Health technology assessment through the six sigma approach in abdominoplasty: Scalpel vs electrosurgery

Abdominoplasty is a surgical procedure conducted to reduce excess abdominal skin and fat and improve body contouring. Despite being commonly performed, it is associated with a risk of complications such as infection, seroma, haematoma and wound dehiscence. To reduce the incidence of complications, different methods are used to create the abdominal flap, i.e., incision with a scalpel or electrosurgery. In this study, health technology assessment (HTA) using the Six Sigma methodology was conducted to compare these incision techniques in patients undergoing abdominoplasty. Two consecutively enroled groups of patients (33 in the scalpel group and 35 in the electrosurgery group) who underwent surgery at a single institution, the University of Campania "Luigi Vanvitelli", were analysed using the drain output as the main outcome for comparison of the incision techniques. While no difference was found regarding haematoma or seroma formation (no cases in either group), the main results also indicate a greater drain output (p-value<0.001) and a greater incidence of dehiscence (p-value=0.056) in patients whose incisions were made through electrosurgery. The combination of HTA and the Six Sigma methodology was useful to prove the possible advantages of creating skin incisions with a scalpel in full abdominoplasty, particularly a significant reduction in the total drain output and a reduction in wound healing problems, namely, wound dehiscence, when compared with electrosurgery, despite considering two limited and heterogeneous groups.

Classifying the type of delivery from cardiotocographic signals: A machine learning approach

BACKGROUND AND OBJECTIVE

Cardiotocography (CTG) is the most employed methodology to monitor the foetus in the prenatal phase. Since the evaluation of CTG is often visual, and hence qualitative and too subjective, some automated methods have been introduced for its assessment.

METHODS

In this paper, a custom-made software is exploited to extract 17 features from the available CTG. A preliminary univariate statistical analysis is performed; then, five machine learning algorithms, exploiting ensemble learning, were implemented (J48, Random Forests (RF), Ada-boosting of decision tree (ADA-B), Gradient Boosting and Decorate) through Knime analytics platform to classify patients according to their delivery: vaginal or caesarean section. The dataset is composed by 370 signals collected between 2000 and 2009 in both public and private hospitals. The performance of the algorithms was evaluated using 10 folds cross validation with different evaluation metrics: accuracy, precision, sensitivity, specificity, area under the curve receiver operating characteristic (AUCROC).

RESULTS

While only two features were significantly different (gestation week and power expressed by the high frequency band of FHR power spectrum), from the statistical point of view, machine learning results were great. The RF obtained the best results: accuracy (91.1%), sensitivity (90.0%) and AUCROC (96.7%). The ADA-B achieved the highest precision (92.6%) and specificity (93.1%). As expected, the lowest scores were obtained by J48 that was the base classifier employed in all the others empowered implementations. Excluding the J48 results, the AUCROC of all the algorithms was greater than 94.9%.

CONCLUSION

In the light of the obtained results, that are greater than those ones found in the literature from comparable researches, it can be stated that the machine learning approach can actually help the physicians in their decision process when evaluating the foetal well-being.

Malignant tumours of the parotid gland: management of the neck (including the clinically negative neck) and a literature review

Major salivary gland malignancies are rare, constituting 1%-3% of head-neck tumours. The surgical management of the clinically negative neck (cN0) does not have a univocal consensus yet. We have carried out a retrospective study on 119 cases of malignant parotid tumours that were surgically treated between January 1999 and January 2014. Our aim was to analyse preoperative findings (cytotype, cTNM) and to correlate these with postoperative results (grading, histotype, occult neck metastasis) in patients with parotid tumours to obtain an appropriate indication for neck management. In cN0 patients with a T1, T2 low-grade cancer a wait-and-see approach is preferred. Instead, in cNO patients with high-grade or low-grade T3, T4 tumours an elective neck dissection (END) is always planned. Levels II, III and IV, at least, must be dissected. The decision to dissect level V or I depends on the location of the primary tumour. In the cN0 group 19 of 58 (32.7%) patients who underwent an END had occult metastases. In clinically positive neck (cN+) patients a Modified Radical Neck Dissection (MRND), at least, must be performed. The criteria to add adjuvant radiotherapy (PORT) include deep lobe parotid tumours, advanced lesions (T3-T4), microscopic (R2) or macroscopic (R1) residual disease after surgery, high grade tumours, perineural diffusion, lymph node metastasis, capsular rupture, and local recurrence after previous surgery. Kaplan-Meier analyses have shown a reduction in the overall survival (OS) from 100% to 91% and in disease-free survival (DFS) from 100% to 95.5% for the NO-PORT and PORT group, respectively. In our study, the cN0 pN+ patients had a higher degree of DFS compared to the cN+.

Foot and ankle measurements on cone beam weightbearing computed tomography

Over the last years, an increased number of studies have reported the use of cone beam weightbearing computed tomography (WBCT) in the assessment of foot and ankle pathology. This new technology has enabled to overcome the limits inherently related to two-dimensional radiographs (superimposition bias, operator-related bias, rotation bias) and to obtain images reproducing the bones and joints anatomy during physiological standing with a low radiation dose. We performed a review of the current literature to summarize the evidence about the use of 2D or 3D measurements on WBCT images in various foot and ankle conditions. Our aims were to describe measurements proposed so far and to report data on reliability and validity from primary authors.

Digital Innovation in Healthcare: A Device with A Method for Monitoring, Managing and Preventing the Risk of Chronic Polypathological Patients

New digital technologies can have a huge impact on the traditional healthcare sector, both from a clinical and economic perspective. Doctors and health specialists will increasingly need technology to improve the services they provide to their patients. Here a novel patented device for automatic processing of clinical data of chronic poly-pathological patients is presented. The invention consists of a reconfigurable equipment that allows the assessment of clinical risk severity indexes that can be customized for polypathological patients and which acts both as a decision support system for specialist doctors in the diagnosis and treatment phases, and as a monitoring system in the clinical environment.

Agreement between Opal and G-Walk Wearable Inertial Systems in Gait Analysis on Normal and Pathological Subjects

Despite the growing use of different wearable inertial systems, increasingly diffused in clinical practice, there is still a lack of knowledge about the agreement between systems based also on different sensor configuration. Aim of the study has been the investigation of the agreement between Opal and G-Walk wearable inertial systems in gait analysis on normal and post stroke subjects. Although both systems are able to describe significant gait differences in the two populations, study results suggest that gait analysis evaluations carried out by different inertial systems does not give completely overlapping estimation about the different parameters and that this must be taken in correct account especially comparing results of clinical trials obtained by different systems and sensor's placements.

Preliminary focus on the mechanical and antibacterial activity of a PMMA-based bone cement loaded with gold nanoparticles

In total knee arthroplasty (TKA) and total hip replacement (THR) the restoration of the normal joint function represents a fundamental feature. A prosthetic joint must be able to provide motions and to transmit functional loads.

As reported in the literature, the stress distribution may be altered in bones after the implantation of a total joint prosthesis. Some scientific works have also correlated uncemented TKA to a progressive decrease of bone density below the tibial component. Antibiotic-loaded bone cements are commonly employed in conjunction with systemic antibiotics to treat infections. Furthermore, nanoparticles with antimicrobial activity have been widely analysed. Accordingly, the current research was focused on a preliminary analysis of the mechanical and antibacterial activity of a PMMA-based bone cement loaded with gold nanoparticles. The obtained results demonstrated that nanocomposite cements with a specific concentration of gold nanoparticles improved the punching performance and antibacterial activity. However, critical aspects were found in the optimization of the nanocomposite bone cement.

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Evaluation of the in vitro effects of bacterial adhesion and proliferation on modified bone cement samples.

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Assessment of anti-bacterial and anti-biofilm activities of the nanocomposite bone cement.

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Analysis of the effect of the inclusion of gold nanoparticles on mechanical performances of a PMMA-based bone cement.

Software for computerised analysis of cardiotocographic traces

Despite the widespread use of cardiotocography in foetal monitoring, the evaluation of foetal status suffers from a considerable inter and intra-observer variability. In order to overcome the main limitations of visual cardiotocographic assessment, computerised methods to analyse cardiotocographic recordings have been recently developed. In this study, a new software for automated analysis of foetal heart rate is presented. It allows an automatic procedure for measuring the most relevant parameters derivable from cardiotocographic traces. Simulated and real cardiotocographic traces were analysed to test software reliability. In artificial traces, we simulated a set number of events (accelerations, decelerations and contractions) to be recognised. In the case of real signals, instead, results of the computerised analysis were compared with the visual assessment performed by 18 expert clinicians and three performance indexes were computed to gain information about performances of the proposed software. The software showed preliminary performance we judged satisfactory in that the results matched completely the requirements, as proved by tests on artificial signals in which all simulated events were detected from the software. Performance indexes computed in comparison with obstetricians' evaluations are, on the contrary, not so satisfactory; in fact they led to obtain the following values of the statistical parameters: sensitivity equal to 93%, positive predictive value equal to 82% and accuracy equal to 77%. Very probably this arises from the high variability of trace annotation carried out by clinicians.

Poly (ADP-ribose) polymerase 1 protein expression in normal and neoplastic prostatic tissue

A genetic background has been implicated in the development of prostate cancer. Protein microarrays have enabled the identification of proteins, some of which associated with apoptosis, that may play a role in the development of such a tumor. Inhibition of apoptosis is a co-factor that contributes to the onset and progression of prostate cancer, though the molecular mechanisms are not entirely understood. Poly (ADP-ribose) polymerase 1 (PARP-1) gene is required for translocation of the apoptosis-inducing factor (AIF) from the mitochondria to the nucleus. Hence, it is involved in programmed cell death. Different PARP-1 gene expression has been observed in various tumors such as glioblastoma, lung, ovarian, endometrial, and skin cancers. We evaluated the expression of PARP-1 protein in prostatic cancer and normal prostate tissues by immunohistochemistry in 40 men with prostate cancer and in 37 normal men. Positive nuclear PARP-1 staining was found in all samples (normal prostate and prostate cancer tissues). No cytoplasmic staining was observed in any sample. PARP-1-positive cells resulted significantly higher in patients with prostate carcinoma compared with controls (P<0.001). PARP-1 over-expression in prostate cancer tissue compared with normal prostate suggests a greater activity of PARP-1 in these tumors. These findings suggest that PARP-1 expression in prostate cancer is an attempt to trigger apoptosis in this type of tumor similarly to what reported in other cancers.

TLQP-21, a VGF-derived peptide, stimulates exocrine pancreatic secretion in the rat

The aims of this paper were to study: (1) the effects of TLQP-21 (non-acronic name), the C-terminal region of the VGF (non-acronic name), polypeptide (from residue 557 to 576 of VGF), on in vitro amylase release from rat isolated pancreatic lobules and acinar cells; (2) the mechanism through which TLQP-21 regulates exocrine pancreatic secretion, by using the muscarinic receptor antagonist atropine (10(-6)M) and the cyclo-oxygenase inhibitor, indomethacin (10(-6)M). On pancreatic lobules of rats, concentrations of TLQP-21 from 10(-7) to 10(-5)M significantly (p<0.05) induced a 2-3-fold increase of baseline pancreatic amylase release, measured at the end of 60 min incubation period. Co-incubation with atropine 10(-6)M did not antagonise the enzyme outflow induced by the peptide. On the contrary, co-incubation of TLQP-21 (10(-7) and 10(-6)M) with indomethacin, at concentration of 10(-6)M, which alone did not modify enzyme secretion, completely suppressed the increase of amylase evoked by TLQP-21 on pancreatic lobules. On rat pancreatic acinar cells, TLQP-21, at all the concentrations tested, was unable to affect exocrine pancreatic secretion, indicating an indirect mechanism of action on acinar cells. These results put in evidence, for the first time, that TLQP-21, a VGF-derived peptide, modulates exocrine pancreatic secretion in rats through a stimulatory mechanism involving prostaglandin release. In conclusion, TLQP-21 could be included among the neurohumoral signals regulating pancreatic exocrine secretion, and increases the knowledge concerning the systems controlling this function.

Cannabinoid agonist WIN55,212 in vitro inhibits interleukin-6 (IL-6) and monocyte chemo-attractant protein-1 (MCP-1) release by rat pancreatic acini and in vivo induces dual effects on the course of acute pancreatitis

BACKGROUND

Cannabinoids (CBs) evoke their effects by activating the cannabinoid receptor subtypes CB1-r and CB2-r and exert anti-inflammatory effects altering chemokine and cytokine expression. Various cytokines and chemokines are produced and released by rodent pancreatic acini in acute pancreatitis. Although CB1-r and CB2-r expressed in rat exocrine pancreatic acinar cells do not modulate digestive enzyme release, whether they modulate inflammatory mediators remains unclear. We investigated the CB-r system role on exocrine pancreas in unstimulated conditions and during acute pancreatitis.

METHODS

We evaluated in vitro and in vivo changes induced by WIN55,212 on the inflammatory variables amylasemia, pancreatic edema and morphology, and on acinar release and content of the cytokine interleukin-6 (IL-6) and chemokine monocyte chemo-attractant protein-1 (MCP-1) in untreated rats and rats with caerulein (CK)-induced pancreatitis.

KEY RESULTS

In the in vitro experiments, WIN55,212 (10(-6) mol L(-1)) inhibited IL-6 and MCP-1 release from acinar cells of unstimulated rats and after CK-induced pancreatitis. In vivo, when rats were pretreated with WIN55,212 (2 mg kg(-1), intraperitoneally) before experimentally-induced pancreatitis, serum amylase, pancreatic edema and IL-6 and MCP-1 acinar content diminished and pancreatic morphology improved. Conversely, when rats with experimentally-induced pancreatitis were post-treated with WIN55,212, pancreatitis worsened.

CONCLUSIONS & INFERENCES

These findings provide new evidence showing that the pancreatic CB1-r/CB2-r system modulates pro-inflammatory factor levels in rat exocrine pancreatic acinar cells. The dual, time-dependent WIN55,212-induced changes in the development and course of acute pancreatitis support the idea that the role of the endogenous CB receptor system differs according to the local inflammatory status.

In vitro and in vivo pharmacological role of TLQP-21, a VGF-derived peptide, in the regulation of rat gastric motor functions

BACKGROUND AND PURPOSE

Vgf gene expression has been detected in various endocrine and neuronal cells in the gastrointestinal tract. In this study we investigated the pharmacological activity of different VGF-derived peptides. Among these, TLQP-21, corresponding to the 556-576 fragment of the protein was the unique active peptide, and its pharmacological profile was further studied.

EXPERIMENTAL APPROACH

The effects of TLQP-21 were examined in vitro by smooth muscle contraction in isolated preparations from the rat gastrointestinal tract and, in vivo, by assessing gastric emptying in rats. Rat stomach tissues were also processed for immunohistochemical and biochemical characterization.

KEY RESULTS

In rat longitudinal forestomach strips, TLQP-21 (100 nmol x L(-1)-10 micromol x L(-1)) concentration-dependently induced muscle contraction (in female rats, EC(50) = 0.47 micromol.L(-1), E(max): 85.7 +/- 7.9 and in male rats, 0.87 micromol x L(-1), E(max): 33.4 +/- 5.3; n = 8), by release of prostaglandin (PG)E(2) and PGF(2a) from the mucosal layer. This effect was significantly antagonized by indomethacin and selective inhibitors of either cyclooxygenase-1 (S560) or cyclooxygenase-2 (NS398). Immunostaining and biochemical studies confirmed the presence of VGF in the gastric neuronal cells. TLQP-21, injected i.c.v. (2-32 nmol per rat), significantly decreased gastric emptying by about 40%. This effect was significantly (P < 0.05) blocked by i.c.v. injection of indomethacin, suggesting that, also in vivo, this peptide acts in the brain stimulating PG release.

CONCLUSIONS AND IMPLICATIONS

The present results demonstrate that this VGF-derived peptide plays a central and local role in the regulation of rat gastric motor functions.

Central and peripheral role of the nociceptin/orphaninFQ system on normal and disturbed colonic motor function and faecal pellet output in the rat

In this study, seeking further information on the role of the nociceptin/orphanin FQ (N/OFQ)-ergic system in normal and disturbed colonic motor function in rats, we compared the colonic effects of UFP-112, a novel highly potent agonist, with those of N/OFQ. When injected intracerebroventricularly (i.c.v.) and intraperitoneally (i.p.), UFP-112 and N/OFQ increased bead expulsion time in a statistically significant and dose-related manner and reduced the percentage of rats with castor oil-induced diarrhoea. UFP-112 showed greater efficacy, higher potency and longer-lasting inhibitory effects than N/OFQ, and pretreatment with UFP-101, a selective antagonist, blocked the N/OFQ analogue-induced responses in both tests. When injected i.c.v., UFP-112 and N/OFQ inhibited corticotrophin releasing factor- and restrain stress-stimulated faecal pellet excretion significantly and in a dose-related manner. Conversely, when injected peripherally both peptides significantly inhibited colonic propulsive motility but did so in a non-dose-related manner. In conclusion, these findings indicate that, in the rat, the central and peripheral N/OFQ systems have an inhibitory role in modulating distal colonic propulsive motility under physiological and pathological conditions. UFP-112 therefore promises to be a useful pharmacological tool for investigating the role of the N/OFQ system in motor functions in the distal colonic tract under physiological and pathological conditions.

The gastric effects of UFP-112, a new nociceptin/orphanin receptor agonist, in physiological and pathological conditions

Nociceptin/orphanin FQ (N/OFQ), the endogenous NOP receptor ligand, centrally modulates gastric motor and secretory functions and prevents ethanol-induced gastric lesions in rats. A recently synthesized N/OFQ analog, [(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-112), acts as a highly potent and selective peptide agonist for NOP receptors and produces longer-lasting in vitro and in vivo effects in mice than the natural ligand N/OFQ. In this study, we evaluated the effects of centrally (intracerebroventricularly/icv) and peripherally (intraperitoneally/ip) injected UFP-112 on gastric emptying and gastric acid secretion, and on the development of gastric mucosal lesions induced by 50% ethanol in the rat. When injected icv, it dose-dependently delayed gastric emptying of a phenol red meal (by up to 70%), decreased gastric secretion in water-loaded rats after 90 pylorus ligature, and reduced ethanol-induced gastric lesions (by up to 87%). In all three assays, UFP-112 was more effective than N/OFQ. The highly selective NOP receptor antagonist, UFP-101, decreased the efficacy of UFP-112, thus confirming that central NOP receptors mediate inhibitory control on these functional and pathological conditions in rats. Ip injected N/OFQ and UFP-112 induced non-dose-related gastric hypersecretory and antiulcer effects, which UFP-101 partially abolished. Ip N/OFQ appeared equiactive but about 30-100 times less potent than ip UFP-112 in stimulating gastric acid secretion and preventing lesion formation. When ip injected, both UFP-112 and N/OFQ left gastric emptying in rats unchanged, suggesting that peripheral NOP receptors have a role in mediating gastric hypersecretory and antiulcer effects but are not involved in regulating gastric motility. In addition, the inhibitory effects induced by this novel NOP receptor agonist lasted longer than those induced by N/OFQ. In conclusion, UFP-112 is a promising new pharmacological tool for studying the functional roles of the central and peripheral N/OFQ receptor system.

Nociceptin/orphanin FQ-induced delay in gastric emptying: role of central corticotropin-releasing factor and glucocorticoid receptors

When injected intracerebroventricularly (i.c.v.) in rats, nociceptin/orphanin FQ (N/OFQ) delays gastric emptying and increases plasma corticosterone levels. Our aim in this study was to investigate changes in gastric emptying of a phenol red meal, and the plasma corticosterone response to N/OFQ in adrenalectomized (ADX) rats, in ADX rats injected with corticosterone at 1, 24 and 72 h before the gastric emptying assay, and in intact rats i.c.v. pretreated with a glucocorticoid antagonist (RU486) and with a corticotropin-releasing factor receptor antagonist (alpha-helical CRF9-41). In adrenal intact rats, i.c.v. injection of N/OFQ (2.5 nmol rat-1) significantly delayed gastric emptying (by 70%) and increased plasma corticosterone concentrations. Conversely, in ADX rats, N/OFQ left gastric emptying unchanged. In ADX rats, corticosterone injected at 1, 24 and 72 h before the gastric emptying assay almost restored the N/OFQ-induced delay in gastric emptying. Finally, pretreatment with RU486- and alpha-helical CRF9-41 abolished the N/OFQ-induced inhibition of gastric emptying. These findings suggest that central N/OFQ inhibits gastric emptying through an integrated orphaninergic system-CRF interaction in which corticosterone plays a permissive role.

The effects of [Arg14, Lys15] nociceptin/orphanin FQ, a highly potent agonist of the NOP receptor, on in vitro and in vivo gastrointestinal functions

Nociceptin/orphanin FQ (N/OFQ) administered into the lateral left cerebral ventricle of rats has been reported to inhibit in vivo gut motor and secretory functions. Recently, a novel N/OFQ analog, [Arg14, Lys15] N/OFQ, was synthesized and demonstrated to behave as a highly potent agonist at the human recombinant N/OFQ peptide (NOP) receptors and to produce long-lasting effects in vivo in mice compared with the natural ligand N/OFQ. In the present study, the pharmacological profile of [Arg14, Lys15] N/OFQ was further evaluated and compared with that of N/OFQ in vitro on guinea pig exocrine pancreas and in vivo on gastric emptying, colonic propulsion and gastric acid secretion in rats. [Arg14, Lys15] N/OFQ and N/OFQ significantly decreased the KCl-evoked amylase secretion from isolated pancreatic lobules of the guinea pig. In in vivo experiments, [Arg14, Lys15] N/OFQ mimicked the effects of N/OFQ, inducing, after intracerebroventricular injection, a delay (up to 70%) in the gastric emptying of a phenol red meal, an increase (about 40 times) of the mean bead colonic expulsion time and a decrease (up to 90%) of gastric acid secretion in water loaded rats after 90 min pylorus ligature. In all these assays, [Arg14, Lys15] N/OFQ was more effective than N/OFQ, and its effective doses were at least 10-fold lower than N/OFQ effective doses. The highly selective NOP receptor antagonist, UFP-101, decreased the efficacy of [Arg14, Lys15] N/OFQ in in vitro and in vivo assays above reported. These findings: (a) show that pancreatic NOP receptors mediate an in vitro inhibitory effect on stimulated guinea pig amylase secretion; (b) confirm that the stimulation of central NOP receptors exerts an inhibitory control on gastric emptying, colonic motility and gastric secretion in rats and (c) put in evidence that [Arg14, Lys15] N/OFQ, being more potent and effective than the natural ligand N/OFQ, represents a new pharmacological tool for the study of the physiological and pharmacological roles mediated by the N/OFQ-NOP receptor system.

Stimulatory effect of PG-KII, an NK3 tachykinin receptor agonist, on isolated pancreatic acini: species-related differences

More information is needed on the physiological role of the tachykinins (TKs), especially neurokinin3-receptor (NK3) agonists, in the pancreas. In this paper we investigated and compared the effect of PG-KII (10(-9) to 10(-6) M), a natural NK3-receptor agonist, with that of the known secretagogues substance P (10(-9) to 10(-6)M), caerulein (10(-11) to 10(-8) M) and carbachol (10(-8) to 10(-5) M), on amylase secretion from dispersed pancreatic acini of the guinea pig and rat. PG-KII (10(-7) M) significantly increased basal amylase release from guinea pig pancreatic acini (from 5.4+/-0.9% to 11.3+/-0.5%, P < 0.05) but left basal release in the rat unchanged (6.5+/-0.5%). The stimulant effect of PG-KII on guinea pig acini was significantly reduced by the NK3-receptor antagonist, SR 142801 (5 x 10(-7) M), and left unchanged by the NK1-receptor antagonist, SR 140333 (5 x 10(-7) M). Conversely, substance P (10(-7) M) significantly stimulated amylase secretion from rat and guinea pig acini (12.6+/-0.6% and 12.1+/-0.7%, P < 0.05). This stimulated effect of substance P was antagonized by the NK1--receptor antagonist (5 x 10(-7) M), but not by the NK3-receptor antagonist (5 x 10(-7) M). The PG-KII- and substance P-evoked maximal responses were lower than those evoked by caerulein (10(-9) M) (guinea pig, 19.1+/-1.3%; rat, 1802+/-0.9%, P < 0.01) and carbachol (10(-5) M) (guinea pig, 23.3+/-1.2%; rat, 24.0+/-1.1%, P < 0.01). The inhibitors of phospholipase C U-73122 (10(-5) M), phospholipase A2 quinacrine (10(-5)M), and protein tyrosine kinase genistein (10(-4) M), partly but significantly inhibited PG-KII, as well as carbachol-stimulated amylase release. Coincubation of PG-KII 10(-7) M with submaximal doses of caerulein (10(-11) to 10(-10) M) and carbachol (10(-7) to 10(-6) M) had an additive effect on amylase release. Pre-incubation with PG-KII (10(-7) M) for 30 min significantly reduced the subsequent amylase response to PG-KII, whereas pre-incubation with caerulein 10(-10) M or carbachol 10(-6) M did not. These findings suggest that PG-KII directly contributes to pancreatic exocrine secretion by interacting with acinar NK3 receptors of the guinea pig but not of the rat. PG-KII signal transduction involves the intracellular phospholipase C, phospholipase A2 and protein tyrosine kinase pathways. The NK3 receptor system cooperates with the other known secretagogues in regulating guinea pig exocrine pancreatic secretion and undergoes rapid homologous desensitization.

In vitro and in vivo opioid activity of [DPro(6)]dermorphin, a new dermorphin analogue

To study the effects of inducing stereo-chemical modifications in the structure of dermorphin (DM) so as to improve its mu-opioid receptor affinity and its resistance to C-terminal enzymatic degradation, in the Institute of Molecular Genetics of Moscow, we synthesized a new DM analogue ([DPro(6)]DM) and analyzed the changes induced in the biological activities of DM by substituting the Pro(6) residue with DPro(6). We compared the activity of the new DM analogue and DM in in vitro assays and in in vivo tests of analgesia, thermoregulation, heart rate recordings, and gastrointestinal motility in rats. In the in vitro tests, guinea pig ileum (GPI) and mouse vas deferens (MVD), although the opioid activities of [DPro(6)]DM indicated that the peptide was always less potent than DM, its lower IC(50) ratios (mu/delta) showed that it had higher mu-opioid receptor selectivity. In the in vivo analgesic test, [DPro(6)]DM, when injected intraperitoneally (i.p.) (0.5-5 and 10mg/kg) in rats, had the same antinociceptive efficacy as DM and when injected intranasally (i.n.) (0.005 and 0.02 mg/kg) it induced a more stable and long-lasting analgesia than DM (the AUC was about 91% higher for [DPro(6)]DM than for DM). Moreover, these data confirm that the intranasal route is advantageous for peripheral drug administration. In the heart rate study, [DPro(6)]DM and DM (0.5mg/kg, i.p.), induced a similar, weak bradycardia. The only difference was that [DPro(6)]DM induced a longer-lasting effect than DM. Conversely, in body temperature regulation [DPro(6)]DM induced weaker inhibitory activity than DM (56% of the DM-induced response); it did so only in a cold environment and at the maximal used dose (0.5mg/kg, i.p.) without inducing vasomotor effects. In the gastrointestinal study, [DPro(6)]DM and DM (0.005, 0.05, and 0.5mg/kg, i.p.) significantly slowed upper gastrointestinal transit of a charcoal meal and inhibited colonic propulsion. Comparison of the ED(50) values of [DPro(6)]DM (0.03 mg/kg) and DM (0.009 mg/kg) showed that the DM analogue was about three times less potent than DM in slowing gastrointestinal and colonic transit. In conclusion, all these data overall suggest that structural maneuvering in the Pro(6)-residue of the DM molecule changes its affinity for mu-opioid receptor subtypes and confirms the usefulness of experimental studies involving structural modifications in obtaining new therapeutic agents.

Selective tachykinin NK3-receptor agonists stimulate in vitro exocrine pancreatic secretion in the guinea pig

The tachykinins, including substance P, neurokinin A and neurokinin B, are a mammalian peptide family that have documented motor, sensory and circulatory neurotransmitter functions in the gut. Little is known about their action on the exocrine pancreas. In this study we investigated the effects of PG-KII, a natural NK3-tachykinin receptor agonist, and senktide, a synthetic NK3-tachykinin receptor agonist, on amylase release from isolated pancreatic lobules of the guinea pig in comparison with the secretagogues carbachol, caerulein and substance P and the depolarizing agent KCl. When added to incubation flasks at various concentrations (from 10(-10) to 10(-6)M), PG-KII and senktide both caused a dose-dependent increase in amylase release from pancreatic lobules. PG-KII and senktide elicited a lower maximal response (7.5+/-0.8 and 8.1+/-0.6% of the total lobular amylase content) than carbachol (34.4+/-3.9%), caerulein (26.5+/-2.8%) and KCl (22.5+/-3.8%). Whereas atropine left PG-KII and senktide-stimulated secretion unaffected, the non peptide NK3 receptor antagonist SR 142801 significantly reduced the stimulant effect of PG-KII and senktide. PG-KII (10(-7)M) also slightly though significantly increased the response to lower concentrations of caerulein (10(-11) and 10(-10)M) and carbachol (10(-7) and 10(-6)M). These findings show that PG-KII and senktide are weak stimulants of exocrine pancreatic secretion that act directly on the acinar cells through NK3 receptors, without cholinergic involvement. We suggest also that the tachykininergic NK3 receptor system cooperates with the other known secretagogues in the control of pancreatic exocrine secretion.

HS-599: a novel long acting opioid analgesic does not induce place-preference in rats

1. When administered subcutaneously HS-599, a new didehydroderivative of buprenorphine (18,19-dehydrobuprenorphine), produced a long-lasting antinociceptive response in rats. Its potency exceeded twice that of buprenorphine. In the tail-flick test it acted as a full agonist but in the plantar test only as a partial agonist. Whereas the mu-opioid antagonists naloxone and naltrexone antagonized HS-599 antinociception the delta-opioid antagonist naltrindole and the kappa-opioid antagonist nor-binaltorphimine did not. 2. Unlike buprenorphine and morphine, HS-599 never induced conditioned place-preference in rats. 3. In radioligand binding assays, compared with buprenorphine HS-599 had 3 fold higher mu-opioid receptor affinity but lower delta- and kappa-opioid receptor affinity. 4. In isolated guinea-pig ileum preparations, HS-599 only partially inhibited the electrically-stimulated contraction, acting as a partial opioid agonist. When tested against the mu-opioid receptor agonist dermorphin, it behaved as a non-equilibrium antagonist. Conversely, in mouse vas deferens (rich in delta-opioid receptors) and rabbit vas deferens preparations (rich in kappa-opioid receptors) HS-599 acted as a pure equilibrium antagonist, shifting the log-concentration-response curves of the delta-opioid agonist deltorphin I and the kappa-opioid agonist U-69593 to the right. 5. In conclusion, HS-599 is a novel buprenorphine derivative with higher affinity, selectivity and potency than the parent compound, for mu-opioid receptors. It produces intense and long-lasting antinociception and does not induce place-preference in rats.

Effects of supraspinal administration of PG-SPI and PG-KII, two amphibian tachykinin peptides, on nociception in the rat

We investigated and compared the effects of two amphibian tachykinins, the NK1 receptor agonist PG-SPI and the NK3 receptor agonist PG-KII, and the mammalian tachykinins substance P, neurokinin A and neurokinin B on the reaction time to a painful radiant heat stimulus (tail-flick test in rats) after intracerebroventricular injection. PG-SPI (1, 10 and 20 microg) and PG-KII (1, 5 and 10 microg) significantly increased the reaction time. Substance P (10 microg) injected intracerebroventricularly induced antinociception, whereas neurokinin A and neurokinin B did not. Like analgesia evoked by exogenous substance P, PG-SPI-evoked analgesia was blocked by pretreatment with naloxone. Naloxone left PG-KII antinociception unchanged, but the NK3 receptor selective antagonist markedly reduced it. These findings suggest NK1 and NK3 tachykinin receptor system involvement in supraspinal analgesia in rats.

Central tachykinin NK3 receptors in the inhibitory action on the rat colonic propulsion of a new tachykinin, PG-KII

The inhibitory action of the natural selective tachykinin NK3 receptor agonist, PG-KII, (pGlu-Pro-Asn-Pro-Asp-Glu-Phe-Val-Gly-Leu-Met-NH2), on colonic propulsion was studied in rats after central administration. Intracerebroventricular injection of PG-KII (0.1, 1, 10 and 100 ng/rat) produced a dose-related inhibition of colonic propulsion, measured as the increase in the mean expulsion time of a 5-mm glass bead placed in the distal colon. At the same doses as PG-KII, the selective tachykinin NK3 receptor agonist, senktide, (succ-[Asp6-MePhe8] substance P-(6-11)), induced a similar dose-related inhibition. Conversely, substance P (0.1, 1 and 10 microg/rat), a tachykinin NK1-preferring receptor agonist, had weaker antipropulsive effects, neurokinin A (0.1, 1 and 10 microg/rat), a tachykinin NK2-preferring receptor agonist, at the highest dose used only slightly inhibited colonic propulsion and neurokinin B (0.1, 1 and 10 microg/rat), a tachykinin NK3-preferring receptor agonist, left propulsion unchanged. Pretreatment with the selective tachykinin NK3 receptor antagonist, 3-indolycarbonyl-Hyp-Phg-N(me)-Bzl, referred as to R820 (6.2 microg/rat), prevented PG-KII-induced colonic antipropulsion, whereas the tachykinin NK1 receptor antagonist, (S)-1-(2-[3-(3,4-dichlorophenyl)-1-(3-isopropoxyphenylacetyl)pi peridin-3-yl] ethyl)-4-phenyl-1-azoniabicyclo[2.2.2] octane chloride, referred to as SR 140,333 (1 microg/rat), and the tachykinin NK2 receptor antagonist, ([Tyr5,D-Trp6,8,9, Arg10] neurokinin A-(4-10)), referred to as Men 10,376 (5 microg/rat), left it unchanged. These findings show that of the tachykinins tested, PG-KII and senktide are the most potent central inhibitors of colonic propulsion in the rat, suggesting that the central tachykinin NK3 receptor system plays an inhibitory role in modulating colonic transit. As well as confirming the selectivity of PG-KII for tachykinin NK3 receptors, we show that PG-KII provides useful information about the physiological role of central tachykinin NK3 receptors and that glass bead expulsion test is a reliable non-invasive in vivo method for evaluating the tachykinin NK3 receptor selectivity of new synthetic or natural tachykinins.

Central effect of SNC 80, a selective and systemically active delta-opioid receptor agonist, on gastrointestinal propulsion in the mouse

We investigated the effects of SNC 80 ((+)-4-[alphaR)-alpha-((2S,5R)-4-ally1-2,5-dimethyl-1-pipera zinyl)-3-methoxybenzyl]-N,N-diethylbenzamide), a new highly selective, non-peptidic and systemically active delta-opioid receptor agonist, on gastrointestinal and colonic propulsion in mice. Intraperitoneally (i.p.) SNC 80 (1, 10 and 30 mg/kg) significantly decreased gastrointestinal propulsion measured as transit of an orally administered charcoal meal. Pretreatment with the delta-opioid receptor antagonist, naltrindole (1 mg/kg) subcutaneously (s.c.), with the non-selective opioid antagonist, naloxone (5 mg/kg, s.c.) or the mu1-opioid receptor antagonist, naloxonazine (10 mg/kg, i.p.), significantly decreased the antitransit effect of SNC 80 but pretreatment with the non-selective opioid antagonist, naloxone methiodide (5 mg/kg, s.c.), a quaternary salt of naloxone that does not cross the blood-brain barrier, did not. SNC 80 (1, 5 and 10 mg/kg, i.p.), produced dose-related inhibition of colonic propulsion measured as the increase in mean expulsion time of a 3 mm glass bead placed in the distal colon. Naloxone (5 mg/kg, s.c.) and naltrindole (1 mg/kg, s.c.), completely antagonized the colonic antipropulsive effect of SNC 80. In contrast, naloxone methiodide (5 mg/kg, s.c.), left the inhibitory effect of i.p. SNC 80 on colonic function unchanged. These results suggest that peripherally injected SNC 80 inhibits gastrointestinal transit and colonic propulsion. It does so mainly through a central mechanism. Although the gastrointestinal antitransit effect of SNC 80 is naltrindole- and naloxonazine-sensitive, we cannot exclude an opioid-independent mechanism. The colonic antipropulsive effect of SNC 80 confirms the inhibitory role of the central delta-opioid receptor system on colonic motility.

Central and peripheral antiulcer and antisecretory effects of Ala5NKA(4-10), a tachykinin NK2 receptor agonist, in rats

Analogs of NKA(4-10) which are selective tachykinin NK2 receptor agonists have been tested as anti-secretory and anti-ulcer agents in 2-h pylorus ligation in rats. Peripheral (500 micrograms/kg s.c.) or central (5 micrograms/rat i.c.v.) administration of Ala5NKA(4-10), but not NKA(4-10) or Ala5[beta Ala8]NKA(4-10), inhibited gastric ulcer and secretion. The same effective doses of Ala5NKA(4-10) did not influence gastric emptying. The anti-secretory and anti-ulcer effects of Ala5NKA(4-10) were antagonized by pretreatment with the tachykinin NK2 receptor antagonist MEN 10,627 at a dose (250 micrograms/kg s.c.) which did not affect gastric secretion and ulcers. These findings provide the first evidence that activation of central and peripheral tachykinin NK2 receptors affords protection against gastric ulcers induced by 2 h pylorus ligation in rats, by reducing gastric acid secretion.

Further evidence that the tachykinin PG-KII is a potent agonist at central NK-3, but not NK-1, receptors

Intracerebroventricular (i.c.v.) injection of tachykinins (TKs) inhibits ethanol intake and angiotensin II-induced water intake; the effects are apparently mediated by NK-3 and NK-1 receptors, respectively. The present study evaluated the effect of the TK PG-KII, a novel kassinin-like peptide isolated from the skin of the Australian frog Pseudophryne güntheri, in these in vivo tests for central activity. PG-KII, given by i.c.v. injection, potently inhibited alcohol intake in genetically selected alcohol-preferring rats, being about 3 times more potent than the selective NK-3 receptor agonist NH2-SENK. The dose of 100 ng/rat, that markedly inhibited ethanol intake, did not inhibit food intake and prandial drinking in food deprived rats, providing evidence that the effect of PG-KII on ethanol intake is behaviorally selective. The effect on ethanol intake was inhibited by i.c.v. injection of the NK-3 receptor antagonist R820, but was not modified by the NK-1 receptor antagonist SR 140333. PG-KII inhibited drinking induced by angiotensin II only at doses of 300 or 1000 ng/rat, being about 5 times less potent than the selective NK-1 receptor agonist [Sar9, Met(O2)11] substance P. These doses of PG-KII produced also marked increase in competing behaviors, such as grooming and locomotion. The dose of 1000 ng/rat evoked a general inhibition of the ingestive behavior, reducing also food intake. The i.c.v. injection of the NK-1 receptor antagonist SR 140,333 only slightly inhibited the effect of PG-KII on angiotensin II-induced drinking, while it markedly reduced that of [Sar9, Met(O2)11] substance P. These findings, in accordance with those of previous studies, indicate that PG-KII is endowed with marked activity at central NK-3 receptors, and low activity at NK-1 receptors.

In vitro and in vivo biological activities of PG-KII, a novel kassinin-like peptide from the skin of the Australian frog, Pseudophryne güntheri

We compared the in vitro and in vivo biological activities of PG-KII (pGlu-Pro-Asn-Pro-Asp-Glu-Phe-Val-Gly-Leu-Met-NH2), a new peptide belonging to the tachykinin family, related to kassinin, isolated and sequenced from extracts of the skin of the Australian myobatrachid frog Pseudophryne güntheri, with those of the well-known tachykinins [substance P (SP), neurokinin A (NKA), neurokinin B (NKB), and kassinin (KASS)] to study its pharmacological and receptor profile. PG-KII always proved inactive in the in vitro and in vivo (gastric emptying) NK2 bioassays. It resulted equipotent to SP and more potent than KASS, NKA, and NKB in all in vitro smooth muscle preparations preferentially activated by the NK1-selective agonists. On an in vivo NK3 receptor-mediated function, gastric acid secretion, PG KII had a potency similar to that of NKB. In contracting guinea pig ileum, which contains NK1, NK2, NK3, and also new tachykinin receptor subtypes, PG-KII was more potent than SP, NKB, and NKA. The cholinergic antagonist, atropine, significantly reduced the guinea pig contractile activity of both PG-KII and NKB but not that of SP or NKA. Pretreatment with the NK1 selective antagonist, CP 96,345, and with the NK2-selective antagonist, MEN 10,376, modified neither the in vivo nor the in vitro effects of PG-KII. These findings indicate that PG-KII is neither an NK1 nor an NK2 receptor agonist but has a spectrum of biological actions close to that of the NK3 receptor agonists. PG-KII elicits strong contractile activity in guinea pig ileum. Administered centrally in the rat it regulates inhibition of gastric acid secretion.

Effect of PG-SPI and PG-KII, two novel and natural tachykinins, on salivary secretion in the rat

In an in vivo study of salivation in rats, the scialogogic effects of two natural and amphibian tachykinins, PG-SPI and PG-KII, which activate distinct tachykinin receptors, were compared with those of the tachykinins substance P, neurokinin A and B, and kassinin. The rank order of potencies of these peptides injected intravenously on salivation was: PG-SPI = SP > or = PG-KII = KASS > NKA > > NKB. Atropine (1 mg/kg. i.v.) had no effect on PG-SPI-, SP-, and NKA-induced salivation, but reduced that stimulated by PG-KII and KASS. We conclude that PG-SPI and PG-KII increase salivary secretion through different mechanisms and that rat salivary glands contain PG-SPI-and PG-KII-sensitive receptors.

Interaction between the mu-agonist dermorphin and the delta-agonist [D-Ala2, Glu4]deltorphin in supraspinal antinociception and delta-opioid receptor binding

1. In rats, the interaction between the mu-opioid agonist dermorphin and the delta-opioid agonist [D-Ala2, Glu4]deltorphin was studied in binding experiments to delta-opioid receptors and in the antinociceptive test to radiant heat. 2. When injected i.c.v., doses of [D-Ala2, Glu4]deltorphin higher than 20 nmol produced antinociception in the rat tail-flick test to radiant heat. Lower doses were inactive. None of the doses tested elicited the maximum achievable response. This partial antinociception was accomplished with an in vivo occupancy of more than 97% of brain delta-opioid receptors and of 17% of mu-opioid receptors. Naloxone (0.1 mg kg-1, s.c.), and naloxonazine (10 mg kg-1, i.v., 24 h before), but not the selective delta-opioid antagonist naltrindole, antagonized the antinociception. 3. In vitro competitive inhibition studies in rat brain membranes showed that [D-Ala2, Glu4]deltorphin displaced [3H]-naltrindole from two delta-binding sites of high and low affinity. The addition of 100 microM Gpp[NH]p produced a three fold increase in the [D-Ala2, Glu4]deltorphin Ki value for both binding sites. The addition of 10 nM dermorphin increased the Ki value of the delta-agonist for the high affinity site five times. When Gpp[NH]p was added to the incubation medium together with 10 nM dermorphin, the high affinity Ki of the delta-agonist increased 15 times. 4. Co-administration into the rat brain ventricles of subanalgesic doses of dermorphin and [D-Ala2, Glu4]deltorphin resulted in synergistic antinociceptive responses. 5. Pretreatment with naloxone or with the non-equilibrium mu-antagonists naloxonazine and beta-funaltrexamine completely abolished the antinociceptive response of the mu-delta agonist combinations. 6. Pretreatment with the delta-opioid antagonists naltrindole and DALCE reduced the antinociceptive response of the dermorphin-[D-Ala2, Glu4]deltorphin combinations to a value near that observed after the mu-agonist alone. At the dosage used, naltrindole occupied more than 98% of brain delta-opioid receptors without affecting mu-opioid-receptors. 7. These data suggest that in the rat tail-flick test to radiant heat, mu- and delta-opioid agonists co-operate positively in evoking an antinociceptive response. Although interactions between different opioid pathways cannot be excluded, in vitro binding results indicate that this co-operative antinociception is probably mediated by co-activation of the delta-opioid receptors at the cellular level by the mu- and delta-agonist.

Parallel bioassay of PG-SPI, an amphibian acidic SP-like peptide, mammalian basic substance P, and neurokinins A and B on in vitro and in vivo test systems

In vitro and in vivo test systems were used to compare the biological activities of substance P and the neurokinins A and B with those of a newly isolated substance P-like acidic peptide, PG-SPI (pGlu-Pro-Asn-Pro-Asp-Glu-Phe-Phe-Gly-Leu-Met-NH2). On nearly all the isolated smooth muscle preparations tested, PG-SPI appeared only slightly more potent than SP, but on guinea pig trachea it was 50 times more potent. The in vitro spasmogenic effect of PG-SPI on guinea pig trachea was inhibited by the NK1 receptor antagonist, CP 96,345. In in vivo tests, intracerebroventricularly injected PG-SPI was about 20 times more potent than SP in inhibiting gastric acid secretion and emptying in rats. Tests with antagonists showed that CP 96,345 reduced PG-SPI-induced inhibition of gastric emptying and the NK2 receptor antagonist, MEN 10,376, sharply blocked PG-SPI-induced inhibition of gastric acid secretion. These findings fit poorly into the current classification of tachykinin receptors and suggest that the acidic substance P-like peptide is a valuable tool for studying the functional role of other tachykinin receptor subtypes.

Effect of selective mu 1, mu 2 and delta 2 opioid receptor agonists on gastric functions in the rat

Because the role of mu and delta opioid receptors in modulating gastric functions remains uncertain, we studied whether intracerebroventricular (i.c.v.) and subcutaneous (s.c.) injections of new opioid peptides with high selectivity for mu 1 (Lys7-dermorphin), mu 2 (Trp4-Asn7-dermorphin) and delta 2 (D-Ala2-deltorphin II) opioid receptors would modify gastric secretion (after 2 hr pylorus ligature) and transit (after a phenol red meal) in the rat. Neither i.c.v. nor s.c. injections of the delta 2 opioid agonist affected the gastric functions. In contrast, the mu opioid agonists decreased gastric acid secretion and emptying, i.c.v. injections inducing more potent inhibition than s.c. administration. The mu 1 selective opioid antagonist naloxonazine had no effect on the inhibition of the gastric secretory and motor response to these peptides but naloxone completely blocked their effects. Our findings suggest (1) that in rats, stimulation of central naloxonazine insensitive opioid receptors (mu 2 sites) inhibits gastric acid secretion and emptying; and (2) that delta opioid receptors take no part in mediating these functions.

Sauvagine-induced hypothermia: evidence for an interaction with the dopaminergic system

In rats kept at an ambient temperature of 22 degrees C, centrally and peripherally administered sauvagine induces a dose-dependent hypothermia. To clarify the regulatory mechanisms and to ascertain which neurotransmitter systems mediate sauvagine-induced hypothermia, we administered sauvagine intracerebroventricularly and subcutaneously in rats pretreated with antagonists of muscarinic receptors (atropine), opiate receptors (naloxone), alpha-adrenoceptors (phentolamine, yohimbine and prazosin), beta-adrenoceptors (propranolol) and dopamine receptors (haloperidol and spiperone). Systemic pretreatment of rats with atropine, naloxone, prazosin and propranolol left sauvagine-induced hypothermia unaltered. Pretreatment with phentolamine (4 mg/kg, s.c.), a non-selective alpha-adrenoceptor antagonist, and yohimbine (3 mg/kg, s.c.), a selective alpha 2-adrenoceptor antagonist, enhanced the hypothermic action of sauvagine. Pretreatment with haloperidol (2 mg/kg, s.c.), a non-selective dopamine receptor antagonist, and spiperone (80 micrograms/kg, s.c.), a selective dopamine D2 receptor antagonist, significantly reduced the temperature fall induced by centrally (4 micrograms/rat) and peripherally (20 micrograms/kg) administered sauvagine. Thus, sauvagine-induced hypothermia appears not to be mediated by interactions with cholinergic, endogenous opiate or noradrenergic systems, but rather D2 dopaminergic pathways alone are involved in the inhibitory effect of sauvagine on body temperature in the rat.

Spinal antinociceptive effects of [D-Ala2]deltorphin II, a novel and highly selective delta-opioid receptor agonist

Pharmacological assays in isolated tissues and binding tests have recently shown that two peptides, with the sequence Tyr-D-Ala-Phe-Asp-(or Glu)- Val-Val-Gly-NH2, isolated from skin extracts of Phyllomedusa bicolor and named [D-Ala2]deltorphin I and II, respectively, possess a higher affinity and selectivity for delta-opioid receptors than any other known natural compound. Since much evidence supports the role of spinal delta-opioid sites in producing antinociceptive effects, we investigated whether analgesia might be detected by direct spinal cord administration of [D-Ala2]deltorphin II (DADELT II) in the rat. The thermal antinociceptive effects of intrathecal DADELT II and dermorphin, a potent mu-selective agonist, were compared at different postinjection times by means of the tail-flick test. The DADELT II produced a dose-related inhibition of the tail-flick response, which lasted 10-60 min depending on the dose and appeared to be of shorter duration than the analgesia produced in rats after intrathecal injection of dermorphin (20-120 min). The analgesic effect of infused or injected DADELT II was completely abolished by naltrindole, the highly selective delta antagonist. These results confirm the involvement of delta receptors in spinal analgesic activity in the rat.

Antidiarrheal and colonic antipropulsive effects of spinal and supraspinal administration of the natural delta opioid receptor agonist, [D-Ala2]deltorphin II, in the rat

The ability of the natural selective delta opioid receptor agonist, [D-Ala2]deltorphin II (DADELT II), to inhibit the diarrhea induced by castor oil and colonic glass bead expulsion, was studied in rats after supraspinal and spinal administration. When injected intracerebroventricularly, DADELT II (0.2, 1, 10 micrograms/rat) inhibited diarrhea and colonic bead expulsion in a dose-related fashion but did not affect the rate of small intestine transit. Similar results were obtained when the same dose of DADELT II was administered spinally. The antidiarrheal and colonic antipropulsive effects of supraspinally and spinally DADELT II were partially or completely antagonized by subcutaneous pretreatment with 1 and 10 mg/kg, respectively, of naltrindole, a selective delta opioid receptor antagonist. These findings indicate that, in the rat, supraspinal and spinal delta opioid receptors play a role in modulating diarrhea and colonic propulsion and that DADELT II is a useful tool for investigating the role of the delta opioid system in gastrointestinal function.

Hypothermic effect of D-Ala-deltorphin II, a selective delta opioid receptor agonist

The natural heptapeptide D-Ala-deltorphin II, the most selective agonist for delta-receptors currently available, was used to study the role of brain delta opioid receptors in the control of body temperature. In rats placed in a cold ambient temperature (4 degrees C), intracerebroventricular injections of D-Ala-deltorphin II produced a significant hypothermia. In animals at an ambient temperature of 22 degrees C, only the highest dose employed induced a slight fall in body temperature. At a warm temperature (34 degrees C), D-Ala-deltorphin II induced no significant changes in body temperature. D-Ala-deltorphin II-induced hypothermia, unaffected by naloxone, was significantly reduced by the selective delta receptor antagonist naltrindole. These findings indicate that D-Ala-deltorphin II produces its hypothermic effects at a supraspinal delta receptor, and support the involvement of delta receptors in central control of body temperature.

Inhibitory role on gastric secretion of a central NK-3 tachykinin receptor agonist, senktide

When administered intracerebroventricularly, the highly selective NK-3 tachykinin receptor agonist senktide possesses a potent and dose-related inhibitory effect on gastric acid secretion. The central mechanism governing the antisecretory effect of senktide was examined in perfused-stomach rats by studying its influence on gastric acid secretion elicited by the secretagogues histamine, pentagastrin and bethanechol. Given intracerebroventricularly, senktide reduced the acid response to histamine, but not that to pentagastrin or bethanechol. Stimulation of NK-3 receptors in rat brain thus appears to inhibit gastric acid secretion through histaminergic pathways.

Sauvagine: inhibition of gastric acid secretion in rats

Sauvagine (SV) powerfully inhibits gastric acid secretion by both the central and peripheral mechanisms. We examined whether adrenergic mechanisms or prostaglandin pathways might mediate the inhibitory action of SV on acid production in pylorus-ligated rats. Adrenalectomy altered the extent of the SV suppressive effect, suggesting that adrenal-derived substances participate in the action of the peptide. Blockade of adrenergic receptors by propranolol did not modify the antisecretory effect of SV, while the alpha-adrenergic antagonist, phentolamine, and the dopaminergic antagonist, haloperidol, potentiated the gastric response to the peptide. The action of SV appeared to be independent of prostaglandin pathways. We conclude that the antiacid effect of SV may be mediated by the adrenal but probably not by adrenergic or prostaglandin mechanisms.

Tachykinins: effects on gastric secretion and emptying in rats

To test the effects on gastric acid secretion and gastric emptying of non-mammalian (eledoisin, physalaemin, kassinin), mammalian (substance P. neurokinin A, neurokinin B) and synthetic tachykinins (septide, senktide), intracerebroventricular injections of these peptides were given to conscious pylorus-ligated rats (gastric secretory study) or to animals fed with a phenol red meal (gastric emptying study). The tachykinins able to cause central inhibition of acid output were those active on NK2 and NK3 receptors (eledoisin, kassinin, neurokinin A, neurokinin B and senktide). Tachykinins active on NK1 receptors (substance P. physalaemin and septide) were devoid of this activity. The most potent inhibitor was the synthetic NK3 agonist, senktide. All tested natural tachykinins significantly inhibited gastric emptying, the most potent being those active on NK2 receptors. Septide, the synthetic NK1 agonist, had lowest effect and senktide, the synthetic NK3 agonist, was far less active than eledoisin, kassinin and neurokinin A. Thus, specific tachykinin receptors exist in the rat brain that mediate gastric functions: NK3 receptors participate in the control of gastric secretion, while NK2 receptors seem to be involved in the regulation of gastric emptying by activating inhibitory pathways.

Pituitary-adrenal and vagus modulation of sauvagine- and CRF-induced inhibition of gastric emptying in rats

Sauvagine and CRF significantly delayed gastric emptying in rats: sauvagine was 21 times more potent than CRF in inhibiting gastric emptying when injected subcutaneously and 59 times more potent when injected intracerebroventricularly. The inhibitory effect of intracerebroventricular and subcutaneous injections of sauvagine and CRF was always reversed by vagotomy. Hypophysectomy significantly reduced the inhibitory effect of subcutaneously injected sauvagine and CRF, but not that of intracerebroventricularly injected peptides. Adrenalectomy completely prevented the inhibition of gastric emptying only if it was performed 7 days before peptide administration, whereas the central and peripheral inhibitory effect of sauvagine and CRF was retained after acute (1 h) adrenalectomy. In animals adrenalectomized 7 days previously, chronic administration or a single dose of corticosterone at different intervals (1, 24 and 72 h) before the test caused the peptides to recover their inhibitory activity. These results demonstrate that the inhibitory action of sauvagine and CRF clearly depends on the integrity of the parasympathetic nervous system (vagus), and on corticosterone secretion by the adrenal gland.