Profiling of how nociceptor neurons detect danger - new and old foes.

The host evolves redundant mechanisms to preserve physiological processing and homeostasis. These functions range from sensing internal and external threats, creating a memory of the insult and generating reflexes, which aim to resolve inflammation. Impairment in such functioning leads to chronic inflammatory diseases. By interacting through a common language of ligands and receptors, the immune and sensory nervous systems work in concert to accomplish such protective functions. Whilst this bidirectional communication helps to protect from danger, it can contribute to disease pathophysiology. Thus, the somatosensory nervous system is anatomically positioned within primary and secondary lymphoid tissues and mucosa to modulate immunity directly. Upstream of this interplay, neurons detect danger, which prompts the release of neuropeptides initiating (i) defensive reflexes (ranging from withdrawal response to coughing) and (ii) chemotaxis, adhesion and local infiltration of immune cells. The resulting outcome of such neuro-immune interplay is still ill-defined, but consensual findings start to emerge and support neuropeptides not only as blockers of TH 1-mediated immunity but also as drivers of TH 2 immune responses. However, the modalities detected by nociceptors revealed broader than mechanical pressure and temperature sensing and include signals as various as cytokines and pathogens to immunoglobulins and even microRNAs. Along these lines, we aggregated various dorsal root ganglion sensory neuron expression profiling datasets supporting such wide-ranging sensing capabilities to help identifying new danger detection modalities of these cells. Thus, revealing unexpected aspects of nociceptor neuron biology might prompt the identification of novel drivers of immunity, means to resolve inflammation and strategies to safeguard homeostasis.

Impact of pioglitazone and bradykinin type 1 receptor antagonist on type 2 diabetes in high-fat diet-fed C57BL/6J mice.

AIM: Type 2 diabetes (T2D) is a major complication of obesity and a leading cause of morbidity and mortality. Antagonizing bradykinin type 1 receptor (B1R) improved body and tissue fat mass and reversed vascular and adipose tissue inflammation in a rat model of insulin resistance. This study aimed at evaluating further the role of B1R in a mouse model of T2D by comparing the antidiabetic and anti-inflammatory effects of the B1R antagonist SSR240612 (SSR) in adipose tissue with those of pioglitazone (TZD), an activator of peroxisome proliferator-activated receptor gamma. METHODS: C57BL/6J mice were fed with high-fat diet (HFD) or standard diet (control) for 20 weeks. Yet, during the last 4 weeks, HFD-fed mice were administered SSR and TZD (10 mg kg-1 d-1 each) as monotherapy or combined therapy subcutaneously. The impact of treatments was measured on metabolic hormones levels (ELISA), adipose tissue inflammatory status and the expression of candidate genes involved in T2D (quantitative real-time polymerase chain reaction and western blot). RESULTS: SSR240612 and TZD treatments improved hyperglycaemia, hyperinsulinaemia, insulin resistance, adipose tissue inflammation (expression of B1R, chemokine ligand 2, F4/80 and tumour necrosis factor) and modulated adipogenesis (peroxisome proliferator-activated receptor gamma, adipocytes' protein 2 and CD40 expressions) in HFD-fed mice. Yet, SSR was more effective than TZD to reduce visceral fat mass and resistin. TZD/SSR combined treatment had an additive effect to improve insulin sensitivity and glucose intolerance. CONCLUSION: Bradykinin type 1 receptor antagonism could represent a promising therapeutic tool in combination with TZD for the treatment of T2D, obesity and insulin resistance.

A primary role for kinin B1 receptor in inflammation, organ damage, and lethal thrombosis in a rat model of septic shock in diabetes.

Diabetes mellitus and septic shock increase the incidence of mortality by thrombosis. Although kinin B1 receptor (B1R) is involved in both pathologies, its role in platelet function and thrombosis remains unknown. This study investigates the expression, the inflammatory, and pro-thrombotic effects of B1R in a model of septic shock in diabetic rats. Sprague-Dawley rats were made diabetic with streptozotocin (STZ) (65 mg/kg, i.p.). Four days later, control and STZ-diabetic rats were injected with lipopolysaccharide (LPS) (2 mg/kg, i.p.) or the vehicle. B1R antagonist (SSR240612, 10 mg/kg by gavage) was given either acutely (12 and 24 h prior to endpoint analysis) or daily for up to 7 days. Moreover, a 7-day treatment was given either with cyclooxygenase (COX)-2 inhibitor (niflumic acid, 5 mg/kg, i.p.), non-selective COX-1 and COX-2 inhibitor (indomethacin, 10 mg/kg, i.p.), non-selective nitric oxide synthase (NOS) inhibitor (L-NAME, 50 mg/kg by gavage), iNOS inhibitor (1400W, 5 mg/kg, i.p.), or heparin (100 IU/kg, s.c.). The following endpoints were measured: edema and vascular permeability (Evans blue dye), B1R expression (qRT-PCR, western blot, flow cytometry), aggregation in platelet-rich plasma (optical aggregometry), and organ damage (histology). Rats treated with STZ, LPS, and STZ plus LPS showed significant increases in edema and vascular permeability (heart, kidney, lung, and liver) and increased expression of B1R in heart and kidney (mRNA) and platelets (protein). Lethal septic shock induced by LPS was enhanced in STZ-diabetic rats and was associated with lung and kidney damage, including platelet micro-aggregate formation. SSR240612 prevented all these abnormalities as well as STZ-induced hyperglycemia and LPS-induced hyperthermia. Similarly to SSR240612, blockade of iNOS and COX-2 improved survival. Data provide the first evidence that kinin B1R plays a primary role in lethal thrombosis in a rat model of septic shock in diabetes. Pharmacological rescue was made possible with B1R antagonism or by inhibition of iNOS and COX-2, which may act as downstream mechanisms.

Activation of Mas oncogene-related gene (Mrg) C receptors enhances morphine-induced analgesia through modulation of coupling of µ-opioid receptor to Gi-protein in rat spinal dorsal horn.

Mas oncogene-related gene (Mrg) G protein-coupled receptors are exclusively expressed in small-sized neurons in trigeminal and dorsal root ganglia (DRG) in mammals. The present study investigated the effect of MrgC receptor activation on morphine analgesic potency and addressed its possible mechanisms. Intrathecal (i.t.) administration of the specific MrgC receptor agonist bovine adrenal medulla 8-22 (BAM8-22, 3 nmol) increased morphine-induced analgesia and shifted the morphine dose-response curve to the left in rats. Acute morphine (5 µg) reduced the coupling of µ-opioid receptors (MORs) to Gi-, but not Gs-, protein in the spinal dorsal horn. The i.t. BAM8-22 (3 nmol) prevented this change of G-protein repertoire while the inactive MrgC receptor agonist BAM8-18 (3 nmol, i.t.) failed to do so. A double labeling study showed the co-localization of MrgC and MORs in DRG neurons. The i.t. BAM8-22 also increased the coupling of MORs to Gi-protein and recruited Gi-protein from cytoplasm to the cell membrane in the spinal dorsal horn. Application of BAM8-22 (10nM) in the cultured ganglion explants for 30 min increased Gi-protein mRNA, but not Gs-protein mRNA. The present study demonstrated that acute administration of morphine inhibited the repertoire of MOR/Gi-protein coupling in the spinal dorsal horn in vivo. The findings highlight a novel mechanism by which the activation of MrgC receptors can modulate the coupling of MORs with Gi-protein to enhance morphine-induced analgesia. Hence, adjunct treatment of MrgC agonist BAM8-22 may be of therapeutic value to relieve pain.

Antioxidant/oxidant status and cardiac function in bradykinin B(1)- and B(2)-receptor null mice.

Kinin-vasoactive peptides activate two G-protein-coupled receptors (R), B(1)R (inducible) and B(2)R (constitutive). Their complex role in cardiovascular diseases could be related to differential actions on oxidative stress. This study investigated impacts of B(1)R or B(2)R gene deletion in mice on the cardiac function and plasma antioxidant and oxidant status. Echocardiography-Doppler was performed in B(1)R (B(1)R(-/-)) and B(2)R (B(2)R(-/-)) deficient and wild type (WT) adult male mice. No functional alteration was observed in B(2)R(-/-) hearts. B(1)R(-/-) mice had significantly lowered fractional shortening and increased isovolumetric contraction time. The diastolic E and A waves velocity ratio was similar in all mice groups. Thus B(1)R(-/-) mice provide a model of moderate systolic dysfunction, whereas B(2)R(-/-) mice displayed a normal cardiac phenotype. Plasma antioxidant capacity (ORAC) was significantly decreased in both B(1)R(-/-) and B(2)R(-/-) mice whereas the vitamin C levels were decreased in B(2)R(-/-) mice only. Plasma ascorbyl free radical was significantly higher in B(1)R(-/-) compared to WT and B(2)R(-/-) mice. Therefore, the oxidative stress index, ascorbyl free radical to vitamin C ratio, was increased in both B(1)R(-/-) and B(2)R(-/-) mice. Hence, B(1)R and B(2)R deficiency are associated with increased oxidative stress, but there is a differential imbalance between free radical production and antioxidant defense. The interrelationship between the differential B(1)R and B(2)R roles in oxidative stress and cardiovascular diseases remain to be investigated.

Bradykinin B2 receptors increase hippocampal excitability and susceptibility to seizures in mice.

Bradykinin (BK) and its receptors (B1 and B2) may exert a role in the pathophysiology of certain CNS diseases, including epilepsy. In healthy tissues, B2 receptors are constitutively and widely expressed and B1 receptors are absent or expressed at very low levels, but both receptors, particularly B1, are up-regulated under many pathological conditions. Available data support the notion that up-regulation of B1 receptors in brain areas like the amygdala, hippocampus and entorhinal cortex favors the development and maintenance of an epileptic condition. The role of B2 receptors, instead, is still unclear. In this study, we used two different models to investigate the susceptibility to seizures of B1 knockout (KO) and B2 KO mice. We found that B1 KO are more susceptible to seizures compared with wild-type (WT) mice, and that this may depend on B2 receptors, in that (i) B2 receptors are overexpressed in limbic areas of B1 KO mice, including the hippocampus and the piriform cortex; (ii) hippocampal slices prepared from B1 KO mice are more excitable than those prepared from WT controls, and this phenomenon is B2 receptor-dependent, being abolished by B2 antagonists; (iii) kainate seizure severity is attenuated by pretreatment with a non-peptide B2 antagonist in WT and (more effectively) in B1 KO mice. These data highlight the possibility that B2 receptors may have a role in the responsiveness to epileptogenic insults and/or in the early period of epileptogenesis, that is, in the onset of the molecular and cellular events that lead to the transformation of a normal brain into an epileptic one.

Sorption of arsenite, arsenate, and thioarsenates to iron oxides and iron sulfides: a kinetic and spectroscopic investigation.

Sorption to iron (Fe) minerals determines the fate of the toxic metalloid arsenic (As) in many subsurface environments. Recently, thiolated As species have been shown to dominate aqueous As speciation under a range of environmentally relevant conditions, thus highlighting the need for a quantitative understanding of their sorption behavior. We conducted batch experiments to measure the time-dependent sorption of two S-substituted arsenate species, mono- and tetrathioarsenate, and compared it to the sorption of arsenite and arsenate, in suspensions containing 2-line ferrihydrite, goethite, mackinawite, or pyrite. All four As species strongly sorbed to ferrihydrite. For the other sorbents, binding of the thiolated As species was generally lower compared to arsenate and arsenite, with the exception of the near instantaneous and complete sorption of monothioarsenate to pyrite. Analysis of the X-ray absorption spectroscopy (XAS) spectra of sorbed complexes implied that monothioarsenate binds to Fe oxides as a monodentate, inner-sphere complex. In the presence of Fe sulfides, mono- and tetrathioarsenate were both unstable and partially reduced to arsenite. Adsorption of the thiolated As species to the Fe sulfide minerals also caused the substitution of surface sulfur (S) atoms by As and the formation of As-Fe bonds.

Brain kinin B1 receptor contributes to the onset of stereotypic nocifensive behavior in rat.

While brain kinin B(1) receptor (B(1)R) is virtually absent in control rats, it contributes to hypertension via a midbrain dopaminergic (DA) mechanism in spontaneously hypertensive rat (SHR) and Angiotensin II (Ang II)-induced hypertension. This study aims at determining whether B(1)R can also affect stereotypic nocifensive behavior through DA and/or other neuromediators in the same models. The selective B(1)R agonist Sar[D-Phe(8)][des-Arg(9)]BK was injected i.c.v. (1 µg/site) to freely behaving SHR (16 weeks), Ang II-hypertensive rats (200 ng/kg/min × 2 weeks, s.c.) and control Wistar-Kyoto rats (WKY). Behavioral activity to the agonist was measured before and after treatment with receptor antagonists (10 µg/site i.c.v. or otherwise stated) for B(1) (SSR240612), tachykinin NK(1) (RP67580), glutamate NMDA (DL-AP5), DA D(1) (SCH23390, 0.2mg/kg s.c.) and D(2) (Raclopride, 0.16 mg/kg s.c.). Other studies included inhibitors (10 µg/site) of NOS (l-NNA) and iNOS (1400W). The possible desensitisation of B(1)R upon repeated intracerebral stimulation was also excluded. B(1)R expression was measured by qRT-PCR in selected areas and by immunohistochemistry in the ventral tegmental area. Results showed that the B(1)R agonist had no effect in WKY, yet it induced nocifensive behavioral manifestations in both models of hypertension (face washing, sniffing, head scratching, rearing, teeth chattering, grooming, digging, licking, wet-dog shakes). These responses were prevented by all antagonists and inhibitors tested, but 1400 W had a less inhibitory effect on most behaviors. Compared with WKY, B(1)R mRNA levels were markedly enhanced in hypothalamus, ventral tegmental area and nucleus accumbens of SHR and Ang II-treated rats. B(1)R was detected on DA neuron of the ventral tegmental area in SHR. Data suggest that kinin B(1)R is upregulated in midbrain DA system in hypertensive rats and its i.c.v. activation induced stereotypic nocifensive behavior that is mediated by several mediators, notably substance P, glutamate, DA and NO.

Blockade of kinin B(1) receptor reverses plasma fatty acids composition changes and body and tissue fat gain in a rat model of insulin resistance.

AIM: Kinin B(1) receptor (B(1) R) contributes to insulin resistance through a mechanism involving oxidative stress. This study examined the effect of B(1) R blockade on the changes in plasma fatty acids composition, body and tissue fat mass and adipose tissue inflammation that influence insulin resistance. METHODS: Sprague-Dawley rats were fed with 10% D-glucose or tap water (Control) for 13 weeks and during the last week, rats were administered the B(1) R antagonist SSR240612 (10 mg/kg/day, gavage) or vehicle. The following parameters were assessed: plasma fatty acids (by gas chromatography), body composition (by EchoMRI), metabolic hormone levels (by radioimmunoassay), expression of B(1) R and inflammatory markers in adipose tissue (by Western blot and qRT-PCR). RESULTS: Glucose feeding significantly increased plasma levels of glucose, insulin, leptin, palmitoleic acid (16:1n-7), oleic acid (18:1n-9), Δ6 and Δ9 desaturases while linoleic acid (18:2n-6), arachidonic acid (20:4n-6) and Δ5 desaturase were decreased. SSR240612 reduced plasma levels of insulin, glucose, the homeostasis model assessment index of insulin resistance, palmitoleic acid and n-7 family. Alterations of Δ5, Δ6 and Δ9 desaturases were normalized by SSR240612. The B(1) R antagonist also reversed the enhancing effect of glucose feeding on whole body and epididymal fat mass and on the expression of macrophage CD68, interleukin-1ß, tumour necrosis factor-α and inducible nitric oxide synthase in retroperitoneal adipose tissue. B(1) R protein and mRNA were not detected in retroperitoneal adipose tissue. CONCLUSION: Insulin resistance in glucose-fed rats is associated with low state inflammation in adipose tissue and plasma fatty acids changes which are reversed by B(1) R blockade. These beneficial effects may contribute to insulin sensitivity improvement and the prevention of obesity.

Perceived psychosocial benefits associated with perceived restorative potential of wilderness river-rafting trips.

Analysis of the restorative experiences and psychosocial benefits of wilderness river rafting trips of varying difficulty with 186 Canadian participants of different ages supported the restorative potential of natural settings for all age groups as measured by the Perceived Restorativeness Scale. The two-factor structure (General Restorativeness and Coherence) was confirmed. Significant associations were found between scores on the General Restorative subscale and perceived psychosocial benefits (relaxation, nature appreciation or kinship, and physical fitness or achievement) and positive affect. However, the findings associated with the Coherence subscale were not conclusive.

Contribution of the central dopaminergic system in the anti-hypertensive effect of kinin B1 receptor antagonists in two rat models of hypertension.

Kinins are neuroactive peptides that could play a role in central autonomic control of blood pressure. Whereas kinin B1R binding sites were increased in specific brain areas of spontaneously hypertensive rats (SHR) and Angiotensin II (AngII)-hypertensive rats, the contribution of kinin B1R in hypertension remains controversial. The aims of the study were to determine: (a) the effects on mean arterial blood pressure (MAP) of centrally and peripherally administered B1R antagonists in SHR (16weeks) and AngII-hypertensive rats (200ng/kg/minx2weeks, s.c.); (b) the contribution of central dopamine in the effects of SSR240612. The rationale is based on the overactivity of the dopaminergic system in hypertension. In both models, SSR240612 (1, 5 and 10mg/kg, gavage) reduced dose-dependently MAP (-75mm Hg at least up to 6-8h) and this therapeutic effect was resolved after 24h. At the dose of 5mg/kg, SSR240612-induced anti-hypertension was prevented by two dopamine receptor blockers, namely raclopride (0.16mg/kg, i.v.) and haloperidol (10mg/kg, s.c.). I.c.v. SSR240612 (1mug) decreased rapidly MAP in both models (1-6h) via a raclopride sensitive mechanism. In comparison, peripherally acting B1R antagonists (R-715 and R-954, 2mg/kg, s.c.) caused shorter and very modest decreases of MAP (from -20 to -30mm Hg). Centrally or peripherally administered B1R antagonists had no effect on MAP in control Wistar-Kyoto rats. Data provide the first pharmacological evidence that the up-regulated brain kinin B1R contributes through a central dopaminergic mechanism (DA-D2R) to the maintenance of arterial hypertension in genetic and experimental animal models of hypertension.

Calcium and vitamin D use among adults in periodontal disease maintenance programmes.

OBJECTIVES: To determine the level of calcium and vitamin D oral supplementation in patients in periodontal disease maintenance programmes. DESIGN: Convenience survey. SETTING: St. Louis Metropolitan region. SUBJECTS AND METHODS: Patients (n = 228) in two university-based, periodontal disease maintenance programmes. MAIN OUTCOME MEASURES: Reported amounts of oral calcium and vitamin D supplementation were tested for differences based on gender and race. RESULTS: The last published recommended daily intakes from the United States (US) Food and Nutrition Board (FNB) for adults >50 years of age are 1,200 mg calcium and 400 IU vitamin D (or 600 IU if over 70). The mean age of the 228 patients (125 females and 103 males) was 63.6 +/- 11.0 years (standard deviation). Of the 228 patients surveyed: (1) 204 (89%) were >50 years of age and of these, only 15 (7%) met the US FNB's recommended intakes of calcium and vitamin D from supplementation; (2) 138 (66%) reported that they took no oral supplementation, with significantly more males (n = 82) than females (n = 56) not taking supplementation (p = 0.03); (3) 88 (39%) took calcium supplementation, with females (947 +/- 511 mg/day) taking significantly (p <0.001) more than males (632 +/- 907 mg/day); and (4) 66 (29%) took vitamin D supplementation, with females(420 +/- 227 IU/day) taking approximately the same amount as males (443 +/- 317 IU/day, p >0.05). The amounts of oral supplementation did not vary with race (p >0.05). CONCLUSION: The use of calcium and vitamin D supplementation has been promoted for years, yet the numbers of adults taking supplements remains low and the level of supplementation varies greatly. Knowledge of the benefits of supplementation needs to be better disseminated and research needs to be conducted to determine optimal levels of calcium and vitamin D supplementation.

Retinal plasma extravasation in streptozotocin-diabetic rats mediated by kinin B(1) and B(2) receptors.

BACKGROUND AND PURPOSE: We investigated whether or not kinin receptors play a role in diabetic blood-retinal barrier breakdown, which is a leading cause of vision loss. EXPERIMENTAL APPROACH: Blood-retinal barrier breakdown was quantified using Evans blue, and expression of kinin B(1) receptor mRNA was measured using quantitative reverse transcrition-PCR. Diabetic rats (streptozotocin (STZ), 65 mg kg(-1)) received a single intraocular injection of bradykinin (BK) or des-Arg(9)-BK, alone, or in combination with antagonists for B(1) (des-Arg(10)-Hoe140, R-715) and/or B(2) (Hoe140) receptors, given intraocularly or intravenously (i.v.). KEY RESULTS: In control rats, BK (0.1-10 nmol) dose-dependently increased plasma extravasation, which was inhibited by Hoe140 (0.2 nmol), whereas des-Arg(9)-BK (0.1 and 1 nmol) was without effect. B(1) receptor mRNA was markedly increased in retinas of diabetic rats, and this was prevented by N-acetyl-L-cysteine (1 g kg(-1) day(-1) for 7 days). Plasma extravasation in retinas of STZ-diabetic rats was higher than in controls and enhanced by des-Arg(9)-BK. Response to des-Arg(9)-BK was inhibited by intraocular or i.v. injection of B(1) receptor antagonists. Diabetes-induced plasma extravasation was inhibited only by a combination of des-Arg(10)-Hoe140 and Hoe 140 (100 nmol kg(-1), i.v. 15 min earlier) or by R-715 (1 micromol kg(-1), i.v.) injected daily for 7 days. CONCLUSIONS AND IMPLICATIONS: Kinin B(1) receptors are upregulated in retinas of STZ-diabetic rats through a mechanism involving oxidative stress. Both kinin B(1) and B(2) receptors contribute to increased plasma extravasation in diabetic retinopathy. Chronic inhibition of both kinin receptors, possibly with antioxidant adjuvants, may be a novel therapeutic strategy for diabetic retinopathy.

Role of kinin B1 and B2 receptors in a rat model of neuropathic pain.

Kinin B1 and B2 receptor (R) gene expression (mRNA) is increased in the sensory system after peripheral nerve injury. This study measured the densities of B1R and B2R binding sites in the spinal cord and dorsal root ganglia (DRG) by quantitative autoradiography, and evaluated the effects of two selective non-peptide antagonists at B1R (LF22-0542) and B2R (LF16-0687) on pain behavior after partial ligation of the left sciatic nerve. Increases of B1R binding sites were seen in superficial laminae of the ipsi- and contralateral spinal cord at 2 and 14 days while B2R binding sites were increased on the ipsilateral side at 2 days and on both sides at 14 days. In DRG, B1R and B2R binding sites were significantly increased at 2 days (ipsilateral) and 14 days on both sides. Whereas tactile allodynia started to develop progressively from 2 to 25 days post-ligation, the occurrence of cold allodynia and thermal hyperalgesia became significant from day 8 and day 14 post-ligation, respectively. At day 21 after sciatic nerve ligation, thermal hyperalgesia was blocked by LF22-0542 (10 mg/kg, s.c.) and LF16-0687 (3 mg/kg, s.c.), yet both antagonists had no effect on tactile and cold allodynia. Data highlight the implication of both kinin receptors in thermal hyperalgesia but not in tactile and cold allodynia associated with peripheral nerve injury. Hence LF22-0542 and LF16-0687 present therapeutic potential for the treatment of some aspects of neuropathic pain.

Hemodynamic and renal involvement of B1 and B2 kinin receptors during the acute phase of endotoxin shock in mice.

B1 kinin receptor (B1R) is up-regulated by endotoxins and thus may represent a therapeutic target in sepsis. We investigated the expression and role of B1R and B2R in the acute phase of lipopolysaccharide (LPS)-induced endotoxin shock in C57BL/6 mice (WT) and B1R and B2R knock out mice (B1KO, B2KO). B1R mRNA was enhanced from 6 to 48 h after LPS while B2R mRNA was further increased in B1KO. Maximal hypotension was found 24 h after LPS, and was more pronounced in B1KO, but was reduced in B2KO. Glomerular filtration rate was more reduced by LPS in B1KO than in WT and B2KO. Glycemia was reduced by LPS and particularly in B1KO and B2KO mice. Mortality was increased by LPS in B1KO. These data suggest that the up-regulated B1R plays, at least transiently, a significant beneficial role in acute LPS-induced hypotension. Conversely, supra activation of B2R could be also involved in the increased mortality observed in B1KO mice.

Involvement of kinin B1 receptor and oxidative stress in sensory abnormalities and arterial hypertension in an experimental rat model of insulin resistance.

Diabetes Mellitus leads to pain neuropathy and cardiovascular complications which remain resistant to current therapies involving the control of glycaemia. This study aims at defining the contribution of kinin B(1) receptor (B(1)R) and the oxidative stress on sensory abnormalities and arterial hypertension in a rat model of insulin resistance. Rats were fed with 10% d-glucose for a chronic period of 12-14 weeks and the impact of a diet supplemented with alpha-lipoic acid, a potent antioxidant, was determined on tactile and cold allodynia, arterial hypertension and the expression of kinin B(1)R (real-time PCR and autoradiography) in several tissues. Acute effects of brain penetrant (LF22-0542) and peripherally acting (R-715) B(1)R antagonists were also assessed. Glucose-fed rats exhibited tactile and cold allodynia along with increases in systolic blood pressure between 4 and 12 weeks; these alterations were alleviated by alpha-lipoic acid. The latter regimen also decreased significantly increased plasma levels of insulin and glucose and insulin resistance (HOMA index) at 14 weeks. B(1)R mRNA was virtually absent in liver, aorta, lung, kidney and spinal cord isolated from control rats, yet B(1)R mRNA was markedly increased in all tissues in glucose-fed rats. Up-regulated B(1)R mRNA and B(1)R binding sites (spinal cord) were significantly reduced by alpha-lipoic acid in glucose-fed rats. LF22-0542 reduced tactile and cold allodynia (3h) and reversed arterial hypertension (3-48h) in glucose-fed rats. R-715 abolished tactile and cold allodynia but had not effect on blood pressure. Data suggest that the oxidative stress contributes to the induction and up-regulation of B(1)R in the model of insulin resistance induced by glucose feeding. The over expressed B(1)R contributes centrally to arterial hypertension and in the periphery to sensory abnormalities.

The kinin B1 receptor antagonist SSR240612 reverses tactile and cold allodynia in an experimental rat model of insulin resistance.

BACKGROUND AND PURPOSE: Diabetes causes sensory polyneuropathy with associated pain in the form of tactile allodynia and thermal hyperalgesia which are often intractable and resistant to current therapy. This study tested the beneficial effects of the non-peptide and orally active kinin B(1) receptor antagonist SSR240612 against tactile and cold allodynia in a rat model of insulin resistance. EXPERIMENTAL APPROACH: Rats were fed with 10% D-glucose for 12 weeks and effects of orally administered SSR240612 (0.3-30 mg kg(-1)) were determined on the development of tactile and cold allodynia. Possible interference of SSR240612 with vascular oxidative stress and pancreatic function was also addressed. KEY RESULTS: Glucose-fed rats exhibited tactile and cold allodynia, increases in systolic blood pressure and higher plasma levels of insulin and glucose, at 12 weeks. SSR240612 blocked tactile and cold allodynia at 3 h (ID(50)=5.5 and 7.1 mg kg(-1), respectively) in glucose-fed rats but had no effect in control rats. The antagonist (10 mg kg(-1)) had no effect on plasma glucose and insulin, insulin resistance (HOMA index) and aortic superoxide anion production in glucose-fed rats. CONCLUSIONS AND IMPLICATIONS: We provide the first evidence that the B(1) receptors are involved in allodynia in an experimental rat model of insulin resistance. Allodynia was alleviated by SSR240612 most likely through a direct inhibition of B(1) receptors affecting spinal cord and/or sensory nerve excitation. Thus, orally active non-peptide B(1) receptor antagonists should have clinical therapeutic potential in the treatment of sensory polyneuropathy.

Role of capsaicin-sensitive sensory nerves in mediation of the cardiovascular effects of the essential oil of croton zehntneri leaves in anaesthetized rats.

The essential oil of Croton zehntneri Pax et Hoffm. (EOCZ) contains anethole (42%) and estragole (46%), two isomers that share some chemical structural similarities with capsaicin. The present study investigated the cardiovascular effects of EOCZ and the role of capsaicin-sensitive sensory nerve fibres in the mediation of these effects in anaesthetized rats. 2. Intravenous bolus injection of EOCZ (1-20 mg/kg) elicited dose-dependent hypotension and bradycardia that were immediate and transient. Similar responses were also observed with anethole and estragole (both at 10 mg/kg). After cervical bivagotomy or perineural treatment of both cervical vagus nerves with capsaicin (250 mg/mL) to selectively block the conduction of sensory C-fibres, both cardiovascular responses to EOCZ (10 mg/kg) were abolished. 3. Like capsaicin, an epigastric retrograde intra-arterial injection of EOCZ (10 mg/kg, i.a.) into the femoral artery elicited a monophasic hypotensive response. This reflex response was blocked by either neonatal pretreatment with capsaicin (50 mg/kg, s.c.) or intrathecal injection of the substance P receptor antagonist RP 67580 (7.8 nmol, at the spinal level L5-L6), suggesting that it is mediated exclusively by substance P-containing primary afferent fibres. 4. The cardiovascular responses to EOCZ (10 mg/kg, i.v.) were also significantly reduced by the selective vallinoid TPRV1 receptor antagonist capsazepine (1 mg/kg, i.v.). 5. It is concluded that i.v. administration of EOCZ in anaesthetized rats elicits a capsaicin-like bradycardic and depressor reflex, which appears to be mediated by the activation of vallinoid TPRV1 receptors located on vagal sensory nerves. Like capsaicin, i.a. injection of EOCZ induces a spinally mediated sensory reflex.

A precise receptor-positioning device for subtraction radiography, based on cross-arch stabilization.

OBJECTIVES: To devise and test for reproducibility a new patient-beam alignment device for subtraction radiography. METHODS: A rigid, cross-arch bar was used with bite-registration material. A modified Rinn XCP rod and ring were firmly attached to the bar and were placed in contact with the X-ray cone. The receptor was held by a slot in the bar. Duplicate sets (n=8 pairs) of digital radiographs were made with a modified, calibrated DenOptix photostimulable phosphor system. Image pairs were registered and compared for geometrical and intensity errors by means of quantitative subtraction radiography. The reproducibility of patient-beam alignment for each pair was determined by measuring spatial errors at alveolar crest edges and by comparing magnifications. Intensity errors measured at two predetermined regions of alveolar bone were used to estimate corresponding bone-mass errors. RESULTS: Misalignment at the alveolar crest was generally <1 pixel (0.085 mm), and everywhere < or =0.25 mm. The magnification was constant within a relative standard deviation of 0.13% (n=8). Trabecular features were generally invisible or barely visible in subtraction images. The standard deviation of intensity errors was 1.07% (n=16). This corresponds to a change in bone mass of approximately 2% or less. CONCLUSION: The device has potential for clinical population studies in which the goal is to detect small changes in bone mass and alveolar-crest height. It is convenient to use and comfortable for patients. Because of the cross-arch design, patient-beam alignment is expected to be relatively insensitive to bite-registration errors, tooth movement, and tooth loss.

Targeting kinin receptors for the treatment of neurological diseases.

Kinins (bradykinin, kallidin and their active metabolites) are peptide autacoids with established functions in cardiovascular homeostasis, contraction and relaxation of smooth muscles, inflammation and nociception. They are believed to play a role in disease states like asthma, allergies, rheumatoid arthritis, cancer, diabetes, endotoxic and pancreatic shock, and to contribute to the therapeutic effects of ACE inhibitors in cardiovascular diseases. Although kinins are also neuromediators in the central nervous system, their involvement in neurological diseases has not been intensively investigated thus far. This review analyzes the potential of central kinin receptors as therapeutic targets for neurological disorders. Initial data highlight potential roles for B(1) receptor antagonists as antiepileptic agents, and for B(2) receptor antagonists (and/or B(1) agonists) in the treatment of stroke. Functional B(1) receptors located on T-lymphocytes and on the blood brain-barrier are also putative targets for the management of multiple sclerosis. However, successful elucidation of the therapeutic value of these new pharmacological approaches will require refinement of our knowledge on the physiology and cellular localization of central kinin receptors.