Increased secretion of insulin and proliferation of islet β-cells in rats with mesenteric lymph duct ligation

Background &; aimsIt has been suggested that intestinal lymph flow plays an important role in insulin secretion and glucose metabolism after meals. In this study, we investigated the influence of ligation of the mesenteric lymph duct on glucose metabolism and islet β-cells in rats.MethodsMale Sprague–Dawley rats (10 weeks old) were divided into two groups: one underwent ligation of the mesenteric lymph duct above the cistern (ligation group), and the other underwent a sham operation (sham group). After 1 and 2 weeks, fasting plasma concentrations of glucose, insulin, triglyceride, glucose-dependent insulinotropic polypeptide (GIP), and the active form of glucagon-like peptide-1 (GLP-1) were measured. At 2 weeks after the operation, the oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT) were performed. After the rats had been sacrificed, the insulin content of the pancreas was measured and the proliferation of β-cells was assessed immunohistochemically using antibodies against insulin and Ki-67.ResultsDuring the OGTT, the ligation group showed a significant decrease in the plasma glucose concentration at 120 min (p < 0.05) and a significant increase in the plasma insulin concentration by more than 2-fold at 15 min (p < 0.01). On the other hand, the plasma GIP concentration was significantly decreased at 60 min (p < 0.01) in the ligated group, while the active form of GLP-1 showed a significantly higher level at 90 min (1.7-fold; p < 0.05) and 120 min (2.5-fold; p < 0.01). During the IVGTT, the plasma insulin concentration in the ligation group was significantly higher at 2 min (more than 1.4-fold; p < 0.05). Immunohistochemistry showed that the ratios of β-cell area/acinar cell area and β-cell area/islet area, and also β-cell proliferation, were significantly higher in the ligation group than in the sham group (p < 0.05, p < 0.01 and p < 0.01, respectively). The insulin content per unit wet weight of pancreas was also significantly increased in the ligation group (p < 0.05).ConclusionsIn rats with ligation of the mesenteric lymph duct, insulin secretion during the OGTT or IVGTT was higher, and the insulin content and β-cell proliferation in the pancreas were also increased. Our data show that mesenteric lymph duct flow has a role in glucose metabolism.     

Anti-staphylococcal effect of enterocin in Sunar® and yogurt

Enterocin was used to control the growth of Staphylococcus aureus strains SA1 and Oxford 209P in Sunar (milk nourishment for suckling babies) and during the yogurt-making process. Reduction by three orders of magnitude was noted in the growth of SA1 strain in Sunar milk nourishment between the enterocin-containing (ES) and the control samples (CS) at 1-d cultivation. An inhibitory effect of enterocin was observed when surviving of SA1 cells were checked 6 h after the start of cultivation (2 h after enterocin application; enterocin was applied after 4 h). Decrease in the count of Oxford 209P strain in yogurt was detected in ES after 1 d of storage in comparison with CS (10(3) and 10(0) CFU mL-1 g-1). Thus a decrease by three orders of magnitude was found between ES and CS at the time mentioned. On the other hand, no bacteriocin activity was detected in ES after 1 d. Activity was detected only immediately after enterocin addition to ES (400 AU/mL) as well as after 1 and 3 1/2 h (200 AU/mL). Although the slight regrowth of the indicator was obtained up to 1 week of yogurt storage, the difference between ES and CS persisted. The lowest pH of the final yogurt product was noted in the reference yogurt sample but differences among the pH values of yogurt samples were not significant.     

Spasmolytic and tonic effect of Iberogast® (STW 5) in intestinal smooth muscle

STW 5 (Iberogast^®) is a fixed combination of nine medicinal plant extracts effective in the treatment of functional dyspepsia and irritable bowel syndrome. The effects of STW 5, a combination of Iberis amara fresh plant extract, and other eight plant extracts as well as single extract components including extracts from Menthae piperitae folium, Matricariae flos and Liquiritiae radix, were assayed in guinea pig ileum with or without stimulation with acetylcholine or histamine, in order to find a possible effect on the contractility of intestinal smooth muscle.STW 5 decreased acetylcholine- and histamine-induced contraction of guinea pig ileum. This was also true for extracts of Menthae piperitae folium, Matricariae flos and L. radix. Extract from I. amara, however, showed no spasmolytic action; in contrary, it increased the basal resting tone and contraction of atonic ileal segments. This was also true when STW 5 was employed.A spasmolytic action of STW 5 could also be observed in duodenum, jejunum and colon.These data are the first to show not only the spasmolytic effects of STW 5 and its component extracts in intestinal muscle but also the tonicising effects of STW 5 through its component Iberis amara extract in relaxed intestinal muscle. Thus, pharmacological evidence suggests a dual-action principle and may explain, at least in part, the clinically observed therapeutic efficacy of STW 5 (Iberogast^®) in both hypotonic and spastic dysmotility symptoms of functional dyspepsia and irritable bowel syndrome.     

Role of HMGB1 in TNF-α Combined with Z-VAD-fmk-Induced L929 Cells Necroptosis

Biochemical Genetics - The present study established a necroptosis model in vitro and investigated the role of HMGB1 in cell necroptosis. A combination of tumor necrosis factor-α and z-VAD-fmk...     

Glycosylation profile and biological activity of Remicade® compared with Flixabi® and Remsima®

As biosimilars enter the market, comparisons of product quality are needed. Manufacturing differences may lead to differences in critical quality attributes, which affect efficacy. Therefore, critical quality attributes (structure and biological activity) of Remicade® and of 2 biosimilar products (Flixabi®/Renflexis® and Remsima®/Inflectra®) were determined. We assessed binding to tumor necrosis factor in a fluorescence competitive binding assay; potency in a luciferase reporter gene assay; percentages of galactosylated glycan, afucose plus high mannosylated glycans, and charged glycan; FcγRIIIa (CD16) binding (assessed by 3 methods); and antibody-dependent cell-mediated cytotoxicity (ADCC) in the NK92-CD16a cell line and in peripheral blood mononuclear cells (PBMC). The results of Fab-related activity were similar for all products. Compared with Remicade®, Flixabi® had a lower percentage of charged glycan, and Remsima® had a higher percentage of galactosylated glycan and a lower percentage of afucose plus high mannosylated glycans. Whereas Remsima® and Remicade® are expressed in a Sp2/0 cell line, Flixabi® is expressed in a CHO cell line. Despite this difference, galactosylated glycans from the 3 products were not correlated with the expression system. The results of all 3 methods used in this study indicated that FcγRIIIa binding was lower with Remsima® than with Remicade®. The percentage of ADCC in NK92-CD16a cells was lower with Remsima® and higher with Flixabi® compared with Remicade®, but was similar for all 3 products in PBMC. Surface expression of CD16 was 5.7-fold greater on NK92-CD16a cells than on PBMC. Combined percentages of afucosylated and high mannosylated glycans were positively correlated with FcγRIIIa binding and ADCC in NK92-CD16 cells, while no correlation was observed in PBMC.     

Anticonvulsant effect of cytoskeletal depolymerizers in combination with potassium channel opener and adenylate cyclase activator; a causative link with nerve growth factor?

Anticonvulsant effect of cytoskeletal depolymerizing drugs in combination with potassium channel (KATP) opener and adenylate cyclase activator was evaluated in animal models of epilepsy. Seizures were induced in the animals by subjecting them to maximal electroshock (MES) or by injecting a chemical convulsant, pentylenetetrazole (PTZ). Moreover a correlation with the nerve growth factor (NGF) was also investigated. The anticonvulsant effect of minoxidil (1200 micrograms/kg i.p.) and Deacetylforskolin (600 micrograms/kg i.p.) was significantly enhanced in the mice pre-treated with cytoskeletal depolymerizing drugs. On the other hand nerve growth factor potentiated the convulsive phenomenon and decreased the seizure threshold in both the electroshock and chemically induced convulsions. Another interesting feature was the interaction of cytochalasin B, a microfilament disrupter in preventing the action of mNGF and PTZ. This study demonstrates the importance of interaction between cytoskeletal structures and signalling molecules in determining the convulsive threshold. This study clearly points to the importance of the nerve growth factor in convulsive phenomenon.     

Effects of high fat diet induced obesity on peripheral nerve regeneration and levels of GAP 43 and TGF-β in rats

The increasing frequency of obesity is important because of its accompanying related health problems. The effects of obesity on peripheral nerves have not been elucidated. We investigated the effects of obesity on sciatic nerve regeneration using electrophysiology, stereology, immunohistochemistry, histopathology and functional tests. We used control, obese, control injured and obese injured groups of rats. Electrophysiological results showed that nerve conduction velocity and EMG were same in the experimental groups, but the amplitude of the compound action potential of the control group was significantly higher than that of the obese group. Examination of the nerves showed that the control and obese groups had both larger axon diameters and thicker myelin sheaths. The number of myelinated axons was decreased in both of the injured groups. Axon diameters and myelin sheath thicknesses of the control injured group were significantly greater those of the obese injured group. There were no significant differences in functional tests among the groups. Although growth associated protein 43 immunostaining in the control injured group was significantly greater than that of the obese injured group, no significant difference was observed between the control and obese groups. There was no significant difference in immunohistochemical staining for transforming growth factor beta 3 between the control injured and obese injured groups. Our results suggest that obesity may affect peripheral nerve regeneration negatively after crush injury.     

Chronic citalopram treatment elevates serotonin synthesis in flinders sensitive and flinders resistant lines of rats,with no significant effect on Sprague–Dawley rats

The influence of citalopram on regional 5-hydroxytryptamine (serotonin, 5-HT) synthesis, one of the most important presynaptic parameters of serotonergic neurotransmission, was studied. Sprague–Dawley (SPD) rats were used as the controls, and Flinders Resistant Line (FRL) rats were used as auxiliary controls, to hopefully obtain a better understanding of the effects of citalopram on Flinders Sensitive Line (FSL; “depressed”) rats. Regional 5-HT synthesis was evaluated using a radiographic method with a labelled tryptophan analog tracer. In each strain of rats, the animals were treated with citalopram (10 mg/(kg day)) or saline for 14 days. The groups consisted of between fourteen and twenty rats. There were six groups of rats with citalopram (CIT) and saline (SAL) groups in each of the strains (SPD–SAL, SPD–CIT, FRL–SAL, FRL–CIT, FSL–SAL and FSL–CIT). A two-factor analysis of variance was used to evaluate the effect of the treatment c., SPD-SAL relative to SPD-CIT) followed by planned comparisons to evaluate the effect in each brain region. In addition, the planned comparison with appropriate contrast was used to evaluate a relative effects in SPD relative to FSL and FRL, and FSL relative to FRL groups. A statistical analysis was first performed in the a priori selected regions, because we had learned, from previous work, that it was possible to select the brain regions in which neurochemical variables had been altered by the disorder and subsequent antidepressant treatments. The results clearly show that citalopram treatment does not have an overall effect on synthesis in the control SPD rats; there was no significant (p > 0.05) difference between the SPD–SAL and SPD–CIT rats. In “depressed” FSL rats, citalopram produced a significant (p < 0.05) elevation of synthesis in seventeen out of thirty-four regions, with a significant (p < 0.05) reduction in the dorsal and median raphe. In the FRL rats, there was a significant (p < 0.05) elevation in the synthesis in twenty-two out of thirty-four brain regions, with a reduction in the dorsal raphe. In addition to these regions magnus raphe was different in the SPD and FSL groups, but it was on the statistical grounds identified as an outlier. There were significant changes produced in the FSL and FRL rats in thirteen out of seventeen a priori selected brain regions, while in the SPD rats, citalopram produced significant changes in only four out of seventeen a priori selected regions. The statistical evaluation also revealed that changes produced by citalopram in the FSL and FRL rats were significantly greater than those in the SPD rats and that there was no significant difference between the effect produced in the FSL and FRL rats. The presented results suggest that in “depressed” FSL rats, the antidepressant citalopram elevates 5-HT synthesis, which probably in part relates to the reported improved in behaviour with citalopram.     

Optimization of PCR protocol in microsatellite analysis with silver and SYBR® stains

Here we present the optimization of PCR conditions for microsatellite analysis of coniferous trees. The use of touchdown protocol for annealing resulted in a high success rate for optimization using fewer temperature profiles. The use of SYBR^￠ Green gel stain to detect PCR products in agarose gels was more sensitive than ethidium bromide. This is valuable for determining the success of PCR reactions and estimating the amount of PCR products formed—which is crucial in determining the dilution required to produce bands of similar intensity upon silver staining of the polyacrylamide gels. The use of SYBR^￠ Gold for staining polyacrylamide gels was not satisfactory in terms of the image quality produced. However, it was comparable to silver staining in terms of sensitivity, and could possibly be used in cases where the products are present as sharp single bands. In those cases, the use of SYBR^￠ Gold gel stain would save time and money for staining polyacrylamide gels.     

Combined effects of quercetin and α-tocopherol on lipids and glycoprotein components in isoproterenol induced myocardial infarcted Wistar rats

This study was aimed to evaluate the combined effects of quercetin and α-tocopherol on lipid metabolism and glycoprotein components in isoproterenol induced myocardial infarction in Wistar rats. Myocardial infarction in rats was induced by isoproterenol (100 mg/kg) at an interval of 24 h for 2 days. Quercetin (10 mg/kg) and α-tocopherol (10 mg/kg) were given to rats as pretreatment for 14 days orally using an intragastric tube. Quercetin and α-tocopherol significantly reduced the levels of cholesterol, triglycerides and free fatty acids in the serum and heart and serum phospholipids and significantly increased the levels of heart phospholipids in isoproterenol induced rats. They also significantly decreased the activity of plasma and liver 3-hydroxy-3-methylglutaryl-coenzyme-A reductase and increased the activity of plasma and liver lecithin cholesterol acyl transferase in isoproterenol treated rats. In addition to this, they also significantly reduced the levels of hexose, hexosamine, fucose and sialic acid in the serum and heart of isoproterenol treated rats. Quercetin and α-tocopherol also showed significant decrease in plasma lipid peroxidation products (thiobarbituric acid reactive substances and lipid hydroperoxides). Pretreatment with quercetin alone and α-tocopherol alone showed significant effect in all the biochemical parameters in myocardial infarcted rats. But, combined pretreatment with quercetin and α-tocopherol normalized all the above mentioned biochemical parameters in isoproterenol treated myocardial infarction in rats. Thus, the experiment clearly showed that quercetin and α-tocopherol prevented the accumulation of lipids and glycoprotein components in myocardial infarcted rats by their anti-lipid peroxidative effect. This study also showed that combined pretreatment was better than single pretreatment.     

Neuromuscular degenerative effects of Ankaferd Blood Stopper® in mouse sciatic nerve model

Purpose: Ankaferd Blood Stopper^® (ABS), a licenced medicinal herbal extract, is commonly used as an effective topical haemostatic agent. This study is designed to investigate whether topical ABS application may cause peripheral nerve degeneration and neuromuscular dysfunction in a mouse sciatic nerve model.

Methods: Twenty mice were randomly divided into two groups; an ABS treated experimental group and a saline-treated control group. Left sciatic nerves were treated with 0.3?ml of ABS in the experimental group and 0.3?ml of sterile saline in the control group for 5?min. Peripheral nerve degeneration and neuromuscular dysfunction were evaluated by behavioural tests, electrophysiological analysis and weight ratio comparison of target muscles.

Results: The motor function, assessed by the sciatic function index, was significantly impaired in ABS-treated animals as compared to the animals treated with saline. Motor coordination, evaluated with the rotarod test, was significantly decreased (–42%) in ABS-treated animals compared to the saline-treated animals. The degree of pain, assessed by the reaction latency to thermal stimuli (hot-plate test), was significantly prolonged (313%) in ABS-treated mice when compared to the saline-treated mice. ABS-treated mice showed a significant reduction in motor nerve conduction velocity (MNCV) (–52%) and the compound muscle action potential (CMAP) (–47%); however, it significantly prolonged onset latency (23%). The gastrocnemius muscles weight ratio of the ABS group was considerably lower than that of the control group.

Conclusions: These findings demonstrate that ABS triggers peripheral nerve degeneration and functional impairment and, thus promotes a deterioration of sciatic nerves.     

Contribution of nerve growth factor to upregulation of P2X₃ expression in DRG neurons of rats with femoral artery occlusion

Femoral artery occlusion augments the sympathetic nerve and pressor responses to muscle contraction and muscle metabolites injected into the arterial blood supply of the hindlimb muscles in rats. The underlying mechanism by which these reflex responses are enhanced after muscle vascular insufficiency is unclear. Purinergic P2X(3) receptor has been reported to contribute to the metabolic component of the exercise pressor reflex. Thus the purpose of this study was to examine if chronic femoral occlusion would alter the expression of P2X(3) in dorsal root ganglion (DRG) neurons of rats. Also, P2X(3)-mediated sympathetic responsiveness was examined after femoral occlusion. In addition, the role played by nerve growth factor (NGF) in regulating the expression and response of P2X(3) was examined. Western blot analysis showed that 24 h of femoral ligation increased the levels of P2X(3) (optical density: 0.93 ± 0.07 in control and 1.37 ± 0.10 after occlusion; P < 0.05 vs. control). The fluorescence immunohistochemistry further demonstrated that the occlusion elevated P2X(3) expression in DRG neurons (percentage of P2X(3)-positive cells: 33 ± 3% in control and 51 ± 3% in occlusion; P < 0.05 vs. control). Furthermore, the results showed that responses of renal sympathetic nerve activity and blood pressure to stimulation of P2X were greater in occluded rats than responses in control rats by injection of α,β-methylene ATP into the arterial blood supply of the hindlimb muscle. Finally, infusion of NGF in the hindlimb muscles of healthy rats increased P2X(3) (optical density: 0.98 ± 0.12 in control and 1.37 ± 0.16 with NGF; P < 0.05 vs. control). The pressor response to injection of α,β-methylene ATP was increased in the rats with NGF infusion. Likewise, blocking NGF attenuated exaggeration of the reflex response induced by α,β-methylene ATP in occluded rats. The findings of this study suggest that the levels of P2X(3) in primary afferent neurons are upregulated as the blood supply to the hindlimb is deficient under ischemic conditions, leading to augmentation of the muscle reflex. NGF is closely related to increases in P2X(3) receptor expression and response.     

Stimulative effect of nerve growth factor on α-aminoisobutyric acid uptake and Na,K-ATPase activity in superior cervical sympathetic ganglia excised from adult rats

Effects of nerve growth factor (NGF) on the uptake of non-metabolizable -aminoisobutyric acid (AIB) and on Na,K-ATPase activity in superior cervical sympathetic ganglia (SCG) excised from adult rats were examined during aerobic incubation in vitro. Active uptake of labelled AIB into isolated SCG during 1 to 5 hours incubation at 37°C was significantly accelerated by the addition of NGF to the incubation medium in a dose-dependent manner. Although theK _m value of the AIB uptake by the SCG did not change with the addition of NGF,V _max was nearly doubled. The NGF-evoked increase in AIB uptake was antagonized by the further addition of its specific antiserum in a dose-dependent fashion, and was largely suppressed in a mdium containing ouabain. In SCG, axotomized one week prior to the examination, from which most of the neurons had disappeared and reactive proliferation of satellite glial components was in progress, the NGF-induced acceleration of AIB uptake was completely absent. The ganglionic Na,K-ATPase activity was greatly stimulated in the presence of NGF, and the effect was completely eliminated in the axotomized SCG. These results strongly suggest that the NGF-induced acceleration of active AIB uptake by the isolated SCG occurs not in glial cells but exclusively in the neuronal components with the apparent coupling of an Na ion extrusion process.Dedicated to Professor Yasuzo Tsukada.     

Vagus nerve stimulation inhibits seizure activity and protects blood–brain barrier integrity in kindled rats with cortical dysplasia

AimsThis study investigates the effects of vagus nerve stimulation (VNS) on seizure severity and blood–brain barrier (BBB) integrity in kindled rats with cortical dysplasia (CD).Main methodsPregnant rats were exposed to 145 cGy of gamma-irradiation on day 17 of pregnancy. In offsprings, kindling was induced by giving subconvulsive doses of pentylenetetrazole. Left VNS was performed for 48 h at output currents of 0.5 or 1 mA. Horseradish peroxidase (HRP) was used to study the BBB permeability. Immunohistochemistry for occludin and P-glycoprotein (P-gp) was also performed.Key findingsKindled rats with CD exhibited seizures with mean Racine's scores of 3.57 ± 1.2 during video EEG recording. Kindled animals with CD receiving VNS at 0.5 and 1.0 mA did not exhibit either clinical or electrophysiological signs of seizure. Immunostaining for occludin, a tight junction protein, in hippocampus remained relatively intact in all groups. VNS-treated and -untreated kindled animals with CD revealed intense immunostaining for P-gp in hippocampal formation (P < 0.01). Electron microscopic observations revealed frequent transport vesicles containing electron-dense HRP reaction products in the cytoplasm of brain capillary endothelial cells in both cerebral cortex and hippocampus of kindled animals with CD. Those which were exposed to 1 mA VNS were observed to have brain capillary endothelial cells largely devoid of HRP reaction products in both cerebral cortex and hippocampus.SignificanceThe results of this study suggest that VNS therapy at 1 mA inhibits seizure activity and protects BBB integrity by limiting the enhancement of transcellular pathway in kindled animals with CD.     

The effect of losartan and carvedilol on renal haemodynamics and altered metabolism in fructose-fed Sprague–Dawley rats

The aim of this study is to assess the effects of losartan and carvedilol on metabolic parameters and renal haemodynamic responses to angiotensin II (Ang II) and adrenergic agonists in the model of fructose-fed rat. Thirty-six Sprague-Dawley rats were fed for 8 weeks either 20% fructose solution (F) or tap water (C) ad libitum. F or C group received either losartan or carvedilol (10 mg/kg p.o.) daily for the last 3 weeks of the study (FL and L) and (FCV and CV), respectively, then in acute studies the renal vasoconstrictor actions of Ang II, noradrenaline (NA), phenylephrine (PE) and methoxamine (ME) were determined. Data, mean±SEM were analysed using ANOVA with significance at P <0.05. Losartan and carvedilol decreased the area under the glucose tolerance curve of the fructose-fed group. The responses (%) to NA, PE, ME and Ang II in F were lower (P <0.05) than C (F vs. C, 17±2 vs. 38±3; 24±2 vs. 48±2; 12±2 vs. 34±2; 17±2 vs. 26±2), respectively. L had higher (P <0.05) responses to NA and PE while CV had blunted (P <0.05) responses to NA, PE and Ang II compared to C (L, CV vs. C, 47±3, 9±2 vs. 38±3; 61±3, 29±3 vs. 48±2; 16±3, 4±3 vs. 26±2), respectively. FL but not FCV group had enhanced (P <0.05) responses to NA, PE and ME compared to F (FL vs. F, 33±3 vs. 17±2; 45±3 vs. 24±2; 26±3 vs. 12±2), respectively. Losartan and carvedilol had an important ameliorating effect on fructose-induced insulin resistance. Losartan treatment could be an effective tool to restore normal vascular reactivity in the renal circulation of the fructose-fed rat.     

Effect of iodine supplement on iodine status and 5′-deiodinase activity in the brain of neonatal rats with iodine deficiency

The weanling Wistar rats of iodine deficiency were divided into three groups for supplementation of different levels of iodine (iodine-excessive [IE], iodine-adequate [IA], and iodine-deficient [ID]), with a control group (C). The iodine content in the thyroid was determined by epithermal neutron activation analysis. The activities of 5′-deiodinase and 5-deiodinase in the brains were assayed by determining the conversion ratios of T4 to T3 and rT3, respectively. The thyroid hormones levels in serum were also tested. The results indicated that the ID group had a goiter containing a small amount of iodine, but the IE group had a slightly swollen thyroid with rich iodine; the concentration of iodine per unit mass of thyroid was lower in group IE than in groups IA and C. The highest 5′-deiodinase and lowest 5-deiodinase activities in group ID and the lowest 5′-deiodinase activity in group IE were found. The iodine deficiency or excess resulted in a compensated hypothyroid state. The results suggest that the iodine status and the deiodinases activities would become normal for the rats of iodine deficiency if adequate iodine is supplemented soon after birth. Meanwhile, it is also critical to avoid excessive intake of iodine to reduce the risk for overcorrecting.     

A comparative study of the effect of 17β-estradiol and estriol on peripheral pain behavior in rats

Although estradiol has been reported to influence pain sensitivity, the role of estriol (an estradiol metabolite and another widely used female sex hormone) remains unclear. In this study, pain behavior tests, whole-cell patch clamp recording and Western blotting were used to determine whether estriol plays a role in pain signal transduction and transmission. Either systemic or local administration of 17β-estradiol produced a significant rise of mechanical pain threshold, while estriol lacked this effect in normal and ovariectomized (OVX) rats following estriol replacement. Local administration of 17β-estradiol or estriol significantly decreased ATP-induced spontaneous hind-paw withdrawal duration (PWD), which was blocked by an estrogen receptor antagonist, ICI 182, 780. However, systemic application of estriol in normal or OVX rats lacked this similar effect. In cultured dorsal root ganglion neurons, estriol attenuated α,β-methylene ATP-induced transient currents which were blocked by ICI 182, 780. In complete Freund's adjuvant treated (CFA) rats, systemic application of 17β-estradiol or estriol decreased the mechanical pain threshold significantly, but did not change the inflammatory process. Similar effects were observed after estriol replacement in OVX rats. The expression of c-fos in lumbosacral spinal cord dorsal horn (SCDH) was increased significantly by administration of 17β-estradiol but not estriol, and not by estriol replacement in OVX rats. These results suggest that 17β-estradiol but not estriol plays an anti-hyperalgesic role in physiological pain. However, both peripheral 17β-estradiol and estriol play anti-hyperalgesic roles in ATP-induced inflammatory pain. Systemic application of estriol as well as 17β-estradiol plays hyperalgesic roles in CFA-induced chronic pain.