The function of P2X3 receptor and NK1 receptor antagonists on cyclophosphamide-induced cystitis in rats.

PURPOSE: The purpose of the study is to explore the function of P2X3 and NK1 receptors antagonists on cyclophosphamide (CYP)-induced cystitis in rats. METHODS: Sixty female Sprague-Dawley (SD) rats were randomly divided into three groups. The rats in the control group were intraperitoneally (i.p.) injected with 0.9% saline (4 ml/kg); the rats in the model group were i.p. injected with CYP (150 mg/kg); and the rats in the intervention group were i.p. injected with CYP with subsequently perfusion of bladder with P2X3 and NK1 receptors' antagonists, Suramin and GR 82334. Spontaneous pain behaviors following the administration of CYP were observed. Urodynamic parameters, bladder pressure-volume curve, maximum voiding pressure (MVP), and maximum cystometric capacity (MCC), were recorded. Pathological changes in bladder tissue were observed. Immunofluorescence was used to detect the expression of P2X3 and NK1 receptors in bladder. RESULTS: Cyclophosphamide treatment increased the spontaneous pain behaviors scores. The incidence of bladder instability during urine storage period of model group was significantly higher than intervention group (χ(2) = 7.619, P = 0.007) and control group (χ(2) = 13.755, P = 0.000). MCC in the model group was lower than the control and intervention groups (P < 0.01). Histological changes evident in model and intervention groups rats' bladder included edema, vasodilation, and infiltration of inflammatory cells. In model group, the expression of P2X3 receptor increased in urothelium and suburothelium, and NK1 receptor increased in suburothelium, while the expression of them in intervention group was lower. CONCLUSIONS: In CYP-induced cystitis, the expression of P2X3 and NK1 receptors increased in urothelium and/or suburothelium. Perfusion of bladder with P2X3 and NK1 receptors antagonists ameliorated the bladder function.

Substance P and neurokinin 1 receptors as potential therapeutic targets in children with OSA.

BACKGROUND: Increased substance P (SP) levels and abundant expression of neurokinin (NK) 1 receptor in adenotonsillar tissues of children with OSA but not recurrent tonsillar infection (RI) suggest that NK1 antagonists could be useful in treating OSA. METHODS: The effects of SP and the NK1 antagonist GR-82334 were examined on mixed cell cultures prepared from dissociated tonsils harvested intraoperatively from children with OSA and RI. Proliferation was assessed by [3H]-thymidine or 5-ethynyl-2'-deoxyuridine incorporation, and inflammatory cytokine production (tumor necrosis factor [TNF]-α, IL-6, IL-1ß) was assessed in supernatants by enzyme-linked immunosorbent assay. RESULTS: SP elicited dose-dependent increases in tonsillar cell proliferation in mixed cell cultures from children with OSA but not with RI (P < .0001). The NK1 antagonist exhibited dose-dependent reductions in cellular proliferative rates in OSA-derived cell cultures but not in RI-derived mixed cell cultures (P < .00001). SP treatment was associated with increased TNF-α and IL-6 production, and GR-82334 abrogated SP effects, as well as reduced basal cytokine release (P < .0001). CONCLUSIONS: SP pathways appear to underlie intrinsic proliferative and inflammatory signaling pathways in tonsillar tissues from children with OSA but not with RI. Selective disruption of these pathways may provide nonsurgical alternatives for prevention and treatment of pediatric OSA.

Intra-articular administration of tachykinin NK1 receptor antagonists reduces hyperalgesia and cartilage destruction in the inflammatory joint in rats with adjuvant-induced arthritis.

Persistent pain associated with inflammatory arthritis is an aggravating factor that decreases patients' quality of life. Current therapies for joint pain have limited effectiveness and produce unwanted negative side effects. Although the involvement of substance P and its cognate tachykinin receptor, NK(1), in joint inflammation has been extensively documented through animal experiments, the development of oral tachykinin NK(1) receptor antagonists against arthritis-induced pain has been unsuccessful in humans to date. To explore the possibility of using tachykinin NK(1) receptor antagonists as local therapeutic agents for inflammatory arthritis, we examined the effects of tachykinin NK(1) receptor antagonists administered into the rat ankle joint on hyperalgesia in complete Freund's adjuvant (CFA)-induced inflammatory monoarthritis. Administration of the tachykinin NK(1) receptor antagonist WIN 51708 or GR 82334 into the affected ankle joint at day 3 following intra-articular CFA injection reduced the mechanical hyperalgesia 12 h after the tachykinin NK(1) receptor antagonist injection and their analgesic effects persisted for at least 2 days. Histological examinations revealed that intra-articular WIN 51708 reduced the CFA-induced destructive changes in the cartilage. These findings suggest that intra-articular injection of tachykinin NK(1) receptor antagonists is a promising strategy for relieving the hyperalgesia that occurs in inflammatory arthritis.

The modulatory effect of (+)-TAN-67 on the antinociceptive effects of the nociceptin/orphanin FQ in mice.

To clarify the pharmacological properties of (+)2-Methyl-4aalpha-(3-hydroxyphenyl)-1, 2, 3, 4, 4a, 5, 12, 12aalpha-octahydro-quinolino[2, 3, 3-g]isoquinoline ((+)-TAN-67), the effect of (+)-TAN-67 on the antinociception induced by the intrathecal (i.t.) administration of nociceptin/orphanin FQ was studied in mice using the tail-flick test and the formalin test. I.t. administration of (+)-TAN-67, at doses of 1 to 10 ng, facilitated the tail-flick response in a dose-dependent manner in mice. In addition, i.t. administration of (+)-TAN-67 (1 to 10 ng) in mice produced a marked pain-like aversive responses. I.t. pretreatment with D-Pro(9)-[spiro-gamma-lactam]-Leu(10)-Trp(11)-physalaemin(1-11) (GR82334, 0.1-1.0 nmol), a potent and selective tachykinin NK(1) receptor antagonist, dose-dependently blocked the reduction of the tail-flick response induced by (+)-TAN-67. Furthermore, (+)-TAN-67-induced facilitation of the tail-flick response was abolished in capsaicin-treated mice. On the other hand, (+)-TAN-67-induced flinching responses were dose-dependently and significantly reduced by i.t. pretreatment with GR82334 (0.1-1.0 nmol). The duration of i.t. (+)-TAN-67-induced flinching responses was significantly reduced in capsaicin-treated mice as compared with naive mice. I.t. administration of nociceptin/orphanin FQ (1-10 nmol) dose-dependently increased the tail-flick latency. I.t. administration of nociceptin/orphanin FQ (0.1-1.0 nmol) significantly and dose-dependently reduced the first-phase nociceptive response, but not the second-phase nociceptive response. I.t. pretreatment with (+)-TAN-67 (0.3-3.0 microg) for 30 min dose-dependently attenuated the antinociception induced by i.t. nociceptin (10 nmol) in the tail-flick test. Furthermore, the antinociceptive effect of nociceptin/orphanin FQ (1 nmol, i.t.) on the first-phase response in the formalin test was dose-dependently attenuated by s.c. pretreatment with (+)-TAN-67 (0.3-3.0 microg). (+)-TAN-67 (0.3-3.0 microg, i.t.), by itself, did not facilitate the tail-flick response or produce apparent behavioral changes. It is possible that (+)-TAN-67 has an antagonistic effect on nociceptin/orphanin FQ-induced antinociception.

In vitro growth inhibition of human small cell lung cancer by physalaemin.

Production and secretion of neuroendocrine peptides by small cell lung cancer (SCLC) has been detected in the past years. Most recently the role of bombesin as an autocrine/paracrine growth modifier has been demonstrated. We used the soft agarose clonogenic assay to evaluate the influence of other neuroendocrine peptides on the in vitro proliferation of SCLC cell lines. Neuroendocrine peptides tested were adrenocorticotropic hormone, arginine vasopressin, calcitonin, glucagon, kassinin, neurotensin, physalaemin, somatostatin, and substance P. Experiments were carried out in serum-free and serum-supplemented media with and without serum-free incubation periods. Our results indicated that the amphibian undecapeptide physalaemin inhibits the clonal and mass culture growth of SCLC cell lines at picomolar concentrations. All other neuroendocrine peptides failed to influence SCLC growth in the test systems used. These results suggest a growth regulating effect of physalaemin and a potential new form of neuroendocrine peptide therapy for SCLC.