fibroblast function.

Signaling pathways leading to prostaglandin E(2) production by rat cerebral frontal cortex.

In this paper, we have determined the effect of both muscarinic acetylcholine receptor (mAChR) and exogenous prostaglandin E(2) (PGE(2)) on PGE(2) production and cyclooxygenases (COX) mRNA gene expression on rat cerebral frontal cortex. Carbachol and PGE(2) increase endogenous PGE(2) production and the COX-1 mRNA levels by activation of PLA(2)s. The COX-1 and COX-2 activity participated in the production of PGE(2) triggered by exogenous PGE(2). While in carbachol-PGE(2) only COX-1 activity is affected. The specific inhibition of PGE(2) receptor was able to impair the increase of endogenous PGE(2) production triggered by both carbachol and exogenous PGE(2). These results suggest that carbachol-activation mAChR increased PGE(2) production that in turn interacting with its own receptor triggers an additional production of PGE(2). Both mechanisms appear to occur by using PLA(2) signaling system. This data should be able to contribute to understand the involvement of PGE(2) in normal brain function and its participation in neuroinflammatory processes.

Endogenous signalling system involved in parotid gland adenosine A(1) receptor-amylase release.

AIM: In this study, we have determined signalling pathways involved in adenosine A(1) receptor (A(1) receptor)-dependent stimulation of amylase release in rat parotid gland. METHODS: Amylase release, binding and cyclic adenosine monophosphate (cAMP) assays, inositol phosphates (IPs) production and nitric oxide synthase (NOS) activity in the presence of cyclopentyl-1,3-dipropylxanthine (CPA) alone or in the presence of different inhibitory drugs were performed. RESULTS: The binding parameters of specific A(1) antagonist [(3)H]-cyclopentyl 1,3-dipropilxanthine ([(3)H]-DPCPX) in parotid gland membranes show a population of high affinity sites with K(d) (nm) 0.53 +/- 0.06 and B(max) (fmol mg(-1) protein) 122.6 +/- 10.2. CPA stimulation of A(1) receptor exerts an increase in amylase release, IPs accumulation, cAMP production and NOS activity. All these A(1) agonist effects were blocked by the A(1) receptor antagonist DPCPX. Inhibitors of phospholipase C (PLC), calcium/calmodulin (CaM), protein kinase C (PKC), and adenylate cyclase, but not NOS, activities attenuated the CPA stimulatory effect on amylase release. The effect of CPA on amylase release significantly correlated with its action either on cAMP or on IPs accumulation. CONCLUSION: These results suggest that CPA activation of parotid gland A(1) receptor induces a stimulatory effect on amylase release associated with increased production of cAMP and IPs accumulation. The mechanism appears to occur secondarily to stimulation of phosphoinositide turnover via PLC activation. This, in turn, triggers cascade reactions involving CaM and PKC. The CPA stimulation of NOS does not appear to participate in amylase release.

Neuronal nitric oxide synthase activity in rat urinary bladder detrusor: participation in M3 and M4 muscarinic receptor function.

1. The aim of this paper was to determine the different signalling cascades involved in contraction of the rat urinary bladder detrusor muscle mediated via muscarinic acetylcholine receptors (muscarinic AChR). Contractile responses, phosphoinositides (IPs) accumulation, nitric oxide synthase (NOS) activity and cyclic GMP (cGMP) production were measured to determine the reactions associated with the effect of cholinergic agonist carbachol. The specific muscarinic AChR subtype antagonists and different inhibitors of the enzymatic pathways involved in muscarinic receptor-dependent activation of NOS and cGMP were tested. 2. Carbachol stimulation of M(3) and M(4) muscarinic AChR increased contractility, IPs accumulation, NOS activity and cGMP production. All of these effects were selectively blunted by 4-DAMP and tropicamide, M(3) and M(4) antagonists respectively. 3. The inhibitors of phospholipase C (PLC), calcium/calmodulin (CaM), neuronal NOS (nNOS) and soluble guanylate cyclase, but not of protein kinase C and endothelial NOS (eNOS), inhibited the carbachol action on detrusor contractility. These inhibitors also attenuated the muscarinic receptor-dependent increase in cGMP and activation of NOS. 4. In addition, sodium nitroprusside and 8-bromo-cGMP, induced negative relaxant effect. 5. The results obtained suggest that carbachol activation of M(3) and M(4) muscarinic AChRs, exerts a contractile effect on rat detrusor that is accompanied by an increased production of cGMP and nNOS activity. The mechanism appears to occur secondarily to stimulation of IPs turnover via PLC activation. This in turn, triggers cascade reactions involving CaM, leading to activation of nNOS and soluble guanylate cyclase. They, in turn, exert a modulator inhibitory cGMP-mediated mechanism limiting the effect of muscarinic AChR stimulation of the bladder.

Modulatory effect of the adrenergic system upon fibroblast proliferation: participation of beta 3-adrenoceptors.

1. The beta3-adrenoceptor agonist ZD 7114, like the non-selective beta-adrenoceptor agonist isoprenaline, but unlike the beta1-adrenoceptor agonist dobutamine and the beta2-adrenoceptor agonist salbutamol, produced an increment on mouse embryonic fibroblast proliferation. The half-maximal stimulation of cell growth occurred at substantially lower concentrations with the beta3-adrenoceptor agonist (EC50: 5.5 x 10(-8) m) than with isoprenaline (EC50: 1.25 x 10(-6) m). 2. The selective beta3-adrenoceptor antagonist SR 5923 OA prevented the beta3-stimulated fibroblast proliferation. Conversely, practolol and butoxamine did not prevent fibroblast growth. 3. Additionally, a decrease of cAMP was obtained in fibroblasts cells upon stimulation with isoprenaline and ZD 7114. 4. The expression of beta-adrenoreceptors on fibroblast cells was also studied by radioligand binding. The Ki values in the presence of beta1- and beta2-adrenoceptor antagonist was two-fold higher than the Ki values for beta3 adrenoceptor antagonist indicating the presence of A3-receptor subtype. 5. Inhibitors of different intracellular coupling pathways including phospholipase C (U 73122), protein kinase C (staurosporine), calcium/calmodulin (trifluoroperazine) and calcium channel (verapamil), prevented the stimulatory actions of the selective beta3-adrenoceptor agonist ZD 7114. 6. The presence of beta3-adrenoceptors on embryonic mouse fibroblast cells may play a role in the modulation of cell growth and biologic activity. The mechanism by which ZD 7114 triggers cell proliferation and function, involves the activation of phospholipase C, PKC, calcium/calmodulin and the influx of calcium.

Nitric oxide synthase/PGE(2) cross-talk in rat submandibular gland.

It is known that nitric oxide modulates the prostaglandin generation. However, little is known about the regulatory action of prostaglandin on nitric oxide production. There is a molecular cross-talk between nitric oxide and prostaglandin. Here, we examined biochemical signalling pathways coupled to the prostaglandin E(2) (PGE(2)) receptor related to nitric oxide synthase stimulation in rat submandibular gland. PGE(2) through the stimulation of its own receptor, triggered activation of phosphoinositide turnover (IPs), translocation of protein kinase C (PKC), stimulation of nitric oxide synthase activity (NOS) and increased production of cyclic GMP (cGMP). PGE(2) stimulation of NOS and cGMP production was blunted by agents interfering with calcium influx, calcium/calmodulin and phospholipase C (PLC) activities; while PKC inhibitor was able to stimulate PGE(2) effects. PGE(2) did not evoke amylase release, indicating that NOS/ cGMP pathway were not associated with this enzyme secretion. Our results suggest that this prostanoid could act as vasoactive chemical mediator through its ability to activate NOS-cGMP pathway via own gland membrane receptor.

Interaction of human chagasic IgG with human colon muscarinic acetylcholine receptor: molecular and functional evidence.

BACKGROUND AND AIMS: Gastrointestinal disorders is one of the clinical manifestations of chronic Chagas' disease. The pathogenesis seems to be associated with autonomic dysfunction. Here, we consider the muscarinic cholinoceptor mediated alteration in distal colon function in chagasic megacolon. PATIENTS: Patients were divided into four groups: group I, chronic chagasic patients with megacolon; group II, chronic chagasic patients without megacolon; group III, non-chagasic patients with megacolon; and group IV, normal healthy volunteers (control). METHODS: Binding assay and immunoblot of cholinoceptors from human and rat colon and enzyme immunoassay (ELISA) using a synthetic 24mer peptide corresponding to the second extracellular loop of human M2 muscarinic acetylcholine receptors (mAChR) were used to detect the presence of serum antibodies. The effect of antibodies on basal tone and 3',5'-cyclic monophosphate (cAMP) production of human and rat distal colon strips were also tested. RESULTS: Group I but not the other groups had circulating antibodies capable of interacting with human colon activating M2 mAChR, as they competed with binding of specific radioligand to mAChR and interacted with the second extracellular loop of human M2 mAChR. Moreover, affinity purified anti-M2 peptide IgG from group I, in common with monoclonal antihuman M2 mAChR, recognised bands with a molecular weight corresponding to colon mAChR. This antibody also displayed an agonist-like activity, increasing basal tone and decreasing cAMP accumulation. Both effects were blunted by AF-DX 116 and neutralised by the synthetic peptide. CONCLUSIONS: In chagasic patients with megacolon there are antibodies that can recognise and activate M2 mAChR. The implications of these autoantibodies in the pathogenesis of chagasic megacolon is discussed.

Different intracellular signals coupled to the antiproliferative action of aqueous crude extract from Larrea divaricata Cav. and nor-dihydroguaiaretic acid on a lymphoma cell line.

In this paper, we report the effect of standard NDGA, as compared to that of an aqueous extract of Larrea divaricata Cav., on BW 5147 lymphoma cell-line proliferation. To determine the mechanism of action, the effects of both on the level of intracellular cAMP, protein kinase C activity and calcium influx were studied. Moreover, the NDGA present in the aqueous extract of the plant was quantified. The aqueous extract and the standard NDGA showed antiproliferative action against these cells. While the antiproliferative activity of the aqueous extract was mediated by an increase in cAMP levels, and inhibition of PKC and calcium influx, the antiproliferative activity of NDGA was related only to the inhibition of PKC. Considering the amount of NDGA detected in the aqueous extract of the plant, at the concentrations analyzed in this case, antiproliferative activity of Larrea divaricata cannot be attributed to this compound, but could have an additive effect on the activity of other compounds.

Autoantibodies against neonatal heart M1 muscarinic acetylcholine receptor in children with congenital heart block.

Isolated congenital heart block may be associated with autoimmune disorder such as Sjögren Syndrome and systemic lupus erythematosus. In this work we demonstrate circulating autoantibodies against neonatal heart M1 muscarinic acetylcholine receptor (mAChR) in the sera of children with congenital heart block. This antibody were able to react with the second extracellular loop of the human M1 mAChR as demonstrated using a synthetic peptide in enzyme immune assay and binding assay. Affinity purified anti-peptide IgG as well as total IgG from children with congenital heart block, interfered with the specific radioligand occupancy from neonatal heart M1 mAChR, interacting irreversibly. The antipeptide antibodies also displayed an 'agonist-like' activity, i.e. decreased contractility, activated nitric oxide synthase activity and increased production of cyclic GMP. All of these effects were selectively blunted by pirenzepine and neutralized by the synthetic M1 peptide. Both binding and biological effects were obtained using neonatal rat heart instead adult heart and were independent of Ro/SS-A and La/SS-B antibodies and were also absent in the sera of normal children. A clinical relevance of these findings is demonstrated by a strong association between the existence of circulating M1 mAChR antipeptide antibodies and the presence of isolated congenital heart block, making these antibodies a proper marker of this disease.